SSM整合实战

爱被打了一巴掌 2023-10-15 22:52 42阅读 0赞

## 一、回顾SpringMVC访问接口流程 ##

### 1.容器加载分析 ###

*  容器分析
    
    ![在这里插入图片描述][c0a077c20d9f413c9c8e812ce1126eac.png]
 *  手动注册WebApplicationContext
    
        public class ServletConfig extends AbstractDispatcherServletInitializer {
              
        
            @Override
            protected WebApplicationContext createServletApplicationContext() {
              
                //获取SpringMVC容器
                AnnotationConfigWebApplicationContext context = new AnnotationConfigWebApplicationContext();
                context.register(SpringMvcConfig.class);
                return context;
            }
        
            @Override
            protected String[] getServletMappings() {
              
                return new String[]{
              "/"};
            }
        
            @Override
            protected WebApplicationContext createRootApplicationContext() {
              
                return null;
            }
        }

### 2.容器加载过程分析 ###

*  tomcat 服务器启动的时候，加载ServletConfig类之后，做初始化web容器操作，相当于 web.xml
 *  执行注册容器的方法,获取 SpringMVC容器 WebApplicationContext
    
        @Nullable
            protected WebApplicationContext createRootApplicationContext() {
              
                Class<?>[] configClasses = this.getRootConfigClasses();
                if (!ObjectUtils.isEmpty(configClasses)) {
              
                    AnnotationConfigWebApplicationContext context = new AnnotationConfigWebApplicationContext();
                    context.register(configClasses);
                    return context;
                } else {
              
                    return null;
                }
            }
        
            protected WebApplicationContext createServletApplicationContext() {
              
                AnnotationConfigWebApplicationContext context = new AnnotationConfigWebApplicationContext();
                Class<?>[] configClasses = this.getServletConfigClasses();
                if (!ObjectUtils.isEmpty(configClasses)) {
              
                    context.register(configClasses);
                }
        
                return context;
            }
 *  通过@ComponentScan(“cn.sycoder.controller”) 加载 Controller 下面的bean 进 WebApplicationContext
    
        @RestController
        public class TestController {
              
        
            @GetMapping("/test/{id}")
            public String test(@PathVariable Long id) {
              
                return "ok:" + id;
            }
        }
 *  把使用了 RequestMapping 注解的方法的 value — 对应一个方法，建立起了一对一映射关系（可以想象hashmap）
    
     *  /test/\{id\} ---- test 方法

### 3.请求接口过程 ###

*  访问 http://localhost:8082/test/1
 *  匹配 springmvc 的 / servletMapping 规则，交给 springmvc 处理
 *  解析 /test/1路径找到对应的 test 方法
 *  执行方法
 *  因为使用 RestController ，所以返回方法的返回值作为响应体返回给浏览器

### 4.SSM整合会出现bean界定不清楚问题 ###

*  SpringMVC 需要加载哪些bean?
    
     *  controller 层（表现层即可）
 *  Spring 加载哪些bean?
    
     *  service
     *  dao

#### 4.1如何处理 ####

*  将spring配置注入到 web 容器中
    
        @Configuration
        @ComponentScan(value={
              "cn.sycoder.service","cn.sycoder.dao"})
        public class SpringConfig {
              
        }
    
        public class ServletConfig  extends AbstractAnnotationConfigDispatcherServletInitializer {
              
            @Override
            protected Class<?>[] getRootConfigClasses() {
              
                return new Class[]{
              SpringConfig.class};
            }
        
            @Override
            protected Class<?>[] getServletConfigClasses() {
              
                return new Class[]{
              SpringMvcConfig.class};
            }
        
            @Override
            protected String[] getServletMappings() {
              
                return new String[]{
              "/"};
            }
        }

#### 4.2验证两个容器的bean相互不干扰 ####

*  验证代码
    
        @Test
        public void test(){
              
            AnnotationConfigApplicationContext applicationContext =
                    new AnnotationConfigApplicationContext(SpringConfig.class);
            ITestService bean = applicationContext.getBean(ITestService.class);
            bean.get(1L);
        
            TestController bean1 = applicationContext.getBean(TestController.class);
            System.out.println(bean1.test(1L));
        }

## 二、SSM整合 ##

### 1.SSM整合流程分析 ###

*  概述SSM：Spring SpringMVC Mybatis

#### 1.1创建工程 ####

*  导入依赖
    
     *  ssm 所需要的依赖包
 *  配置 web 项目入口配置替换 web.xml（AbstractAnnotationConfigDispatcherServletInitializer）
    
     *  配置 Spring 配置类交给 web 容器管理
        
            @Override
                protected Class<?>[] getRootConfigClasses() {
                    
                    return new Class[]{
                    SpringConfig.class};
                }
     *  配置 SpringMVC 配置类交给 web 容器管理
        
            @Override
                protected Class<?>[] getServletConfigClasses() {
                    
                    return new Class[]{
                    SpringMvcConfig.class};
                }
     *  配置请求拦截规则,交给 springmvc 处理
        
            @Override
                protected String[] getServletMappings() {
                    
                    return new String[]{
                    "/"};
                }

#### 1.2配置 Spring ####

*  SpringConfig
    
     *  @Configuration 标记Spring配置类，替换Spring-config-xml
     *  @ComponetScan 扫描需要被Spring 管理的bean
     *  @EnableTransactionManagment 启动管理事务支持
     *  @PropertySource 引入db.properties 配置文件
 *  配置 JdbcConfig 配置类
    
     *  使用德鲁伊 DataSource 数据源
     *  构建平台事务管理器 DataSourceTransactionManager
 *  配置 MyBatis 配置类
    
     *  构建 SqlSessionFactoryBean
     *  指定 MapperScanner 设置 mapper 包扫描寻找 mapper.xml 文件

#### 1.3配置 SpringMVC ####

*  配置SpringMvcConfig
    
     *  @Configuration
     *  @ComponentScan 只扫描 Controller
     *  开启SpringMVC 注解支持 @EnableWebMvc

#### 1.4开发业务 ####

*  使用注解
    
     *  注入bean 注解
        
         *  @Autowired
     *  @RestController
        
         *  @GetMapping
            
             *  @RequestParam
         *  @PostMapping
            
             *  @RequestBody
         *  @DeleteMapping
            
             *  @PathVariable
         *  @PutMapping
     *  @Service
        
         *  @Transactional
     *  junit
        
         *  @RunWith
         *  @ContextConfiguration
         *  @Test

### 2.SSM整合 ###

#### 2.1导入依赖 ####

*  依赖
    
        <dependencies>
            <dependency>
              <groupId>org.springframework</groupId>
              <artifactId>spring-webmvc</artifactId>
              <version>5.2.17.RELEASE</version>
            </dependency>
        
            <dependency>
              <groupId>org.springframework</groupId>
              <artifactId>spring-jdbc</artifactId>
              <version>5.2.17.RELEASE</version>
            </dependency>
        
            <dependency>
              <groupId>org.springframework</groupId>
              <artifactId>spring-test</artifactId>
              <version>5.2.17.RELEASE</version>
            </dependency>
        
            <dependency>
              <groupId>org.mybatis</groupId>
              <artifactId>mybatis</artifactId>
              <version>3.5.6</version>
            </dependency>
        
            <dependency>
              <groupId>org.mybatis</groupId>
              <artifactId>mybatis-spring</artifactId>
              <version>1.3.0</version>
            </dependency>
        
            <dependency>
              <groupId>mysql</groupId>
              <artifactId>mysql-connector-java</artifactId>
              <version>8.0.29</version>
            </dependency>
        
            <dependency>
              <groupId>com.alibaba</groupId>
              <artifactId>druid</artifactId>
              <version>1.1.16</version>
            </dependency>
        
            <dependency>
              <groupId>junit</groupId>
              <artifactId>junit</artifactId>
              <version>4.12</version>
              <scope>test</scope>
            </dependency>
        
            <dependency>
              <groupId>javax.servlet</groupId>
              <artifactId>javax.servlet-api</artifactId>
              <version>3.1.0</version>
              <scope>provided</scope>
            </dependency>
        
            <dependency>
              <groupId>com.fasterxml.jackson.core</groupId>
              <artifactId>jackson-databind</artifactId>
              <version>2.9.0</version>
            </dependency>
          </dependencies>

#### 2.2创建各目录结构 ####

*  目录如下
    
    ![在这里插入图片描述][cc7bff1b1b8c482695d84bf02dc7d532.png]

#### 2.3创建SpringConfig ####

*  SpringConfig
    
        @Configuration
        @ComponentScan(value = {
              "cn.sycoder.service","cn.sycoder.dao"})
        @EnableTransactionManagement
        @PropertySource("classpath:db.properties")
        @Import({
              DbConfig.class,MybatisConfig.class})
        public class SpringConfig {
              
        }

#### 2.4创建DbConfig配置类 ####

*  创建数据库配置文件
    
        jdbc.url=jdbc:mysql://localhost:3306/ssm
        jdbc.driver=com.mysql.cj.jdbc.Driver
        jdbc.username=root
        jdbc.password=123456
 *  创建DbConfig
    
        public class DbConfig {
              
            
            @Value("${jdbc.url}")
            private String url;
            @Value("${jdbc.driver}")
            private String driver;
            @Value("${jdbc.username}")
            private String username;
            @Value("${jdbc.password}")
            private String password;
        
            /**
             * 配置德鲁伊连接池
             * @return
             */
            @Bean
            public DataSource dataSource(){
              
                DruidDataSource source = new DruidDataSource();
                source.setUrl(url);
                source.setDriverClassName(driver);
                source.setPassword(password);
                source.setUsername(username);
                return source;
            }
            
            @Bean
            public PlatformTransactionManager transactionManager(DataSource dataSource){
              
                DataSourceTransactionManager manager = new DataSourceTransactionManager();
                manager.setDataSource(dataSource);
                return manager;
            }
            
        }

#### 2.5创建MybatisConfig配置类 ####

*  MyBatisConfig
    
        public class MybatisConfig {
              
            
            @Bean
            public SqlSessionFactoryBean sessionFactoryBean(DataSource dataSource){
              
                SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
                bean.setDataSource(dataSource);
                bean.setTypeAliasesPackage("cn.sycoder.domain");
                return bean;
            }
            
            @Bean
            public MapperScannerConfigurer mapperScannerConfigurer(){
              
                MapperScannerConfigurer configurer = new MapperScannerConfigurer();
                configurer.setBasePackage("cn.sycoder.dao");
                return configurer;
            }
        }

#### 2.6创建SpringMVC配置类 ####

*  SpringMvcConfig
    
        @Configuration
        @ComponentScan("cn.sycoder.controller")
        @EnableWebMvc
        public class SpringMvcConfig {
              
        }

#### 2.7创建Web项目入口配置类 ####

*  ServletConfig
    
        public class ServletConfig extends AbstractAnnotationConfigDispatcherServletInitializer {
              
            @Override
            protected Class<?>[] getRootConfigClasses() {
              
                return new Class[]{
              SpringConfig.class};//配置Spring交给Web 管理
            }
        
            @Override
            protected Class<?>[] getServletConfigClasses() {
              
                return new Class[]{
              SpringMvcConfig.class};
            }
        
            @Override
            protected String[] getServletMappings() {
              
                return new String[]{
              "/"};
            }
        }

### 3.功能开发 ###

#### 3.1创建数据库及表 ####

*  创建 ssm 数据库
 *  创建 item 表
    
        create table item
        (
        	id bigint auto_increment,
        	type varchar(64) null,
        	name varchar(64) null,
        	remark text null,
        	constraint item_pk
        		primary key (id)
        );

#### 3.2编写模型类 ####

*  添加 lombok 依赖
    
        <dependency>
          <groupId>org.projectlombok</groupId>
          <artifactId>lombok</artifactId>
          <version>1.18.22</version>
        </dependency>
 *  模型类
    
        @Data
        public class Item {
              
            private Long id;
            private String name;
            private String type;
            private String remark;
        }

#### 3.3编写Mapper接口 ####

*  Mapper 接口
    
        @Repository
        public interface ItemMapper {
              
            @Insert("insert into item(name,type,remark) value(#{name},#{type},#{remark})")
            public int save(Item item);
            @Delete("delete from item where id = #{id}")
            public int delete(Long id);
            @Update("update item set name = #{name},type = #{type},remark=#{remark} where id=#{id}")
            public int update(Item item);
            @Select("select * from item where id = #{id}")
            public Item getById(Long id);
            @Select("select * from item")
            public List<Item> list();
        
        }

#### 3.4编写Service接口和实现类 ####

*  Service 接口
    
        public interface IItemService {
              
            /**
             * 添加闲置物品方法
             * @param item
             * @return
             */
            public boolean save(Item item);
        
            /**
             * 删除闲置物品
             * @param id
             * @return
             */
            public boolean delete(Long id);
        
            /**
             * 更新闲置物品
             * @param item
             * @return
             */
            public boolean update(Item item);
        
            /**
             * 查询闲置物品通过id
             * @param id
             * @return
             */
            public Item getById(Long id);
        
            /**
             * 查询所有闲置商品
             * @return
             */
            public List<Item> lists();
        }
 *  定义接口实现类
    
        @Service
        public class ItemServiceImpl implements IItemService {
              
            
            @Autowired
            ItemMapper mapper;
            
            @Override
            @Transactional
            public boolean save(Item item) {
              
                return mapper.save(item) > 0;
            }
        
            @Override
            @Transactional
            public boolean delete(Long id) {
              
                return mapper.delete(id) >0;
            }
        
            @Override
            @Transactional
            public boolean update(Item item) {
              
                return mapper.update(item) >0;
            }
        
            @Override
            public Item getById(Long id) {
              
                return mapper.getById(id);
            }
        
            @Override
            public List<Item> lists() {
              
                return mapper.list();
            }
        }

#### 3.5编写Contorller类 ####

*  Controller
    
        @RestController
        @RequestMapping("/item")
        public class ItemController {
              
        
            @Autowired
            IItemService service;
        
            @PostMapping
            public boolean save(@RequestBody Item item){
              
                return service.save(item);
            }
        
            @PutMapping
            public boolean update(@RequestBody Item item){
              
                return service.update(item);
            }
        
            @DeleteMapping("/{id}")
            public boolean delete(@PathVariable Long id){
              
                return service.delete(id);
            }
        
            @GetMapping("/{id}")
            public Item getById(@PathVariable Long id){
              
                return service.getById(id);
            }
        
            @GetMapping
            public List<Item> list(){
              
                return service.lists();
            }
        }

### 4.验证 ssm 整合结果 ###

*  #### 启动项目并且解决问题 ####
    
    ![在这里插入图片描述][65459310d6414ac89614b86da7e57aef.png]
 *  修改Spring配置类
    
        @Configuration
        @ComponentScan(value = {
              "cn.sycoder.service","cn.sycoder.dao"})
        @EnableTransactionManagement
        @PropertySource("classpath:db.properties")
        @Import({
              DbConfig.class,MybatisConfig.class})
        public class SpringConfig {
              
        }

#### 4.1添加item 数据 ####

*  准备 item 数据
    
        {
              "name":"键盘","type":"电脑外设","remark":"9成新，半价卖"}
    
        {
              "name":"笔记本","type":"电脑","remark":"9成新，8折出售"}
    
        {
              "name":"鞋子","type":"收藏鞋","remark":"科比签名的，独一无二"}
 *  添加数据
    
    ![image-20221114161855924][]

#### 4.2修改数据 ####

*  准备数据
    
        {
              "id":4,"name":"二手鞋子","type":"废鞋","remark":"破鞋子"}
 *  修改操作
    
    ![image-20221114162051321][]

#### 4.3查询单个数据 ####

*  查询id=4的物品
    
    ![在这里插入图片描述][c30e7a12b3d44c5eab91070dc4b4f98f.png]

#### 4.4删除单个数据 ####

*  删除id=4的物品
    
    ![在这里插入图片描述][174a0d70654f42bf9bdf34469d7bbea2.png]

#### 4.5查询全部数据操作 ####

*  查询全部
    
    ![image-20221114162255279][]

### 5.整合单元测试 ###

*  目录结构
    
    ![image-20221114163001535][]
 *  新建测试类
    
        @RunWith(SpringJUnit4ClassRunner.class)
        @ContextConfiguration(classes = SpringConfig.class)
        public class ItemTest {
              
        
            @Autowired
            IItemService service;
        
        
            @Test
            public void save(){
              
                Item item = new Item();
                item.setName("单元测试");
                item.setRemark("单元测试");
                item.setType("单元测试");
                boolean save = service.save(item);
                System.out.println(save);
            }
        
            @Test
            public void update(){
              
                Item item = new Item();
                item.setId(5L);
                item.setName("单元测试");
                item.setRemark("单元测试");
                item.setType("单元测试");
                boolean save = service.update(item);
                System.out.println(save);
            }
        
            @Test
            public void getById(){
              
                Item byId = service.getById(5L);
                System.out.println(byId);
            }
        
            @Test
            public void list(){
              
                List<Item> lists = service.lists();
                System.out.println(lists);
            }
        }

## 三、项目实战中细节问题 ##

### 1.导入前端资源 ###

#### 1.1静态资源拦截处理 ####

*  设置访问 index 访问主页
    
        @Controller
        public class IndexController {
              
            @RequestMapping("/index")
            public String index(){
              
                System.out.println("----------------");
                return "/pages/items.html";
            }
        
        }
 *  出现静态资源被拦截问题
    
        @Configuration
        public class StaticSupport extends WebMvcConfigurationSupport {
              
        
            @Override
            protected void addResourceHandlers(ResourceHandlerRegistry registry) {
              
                registry.addResourceHandler("/pages/**").addResourceLocations("/pages/");
                registry.addResourceHandler("/js/**").addResourceLocations("/js/");
                registry.addResourceHandler("/css/**").addResourceLocations("/css/");
                registry.addResourceHandler("/plugins/**").addResourceLocations("/plugins/");
        
            }
        }
 *  将 staticSupport 交给 SpringMvc 管理
    
        @Configuration
        @ComponentScan(value = {
              "cn.sycoder.controller","cn.sycoder.config"})
        @EnableWebMvc
        public class SpringMvcConfig {
              
        }

#### 1.2项目实现 ####

*  保存方法
    
        handleAdd () {
            console.log("========")
            axios.post("/item",this.formData).then((res)=>{
                //todo
            })
        },
 *  列表查询
    
        getAll() {
              
            axios.get("/item",).then((res)=>{
              
                this.dataList = res.data;
            })
        },
 *  删除操作
    
        handleDelete(row) {
              
            axios.delete("/item/"+row.id).then((res)=>{
              
                //todo
            })
        }
 *  编辑操作

### 2.全局统一结果集处理 ###

#### 2.1分析目前写代码存在的问题 ####

*  查询单个物品时返回单条数据
    
        {
              "id":2,"name":"笔记本","type":"电脑","remark":"9成新，8折出售"}
 *  查询列表返回列表数据
    
        [{
              "id":1,"name":"键盘","type":"电脑外设","remark":"9成新，半价卖"},{
              "id":2,"name":"笔记本","type":"电脑","remark":"9成新，8折出售"},{
              "id":3,"name":"鞋子","type":"收藏鞋","remark":"科比签名的，独一无二"},{
              "id":5,"name":"单元测试","type":"单元测试","remark":"单元测试"}]
 *  删除数据返回单个结果
    
        true
 *  **目前对于系统而言参数了三种数据类型**
    
     *  不能做到前后端同时开发
     *  前后端的交互很乱
 *  最后处理
    
        {
              "data":true}
        {
              "data":{
              "id":2,"name":"笔记本","type":"电脑","remark":"9成新，8折出售"}}
        
        
        {
              
            "code":2000,
            "data":true,
            "msg":"详情"  
        }

#### 2.2处理方式 ####

*  通过定义一个统一结果集处理
    
        {
              
            "code":2000,
            "data":true,
            "msg":"详情"  
        }
 *  后端实体
    
        @Data
        public class ResultResp {
              
            private Integer code;
            private Object data;
            private String msg;
        }
 *  后端返回实体最终结果
    
        @Data
        public class ResultResp {
              
            private Integer code;
            private Object data;
            private String msg;
        
            public ResultResp(){
              
            }
        
            public ResultResp(Integer code,Object data){
              
                this.code = code;
                this.data=data;
            }
        
            public ResultResp(Integer code,Object data,String msg){
              
                this.code=code;
                this.data=data;
                this.msg=msg;
            }
        
            public static ResultResp success(Integer code,Object data){
              
                return new ResultResp(code,data);
            }
        }
 *  状态码类
    
        public class Code {
              
            /**
             * 定义好协议之后，前端和后端统一按照协议执行
             */
            public static final Integer SAVE_OK = 20000;
            public static final Integer SAVE_FAIL = 20001;
        
        
            public static final Integer UPDATE_OK = 20010;
            public static final Integer UPDATE_FAIL = 20011;
        
            public static final Integer DELETE_OK = 20020;
            public static final Integer DELETE_FAIL = 20021;
        
            public static final Integer GET_OK = 20030;
            public static final Integer GET_FAIL = 20031;
        
            public static final Integer PAGE_OK = 20040;
            public static final Integer PAGE_FAIL = 20041;
        }
 *  修改控制层返回代码
    
     *  save 方法
        
            @PostMapping
            public ResultResp save(@RequestBody Item item){
                    
                boolean ret = service.save(item);
                return new ResultResp(ret? Code.SAVE_OK:Code.SAVE_FAIL,ret);
            }
     *  update 方法
        
            @PutMapping
            public ResultResp update(@RequestBody Item item){
                    
                boolean ret = service.update(item);
                return new ResultResp(ret? Code.UPDATE_OK:Code.UPDATE_FAIL,ret);
            }
     *  delete 方法
        
            @DeleteMapping("/{id}")
            public ResultResp delete(@PathVariable Long id){
                    
                boolean ret = service.delete(id);
                return new ResultResp(ret? Code.DELETE_OK:Code.DELETE_FAIL,ret);
            }
     *  单个结果集处理
        
            @GetMapping("/{id}")
            public ResultResp getById(@PathVariable Long id){
                    
                Item ret = service.getById(id);
                return ResultResp.success(ret==null?Code.GET_FAIL:Code.GET_OK,ret);
            }
     *  集合结果集
        
            @GetMapping
            public ResultResp list(){
                    
                List<Item> ret = service.lists();
                return ResultResp.success(ret==null?Code.PAGE_FAIL:Code.PAGE_OK,ret);
            }
 *  最终实现截图
    
    ![image-20221117111833027][]

#### 2.3前后端联调 ####

*  保存操作
    
        handleAdd() {
              
            console.log("========")
            axios.post("/item", this.formData).then((res) => {
              
                if (res.data.code == 20000) {
              
                    //关闭新增弹框
                    this.dialogFormVisible = false;
                    this.$message.success("添加物品成功")
                } else {
              
                    this.$message.error("添加失败")
                }
            }).finally(() => {
              
                this.getAll();
            })
        },
 *  列表查询
    
        getAll() {
              
            axios.get("/item",{
              
                    params:{
              
                        name:this.pagination.queryString
                    }
            }).then((res)=>{
              
                // this.dataList = res.data;
                if(res.data.code == 20040){
              
                    this.dataList = res.data.data;
                }else{
              
                    this.$message.error("加载失败")
                }
            })
        },
 *  删除操作
    
        handleDelete(row) {
              
            axios.delete("/item/" + row.id).then((res) => {
              
                if (res.data.code == 20020) {
              
                    this.$message.success("删除物品成功")
                } else {
              
                    this.$message.error("删除失败")
                }
            }).finally(() => {
              
                this.getAll();
            })
        }
 *  编辑操作
    
        handleEdit() {
              
            axios.put("/item", this.formData).then((res) => {
              
                if (res.data.code == 20010) {
              
                    this.dialogFormVisible4Edit = false;
                    this.$message.success("编辑物品成功")
                } else {
              
                    this.$message.error("编辑失败")
                }
            }).finally(() => {
              
                this.getAll();
            })
        },
 *  高级查询修改
    
     *  controller
        
            @GetMapping
                public ResultResp list(@RequestParam(required = false) String name){
                    
                    List<Item> ret = service.lists(name);
                    return ResultResp.success(ret==null?Code.PAGE_FAIL:Code.PAGE_OK,ret);
                }
     *  业务层
        
            @Override
                public List<Item> lists(String name) {
                    
                    if (name != null && !"".equals(name.trim())) {
                    
            
                        return mapper.list(name);
                    }
            
                    return mapper.listNull();
                }
     *  mapper 接口
        
            @Select("select * from item where name like concat('%',#{name},'%')")
            public List<Item> list(String name);
            
            @Select("select * from item ")
            public List<Item> listNull();

### 3.全局统一异常处理 ###

#### 3.1目前存在问题 ####

*  模拟后台出现服务器异常
    
        @GetMapping
            public ResultResp list(@RequestParam(required = false) String name){
              
                System.out.println(1/0);
                List<Item> ret = service.lists(name);
                return ResultResp.success(ret==null?Code.PAGE_FAIL:Code.PAGE_OK,ret);
            }
 *  出现如下错误
    
    ![在这里插入图片描述][5133a5947c064c03b22d0456b7affc0c.png]

#### 3.2后端服务可能会出现的异常 ####

*  框架可能报错
 *  持久层代码报错
 *  业务层业务代码报错
 *  控制层业务代码报错
 *  注意：这些异常不能避免的，此时应该把所有的异常在表现层进行统一的处理（aop）
 *  解决方案
    
        @RestControllerAdvice
        public class ExceptionHandlerController {
              
        
            @ExceptionHandler(ArithmeticException.class)
            public ResultResp handlerException(){
              
                System.out.println("出现异常了");
                return new ResultResp(500,null,"服务繁忙，请稍后再试");
            }
        }

#### 3.3@RestControllerAdvice ####

*  使用来做控制器增强操作
    
    <table> 
     <thead> 
      <tr> 
       <th>名称</th> 
       <th>@RestControllerAdvice</th> 
      </tr> 
     </thead> 
     <tbody> 
      <tr> 
       <td>位置</td> 
       <td>Rest 风格增强类上</td> 
      </tr> 
      <tr> 
       <td>作用</td> 
       <td>给控制器做增强操作</td> 
      </tr> 
      <tr> 
       <td>使用</td> 
       <td>类上面</td> 
      </tr> 
     </tbody> 
    </table>
    
     *  包含了如下注解
        
         *  @ResponseBody
         *  @ControllerAdvice
         *  @Component

#### 3.4@ExceptionHandler ####

*  异常处理器
    
    <table> 
     <thead> 
      <tr> 
       <th>名称</th> 
       <th>@ExceptionHandler</th> 
      </tr> 
     </thead> 
     <tbody> 
      <tr> 
       <td>位置</td> 
       <td>方法上</td> 
      </tr> 
      <tr> 
       <td>属性</td> 
       <td>具体的异常类型</td> 
      </tr> 
      <tr> 
       <td>作用</td> 
       <td>处理具体异常的，设定具体异常类型，出现异常后，终止controller中方法的执行，转入当前方法执行</td> 
      </tr> 
     </tbody> 
    </table>

#### 3.5项目中具体处理 ####

*  业务异常
    
        @Data
        public class BusinessException extends RuntimeException{
              
            private Integer code;
        }
 *  持久层异常
    
        @Data
        public class DaoException extends RuntimeException{
              
            private Integer code;
        }
 *  系统异常
    
        @Data
        public class SystemException extends RuntimeException{
              
            private Integer code;
        }
 *  其它异常
    
        @Data
        public class OtherException extends RuntimeException{
              
            private Integer code;
        }
 *  定义code
    
        public class Code {
              
            /**
             * 定义好协议之后，前端和后端统一按照协议执行
             */
            public static final Integer SAVE_OK = 20000;
            public static final Integer SAVE_FAIL = 20001;
        
        
            public static final Integer UPDATE_OK = 20010;
            public static final Integer UPDATE_FAIL = 20011;
        
            public static final Integer DELETE_OK = 20020;
            public static final Integer DELETE_FAIL = 20021;
        
            public static final Integer GET_OK = 20030;
            public static final Integer GET_FAIL = 20031;
        
            public static final Integer PAGE_OK = 20040;
            public static final Integer PAGE_FAIL = 20041;
        
            
            public static final Integer BUSINESS_ERR = 50001;
            public static final Integer SYSTEM_ERR = 50002;
            public static final Integer DAO_ERR = 50003;
            public static final Integer OTHER_ERR = 50005;
            
            
        
        }
 *  统一异常处理
    
        @RestControllerAdvice
        public class ExceptionHandlerController {
              
            //业务异常的例子：账户名和密码错误
            @ExceptionHandler(BusinessException.class)
            public ResultResp handlerBusinessException(BusinessException e){
              
                return new ResultResp(e.getCode(),null,e.getMessage());
            }
            
            //需要发送短信提醒运维人员
            @ExceptionHandler(SystemException.class)
            public ResultResp handlerSystemException(SystemException e){
              
                //发送短信提醒业务人员的操作
                //日志打印
                return new ResultResp(e.getCode(),null,e.getMessage());
            }
        
            @ExceptionHandler(OtherException.class)
            public ResultResp handlerException(OtherException e){
              
                return new ResultResp(e.getCode(),null,e.getMessage());
            }
        }
 *  控制层方法
    
        @GetMapping
        public ResultResp list(@RequestParam(required = false) String name) {
              
            if (name == null || name.equals(""))
                throw new BusinessException(Code.BUSINESS_ERR,"传参不正常请重试");
            List<Item> ret = null;
            try {
              
                ret = service.lists(name);
            } catch (Exception e) {
              
                throw new SystemException(Code.SYSTEM_ERR,"系统繁忙，请稍后再试");
            }
            return ResultResp.success(ret == null ? Code.PAGE_FAIL : Code.PAGE_OK, ret);
        }

### 4.拦截器 ###

#### 4.1拦截器概述 ####

*  概述：一种动态拦截方法调用的机制，在SpringMVC中动态拦截控制器方法的执行
 *  实际开发中，静态资源（HTML/CSS）不需要交给框架处理，需要拦截的是动态资源

#### 4.2图示 ####

*  图示
    
    ![image-20221117145404971][]

#### 4.3案例实现 ####

*  模拟没有登录拦截操作
 *  新定义拦截器
    
        @Component
        public class LoginInterceptor implements HandlerInterceptor {
              
            @Override
            public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
              
                System.out.println("登录拦截操作");
                String username = request.getParameter("username");
                if("sy".equals(username)){
              
                    return true;
                }
                System.out.println("preHandle");
                return false;
            }
        
            @Override
            public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
              
                System.out.println("postHandle");
            }
        
            @Override
            public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
              
                System.out.println("afterCompletion");
            }
        }
 *  修改SpringMvc 配置
    
        @Configuration
        @ComponentScan({
              "cn.sycoder.controller","cn.sycoder.interceptor"})
        @EnableWebMvc
        public class SpringMvcConfig implements WebMvcConfigurer {
              
        
            @Autowired
            LoginInterceptor loginInterceptor;
        
            @Override
            public void addInterceptors(InterceptorRegistry registry) {
              
                registry.addInterceptor(loginInterceptor).addPathPatterns("/item","/item/*");
            }
        }
 *  controller 确实被拦截
    
        @RestController
        @RequestMapping("/item")
        public class ItemController {
              
        
            @GetMapping("/{id}")
            public String getById(@PathVariable Long id){
              
                return "query"+id;
            }
        
            @GetMapping
            public String list(){
              
                return "list";
            }
        }

#### 4.4拦截器参数讲解 ####

*  HttpServletRequest request
 *  HttpServletResponse response
 *  Object handler 相当于是对访问接口的一种包装

#### 4.5拦截器链 ####

*  新增拦截器
    
        @Component
        public class AuthInterceptor implements HandlerInterceptor {
              
            @Override
            public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
              
                System.out.println("权限拦截的方法");
                return true;
            }
        
            @Override
            public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
              
                System.out.println("权限拦截的postHandle方法");
            }
        
            @Override
            public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
              
                System.out.println("权限拦截的afterCompletion方法");
            }
        }
 *  添加到拦截器链中
    
        @Configuration
        @ComponentScan({
              "cn.sycoder.controller","cn.sycoder.interceptor"})
        @EnableWebMvc
        public class SpringMvcConfig implements WebMvcConfigurer {
              
        
            @Autowired
            LoginInterceptor loginInterceptor;
        
            @Autowired
            AuthInterceptor authInterceptor;
        
            @Override
            public void addInterceptors(InterceptorRegistry registry) {
              
                registry.addInterceptor(loginInterceptor).addPathPatterns("/item","/item/*");
                registry.addInterceptor(authInterceptor).addPathPatterns("/item","/item/*");
            }
        }
 *  拦截器链注意点
    
     *  拦截器有着先进后出的原则
     *  preHandle : 与配置顺序保持一致的执行顺序
     *  postHandle：与配置顺序相反，可能不运行
     *  afterCompletion：与配置顺序相反，可能不运行

#### 4.6面试题拦截器与过滤器的区别 ####

*  区别
    
     *  技术所属不同
        
         *  过滤器：Servlet 技术
         *  拦截器：SpringMVC技术
     *  拦截内容不同
        
         *  Filter : 是对所有访问进行过滤
         *  Interceptor：仅仅针对访问SpringMVC
 *  访问流程
    
    ![image-20221117160848389][]

## 四、SpringMVC执行流程 ##

### 1.SpringMVC 常用组件 ###

*  **DispatcherServlet**：前端控制器，用于对请求和响应进行统一处理
 *  **HandlerMapping**：处理器映射器，根据 url/method可以去找到具体的 Handler(Controller)
 *  **Handler**:具体处理器（程序员，以后开发这一部分需要）
 *  **HandlerAdapter**：处理器适配器，进行处理器方法的执行
 *  **ViewResolver**：处理视图相关的

### 2.处理流程图 ###

![image-20221117165036933][]

### 3.执行流程原理分析 ###

#### 3.1DispatcherServlet ####

*  初始化操作
    
        protected void initStrategies(ApplicationContext context) {
              
                this.initMultipartResolver(context);
                this.initLocaleResolver(context);
                this.initThemeResolver(context);
                this.initHandlerMappings(context);
                this.initHandlerAdapters(context);
                this.initHandlerExceptionResolvers(context);
                this.initRequestToViewNameTranslator(context);
                this.initViewResolvers(context);
                this.initFlashMapManager(context);
            }
 *  具体处理请求的方法
    
        protected final void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
              
                //删掉了一系列没用方法
        
                try {
              
                    //具体执行方法
                    this.doService(request, response);
                } catch (IOException | ServletException var16) {
              
                    failureCause = var16;
                    throw var16;
                } catch (Throwable var17) {
              
                    failureCause = var17;
                    throw new NestedServletException("Request processing failed", var17);
                } finally {
              
                    this.resetContextHolders(request, previousLocaleContext, previousAttributes);
                    if (requestAttributes != null) {
              
                        requestAttributes.requestCompleted();
                    }
        
                    this.logResult(request, response, (Throwable)failureCause, asyncManager);
                    this.publishRequestHandledEvent(request, response, startTime, (Throwable)failureCause);
                }
        
            }
    
        protected void doService(HttpServletRequest request, HttpServletResponse response) throws Exception {
              
                //删掉一系列干扰代码
        
                try {
              
                    //具体执行
                    this.doDispatch(request, response);
                } finally {
              
                    if (!WebAsyncUtils.getAsyncManager(request).isConcurrentHandlingStarted() && attributesSnapshot != null) {
              
                        this.restoreAttributesAfterInclude(request, attributesSnapshot);
                    }
        
                }
        
            }
    
        protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception {
              
                HttpServletRequest processedRequest = request;
                HandlerExecutionChain mappedHandler = null;
                boolean multipartRequestParsed = false;
                WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);
        
                try {
              
                    try {
              
                        ModelAndView mv = null;
                        Object dispatchException = null;
        
                        try {
              
                            processedRequest = this.checkMultipart(request);
                            multipartRequestParsed = processedRequest != request;
                            //获取处理器就是具体的需要执行的 Tontroller
                            mappedHandler = this.getHandler(processedRequest);
                            if (mappedHandler == null) {
              
                                this.noHandlerFound(processedRequest, response);
                                return;
                            }
        					//获取处理器适配器
                            HandlerAdapter ha = this.getHandlerAdapter(mappedHandler.getHandler());
                            String method = request.getMethod();
                            boolean isGet = "GET".equals(method);
                            if (isGet || "HEAD".equals(method)) {
              
                                long lastModified = ha.getLastModified(request, mappedHandler.getHandler());
                                if ((new ServletWebRequest(request, response)).checkNotModified(lastModified) && isGet) {
              
                                    return;
                                }
                            }
        
                            if (!mappedHandler.applyPreHandle(processedRequest, response)) {
              
                                return;
                            }
        					//具体调用 Controller 中的方法
                            mv = ha.handle(processedRequest, response, mappedHandler.getHandler());
                            if (asyncManager.isConcurrentHandlingStarted()) {
              
                                return;
                            }
        
                            this.applyDefaultViewName(processedRequest, mv);
                            mappedHandler.applyPostHandle(processedRequest, response, mv);
                        } catch (Exception var20) {
              
                            dispatchException = var20;
                        } catch (Throwable var21) {
              
                            dispatchException = new NestedServletException("Handler dispatch failed", var21);
                        }
        
                        this.processDispatchResult(processedRequest, response, mappedHandler, mv, (Exception)dispatchException);
                    } catch (Exception var22) {
              
                        this.triggerAfterCompletion(processedRequest, response, mappedHandler, var22);
                    } catch (Throwable var23) {
              
                        this.triggerAfterCompletion(processedRequest, response, mappedHandler, new NestedServletException("Handler processing failed", var23));
                    }
        
                } finally {
              
                    if (asyncManager.isConcurrentHandlingStarted()) {
              
                        if (mappedHandler != null) {
              
                            mappedHandler.applyAfterConcurrentHandlingStarted(processedRequest, response);
                        }
                    } else if (multipartRequestParsed) {
              
                        this.cleanupMultipart(processedRequest);
                    }
        
                }
            }
    
        //获取具体执行的
        protected HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {
              
                if (this.handlerMappings != null) {
              
                    Iterator var2 = this.handlerMappings.iterator();
        
                    while(var2.hasNext()) {
              
                        HandlerMapping mapping = (HandlerMapping)var2.next();
                        HandlerExecutionChain handler = mapping.getHandler(request);
                        if (handler != null) {
              
                            return handler;
                        }
                    }
                }
        
                return null;
            }

#### 3.2HandlerMapping ####

*  dbug 的图示
    
    ![image-20221117170245433][]
    
    dispatchException = new NestedServletException(“Handler dispatch failed”, var21);  
    \}
    
        this.processDispatchResult(processedRequest, response, mappedHandler, mv, (Exception)dispatchException);
                } catch (Exception var22) {
                    this.triggerAfterCompletion(processedRequest, response, mappedHandler, var22);
                } catch (Throwable var23) {
                    this.triggerAfterCompletion(processedRequest, response, mappedHandler, new NestedServletException("Handler processing failed", var23));
                }
        
            } finally {
                if (asyncManager.isConcurrentHandlingStarted()) {
                    if (mappedHandler != null) {
                        mappedHandler.applyAfterConcurrentHandlingStarted(processedRequest, response);
                    }
                } else if (multipartRequestParsed) {
                    this.cleanupMultipart(processedRequest);
                }
        
            }
        }
    
        ```java
        //获取具体执行的
        protected HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {
                if (this.handlerMappings != null) {
                    Iterator var2 = this.handlerMappings.iterator();
        
                    while(var2.hasNext()) {
                        HandlerMapping mapping = (HandlerMapping)var2.next();
                        HandlerExecutionChain handler = mapping.getHandler(request);
                        if (handler != null) {
                            return handler;
                        }
                    }
                }
        
                return null;
            }

#### 3.2HandlerMapping ####

*  dbug 的图示
    
    ![在这里插入图片描述][4029b2bcf6154505a581f6c82cd6b658.png]

[c0a077c20d9f413c9c8e812ce1126eac.png]: https://img-blog.csdnimg.cn/c0a077c20d9f413c9c8e812ce1126eac.png
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[image-20221114161855924]: https://img-blog.csdnimg.cn/img_convert/22383e6cc060aa1726faa1ab3100073a.png
[image-20221114162051321]: https://img-blog.csdnimg.cn/img_convert/2f419cdde6131c62df70f0375b84999b.png
[c30e7a12b3d44c5eab91070dc4b4f98f.png]: https://img-blog.csdnimg.cn/c30e7a12b3d44c5eab91070dc4b4f98f.png
[174a0d70654f42bf9bdf34469d7bbea2.png]: https://img-blog.csdnimg.cn/174a0d70654f42bf9bdf34469d7bbea2.png
[image-20221114162255279]: https://img-blog.csdnimg.cn/img_convert/7d53890e38ded57b8e22da7f5613944b.png
[image-20221114163001535]: https://img-blog.csdnimg.cn/img_convert/7342599c2a43d98a5515326f56e3ce3a.png
[image-20221117111833027]: https://img-blog.csdnimg.cn/img_convert/b4468dc502f47db9cc83937843ca99fb.png
[5133a5947c064c03b22d0456b7affc0c.png]: https://img-blog.csdnimg.cn/5133a5947c064c03b22d0456b7affc0c.png
[image-20221117145404971]: https://img-blog.csdnimg.cn/img_convert/3db86f9fb23c7e7b69a5c96fa97b06e2.png
[image-20221117160848389]: https://img-blog.csdnimg.cn/img_convert/48eddeb5c9e314cf40914bc1b3b587e4.png
[image-20221117165036933]: https://img-blog.csdnimg.cn/img_convert/af6de30775f75f3f016a46d3a59210ea.png
[image-20221117170245433]: https://img-blog.csdnimg.cn/img_convert/8f7fc284c900a13c42dc0c3afabc7d4e.png
[4029b2bcf6154505a581f6c82cd6b658.png]: https://img-blog.csdnimg.cn/4029b2bcf6154505a581f6c82cd6b658.png