《Spring实战》学习笔记（一）装配Bean

自动转配Bean

创建可被发现的Bean

代码结构：

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);    }}

通过XML启用组件扫描

代码结构

程序清单

PS：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">    <!-- 启用组件扫描 -->    <context:component-scan base-package="soundsystem"/></beans>

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);    }}

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

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

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());    }}

---

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

<bean class="soundsystem.SgtPeppers"/>

（2）bean的ID为compactDisc

<bean id="compactDisc" class="soundsystem.SgtPeppers"/>

借助构造器注入初始化bean

构造器注入bean引用

（1）

<bean id="cdPlayer" class="soundsystem.CDPlayer">    <constructor-arg ref="compactDisc"/></bean>

（2）

<bean id="cdPlayer" class="soundsystem.CDPlayer" c:cd-ref="compactDisc" />

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）

<bean id="compactDisc" class="soundsystem.BlankDisc">    <constructor-arg value="hello"/>    <constructor-arg value="world"/></bean>

（2）

<bean id="compactDisc" class="soundsystem.BlankDisc"    c:_title="hello"    c:_artist="world" />

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

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

（1）

<bean id="cdPlayer" class="soundsystem.CDPlayer">    <property name="compactDisc" ref="compactDisc"/></bean>

（2）

<bean id="cdPlayer" class="soundsystem.CDPlayer" p:compactDisc-ref="compactDisc" />

将字面量注入到属性中

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.println("Playing "+title+" by "+artist);        for(String track : tracks) {            System.out.println("-Track: "+track);        }    }}

（1）

<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>

（2）

<bean id="compactDisc" class="soundsystem.BlankDisc" p:title="hello" p:artist="world">    <property name="tracks">        <list>            <value>11111</value>            <value>22222</value>            <value>33333</value>            <value>44444</value>            <value>55555</value>        <list>    </property></bean>

测试

代码结构

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">    <!-- 设置属性注入bean -->    <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>    <!-- 构造器注入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());    }}