Spring的autoware自动装配，xml版

1.BookDaoImpl.class

这个类的对象将会被自动装配注入到BookServiceImpl类里面。

BookServiceImpl类里面讲调用BookDaoImpl类的方法。

package com.oxygen.dao.impl;

import com.oxygen.dao.BookDao;

public class BookDaoImpl implements BookDao {

    public void save() {
        System.out.println("Book Dao Save...");
    }
}

 

2.BookServiceImpl.class

此类和BookDaoImpl有依赖关系.

注意:在使用autowaire自动装配时，必须有个setter方法，也即setter注入。

package com.oxygen.service.impl;

import com.oxygen.dao.BookDao;
import com.oxygen.service.BookService;

public class BookServiceImpl implements BookService {
    private BookDao bookDao;

    //使用autowaire，需要有setter方法
    //如果没有setter，会报空指针异常
    public void setBookDao(BookDao bookDao) {
        this.bookDao = bookDao;
    }


    public void save() {
        System.out.println("Book Service save...");
        bookDao.save();
    }
}

 

3.XML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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
    
    <bean id="bookDao" class="com.oxygen.dao.impl.BookDaoImpl"/>
    <bean id="bookService" class="com.oxygen.service.impl.BookServiceImpl" autowire="byType"/>
    
</beans>

　　

4.测试:

package com.oxygen;

import com.oxygen.service.BookService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * Hello world!
 *
 */
public class App 
{
    public static void main( String[] args )
    {

        ApplicationContext context=new ClassPathXmlApplicationContext("applicationContext.xml");
        BookService bookService = (BookService) context.getBean("bookService");
        bookService.save();
    }
}

 

自动装配的优先级低于setter注入与构造器注入。