Spring IoC、DI入门小程序

Alt+/智能提示xml配置文件节点及属性；在接口上使用Ctrl+T可以提示其实现类

一、IoC控制反转(将创建对象的权利交给spring)入门小程序

1、引入jar包

2、工程基本结构

3、新建UserService类

package hjp.spring.demo1;

import org.junit.Test;

public class UserService {
    public void addUser() {
        System.out.println("addUser");
    }
}

4、新建beans.xml文件配置bean

<?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.xsd">
<bean id="userServiceId" class="hjp.spring.demo1.UserService"></bean>
</beans>

5、新建测试类TestApp

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

public class TestApp {
    @Test
    public void demo1() {
        // 1、加载配置文件
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("hjp/spring/demo1/beans.xml");
        // 2、从Spring工厂获得对象
        UserService userService = (UserService) applicationContext.getBean("userServiceId");
        userService.addUser();
    }
}

二、DI依赖注入(自动实例化类中属性对象)入门小程序

1、沿用上面工程

2、新增包，结构如下

3、新建BookDao类

package hjp.spring.demo2;

public class BookDao {
    public void save() {
        System.out.println("save book");
    }
}

4、新建BookService类

package hjp.spring.demo2;

public class BookService {
    private BookDao bookDao;

    public BookDao getBookDao() {
        return bookDao;
    }

    public void setBookDao(BookDao bookDao) {
        this.bookDao = bookDao;
    }

    public void addBook() {
        bookDao.save();
    }
}

5、新建beans.xml文件配置bean

<?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.xsd">
    <!-- 创建dao -->
    <bean id="bookDaoId" class="hjp.spring.demo2.BookDao">
    </bean>
    <!-- 创建service -->
    <bean id="bookServiceId" class="hjp.spring.demo2.BookService">
        <!-- <property>进行依赖注入过程，底层将执行setter方法
        name 指BookService类bookDao属性
        ref 指属性实例引用
        -->
        <property name="bookDao" ref="bookDaoId"></property>
    </bean>
</beans>

6、新建测试类TestAPP

package hjp.spring.demo2;

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

public class TestApp {
    @Test
    public void demo1() {
        //获得容器
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("hjp/spring/demo2/beans.xml");
        //获得对象
        BookService bookService = applicationContext.getBean("bookServiceId", BookService.class);
        bookService.addBook();
    }
}