Spring 常用注入注解（annotation）和其对应xml标签

使用注解需要修改bean.xml：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns:context="http://www.springframework.org/schema/context"
  xsi:schemaLocation="http://www.springframework.org/schema/beans
      http://www.springframework.org/schema/beans/spring-beans.xsd
      http://www.springframework.org/schema/context
      http://www.springframework.org/schema/context/spring-context.xsd">

  <context:annotation-config/>

  <bean class="example.SimpleMovieCatalog">
      <qualifier value="main"/>
      <!-- inject any dependencies required by this bean -->
  </bean>

  <bean class="example.SimpleMovieCatalog">
      <qualifier value="action"/>
      <!-- inject any dependencies required by this bean -->
  </bean>

  <bean id="movieRecommender" class="example.MovieRecommender"/>

</beans>

黄色部分内容会使spring加载AutowiredAnnotationBeanPostProcessor等可以识别注解的bean。

@AutoWire，自动注入，一般放在属性的set方法上，会为该属性自动注入。默认的注入是使用byType，就是根据xml中bean的类型去匹配。

可以和@Qualifier匹配使用。

注解实现方式：

package com.bjsxt.service;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;

import com.bjsxt.dao.UserDAO;
import com.bjsxt.model.User;

public class UserService {
   
    private UserDAO userDAO; 
   
    public void init() {
        System.out.println("init");
    }
   
    public void add(User user) {
        userDAO.save(user);
    }
    public UserDAO getUserDAO() {
        return userDAO;
    }
   
    @Autowired
    public void setUserDAO(@Qualifier("u") UserDAO userDAO) {//Qualifier：根据qualifier标签去查找，也可以根据name或者id去查找匹配的bean
        this.userDAO = userDAO;
    }
   

   
    public void destroy() {
        System.out.println("destroy");
    }
}

对应的xml实现方式：

<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans"          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"          xsi:schemaLocation="http://www.springframework.org/schema/beans              http://www.springframework.org/schema/beans/spring-beans-2.5.xsd"             >

  <bean name="userDAO" class="com.bjsxt.dao.impl.UserDAOImpl">       <property name="daoId" value="1"></property>      </bean>        <bean name="userDAO2" class="com.bjsxt.dao.impl.UserDAOImpl">          <property name="daoId" value="2"></property>      </bean>         <bean id="userService" class="com.bjsxt.service.UserService" scope="prototype" autowire="byType"><!-- 也可以设在beans标签上，好像是default-autowire scope="prototype"表示每次都创建一个新的实例对应的有singleton--只有一个实例 -->     </bean>   

</beans>

@Resource

此标签也用于注入属性。相对来说用的比较多。

该标签需要导入J2EE的JAR包：common-annotations.jar

javax.annotation.Resource，默认byName，如果找不到对应name会去找对应type

    @Resource
    public void setUserDAO（UserDAO userDAO) { 
        this.userDAO = userDAO;
    }

@Resource（name=”uuu”) //可以byName

以上两种注解虽然可以在代码中设置注入，但是还要求在xml文件中配置bean。

Component可以省去。

5.10.3 Using filters to customize scanning

By default, classes annotated with @Component, @Repository, @Service, @Controller, or a custom annotation that itself is annotated with @Component are the only detected candidate components. However, you can modify and extend this behavior simply by applying custom filters. Add them as include-filter or exclude-filter sub-elements of thecomponent-scan element. Each filter element requires the type and expression attributes. The following table describes the filtering options.

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
           http://www.springframework.org/schema/context
           http://www.springframework.org/schema/context/spring-context-2.5.xsd">
    <context:annotation-config />
    <context:component-scan base-package="com.bjsxt"/>

</beans>

scan：扫描。表示扫描某个包和其自包，将能作为组件（添加了@Component）的内容解析出来。

package com.bjsxt.dao.impl;

import org.springframework.stereotype.Component;

import com.bjsxt.dao.UserDAO;
import com.bjsxt.model.User;

@Component("u") //这样写表示这个类是一个组件，在另外一个类看来它就是一个资源。不指定它的key默认会是userDAOImpl（即类名首字母改成小写）

public class UserDAOImpl implements UserDAO {

    public void save(User user) {
        //Hibernate
        //JDBC
        //XML
        //NetWork
        System.out.println("user saved!");
    }

}

package com.bjsxt.service;
import javax.annotation.Resource;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Component;

import com.bjsxt.dao.UserDAO;
import com.bjsxt.model.User;

@Component("userService")
public class UserService {
   
    private UserDAO userDAO; 
   
    public void init() {
        System.out.println("init");
    }
   
    public void add(User user) {
        userDAO.save(user);
    }
    public UserDAO getUserDAO() {
        return userDAO;
    }
   
    @Resource(name="u")
    public void setUserDAO( UserDAO userDAO) {
        this.userDAO = userDAO;
    }
   

   
    public void destroy() {
        System.out.println("destroy");
    }
}

额外的一些内容：

<bean id="userService" class="com.bjsxt.service.UserService" init-method="init" destroy-method="destroy" scope="prototype">

scope对应的注解是@Scope（“”）

init-method对应的注解是@PostConstruct，表示构造完成之后再执行它注解的方法。

destroy-method对应的注解是@PreDestroy，容器销毁之前。