6.装配Bean基于注解

1.注解：就是一个类，使用@注解名称

开发中：使用注解 取代 xml配置文件。

@Component取代<bean class="">

@Component("id") 取代 <bean id="" class="">

 

2.web开发，提供3个@Component注解衍生注解（功能一样）取代<bean class="">

@Repository ：dao层

@Service：service层

@Controller：web层

 

3.依赖注入 ，给私有字段设置，也可以给setter方法设置

普通值：@Value("")

引用值：

方式1：按照【类型】注入

@Autowired

方式2：按照【名称】注入1

@Autowired

@Qualifier("名称")

方式3：按照【名称】注入2
@Resource("名称")

 

 

4.生命周期

初始化：@PostConstruct

销毁：@PreDestroy

5.作用域

@Scope("prototype") 多例

 

 注解使用前提，添加命名空间，让spring扫描含有注解类

 

例子一:

beans.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">
    <!-- 组件扫描，扫描含有注解的类 -->
    <context:component-scan base-package="com.jd.annotation.ioc"></context:component-scan>
</beans>

UserService.java

package com.jd.annotation.ioc;

/**
 * @author weihu
 * @date 2018/8/14/014 0:16
 */
public interface UserService {
    void addUser();
}

UserServiceImpl.java

package com.jd.annotation.ioc;

import org.springframework.stereotype.Component;

/**
 * @author weihu
 * @date 2018/8/14/014 0:16
 *
 * @Component("id") 取代 <bean id="" class="">
 */
@Component("userServiceId")
public class UserServiceImpl implements UserService {
    @Override
    public void addUser() {
        System.out.println("添加用户成功!");
    }
}

TestAnnoIoC.java

package com.jd.annotation.ioc;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * @author weihu
 * @date 2018/8/14/014 0:19
 */
public class TestAnnoIoC {

    @Test
    public void testAnnotitaion(){
        String xmlPath="com/jd/annotation/ioc/beans.xml";
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
        UserService userService = (UserService) applicationContext.getBean("userServiceId");
        userService.addUser();
    }
}

 

例子二:

beans.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">
    <!-- 组件扫描，扫描含有注解的类 -->
    <context:component-scan base-package="com.jd.annotation.web"></context:component-scan>
</beans>

StudentAction.java

package com.jd.annotation.web;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;

/**
 * @author weihu
 * @date 2018/8/14/014 0:25 controller层
 */
@Controller("studentActionId")
public class StudentAction {

    @Autowired  //默认按照类型
    private StudentService studentService;

    public void execute(){
        studentService.addStudent();
    }
}

StudentDao.java

package com.jd.annotation.web;

/**
 * @author weihu
 * @date 2018/8/14/014 0:28
 */
public interface StudentDao {
    void save();
}

StudentDaoImpl.java

package com.jd.annotation.web;
import org.springframework.stereotype.Repository;

/**
 * @author weihu
 * @date 2018/8/14/014 0:29
 *
 * Repository ：dao层
 */
@Repository("studentDaoId")
public class StudentDaoImpl implements StudentDao{
    @Override
    public void save() {
        System.out.println("save dao");
    }
}

StudentService.java

package com.jd.annotation.web;

/**
 * @author weihu
 * @date 2018/8/14/014 0:26
 */
public interface StudentService {
    void addStudent();
}

StudentServiceImpl.java

package com.jd.annotation.web;

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

/**
 * @author weihu
 * @date 2018/8/14/014 0:27 service层
 */
@Service
public class StudentServiceImpl implements StudentService {

    private StudentDao studentDao;

    @Autowired
    @Qualifier("studentDaoId")
    public void setStudentDao(StudentDao studentDao) {
        this.studentDao = studentDao;
    }

    @Override
    public void addStudent() {
        studentDao.save();

    }
}

TestAnnoWeb.java

package com.jd.annotation.web;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * @author weihu
 * @date 2018/8/14/014 0:44
 */
public class TestAnnoWeb {
    @Test
    public void testAnnotion(){
        String xmlPath="com/jd/annotation/web/beans.xml";
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
        StudentAction studentAction = applicationContext.getBean("studentActionId", StudentAction.class);
        studentAction.execute();
    }
}

 

例子三:

beans.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">
    <!-- 组件扫描，扫描含有注解的类 -->
    <context:component-scan base-package="com.jd.annotation.other"></context:component-scan>
</beans>

UserService.java

package com.jd.annotation.other;

public interface UserService {
    
    public void addUser();

}

UserServiceImpl.java

package com.jd.annotation.other;

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;

import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Service;

@Service("userServiceId")
//@Scope("prototype")
public class UserServiceImpl implements UserService {

    @Override
    public void addUser() {
        System.out.println("d_scope add user");
    }
    
    @PostConstruct
    public void myInit(){
        System.out.println("初始化");
    }
    @PreDestroy
    public void myDestroy(){
        System.out.println("销毁");
    }

}

TestOther.java

package com.jd.annotation.other;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class TestOther {
    
    @Test
    public void testBeforeAndAfter(){
        //spring 工厂
        String xmlPath = "com/jd/annotation/other/beans.xml";
        ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
        UserService userService = applicationContext.getBean("userServiceId" ,UserService.class);
        UserService userService2 = applicationContext.getBean("userServiceId" ,UserService.class);
        
        System.out.println(userService);
        System.out.println(userService2);
        
        applicationContext.close();
    }

}