Assembly Bean- automated assembly Bean

Automated assembly Bean 1.0

Spring configuration options:

Assembly is dependent on the nature of the DI injection, Spring assembly mechanism provides the following three injection:

To be explicitly configured in the XMl
To be explicitly configured in java
Bean implicit discovery mechanism and automatic assembly

Automated assembly Bean:

Spring from two angles to automate the assembly:

Component scans (the Component Scanning): the Spring Bean will be used in the context created by auto-discovery.
Automatic assembly (as autowiring): the Spring automatically satisfy the dependencies between the bean.

Example:

CD and CDPlayer, if you do not insert the CD into (injected) into the player, the CD player is actually not much use, so to say, a CD player is dependent on the CD to complete its mission.

package com.CDDemo;
//CD的接口
public interface CompactDisc {
   public void play();
}

package com.CDDemo;
import org.springframework.stereotype.Component;
//CD的实现类 歌曲
@Component
public class SgtPeppers implements CompactDisc {
    private String title = "sgt";
    private String song = "Twinkle, twinkle, little start";
    public void play() {
        System.out.println("title:" + title + "song:" + song);
    }
}

package com.CDDemo;
import org.springframework.stereotype.Component;
//CD的实现类 歌曲
@Component
public class SgtPeppers implements CompactDisc {
    private String title = "sgt";
    private String song = "Twinkle, twinkle, little start";
    public void play() {
        System.out.println("title:" + title + "song:" + song);
    }
}

package com.CDDemo;
//测试类
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 static org.junit.Assert.assertNotNull;
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = CDPlayerConfig.class)
public class CDTest {
    @Autowired
    private CompactDisc cd;
    @Test
    public void cdShouldNotBeNull() {
      assertNotNull(cd);
      cd.play();
    }
}

Note that the above:

@Configuration

Spring assembly defines rules

@ComponentScan

The default configuration with the same scanning type package (herein scanning package com.CDDemo; the same package, and all of the following sub-packets).

Find out the class with @Component annotated so that we can find CompactDisc (notes because its example) and create a Bean for it in Spring.

Of course, you can also enable component scans through XML configuration way:

Assembly Bean- automated assembly Bean

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