Detailed description of JSP Spring Automatic Assembly Bean instance, springbean

Detailed description of JSP Spring Automatic Assembly Bean instance, springbean

Spring automated Bean assembly

Declare a cd interface:

public interface CompactDisc {  public abstract void play();}

Implement the cd interface:

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

Declare cdplayer:

@ Component ("CDplayer") // indicates that this class is used as a Component class and configuration Bean instance is unnecessary, the component name public class CDPlayer {/** @ Autowired annotation in parentheses can be used on the constructor or the set method, it can also be directly put in the following code. * spring will satisfy the dependencies with this annotation. If only one bean matches the dependency requirement, this bean will be assembled. @ Autowired is assembled by type by default. **/@ Autowired private CompactDisc cd; public CompactDisc getCd () {return cd;} public void setCd (CompactDisc cd) {this. cd = cd;} public void play () {cd. play ();}}

Test class:

public class CDPlayerTest {  public static void main(String[] args) {    ApplicationContext context=new ClassPathXmlApplicationContext("applicationContext.xml");    CDPlayer cdPlayer= (CDPlayer) context.getBean("CDplayer");    cdPlayer.play();  }}

Xml: automatically scans packages to find annotation classes.

<context:component-scan base-package="com.xue.soundsystem"></context:component-scan>

Summary: @ Component: equivalent to adding an instance to the bean of xml, with the id in the brackets. @ Autowired searches for matched instances by type for matching. @ Resource can be assembled by name.

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