java框架篇---spring IOC依赖注入

spring依赖注入的方式有4种

构造方法注入
属性注入
工厂注入
注解注入

下面通过一个实例统一讲解：

User.java

package com.bjsxt.model;

public class User {
    private String username;
    private String password;
    public User(){}
    public User(String username, String password) {
        super();
        this.username = username;
        this.password = password;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    @Override
    public String toString() {
        return "User [username=" + username + ", password=" + password + "]";
    }
}

UserDAO.java

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


public interface UserDAO {
    public void save(User user);
}

UserDAO实现类UserDAOImpl

package com.bjsxt.dao.impl;

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


public class UserDAOImpl implements UserDAO {

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

}

工厂类

第一个：UserFactory

package com.bjsxt.factory;

import com.bjsxt.model.User;

public class UserFactory {
    public User CreatUser () {
        User user=new User();
        user.setUsername("周1");
        user.setPassword("oumyye");
        return user;
    }
}

第二个：UserFactory2

package com.bjsxt.factory;

import com.bjsxt.model.User;

public class UserFactory2 {
    public static User CreatUser () {
        User user=new User();
        user.setUsername("偶my耶1");
        user.setPassword("oumyye");
        return user;
    }
}

控制层：UserService

package com.bjsxt.service;
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 save(User user) {
        userDAO.save(user);
    }
    public UserDAO getUserDAO() {
        return userDAO;
    }
    public void setUserDAO(UserDAO userDAO) {
        this.userDAO = userDAO;
    }
    
    public UserService(UserDAO userDAO) {
        super();
        this.userDAO = userDAO;
    }
    
    public void destroy() {
        System.out.println("destroy");
    }
}

配置文件：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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">
    <!--        构造方法注入 -->
    <bean id="user" class="com.bjsxt.model.User" >
    <constructor-arg index="0" type="String" value="zhou"></constructor-arg>
    <constructor-arg index="1" type="String" value="password"></constructor-arg>
    </bean>
    
    <!-- 属性注入 -->
    <bean id="user1" class="com.bjsxt.model.User" >
    <property name="username" value="zhang"></property>
    <property name="password" value="oumyye"></property>
    </bean>
    <!-- 工厂注入 -->
    <bean  id= "userFactory" class="com.bjsxt.factory.UserFactory" > </bean>
    <bean id="user2" factory-bean="userFactory" factory-method="CreatUser"></bean>
    
    <!-- 静态工厂注入 -->
    <bean  id= "user3" class="com.bjsxt.factory.UserFactory2" factory-method="CreatUser"> </bean>
    
      <bean id="u" class="com.bjsxt.dao.impl.UserDAOImpl"></bean> 
    
      <bean id="userService" class="com.bjsxt.service.UserService" init-method="init" destroy-method="destroy" scope="prototype">
      
      <!-- <property name="userDAO" ref="u" /> -->
      
<!--        构造方法注入 -->
       <constructor-arg>
           <ref bean="u"/>
       </constructor-arg>
  </bean>
  

</beans>

测试类：

package com.bjsxt.service;

import static org.junit.Assert.*;

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

import com.bjsxt.model.User;

public class UserServiceTest {

    @Test
    public void test() {
        ApplicationContext applicationContext=new ClassPathXmlApplicationContext("beans.xml");
        UserService userService=(UserService) applicationContext.getBean("userService");
        //构造方法注入
        User user=(User) applicationContext.getBean("user");
        //属性注入
        User user1=(User) applicationContext.getBean("user1");
        //工厂注入
        User user2=(User) applicationContext.getBean("user2");
        //工厂注入
        User user3=(User) applicationContext.getBean("user3");
        
        System.out.println(user);
        System.out.println(user1);
        System.out.println(user2);
        System.out.println(user3);
        userService.save(user);
        userService.destroy();
    }

}

结果：

###########init
User [username=zhou, password=password]
User [username=zhang, password=oumyye]
User [username=周1, password=oumyye]
User [username=偶my耶1, password=oumyye]
user saved!
destroy

注解方式在后面详细介绍