Spring Boot 入门之Spring的纯注解配置

小鱼儿 2024-05-07 22:25 8阅读 0赞

### 1.待改造的问题 ###

我们发现，之所以我们现在离不开xml配置文件，是因为我们有一处很关键的配置，如果他要也能用注解配置，那么我们就可以脱离xml文件了

#### 1.1.jdbc配置 ####

<context:property-placeholder location="classpath:db.properties">
    </context:property-placeholder>
    
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource" 
          destroy-method="close">
        <property name="url" value="${jdbc.url}" />
        <property name="username" value="${jdbc.username}" />
        <property name="password" value="${jdbc.password}" />
        <property name="driverClassName" value="${jdbc.driver}" />
        <property name="maxActive" value="10" />
        <property name="minIdle" value="5" />
    </bean>

#### 1.2.mybatis配置 ####

<bean id="sessionFactoryBean" class="org.mybatis.spring.SqlSessionFactoryBean">
            <property name="dataSource" ref="dataSource"></property>
            <property name="typeAliasesPackage" value="com.by.pojo"></property>
        </bean>
    
        
        <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
            <property name="basePackage" value="com.by.mapper"></property>
            <property name="sqlSessionFactoryBeanName" value="sessionFactoryBean"></property>
        </bean>

#### 1.3.transactional配置 ####

#### 1.4.service配置 ####

<context:component-scan base-package="com.by.service"></context:component-scan>

#### 1.5.springmvc配置 ####

<context:component-scan base-package="com.by.controller,com.by.exception"></context:component-scan>
    
        
        <mvc:annotation-driven conversion-service="cs"></mvc:annotation-driven>
    
        
        <bean id="cs" class="org.springframework.context.support.ConversionServiceFactoryBean">
            <property name="converters">
                <set>
                    <bean class="com.by.converter.MyDateConverter"></bean>
                </set>
            </property>
        </bean>
    
        
        <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
            <property name="prefix" value="/WEB-INF/pages/"></property>
            <property name="suffix" value=".jsp"></property>
        </bean>
    
        
        <bean id="multipartResolver"
              class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
            <property name="maxUploadSize" value="5242880" />
            <property name="defaultEncoding" value="UTF-8" />
        </bean>
        
        <mvc:resources location="/head/" mapping="/head/**"/>
    
        
        <mvc:interceptors>
            <mvc:interceptor>
                <mvc:mapping path="/account/**"/>
                <mvc:exclude-mapping path="/account/login"></mvc:exclude-mapping>
                <bean class="com.by.interceptor.LoginInterceptor"></bean>
            </mvc:interceptor>
        </mvc:interceptors>

#### 1.6.servlet配置 ####

<context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:applicationContext-*.xml</param-value>
    </context-param>
    <listener>
        <listener-class>
            org.springframework.web.context.ContextLoaderListener
        </listener-class>
    </listener>
    
    
    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:springmvc.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
    
    <filter>
        <filter-name>CharacterEncodingFilter</filter-name>
        <filter-class>
            org.springframework.web.filter.CharacterEncodingFilter
        </filter-class>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>UTF-8</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>CharacterEncodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

#### 1.2.1.jdbc配置 ####

#### 1.2.2.mybatis配置 ####

#### 1.2.3.transactional配置 ####

#### 1.2.4.service配置 ####

<context:component-scan base-package="com.by.service"></context:component-scan>

#### 1.2.5.springmvc配置 ####

#### 1.2.6.servlet配置 ####

### 2.新注解说明 ###

### \#2.1.@Configuration ###

*  作用：
    
    用于指定当前类是一个spring配置类，可替换xml配置文件，作用和在spring的xml配置文件中的：`<beans></beans>`是一样的。
 *  示例代码
    
        /**
         * spring的配置类
         */
        @Configuration//等价于<beans>，当从一个类上加载到该注解时会创建spring容器
        public class SpringConfiguration{
              
        }

#### 2.2.@ComponentScan ####

*  作用：
    
    用于指定spring在初始化容器时要扫描的包。作用和在spring的xml配置文件中的：
    
    `<context:component-scan base-package="com.by"/>`是一样的。
 *  属性：
    
    basePackages：用于指定要扫描的包。和该注解中的value属性作用一样。
 *  示例代码
    
        /**
         * spring的配置类
         */
        @Configuration
        @ComponentScan(basePackages = "com.by")//等价于<context:component-scan>
        public class SpringConfiguration{
              
        }

#### 2.3.@Bean ####

*  作用：
    
    该注解只能写在方法上，表明使用此方法创建一个对象，并且放入spring容器。作用和在spring的xml配置文件中的：`<bean/>`是一样的。
 *  属性：
    
    name：给当前@Bean注解方法创建的对象指定一个名称(即bean的id）。
 *  示例代码
    
        public class Dog {
              
            private String nam;
            private Integer age;
        	//set get......
        }
    
        @Bean
        public Dog dog(){
              
            Dog dog = new Dog();
            dog.setNam("二狗");
            dog.setAge(18);
            return dog;
        }

#### 2.4.@PropertySource ####

*  作用：
    
    用于加载\*.properties文件中的配置。作用和在spring的xml配置文件中的：`<context:property-placeholder location="">`是一样的。
 *  属性：
    
    value\[\]：用于指定properties文件位置。如果是在类路径下，需要写上classpath:
 *  示例代码
    
        #config.properties
        nam=二狗
        age=18
    
        @PropertySource("classpath:config.properties")
        public class SpringConfiguration {
              
        
            @Value("${nam}")
            private String nam;
            @Value("${age}")
            private Integer age;
        
            @Bean
            public Dog dog(){
              
                Dog dog = new Dog();
                dog.setNam(nam);
                dog.setAge(age);
                return dog;
            }
        }

#### 2.5.@Import ####

*  作用：
    
    @Import注解是用来导入配置类或者一些需要前置加载的类。作用和在spring的xml配置文件中的：`<import resource=""></import>`是一样.
 *  属性：
    
    value\[\]：用于指定其他配置类的字节码。
 *  示例代码
    
        @Configuration
        @ComponentScan(basePackages = "com.by")
        @Import({
              Configuration_Other.class})
        public class SpringConfiguration {
              
        
        }
        
        @PropertySource("classpath:config.properties")
        public class Configuration_Other {
              
        
        }

##  ##

### 3.Spring的纯注解配置 ###

#### 3.1.JdbcConfig ####

import com.alibaba.druid.pool.DruidDataSource;
    import org.springframework.beans.factory.annotation.Value;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.PropertySource;
    import javax.sql.DataSource;
     
    @PropertySource("classpath:db.properties")
    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("dataSource")
        public DataSource getDatasource() {
        
            DruidDataSource ds = new DruidDataSource();
            ds.setDriverClassName(driver);
            ds.setUrl(url);
            ds.setUsername(userName);
            ds.setPassword(password);
            return ds;
        }
    }

#### 3.2.MybatisConfig ####

import org.mybatis.spring.SqlSessionFactoryBean;
    import org.mybatis.spring.mapper.MapperScannerConfigurer;
    import org.springframework.context.annotation.Bean;
     
    import javax.sql.DataSource;
     
    public class MyBatisConfig {
        
        @Bean
        public SqlSessionFactoryBean getSqlSessionFactoryBean(
                 DataSource dataSource){
        
            SqlSessionFactoryBean ssfb=new SqlSessionFactoryBean();
            ssfb.setDataSource(dataSource);
            ssfb.setTypeAliasesPackage("com.by.pojo");
            return ssfb;
        }
        @Bean
        public MapperScannerConfigurer getMapperScannerConfigurer(){
        
            MapperScannerConfigurer msc=new MapperScannerConfigurer();
            msc.setBasePackage("com.by.mapper");
            return msc;
        }
    }

#### 3.3.TxConfig ####

import org.springframework.context.annotation.Bean;
    import org.springframework.jdbc.datasource.DataSourceTransactionManager;
    import org.springframework.transaction.PlatformTransactionManager;
    import javax.sql.DataSource;
    
    public class TxConfig {
        
    
        @Bean
        public PlatformTransactionManager transactionManager(DataSource dataSource){
        
            DataSourceTransactionManager ds = new DataSourceTransactionManager();
            ds.setDataSource(dataSource);
            return ds;
        }
    }

#### 3.4.SpringConfig ####

import org.springframework.context.annotation.ComponentScan;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.context.annotation.Import;
    import org.springframework.transaction.annotation.EnableTransactionManagement;
    
    @Configuration
    @Import({
        MyBatisConfig.class, JdbcConfig.class, TxConfig.class})
    //等同<context:component-scan base-package="com.by"/>`
    @ComponentScan(value = "com.by.service")
    //等同于<tx:annotation-driven />，bean的名称默认取transactionManager
    @EnableTransactionManagement
    public class SpringConfig {
        
     
    }

#### 3.5.SpringMvcConfig ####

import com.by.converter.MyDateConverter;
    import com.by.interceptor.LoginInterceptor;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.ComponentScan;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.format.FormatterRegistry;
    import org.springframework.web.multipart.commons.CommonsMultipartResolver;
    import org.springframework.web.servlet.ViewResolver;
    import org.springframework.web.servlet.config.annotation.EnableWebMvc;
    import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
    import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
    import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
    import org.springframework.web.servlet.view.InternalResourceViewResolver;
    
    @Configuration
    //等同于<context:component-scan base-package="com.by.controller>
    @ComponentScan("com.by.controller")
    //等同于<mvc:annotation-driven></mvc:annotation-driven>
    @EnableWebMvc
    public class SpringMvcConfig implements WebMvcConfigurer {
        
    
        @Bean
        public ViewResolver viewResolver() {
        
            InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
            viewResolver.setPrefix("/WEB-INF/pages/"); // 设置视图文件所在目录
            viewResolver.setSuffix(".jsp"); // 设置视图文件后缀名
            return viewResolver;
        }
    
        @Bean
        public CommonsMultipartResolver multipartResolver(){
        
            CommonsMultipartResolver commonsMultipartResolver=new CommonsMultipartResolver();
            return commonsMultipartResolver;
        }
    
        @Override
        public void addFormatters(FormatterRegistry registry) {
        
            registry.addConverter(new MyDateConverter());
        }
    
        @Override
        public void addInterceptors(InterceptorRegistry registry) {
        
            registry.addInterceptor(new LoginInterceptor()).addPathPatterns("/emp/**");
        }
    
        @Override
        public void addResourceHandlers(ResourceHandlerRegistry registry) {
        
            registry.addResourceHandler("/head/**").addResourceLocations("/head/");
        }
    }

#### 3.6.WebConfig ####

import org.springframework.web.filter.CharacterEncodingFilter;
    import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;
    
    import javax.servlet.Filter;
    
    /**
     * 当类扩展了AbstractAnnotationConfigDispatcherServletlnitializer并将其部署到 Servlet容器时，
     * 容器会自动发现它，并用它来配置Servlet环境
     */
    public class WebConfig extends AbstractAnnotationConfigDispatcherServletInitializer {
        
        
        //加载Spring配置类
        protected Class<?>[] getRootConfigClasses() {
        
            return new Class[]{
        SpringConfig.class};
        }
        
        //加载SpringMVC配置类
        protected Class<?>[] getServletConfigClasses() {
        
            return new Class[]{
        SpringMvcConfig.class};
        }
        
        //设置SpringMVC请求地址拦截规则
        protected String[] getServletMappings() {
        
            return new String[]{
        "/"};
        }
        
        //设置post请求中文乱码过滤器
        @Override
        protected Filter[] getServletFilters() {
        
            CharacterEncodingFilter filter = new CharacterEncodingFilter();
            filter.setEncoding("utf-8");
            return new Filter[]{
        filter};
        }
    }

#### 3.7.删除xml配置文件 ####

![d63ab47ec5644f94a07dbc3dc33edd4a.png][]

#### 3.8.修改web.xml ####

<?xml version="1.0" encoding="UTF-8"?>
    <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
             version="4.0">
        <welcome-file-list>
            <welcome-file>login.jsp</welcome-file>
        </welcome-file-list>
    </web-app>

#### 3.9.测试 ####

略…

[d63ab47ec5644f94a07dbc3dc33edd4a.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/05/07/3b702cc516654ebe8e3d2a09ff08791b.png