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淡煙疏雨清明日渡紫，飛絮落花游子心。
燕話春愁初睡起，一簾草色暮池深

Spring針對Bean管理中創(chuàng)建對象提供注解

(1) @Component

(2) @Service

(3) @Controller

(4)@Repository

上面的4個注解功能是一樣的灶挟，都可以用來創(chuàng)建bean的實例

• 第一步引入依賴

  spring-aop.jar

• 開啟組件掃描

  <?xml version="1.0" encoding="UTF-8"?>
  <beans xmlns="http://www.springframework.org/schema/beans"
         xmlns:context="http://www.springframework.org/schema/context"
         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.xsd
                             http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
      <!--  開啟組件掃描  -->
      <context:component-scan base-package="com.company.user"></context:component-scan>
  </beans>
  

  測試：

  package com.company.user;
  
  import org.springframework.stereotype.Component;
  
  @Component(value = "user")
  public class User {
      private String name;
      private int age;
  
      public User() {
      }
  
      public void setName(String name) {
          this.name = name;
      }
  
      public void setAge(int age) {
          this.age = age;
      }
  
      @Override
      public String toString() {
          return "User{" +
                  "name='" + name + '\'' +
                  ", age=" + age +
                  '}';
      }
  
      public void show() {
          System.out.println("add.....");
      }
  }
  

  package com.company.test;
  
  import com.company.user.User;
  import org.junit.Test;
  import org.springframework.context.ApplicationContext;
  import org.springframework.context.support.ClassPathXmlApplicationContext;
  
  public class SpringTest {
  
  
      @Test
      public void test() {
          ApplicationContext context = new ClassPathXmlApplicationContext("bean.xml");
          User user = context.getBean("user", User.class);
          System.out.println(user);
          user.show();
      }
  
  }
  

  • 組件掃描細節(jié)配置

    <context:component-scan base-package="com.company.user" use-default-filters="false">
        <context:include-filter type="annotation" expression="org.springframework.stereotype.Component"/>
    </context:component-scan>
    

• 基于注解方式實現(xiàn)屬性注解

  @AutoWired 根據(jù)屬性類型自動裝配

  1. 把service和dao對象創(chuàng)建，在service和dao類添加創(chuàng)建對象注解
  2. 在service注入dao對象域帐，在service類添加dao類型屬性，在屬性上面使用注解

  @Qualifier 根據(jù)屬性名稱注入

  這個@Qualifier注解需要跟是整！@AutoWired一起使用

package com.company.dao;
 
import org.springframework.stereotype.Repository;
 
@Repository(value = "userDaoImpl")
 public class UserDaoImpl implements UserDao{
     @Override
     public void add() {
         System.out.println("dao add肖揣。。浮入。");
     }
 }

package com.company.service;

import com.company.dao.UserDao;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Service;

@Service
public class UserService {


    @Autowired
    @Qualifier(value = "userDaoImpl")
    private UserDao userDao;

    public void add() {
        System.out.println("service add....");
        userDao.add();
    }

}

@Resource 可以根據(jù)類型龙优，可以根據(jù)名稱

package com.company.service;

import com.company.dao.UserDao;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;

@Service
public class UserService {


//    @Autowired
//    @Qualifier(value = "userDaoImpl")
//    private UserDao userDao;

    @Resource(name = "userDaoImpl")
    private UserDao userDao;

    public void add() {
        System.out.println("service add....");
        userDao.add();
    }

}

@Value

@Value(value = "abc")
private String name;

完全注解來發(fā)

1. 創(chuàng)建配置類，替代xml配置文件

package com.company.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

@Configuration
@ComponentScan(basePackages = "com.company")
public class SpringConfig {



}

@Test
public void test3() {
    ApplicationContext context = new AnnotationConfigApplicationContext(SpringConfig.class);
    UserService userService = context.getBean("userService", UserService.class);
    userService.add();
}