《Spring實戰》學習筆記（二）JavaConfig @Import 和 @ImportResource注解的使用

2019-11-14 11:14:52

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最近在看《sPRing in Action 4th》,講到javaConfig的@Import和@ImportResource的使用，于是照著例子做了個小demo，加深自己的印象。在Spring中配置有xml和JavaConfig的配置方式，相比來說，使用JavaConfig的方式配置會更利于管理，類型安全。

demo項目結構(Maven約定)：

├── pom.xml└── src ├── main │ ├── java │ │ └── com │ │ └── jiaobuchong │ │ ├── config │ │ │ ├── CDConfig.java │ │ │ ├── CDPlayerConfig.java │ │ │ └── SoundSystemConfig.java │ │ ├── dao │ │ │ └── CompactDisc.java │ │ └── soundsystem │ │ ├── BlankDisc.java │ │ ├── CDPlayer.java │ │ └── SgtPeppers.java │ └── resources │ └── cons-injec.xml └── test └── java └── com └── jiaobuchong ├── soundsystem ├── CDPlayerTest.java ├── CDPlayerTest1.java └── CDPlayerTest2.java1234567891011121314151617181920212223242526

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config包下的三個配置類

CDConfig.java：

package com.jiaobuchong.config;import com.jiaobuchong.dao.CompactDisc;import com.jiaobuchong.soundsystem.SgtPeppers;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;@Configurationpublic class CDConfig { @Bean // 將SgtPeppers注冊為 SpringContext中的bean public CompactDisc compactDisc() { return new SgtPeppers(); // CompactDisc類型的 }}1234567891011121314

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CDPlayerConfig.java：

package com.jiaobuchong.config;import com.jiaobuchong.dao.CompactDisc;import com.jiaobuchong.soundsystem.CDPlayer;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.ComponentScan;import org.springframework.context.annotation.Configuration;import org.springframework.context.annotation.Import;@Configuration@Import(CDConfig.class) //導入CDConfig的配置public class CDPlayerConfig { @Bean(name = "cDPlayer") public CDPlayer cdPlayer(CompactDisc compactDisc) { /*這里會注入CompactDisc類型的bean 這里注入的這個bean是CDConfig.class中的CompactDisc類型的那個bean*/ return new CDPlayer(compactDisc); }}1234567891011121314151617181920

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SoundSystemConfig.java：

package com.jiaobuchong.config;import org.springframework.context.annotation.Configuration;import org.springframework.context.annotation.Import;import org.springframework.context.annotation.ImportResource;@Configuration@Import(CDPlayerConfig.class) @ImportResource("classpath:cons-injec.xml") //導入xml配置項public class SoundSystemConfig {}12345678910111213

12345678910111213@Configuration注解表示定義一個配置類，這里使用注解@Bean就好比如xml配置時的<bean>元素，如：<bean id="cdPlayer" class="com.jiaobuchong.soundsystem.CDPlayer"> <property name="cd" ref="compactDisc" /></bean>123

123@ImportResource類似于xml配置時的：<import resource="cons-injecxml" />1

dao包下的一個接口：

CompactDisc.java：

package com.jiaobuchong.dao;public interface CompactDisc { void play();}123456

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soundsystem包下的類：

BlankDisc.java：

package com.jiaobuchong.soundsystem;import com.jiaobuchong.dao.CompactDisc;import java.util.List;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); } }}123456789101112131415161718192021222324

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CDPlayer.java：

package com.jiaobuchong.soundsystem;import com.jiaobuchong.dao.CompactDisc;import org.springframework.beans.factory.annotation.Autowired;public class CDPlayer implements CompactDisc { private CompactDisc cd; @Autowired //構造函數注入 public CDPlayer(CompactDisc cd) { this.cd = cd; } public void play() { cd.play(); }}123456789101112131415161718

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SgtPeppers.java：

package com.jiaobuchong.soundsystem;import com.jiaobuchong.dao.CompactDisc;import org.springframework.stereotype.Component;public class SgtPeppers implements CompactDisc { private String title = "Sgt. Pepper's Lonely Hearts Club Band"; private String artist = "The Beatles"; public void play() { System.out.println("Playing " + title + " by " + artist); }}123456789101112

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xml配置文件

cons-injec.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:c="http://www.springframework.org/schema/c" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd "> <bean id="compactDisc" class="com.jiaobuchong.soundsystem.BlankDisc" c:_0="Sgt. Pepper's Lonely Hearts Club Band" c:_1="The Beatles"> <constructor-arg> <list> <value>Sgt. Pepper's Lonely Hearts Club Band</value> <value>With a Little Help from My Friends</value> <value>Lucy in the Sky with Diamonds</value> <value>Getting Better</value> <value>Fixing a Hole</value>  </list> </constructor-arg> </bean></beans>1234567891011121314151617181920212223

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測試類

CDPlayerTest.java：

package com.jiaobuchong.soundsystem;import com.jiaobuchong.config.CDConfig;import com.jiaobuchong.config.CDPlayerConfig;import com.jiaobuchong.dao.CompactDisc;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;/*CDPlayerTest takes advantage of Spring’s SpringJUnit4ClassRunner to have a Spring applicationcontext automatically created when the test starts. And the @Context-Configuration annotationtells it to load its configuration from the CDPlayerConfig class. */@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(classes = CDConfig.class)public class CDPlayerTest { @Autowired private CompactDisc cd; @Test public void cdShouldNotBeNull() {// assertNotNull(cd); cd.play(); }}1234567891011121314151617181920212223242526272829

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CDPlayerTest1.java：

package com.jiaobuchong.soundsystem;import com.jiaobuchong.config.CDConfig;import com.jiaobuchong.config.CDPlayerConfig;import com.jiaobuchong.dao.CompactDisc;import org.junit.Test;import org.junit.runner.RunWith;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.beans.factory.annotation.Qualifier;import org.springframework.test.context.ContextConfiguration;import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(classes = CDPlayerConfig.class)public class CDPlayerTest1 { @Autowired @Qualifier("cDPlayer") private CompactDisc cd; @Test public void cdShouldNotBeNull() {// assertNotNull(cd); cd.play(); }}123456789101112131415161718192021222324252627

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CDPlayerTest2.java：

package com.jiaobuchong.soundsystem;import com.jiaobuchong.config.CDPlayerConfig;import com.jiaobuchong.config.SoundSystemConfig;import com.jiaobuchong.dao.CompactDisc;import org.junit.Test;import org.junit.runner.RunWith;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.beans.factory.annotation.Qualifier;import org.springframework.test.context.ContextConfiguration;import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(classes = SoundSystemConfig.class)public class CDPlayerTest2 { @Autowired @Qualifier("cDPlayer") private CompactDisc cd; @Autowired @Qualifier("compactDisc") private CompactDisc cd1; @Test public void cdShouldNotBeNull() {// assertNotNull(cd); cd.play(); } @Test public void testBlankDisc() { cd1.play(); }}1234567891011121314151617181920212223242526272829303132333435

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看完這個demo代碼，基本上@Import和ImportResource的意義應該也就明白了，更多細節請參考《Spring in Action 4th》。

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