Spring 装配

摘要：有以下三种配置在中配置在中配置自动装配自动装配这里以转载为例子首先需要建立概念即，定义一个接口只需要实现添加两个注解，定义接口规定方法为启用组件扫描标题内容规定方法为扫描的时候，会直接按照该类所在的包，作为基础包，进行扫描对依赖的实现自动装

有以下三种配置
在xml中配置
在java中配置
bean自动装配

这里以转载CD为例子

首先需要建立CD概念

即，定义一个cd接口

只需要实现添加两个注解，

package com.ming;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

/**
 * 定义cd接口
 * @author ming
 */
@Configuration
@ComponentScan
public interface CompactDisc {
    /**
     * 规定方法为play
     */
    void play();
}

package com.ming;

import org.springframework.stereotype.Component;

/**
 *
 * @author ming
 */

// 启用组件扫描
@Component
class SgtPeppers implements CompactDisc {
    private String title = "标题";
    private String artist = "内容";
    /**
     * 规定方法为play
     */
    @Override
    public void play() {
        System.out.println(this.artist + this.title);
    }
}

package com.ming;

import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import static org.junit.Assert.*;

public class CompactDiscTest {
    private ApplicationContext applicationContext = null;

    @Before
    public void setUp() throws Exception {
        applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
    }

    @After
    public void tearDown() throws Exception {
    }

    @Test
    public void play() {
        CompactDisc compactDisc = applicationContext.getBean(CompactDisc.class);
        assertNotNull(compactDisc);
    }
}

扫描的时候，会直接按照该类所在的包，作为基础包，进行扫描

添加注解以后，初始化bean以后，会尽可能的满足bean的依赖

目录如下

package com.ming;

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

/**
 *
 * @author ming
 */
@Component
public class CDPlay implements MediaPlayer {
    CompactDisc compactDisc = null;

    @Autowired
    public CDPlay(CompactDisc compactDisc){
        this.compactDisc = compactDisc;
    }

    /**
     * 规定方法为play
     */
    @Override
    public void play() {
        compactDisc.play();
    }
}

package com.ming;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

/**
 * 定义cd接口
 * @author ming
 */
@Configuration
@ComponentScan
public interface CompactDisc {
    /**
     * 规定方法为play
     */
    void play();
}

package com.ming;

import org.springframework.context.annotation.ComponentScan;

/**
 * @author ming
 */
@ComponentScan
public interface MediaPlayer {
    /**
     * 规定方法为play
     */
    public void play();
}

package com.ming;

import org.springframework.stereotype.Component;

/**
 *
 * @author ming
 */

// 启用组件扫描
@Component
class SgtPeppers implements CompactDisc {
    private String title = "标题";
    private String artist = "内容";
    /**
     * 规定方法为play
     */
    @Override
    public void play() {
        System.out.println(this.artist + this.title);
    }
}

package com.ming;

import org.junit.After;
import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import static org.junit.Assert.*;

public class CompactDiscTest {
    private ApplicationContext applicationContext = null;

    @Before
    public void setUp() throws Exception {
        applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
    }

    @After
    public void tearDown() throws Exception {

    }

    @Test
    public void play() {
        MediaPlayer mediaPlayer = (MediaPlayer) applicationContext.getBean(MediaPlayer.class);
        mediaPlayer.play();
        assertNotNull(mediaPlayer);
    }
}

运行结果

在这里，在装配的时候，尽量满足配置规则进行装配

package com.ming;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 *
 * @author ming
 */
@Configuration  // 注解表明这是一个配置类
public class CDPlayerConfig {

    @Bean
    public CompactDisc sgtPeppers(){
        // 此处进行装配
        return new SgtPeppers();
    }

    /**
     * 注入装配
     * @return
     */
    @Bean
    public CDPlay cdPlay(){
        return new CDPlay(this.sgtPeppers());
    }
}