【SSM】篇五：REST风格与SSM整合开发￥￥￥

野性酷女 2023-10-08 20:08 6阅读 0赞

#### 文章目录 ####

*  一、REST
 *   *  1、REST简介
     *  2、RESTful入门案例
     *  3、REST快速开发
     *  4、案例
 *  二、SSM整合
 *   *  1、配置整合
     *  2、功能模块开发
     *  3、接口测试
     *  4、表现层与前端数据传输协议定义
     *  5、异常处理器
 *  三、拦截器
 *   *  1、初识拦截器
     *  2、入门案例
     *  3、拦截器的参数
     *  4、拦截器链配置

## 一、REST ##

### 1、REST简介 ###

![在这里插入图片描述][7d81ff2336c54d99b6785ba8de8d1571.png]  
![在这里插入图片描述][9eaed1921aa34f0cb07c141f9dff02bf.png]

### 2、RESTful入门案例 ###

**相关步骤：**

> **1) 设定HTTP请求动作词**

![在这里插入图片描述][64fa66839b9b49428eda79a6edba9806.png]

> **2) 设定路径变量**

![在这里插入图片描述][ba6fc5d5d1d345198f6006c055da5f31.png]

**相关注解：**

![在这里插入图片描述][0399197d4dd64a14ba37b8e00ecd015a.png]  
![在这里插入图片描述][21a96ee10df54347a4af8bad9ac852f6.png]  
数据接收的三个注解的对比：

![在这里插入图片描述][ebd1b95e5df540bb957686b521f4e750.png]  
实际开发中，常封装成一个pojo，所以@RequestBody使用的最多。([pojo][]，即Java普通对象）

**实现代码：**

@Controller
    //@RequestMapping("/user")
    public class UserController {
        
    
        /**
         * 增
         * @return
         */
        @RequestMapping(value="/users",method = RequestMethod.POST)
        @ResponseBody
        public String save(){
        
            System.out.println("User save ...");
            return "{'msg':'do user save'}";
        }
    
        /**
         * 删
         * @param id
         * @return
         */
        @RequestMapping(value="/users/{id}",method = RequestMethod.DELETE)
        @ResponseBody
        public String delete(@PathVariable Integer id){
        
            System.out.println("do user delete ..." + id);
            return "{'msg':'user delete'}";
        }
    
        /**
         * 改
         * @param user
         * @return
         */
        @RequestMapping(value="/users",method = RequestMethod.PUT)
        @ResponseBody
        public String update(@RequestBody User user){
        
            System.out.println("do user update ..." + user);
            return "{'msg':'user update}";
        }
    
        /**
         * 查
         * @return
         */
        @RequestMapping(value="/users",method = RequestMethod.GET)
        @ResponseBody
        public String select(){
        
            System.out.println("do user select ...");
            return "{'msg':'use select'}";
        }
    
        /**
         * 根据id查询
         * @param id
         * @return
         */
        @RequestMapping(value = "/users/{id}", method = RequestMethod.GET)
        @ResponseBody
        public String getById(@PathVariable Integer id){
        
            System.out.println("select by id..." + id);
            return "{'msg':'use select by id'}";
        }
    }

测试：

![在这里插入图片描述][e3d190bfe291418ca2ddf4c8f7d20321.png]

### 3、REST快速开发 ###

入门案例中，有一些重复的代码可以继续优化，如每个方法中的RequestMapping中的value，还有@RequestBody

![在这里插入图片描述][24b50d5a59b24320a4cb6cd64762266f.png]

**相关注解：**

> @RestController

![在这里插入图片描述][076c96a6cbf74d72b4979431f4aa4d5f.png]

> @GetMapping

![在这里插入图片描述][3e76dc4c976a4e09892b0dc751a12899.png]

### 4、案例 ###

> 案例–基于RESTful页面数据交互

1)制作SpringMvc控制器

![在这里插入图片描述][78cbd6b82c324a009523808247730fb9.png]

2)设置对静态资源的访问放行

当前设置的所有请求都归SpringMvc处理：  
![在这里插入图片描述][4b4f11057389473ab7319a942973beab.png]

继承WebMvcConfigSupport，对静态资源做放行：

![在这里插入图片描述][a291940fc0d642259941194b4de683ee.png]  
![在这里插入图片描述][1842bce1d76c4d1c86e6c56627178326.png]

## 二、SSM整合 ##

> **整合的思路：**

![在这里插入图片描述][9c001e7320ef44dfbe3f42b606128fb2.png]

### 1、配置整合 ###

*  pom.xml文件中插件和依赖：

<build>
        <plugins>
    
          <plugin>
            <groupId>org.apache.tomcat.maven</groupId>
            <artifactId>tomcat7-maven-plugin</artifactId>
            <version>2.1</version>
    
            <configuration>
              <path>/</path> 
              <port>8088</port>
            </configuration>
          </plugin>
    
        </plugins>
      </build>
    
      <properties>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
      </properties>
    
    
        <dependencies>
    
          <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.2.9.RELEASE</version>
          </dependency>
          
        <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-jdbc</artifactId>
          <version>5.2.10.RELEASE</version>
        </dependency>
    
        <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-test</artifactId>
          <version>5.2.10.RELEASE</version>
        </dependency>
    
        
        <dependency>
          <groupId>org.mybatis</groupId>
          <artifactId>mybatis</artifactId>
          <version>3.5.9</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>5.1.47</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>

*  新建项目：  
    ![在这里插入图片描述][75fa82888fd14802aed86987f30717b0.png]  
    ![在这里插入图片描述][d80396f059f5450fa3c81cd75e9ac603.png]
 *  Spring配置

@Configuration
    @ComponentScan({
        "com.llg.service","com.llg.config"})
    @PropertySource("classpath:jdbc.properties")
    @EnableTransactionManagement
    @Import({
        JdbcConfig.class,MyBatisConfig.class})
    public class SpringConfig {
        
    }

*  SpringMvc配置

@Configuration
    @ComponentScan({
        "com.llg.controller","com.llg.config"})
    @EnableWebMvc
    public class SpringMvcConfig {
        
    }

*  Jdbc数据源和Mybatis配置

public class JdbcConfig {
        
        @Value("${jdbc.driver}")
        private String driver;
        @Value("${jdbc.url}")
        private String url;
        @Value("${jdbc.username}")
        private String username;
        @Value("${jdbc.password}")
        private String password;
    
        @Bean
        public DataSource dataSource(){
        
            DruidDataSource dataSource = new DruidDataSource();
            dataSource.setDriverClassName(driver);
            dataSource.setUrl(url);
            dataSource.setUsername(username);
            dataSource.setPassword(password);
            return dataSource;
        }
    
        //开启事务管理
        @Bean
        public PlatformTransactionManager transactionManager(DataSource dataSource){
        
            DataSourceTransactionManager ds = new DataSourceTransactionManager();
            ds.setDataSource(dataSource);
            return ds;
        }
    }

public class MyBatisConfig {
        
    
        @Bean
        public SqlSessionFactoryBean sqlSessionFactory(DataSource dataSource){
        
            SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
            sqlSessionFactoryBean.setDataSource(dataSource);
            sqlSessionFactoryBean.setTypeAliasesPackage("com.llg.domain");
            return sqlSessionFactoryBean;
        }
    
        @Bean
        public MapperScannerConfigurer mapperScannerConfigurer(){
        
            MapperScannerConfigurer mapperScannerConfigurer = new MapperScannerConfigurer();
            mapperScannerConfigurer.setBasePackage("com.llg.dao");
            return mapperScannerConfigurer;
        }
    }

*  初始化Servlet容器，加载SpringMVC环境，ServletConfig配置

public class ServletConfig extends AbstractAnnotationConfigDispatcherServletInitializer {
        
    
        protected Class<?>[] getRootConfigClasses() {
        
            return new Class[]{
        SpringConfig.class};
        }
    
        protected Class<?>[] getServletConfigClasses() {
        
            return new Class[]{
        SpringMvcConfig.class};
        }
    
        protected String[] getServletMappings() {
        
            return new String[]{
        "/"};
        }
    
    }

### 2、功能模块开发 ###

*  表与实体类  
    ![在这里插入图片描述][f67221d5190448cc861c018b9aca7ef0.png]

//实体类
    package com.llg.domain;
    
    public class Book {
        
    
        private Integer id;
    
        private String type;
    
        private String name;
    
        private String description;
    
        public Integer getId() {
        
            return id;
        }
    
        public void setId(Integer id) {
        
            this.id = id;
        }
    
        public String getType() {
        
            return type;
        }
    
        public void setType(String type) {
        
            this.type = type;
        }
    
        public String getName() {
        
            return name;
        }
    
        public void setName(String name) {
        
            this.name = name;
        }
    
        public String getDescription() {
        
            return description;
        }
    
        public void setDescription(String description) {
        
            this.description = description;
        }
    
        public Book() {
        
        }
    
        public Book(Integer id, String type, String name, String description) {
        
            this.id = id;
            this.type = type;
            this.name = name;
            this.description = description;
        }
    
        @Override
        public String toString() {
        
            return "Book{" +
                    "id=" + id +
                    ", type='" + type + '\'' +
                    ", name='" + name + '\'' +
                    ", description='" + description + '\'' +
                    '}';
        }
    }

*  dao（接口+自动代理）

数据层dao不用实现类，mybatis自动代理创建对象

package com.llg.dao;
    
    public interface BookDao {
        
        @Insert("insert into t_book values(null, #{type}, #{name}, #{description})")
        //@Insert("insert into t_book (type,name,description) values(#{type},#{name},#{description})")
        public int save(Book book);
    
        @Update("update t_book set type = #{type}, name = #{name}, description = #{description} where id = #{id}")
        public int update(Book book);
    
        @Delete("delete from t_book where id = #{id}")
        public int delete(Integer id);
    
        @Select("select * from t_book where id = #{id}")
        public Book getById(Integer id);
    
        @Select("select * from t_book")
        public List<Book> getAllBook();
    }

*  service（接口+实现类）

package com.llg.service;
    
    @Transactional
    public interface BookService {
        
    
        /**
         * 新增书籍信息
         * @param book
         * @return
         */
        public boolean saveBook(Book book);
    
        /**
         * 删除书籍信息
         * @param id
         * @return
         */
        public boolean deleteBook(Integer id);
    
        /**
         * 更新书籍信息
         * @param book
         * @return
         */
        public boolean updateBook(Book book);
    
        /**
         * 按照id查询书籍
         * @param id
         * @return
         */
        public Book getBookById(Integer id);
    
        /**
         * 查询所有书籍信息
         * @return
         */
        public List<Book> getAllBook();
    }

package com.llg.service.impl;
    
    @Service
    public class BookServiceImpl implements BookService {
        
    
        @Autowired
        private BookDao bookDao;
    
        public boolean saveBook(Book book) {
        
            return bookDao.save(book) > 0;
    
        }
    
        public boolean deleteBook(Integer id) {
        
            return bookDao.delete(id) > 0;
        }
    
        public boolean updateBook(Book book) {
        
            return bookDao.update(book) > 0;
    
        }
    
        public Book getBookById(Integer id) {
        
            if(id == 1){
        
                throw new BusinessException(Code.BUSINESS_ERR,"执行参数校验时，参数格式不合规");
            }
            return bookDao.getById(id);
        }
    
        public List<Book> getAllBook() {
        
            return bookDao.getAllBook();
    
        }
    }

*  controller

package com.llg.controller;
    
    @RestController
    @RequestMapping("/books")
    public class BookController {
        
        @Autowired
        private BookService bookService;
    
        @PostMapping
        public boolean saveBook(@RequestBody Book book){
        
            return bookService.saveBook(book);
        }
    
        @DeleteMapping("/{id}")
        public boolean deleteBook(@PathVariable Integer id) {
        
            return bookService.deleteBook(id);
        }
    
        @PutMapping
        public boolean updateBook(@RequestBody Book book) {
        
            return bookService.updateBook(book);
        }
    
        @GetMapping("/{id}")
        public Book getBookById(@PathVariable Integer id) {
        
            return bookService.getBookById(id);
        }
    
        @GetMapping
        public List<Book> getAllBook() {
        
            return bookService.getAllBook();
    
        }
    
    }

### 3、接口测试 ###

业务层（service）写完以后，使用junit做测试，表现层（controller）写完以后，用postman做接口测试

*  junit测试业务层方法

@RunWith(SpringJUnit4ClassRunner.class)
    @ContextConfiguration(classes = SpringConfig.class)
    public class BookServiceTest {
        
    
        @Autowired
        private BookService bookService;
    
        @Test
        public void testGetById(){
        
            Book book = bookService.getBookById(1);
            System.out.println(book);
        }
    
        @Test
        public void testGetAll(){
        
            List<Book> bookList = bookService.getAllBook();
            System.out.println(bookList);
        }
    }

![在这里插入图片描述][9ff60b7fa3b546c298f3592f9ce13fca.png]

*  postman测试表现层接口  
    ![在这里插入图片描述][08792c0fe5ee4f9986d1aab09be76c94.png]

### 4、表现层与前端数据传输协议定义 ###

当前，后端接口返回的数据格式不一致，前后端对接繁琐：  
![在这里插入图片描述][3743815bade046e8b8059476c492ef5f.png]  
**前端接收数据格式：**

*  创建结果模型类，封装数据到data属性中
 *  使用code区分是增删改查的哪种操作，成功或失败
 *  封装特殊消息到message（即msg），告诉用户信息

![在这里插入图片描述][ac7d2566fd694d74a27f7aab8080fe3a.png]

> **设置统一数据返回结果类：**

![在这里插入图片描述][639825f740f7417bba228d8e9511bd6a.png]

> **代码实现：**

*  设置统一返回的数据结果类，其属性可以根据前端要求适当增减

package com.llg.controller;
    
    
    public class Result {
        
    
        private Object data;
    
        private Integer code;
    
        private String msg;
    
        public Result() {
        
        }
    
        public Result(Integer code,Object data,  String msg) {
        
            this.data = data;
            this.code = code;
            this.msg = msg;
        }
    
        public Result(Integer code,Object data) {
        
            this.data = data;
            this.code = code;
        }
    
        public Result(Integer code, String msg) {
        
            this.code = code;
            this.msg = msg;
        }
    
        public Object getData() {
        
            return data;
        }
    
        public void setData(Object data) {
        
            this.data = data;
        }
    
        public Integer getCode() {
        
            return code;
        }
    
        public void setCode(Integer code) {
        
            this.code = code;
        }
    
        public String getMsg() {
        
            return msg;
        }
    
        public void setMsg(String msg) {
        
            this.msg = msg;
        }
    }

*  定义返回结果编码，code类，自行定制

package com.llg.controller;
    
    
    public class Code {
        
        public static final Integer SAVE_OK = 20011;
        public static final Integer DELETE_OK = 20012;
        public static final Integer UPDATE_OK = 20013;
        public static final Integer GET_OK = 20014;
    
        public static final Integer SAVE_ERR = 20010;
        public static final Integer DELETE_ERR = 20010;
        public static final Integer UPDATE_ERR = 20010;
        public static final Integer GET_ERR = 20010;
    
        public static final Integer SYSTEM_ERR = 50001;
        public static final Integer SYSTEM_ERR_TIMEOUT = 50003;
        public static final Integer SYSTEM_UNKNOW_ERR = 50003;
        public static final Integer BUSINESS_ERR = 50002;
    
    }

*  根据情况设定合理的Result并返回

package com.llg.controller;
    
    @RestController
    @RequestMapping("/books")
    public class BookController {
        
        @Autowired
        private BookService bookService;
    
        @PostMapping
        public Result saveBook(@RequestBody Book book){
        
            boolean flag = bookService.saveBook(book);
            return new Result(flag ? Code.SAVE_OK:Code.SAVE_ERR,flag);
        }
    
        @DeleteMapping("/{id}")
        public Result deleteBook(@PathVariable Integer id) {
        
            boolean flag = bookService.deleteBook(id);
            return new Result(flag ? Code.DELETE_OK:Code.DELETE_ERR,flag);
        }
    
        @PutMapping
        public Result updateBook(@RequestBody Book book) {
        
            boolean flag = bookService.updateBook(book);
            return new Result(flag ? Code.UPDATE_OK:Code.UPDATE_ERR,flag);
        }
    
        @GetMapping("/{id}")
        public Result getBookById(@PathVariable Integer id) {
        
            Book book = bookService.getBookById(id);
            Integer code = book != null ? Code.GET_OK : Code.GET_ERR;
            String msg = book != null ? "查询成功" : "数据查询失败，请重试...";
            return new Result(code,book,msg);
        }
    
        @GetMapping
        public Result getAllBook() {
        
            List<Book> bookList = bookService.getAllBook();
            Integer code = bookList != null ? Code.GET_OK : Code.GET_ERR;
            String msg = bookList != null ? "查询成功" : "数据查询失败，请重试...";
            return new Result(code,bookList,msg);
    
        }
    
    }

到此，剩下的交给前端自己拿，自己解析

### 5、异常处理器 ###

> **5.1 初识处理器**

接口调用过程中，异常难以避免：

![在这里插入图片描述][63f58333056a49c8871cbe0ecf8327e5.png]  
出现异常现场的常见位置与常见诱因如下：

![在这里插入图片描述][d9964362365544fcb919020dcd9101bb.png]  
让所有的异常均抛出，直到表现层再进行处理。

`声明异常处理器，集中、统一处理项目中出现的异常`：

![在这里插入图片描述][ee69d15e59e94d1993147d543cdb110e.png]

**相关注解**–`@RestControllerAdvice`

![在这里插入图片描述][8c70ba96c3e94c2b953e59a1a6cb11bd.png]  
**相关注解**–`@ExceptionHandler`

![在这里插入图片描述][8715a400bff5451fb178ac37bee33fe3.png]

> **5.2 项目异常处理方案**

![在这里插入图片描述][a7492b8c878445579c4436320429dd7c.png]

--------------------

**项目异常分类：**

![在这里插入图片描述][6c7f92458d5647ea8ccd850c0bdd3663.png]

--------------------

**项目异常处理方案：**  
![在这里插入图片描述][4742e37659c64c2ab2090804fdb88842.png]

--------------------

**项目异常处理代码实现：**

*  自定义项目系统级异常

package com.llg.exception;
    
    /**
     * 继承运行时异常，这种异常，出现以后可以不处理，自动向上抛，以后不用throws
     * @author LLg
     * @date 2023/3/15
     */
    public class SystemException extends RuntimeException{
        
    
        private Integer code;
    
        public SystemException(Integer code, String message, Throwable cause) {
        
            super(message, cause);
            this.code = code;
        }
    
        public SystemException(Integer code, String message) {
        
            super(message);
            this.code = code;
        }
    
        public Integer getCode() {
        
            return code;
        }
    
        public void setCode(Integer code) {
        
            this.code = code;
        }
    }

//写法一样，改个名字
    
    package com.llg.exception;
    
    public class BusinessException extends RuntimeException{
        
    
        private Integer code;
    
        public BusinessException(Integer code, String message, Throwable cause) {
        
            super(message, cause);
            this.code = code;
        }
    
        public BusinessException(Integer code, String message) {
        
            super(message);
            this.code = code;
        }
    
        public Integer getCode() {
        
            return code;
        }
    
        public void setCode(Integer code) {
        
            this.code = code;
        }
    }

*  自定义异常码

package com.llg.controller;
    
    public class Code {
        
        public static final Integer SAVE_OK = 20011;
        public static final Integer DELETE_OK = 20012;
        public static final Integer UPDATE_OK = 20013;
        public static final Integer GET_OK = 20014;
    
        public static final Integer SAVE_ERR = 20010;
        public static final Integer DELETE_ERR = 20010;
        public static final Integer UPDATE_ERR = 20010;
        public static final Integer GET_ERR = 20010;
    
        public static final Integer SYSTEM_ERR = 50001;
        public static final Integer SYSTEM_ERR_TIMEOUT = 50003;
        public static final Integer SYSTEM_UNKNOW_ERR = 50003;
        public static final Integer BUSINESS_ERR = 50002;
    
    }

*  包装、触发自定义异常  
    ![在这里插入图片描述][f70d1a7205f247fab6ed1d5daebf0436.png]  
    不管是业务层的异常，还是系统的异常，都封装成了我们定义的两种异常，然后到异常处理器类中进行分门别类的处理，返回统一的result

package com.llg.service.impl;
    
    @Service
    public class BookServiceImpl implements BookService {
        
    
        @Autowired
        private BookDao bookDao;
    
    
    
        public Book getBookById(Integer id) {
        
            if(id == 1){
        
                throw new BusinessException(Code.BUSINESS_ERR,"执行参数校验时，参数格式不合规");
            }
            //将可能出现的异常进行包装，转换成自定义异常
            /*try{
                int i = 1/0;
            }catch(Exception e){
                throw new SystemException(Code.SYSTEM_ERR_TIMEOUT,"服务器访问超时，请稍后重试",e);
            }*/
            return bookDao.getById(id);
        }
    
    
    }

*  处理器拦截并处理异常

在这里插入代码片package com.llg.controller;
    
    @RestControllerAdvice
    public class ProjectExceptionAdvice {
        
    
        /**
         * 拦截处理系统异常
         * @param e
         * @return
         */
        @ExceptionHandler(SystemException.class)
        public Result doSystemException(SystemException e){
        
            //记录日志
            //发送消息给运维和开发人员
            return new Result(e.getCode(),null,e.getMessage());
        }
    
        /**
         * 业务异常
         * @param e
         * @return
         */
    
        @ExceptionHandler(BusinessException.class)
        public Result doBusinessException(BusinessException e){
        
            return new Result(e.getCode(),null,e.getMessage());
        }
    
        @ExceptionHandler(Exception.class)
        public Result doException(Exception e){
        
            //记录日志
            //发送消息给运维和开发人员
            return new Result(Code.SYSTEM_UNKNOW_ERR,null,"系统繁忙..");
        }
    }

效果测试：  
![在这里插入图片描述][6b119651502049b2a0702694d3dbcd6d.png]

## 三、拦截器 ##

### 1、初识拦截器 ###

在不同请求路径，访问到不同controller的不同方法前，增加拦截：

![在这里插入图片描述][ed77e490beae4f2fb3c01a49e202d39d.png]

拦截器（Intercptor）是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

**作用：**

*  在指定的方法调用前后执行预设定的代码
 *  阻止原始方法执行

类比于进入机房前，层层保安要求你带眼镜、带鞋套、穿防护服：  
![在这里插入图片描述][f69aaaf42e22409ba647c5a1261d3444.png]  
层层拦截：  
![在这里插入图片描述][c25998a3b1874cd6beb17ac253f7e06f.png]  
**关于拦截器和过滤器：**

![在这里插入图片描述][6c648bed0978456981308e0a694cba5f.png]

### 2、入门案例 ###

*  **第一步：制作拦截器的功能类，实现HandlerInterseptor接口，声明拦截器的bean**，这个类写在controller，一则是表现层，二则是不用在SpringMvcConfig中再单独写加载的配置了  
    ![在这里插入图片描述][de941fb5d6de4800bf212e39ba988dc9.png]preHandle方法妙在：可以校验一个条件是否满足，满足则返回true，继续执行，不满足则返回false，跳过原始操作。  
    ![在这里插入图片描述][fc286f96c62646c08e5b867bd70664a4.png]
 *  **第二步：定义配置类，继承WebMvcConfigurationSupport，覆盖addInterceptors方法**  
    ![在这里插入图片描述][b67efe130ad548208aed880d3f96033d.png]
 *  **第三步：添加拦截器，并设定拦截的访问路径**，路径的传参是可变长参数，可设置多个  
    ![在这里插入图片描述][c7997a3bd0814aa0a0d347274e7c3330.png]

--------------------

结构优化：

![在这里插入图片描述][216b5378656d4d00804349cc2b0449f0.png]

单独写个SpringMvcSupport类，再在SpringMvcConfig中扫描config包来加载，很繁琐，可以直接在SpringMvcConfig类中，实现WebMvcConfig接口：

![在这里插入图片描述][6144169056034bf5916fabddba2f63ec.png]

--------------------

**拦截器整体流程：**

![在这里插入图片描述][64324bbcd8cd43aea1df60b45149cb2e.png]

### 3、拦截器的参数 ###

*  **前置方法**  
    ![在这里插入图片描述][feb844d3866d40918e6f7d5ba8559258.png]
 *  **后置方法：**  
    ![在这里插入图片描述][7fd78ac183c2474ba4d43d6c6bff5ad4.png]
 *  **完成后处理方法：**  
    ![在这里插入图片描述][bdec092989ec4a058c978a835d22f74f.png]

### 4、拦截器链配置 ###

当配置多个拦截器的时候，形成拦截器链。拦截器的运行顺序参照拦截器的添加顺序：  
![在这里插入图片描述][34074d94b30c431fae929dd6b6b12131.png]

且，对于每个拦截器中的三个方法的顺序：

![在这里插入图片描述][f0ffba49db054ba3a2778c472f2372b9.png]

preHandle方法return true的时候，一切就是上面的顺序。**有一个return false，则所有的postHandle一概不执行**，并且从出现位置开始，后面的preHandle也不再运行，afterCompletion，在这个return false之前的都要运行。

--------------------

假设有个三个拦截器组成的拦截器链：

![在这里插入图片描述][a5ee68b7f0fa4ef1a99a5bfa76bff7bb.png]

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