SPRING IN ACTION 第4版筆記-第二章-002-@ComponentScan、@Autowired的用法

一、@ComponentScan

1.

@Configuration    //說明此類是配置文件
@ComponentScan //開啟掃描，會掃描當前類的包及其子包
public class CDPlayerConfig { 
}

2.

@ComponentScan(basePackages={"soundsystem", "video"})//掃描多個包
public class CDPlayerConfig { 
}

3.

@ComponentScan(basePackageClasses={CDPlayer.class,AAA.class})//指定要掃描的類
public class CDPlayerConfig { 
}

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二、@Autowired

1.可以在構造方法中用

@Component
public class CDPlayer implements MediaPlayer {private CompactDisc cd;@Autowired//@Injectpublic CDPlayer(CompactDisc cd) {this.cd = cd;}public void play() {cd.play();}}

2.在set方法中

@Autowired
public void setCompactDisc(CompactDisc cd) {
this.cd = cd;
}

3.在一般的方法中

@Autowired
public void insertDisc(CompactDisc cd) {
this.cd = cd;
}

4.如果依賴不是必需的，可設置屬性

@Autowired(required=false)
public CDPlayer(CompactDisc cd) {
this.cd = cd;
}

5.可用@Inject替代

package soundsystem;
import javax.inject.Inject;
import javax.inject.Named;
@Named
public class CDPlayer {
...
@Inject
public CDPlayer(CompactDisc cd) {
this.cd = cd;
}
...
}

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