《Spring实战》学习笔记（一）装配Bean

2019-11-14 11:17:31

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自动转配Bean

创建可被发现的Bean

代码结构：

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程序清单：

package soundsystem;public interface CompactDisc { void play();}

PS：@Component表明组件类

package soundsystem;import org.sPRingframework.stereotype.Component;@Componentpublic class SgtPeppers implements CompactDisc{ private String title = "Sgt.Pepper's Lonely Hearts Club Bands"; private String artist = "The Beatles"; public void play() { System.out.println("Playing "+title+" by "+artist); }}

PS：@ComponentScan注解启用了组件扫描，如果没有其他配置的话，@ComponentScan默认会扫描与配置类相同的包以及它的子包。这里是基于java的配置启用组件扫描

package soundsystem;import org.springframework.context.annotation.ComponentScan;import org.springframework.context.annotation.Configuration;@Configuration@ComponentScanpublic class CDPlayerConfig {}

测试

PS：@Autowired注解表明自动装配

import org.junit.Test;import org.junit.runner.RunWith;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.test.context.ContextConfiguration;import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;import soundsystem.CDPlayerConfig;import soundsystem.CompactDisc;import static org.junit.Assert.assertNotNull;@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(classes=CDPlayerConfig.class)public class CDPlayerTest { @Autowired private CompactDisc cd; @Test public void cdShouldNotBeNull() { assertNotNull(cd); }}

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通过xml启用组件扫描

代码结构

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程序清单

PS：applicationContext.xml

PS：一样

package soundsystem;public interface CompactDisc { void play();}

PS：一样

package soundsystem;import org.springframework.stereotype.Component;@Componentpublic class SgtPeppers implements CompactDisc{ private String title = "Sgt.Pepper's Lonely Hearts Club Bands"; private String artist = "The Beatles"; public void play() { System.out.println("Playing "+title+" by "+artist); }}

测试

PS：变为 @ContextConfiguration(locations = { “classpath*:/applicationContext.xml”})

import static org.junit.Assert.assertNotNull;@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(locations = { "classpath*:/applicationContext.xml"})public class CDPlayerTest { @Autowired private CompactDisc cd; @Test public void cdShouldNotBeNull() { assertNotNull(cd); }}

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为组件扫描的bean命名

（1）默认bean的ID为sgtPeppers

@Componentpublic class SgtPeppers implements CompactDisc{ private String title = "Sgt.Pepper's Lonely Hearts Club Bands"; private String artist = "The Beatles"; public void play() { System.out.println("Playing "+title+" by "+artist); }}

（2）bean的ID为Leo

@Component("Leo")public class SgtPeppers implements CompactDisc{ private String title = "Sgt.Pepper's Lonely Hearts Club Bands"; private String artist = "The Beatles"; public void play() { System.out.println("Playing "+title+" by "+artist); }}

（3）bean的ID为Leo

@Named("Leo")public class SgtPeppers implements CompactDisc{ private String title = "Sgt.Pepper's Lonely Hearts Club Bands"; private String artist = "The Beatles"; public void play() { System.out.println("Playing "+title+" by "+artist); }}

设置组件扫描的基础包

（1）扫描soundsystem

@Configuration@ComponentScan("soundsystem")public class CDPlayerConfig {}

（2）扫描soundsystem,video

@Configuration@ComponentScan(basePackages={"soundsystem","video"})public class CDPlayerConfig {}

（3）扫描CDPlayer类,DVDPlayer类所在的包

@Configuration@ComponentScan(basePackageClasses = {CDPlayer.class,DVDPlayer.class})public class CDPlayerConfig {}

通过为bean添加注解实现自动装配

代码结构

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程序清单

PS：任何方法都可以实现自动装配

package soundsystem;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Component;@Componentpublic class CDPlayer implements MediaPlayer { private CompactDisc cd; @Autowired public CDPlayer(CompactDisc cd) { this.cd = cd; } @Autowired public void setCompactDisc(CompactDisc cd) { this.cd = cd; } @Autowired public void insertDisc(CompactDisc cd) { this.cd = cd; } public void play() { cd.play(); }}

PS：Java配置组件扫描

package soundsystem;import org.springframework.context.annotation.ComponentScan;import org.springframework.context.annotation.Configuration;@Configuration@ComponentScanpublic class CDPlayerConfig {}package soundsystem;public interface CompactDisc { void play();}package soundsystem;public interface MediaPlayer { public void play();}package soundsystem;import org.springframework.stereotype.Component;/** * Created by adc333 on 2017/2/3. */@Componentpublic class SgtPeppers implements CompactDisc{ private String title = "hello"; private String artist = " world"; public void play() { System.out.print(title+artist); }}

测试

PS：控制台输出比较，这里简单输出hello world

import org.junit.Rule;import org.junit.Test;import org.junit.contrib.java.lang.system.StandardOutputStreamLog;import org.junit.runner.RunWith;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.test.context.ContextConfiguration;import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;import soundsystem.CDPlayerConfig;import soundsystem.CompactDisc;import soundsystem.MediaPlayer;import static org.junit.Assert.assertEquals;import static org.junit.Assert.assertNotNull;@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(classes = CDPlayerConfig.class)public class CDPlayerTest { @Rule public final StandardOutputStreamLog log = new StandardOutputStreamLog(); @Autowired private MediaPlayer player; @Autowired private CompactDisc cd; @Test public void cdShouldNotBeNull() { assertNotNull(cd); } @Test public void play() { player.play(); assertEquals("hello world",log.getLog()); }}

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通过Java代码装配bean

创建配置类

package soundsystem;import org.springframework.context.annotation.Configuration;@Configurationpublic class CDPlayerConfig {}

声明简单的bean

（1）默认bean的ID为sgtPeppers

package soundsystem;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;@Configurationpublic class CDPlayerConfig { @Bean public CompactDisc sgtPeppers() { return new SgtPeppers(); }}

（2）bean的ID为Leo

package soundsystem;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;@Configurationpublic class CDPlayerConfig { @Bean(name="Leo") public CompactDisc sgtPeppers() { return new SgtPeppers(); }}

借助JavaConfig实现注入

ackage soundsystem;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;@Configurationpublic class CDPlayerConfig { @Bean public CompactDisc sgtPeppers() { return new SgtPeppers(); } @Bean public CDPlayer cdPlayer(CompactDisc compactDisc) { return new CDPlayer(compactDisc); }}

测试

代码结构

程序清单

package soundsystem;import org.springframework.beans.factory.annotation.Autowired;public class CDPlayer implements MediaPlayer { private CompactDisc cd; @Autowired public CDPlayer(CompactDisc cd) { this.cd = cd; } @Autowired public void setCompactDisc(CompactDisc cd) { this.cd = cd; } @Autowired public void insertDisc(CompactDisc cd) { this.cd = cd; } public void play() { cd.play(); }}package soundsystem;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;@Configurationpublic class CDPlayerConfig { @Bean public CompactDisc sgtPeppers() { return new SgtPeppers(); } @Bean public CDPlayer cdPlayer(CompactDisc compactDisc) { return new CDPlayer(compactDisc); }}package soundsystem;public interface CompactDisc { void play();}package soundsystem;public interface MediaPlayer { public void play();}package soundsystem;public class SgtPeppers implements CompactDisc{ private String title = "hello"; private String artist = " world"; public void play() { System.out.print(title+artist); }}

测试

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通过XML装配bean

声明一个简单的bean

（1）bean的ID为soundsystem.SgtPeppers#0，如果声明了另外一个SgtPeppers，同样没有明确标识，bean的ID为soundsystem.SgtPeppers#1

（2）bean的ID为compactDisc

借助构造器注入初始化bean

构造器注入bean引用

（1）

（2）

将字面量注入到构造器中

package soundsystem;public class BlankDisc implements CompactDisc { private String title; private String artist; public BlankDisc(String title, String artist) { this.title = title; this.artist = artist; } public void play() { System.out.println("Playing "+title+" by "+artist); }}

（1）

（2）

装配集合

package soundsystem;import java.util.List;/** * Created by adc333 on 2017/2/3. */public class BlankDisc implements CompactDisc { private String title; private String artist; private List<String> tracks; public BlankDisc(String title, String artist, List<String> tracks) { this.title = title; this.artist = artist; this.tracks = tracks; } public void play() { System.out.println("Playing "+title+" by "+artist); for(String track : tracks) { System.out.println("-Track: "+track); } }}<bean id="compactDisc" class="soundsystem.BlankDisc"> <constructor-arg value="hello"/> <constructor-arg value="world"/> <constructor-arg> <list> <value>11111</value> <value>22222</value> <value>33333</value> <value>44444</value> <value>55555</value> <list> </constructor-arg></bean>

设置属性

（1）

（2）

将字面量注入到属性中

（1）

（2）

测试

代码结构

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程序清单

package soundsystem;import java.util.List;public class BlankDisc implements CompactDisc { private String title; private String artist; private List<String> tracks; public void setTitle(String title) { this.title = title; } public void setArtist(String artist) { this.artist = artist; } public void setTracks(List<String> tracks) { this.tracks = tracks; } public void play() { System.out.print(title+artist); for(String track : tracks) { System.out.print(track); } }}package soundsystem;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Component;public class CDPlayer implements MediaPlayer { private CompactDisc cd; public CDPlayer(CompactDisc cd) { this.cd = cd; } public void play() { cd.play(); }}package soundsystem;public interface CompactDisc { void play();}package soundsystem;public interface MediaPlayer { public void play();}

applicationContext.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">  <bean id="compactDisc" class="soundsystem.BlankDisc"> <property name="title" value="hello"/> <property name="artist" value="world"/> <property name="tracks"> <list> <value>11111</value> <value>22222</value> <value>33333</value> <value>44444</value> <value>55555</value> </list> </property> </bean>  <bean id="cdPlayer" class="soundsystem.CDPlayer"> <constructor-arg ref="compactDisc"/> </bean></beans>

测试

import org.junit.Rule;import org.junit.Test;import org.junit.contrib.java.lang.system.StandardOutputStreamLog;import org.junit.runner.RunWith;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.context.ApplicationContext;import org.springframework.test.context.ContextConfiguration;import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;import soundsystem.*;import static org.junit.Assert.assertEquals;@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(locations = { "classpath*:/applicationContext.xml"})public class CDPlayerTest { @Autowired private ApplicationContext context; @Rule public final StandardOutputStreamLog log = new StandardOutputStreamLog(); @Test public void play() { CompactDisc compactDisc = (CompactDisc)context.getBean(BlankDisc.class); MediaPlayer cdPlayer = (MediaPlayer)context.getBean(CDPlayer.class); cdPlayer.play(); assertEquals("helloworld1111122222333334444455555",log.getLog()); }}

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