Spring框架annotation实现IOC介绍

Spring学习笔记（三）

续Spring 学习笔记(二)之后，对Spring框架的annotation实现方法进行整理

本文目录

@Autowire 
1 @Autowire+@Qualifier tips 
2 myeclipse content小技巧
@Resource
1@Resource(name,type)
2与@Autowire的区别 按名字和按类型
@Component
1@Resource+@Component
2@Resource(NAME)+@Component(NAME)
@scope
@PostConstruct and @PreDestroy

annotation实现的Spring XML配置

1 查询文档http://docs.spring.io/spring/docs/4.0.0.BUILD-SNAPSHOT/spring-framework-reference/htmlsingle/

<?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/> 

</beans>

注意

1 http://www.springframework.org/schema/context/spring-context.xsd 找到所在的文件位置并添加到中xml catalog 

2  写上 <context:annotation-config/> 表示启用annotation配置

3 介绍@Resource与@Autowire（通常使用@Resource）

1 @Resource与@Autowire的区别在于，Resource先是按照名字查找，然后再按照类型查找，

                                                      Autowire按照类型查找

2 通常我们只使用@Resource就可以了。

3 @Resource的语法 

@Resource(name="userDaoImpl") 如果不指定name则按照set的参数的名字来查找，一般情况下建议指定NAME的值，便于对多种实现进行明确定位

UserServiceImpl

package com.serviceImpl;

import javax.annotation.Resource;
import com.dao.UserDao;
import com.entity.User;
public class UserServiceImpl {

    private UserDao userDao;

    public void add(User user) {
        userDao.save(user);
    }
    public void update(User user) {
        userDao.update(user);
    }

    public void init() {// 初始方法
        System.out.println("init");
    }

    public void destroy() {// 销毁方法
        System.out.println("destory");
    }


    public UserDao getUserDao() {
        return userDao;
    }
    
    @Resource(name="userDaoImpl")
    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }
}

再来看配置文件

<?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 name="userDaoImpl" class="com.daoImpl.UserDaoImpl"/>
    <bean name="userDaoImpl2" class="com.daoImpl.UserDaoImpl2"/>
    
    <bean name="userServiceImpl" class="com.serviceImpl.UserServiceImpl">
         <!--        <property name="userDao" ref="userDaoImpl"></property>       使用了@Resource与@Autowire之后这一行就可以不用写了--> 
    </bean>
    

</beans>

测试类

package com.serviceImpl.test;
import org.junit.Before;
import org.junit.Test;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.entity.User;
import com.serviceImpl.UserServiceImpl;

public class UserServiceImplTest {
    User user;

    @Before
    public void setUp() throws Exception {
        user = new User();
        user.setName("testName");
        user.setRemark("testRemark");
    }

    @Test
    public void testAdd() {
        ClassPathXmlApplicationContext app = new ClassPathXmlApplicationContext("beans.xml");
         UserServiceImpl UserServiceImpl = (UserServiceImpl)app.getBean("userServiceImpl");
         UserServiceImpl.add(user);//调用方法
         UserServiceImpl.update(user);//调用方法
    }

}

执行结果

testName-->testRemark save --调用UserDaoImpl!
testName-->testRemark update --调用UserDaoImpl!

TIPS:如果按@不出现提示怎么办？

在Myeclipse 中的JAVA editor中配置一下即可

4 @Component介绍

1 Component是组件化的注解对整个类进行初始化时使用

2 @Component的语法 

   Component注释位于类的上方，Component（NAME）用于指定名字，不指定则用类名（第一个首字母小写）

package com.daoImpl;
import org.springframework.stereotype.Component;

import com.dao.UserDao;
import com.entity.User;
@Component
public class UserDaoImpl implements UserDao{

    public void save(User user) {
        System.out.println(user.getName()+"-->"+user.getRemark()+"  save --调用UserDaoImpl!");
    }

    public void update(User user) {
        System.out.println(user.getName()+"-->"+user.getRemark()+"  update --调用UserDaoImpl!");
    }
}

  @Component需要在XML里配置搜索带有@Component注解路径

<?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/>
    <context:component-scan base-package="com.daoImpl"></context:component-scan>  <!--  配置component路径，如果配置根目录会很方便，不过初始化速度会有点影响--> 
    <bean name="userDaoImpl2" class="com.daoImpl.UserDaoImpl2"/>
    
    <bean name="userServiceImpl" class="com.serviceImpl.UserServiceImpl">
         <!--        <property name="userDao" ref="userDaoImpl"></property>       使用了@Resource与@Autowire之后这一行就可以不用写了--> 
    </bean>
    

</beans>

3 让我们把所有的类全部配上，这样XML里会少很多内容

package com.serviceImpl;

import javax.annotation.Resource;

import org.springframework.stereotype.Component;

import com.dao.UserDao;
import com.entity.User;
@Component
public class UserServiceImpl {

    private UserDao userDao;

    public void add(User user) {
        userDao.save(user);
    }
    public void update(User user) {
        userDao.update(user);
    }

    public void init() {// 初始方法
        System.out.println("init");
    }

    public void destroy() {// 销毁方法
        System.out.println("destory");
    }


    public UserDao getUserDao() {
        return userDao;
    }
    
    @Resource(name="userDaoImpl")
    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }
}

package com.daoImpl;
import org.springframework.stereotype.Component;

import com.dao.UserDao;
import com.entity.User;
@Component
public class UserDaoImpl implements UserDao{

    public void save(User user) {
        System.out.println(user.getName()+"-->"+user.getRemark()+"  save --调用UserDaoImpl!");
    }

    public void update(User user) {
        System.out.println(user.getName()+"-->"+user.getRemark()+"  update --调用UserDaoImpl!");
    }
}

package com.daoImpl;

import org.springframework.stereotype.Component;

import com.dao.UserDao;
import com.entity.User;
@Component
public class UserDaoImpl2 implements UserDao{

    public void save(User user) {
        System.out.println(user.getName()+"-->"+user.getRemark()+"  save --调用UserDaoImpl2!");
    }

    public void update(User user) {
        System.out.println(user.getName()+"-->"+user.getRemark()+"  update  --调用UserDaoImpl2!");
    }
}

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/>
    <context:component-scan base-package="com.daoImpl"></context:component-scan>  <!--  配置component路径，如果配置根目录会很方便，不过初始化速度会有点影响--> 
    <context:component-scan base-package="com.serviceImpl"></context:component-scan>
    
 <!--   <bean name="userDaoImpl2" class="com.daoImpl.UserDaoImpl2"/>  使用了component配置这个不需要了       --> 
    
<!--    <bean name="userServiceImpl" class="com.serviceImpl.UserServiceImpl">     使用了component配置这个不需要了       --> 
         <!--        <property name="userDao" ref="userDaoImpl"></property>       使用了@Resource与@Autowire之后这一行就可以不用写了--> 
<!--    </bean>-->
    

</beans>

测试类

package com.serviceImpl.test;
import org.junit.Before;
import org.junit.Test;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.entity.User;
import com.serviceImpl.UserServiceImpl;

public class UserServiceImplTest {
    User user;

    @Before
    public void setUp() throws Exception {
        user = new User();
        user.setName("testName");
        user.setRemark("testRemark");
    }

    @Test
    public void testAdd() {
        ClassPathXmlApplicationContext app = new ClassPathXmlApplicationContext("beans.xml");
         UserServiceImpl UserServiceImpl = (UserServiceImpl)app.getBean("userServiceImpl");
         UserServiceImpl.add(user);//调用方法
         UserServiceImpl.update(user);//调用方法
    }

}

执行结果

testName-->testRemark save --调用UserDaoImpl!
testName-->testRemark update --调用UserDaoImpl!

总结@Component与@Resource

1 Component是定义初始化的类，相当于<bean />里的配置，且必须在XML里配置初始化component的搜索范围

2 @Resource是定义<bean></bean>里的<proptity >里的配置

3 两者结合的时候，开发速度能够明显加快，毕竟代码量少了很多

4 @scope

1 在类的上面配置

package com.serviceImpl;

import javax.annotation.Resource;

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

import com.dao.UserDao;
import com.entity.User;
@Scope("singleton")
@Component
public class UserServiceImpl {

    private UserDao userDao;

    public void add(User user) {
        userDao.save(user);
    }
    public void update(User user) {
        userDao.update(user);
    }

    public void init() {// 初始方法
        System.out.println("init");
    }

    public void destroy() {// 销毁方法
        System.out.println("destory");
    }


    public UserDao getUserDao() {
        return userDao;
    }
    
    @Resource(name="userDaoImpl")
    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }
}

执行效果不再演示

总结@scope

1 相当于在bean的类上面配置了scope，执行结果可参考笔记（一）

5@PostConstruct and @PreDestroy

package com.serviceImpl;

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

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

import com.dao.UserDao;
import com.entity.User;
@Scope("singleton")
@Component
public class UserServiceImpl {

    private UserDao userDao;

    public void add(User user) {
        userDao.save(user);
    }
    public void update(User user) {
        userDao.update(user);
    }
    @PostConstruct
    public void init() {// 初始方法
        System.out.println("init");
    }
    @PreDestroy
    public void destroy() {// 销毁方法
        System.out.println("destory");
    }


    public UserDao getUserDao() {
        return userDao;
    }
    
    @Resource(name="userDaoImpl")
    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }
}

执行结果

init
testName-->testRemark save --调用UserDaoImpl!
testName-->testRemark update --调用UserDaoImpl!
destory

总结@PostConstruct and @PreDestroy

1 相当于在bean的类上面配置了init-method，和destroy-method，在annotation里面配置则是在bean类的方法上配置即可

通过本文可以了解

@Autowire 
1 @Autowire+@Qualifier tips
2 myeclipse content小技巧
@Resource
1@Resource(name,type)
2与@Autowire的区别 按名字和按类型
@Component
1@Resource+@Component
2@Resource(NAME)+@Component(NAME)
@scope
@PostConstruct and @PreDestroy