depends-on的作用

depends-on的作用一般是一個bean依賴於另外一個bean，被依賴的bean一般用於一些初始化和收尾的工作

  先執行依賴bean的destory方法，後執行被依賴bean的destory方法

/**
 * 
 * 
 * <pre>HISTORY
 * ****************************************************************************
 *  ID   DATE           PERSON          REASON
 *  1    2018年1月17日      Simba.Hua         Create
 * ****************************************************************************
 * </pre>
 * @author Simba.Hua
 */
public class DependentBean {
	private ResourceBean resourceBean;
	
	public void write(String str) throws IOException {
		System.out.println("DependentBean寫資源" + str);
		resourceBean.getFos().write(str.getBytes());
	}
	public void init() throws IOException {
		System.out.println("DependentBean:初始化");
		resourceBean.getFos().write("DependentBean:初始化\r\n".getBytes());
	}
	public void destroy() throws IOException {
		System.out.println("DependentBean：銷燬資源");
		resourceBean.getFos().write("DependentBean:銷燬資源\r\n".getBytes());
	}
	public ResourceBean getResourceBean() {
		return resourceBean;
	}
	public void setResourceBean(ResourceBean resourceBean) {
		this.resourceBean = resourceBean;
	}
	
}
 

package com.shux.springsource.depends.on;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

/**
 * 描述：測試spring中，depends-on的作用
 * 
 * 
 * <pre>HISTORY
 * ****************************************************************************
 *  ID   DATE           PERSON          REASON
 *  1    2018年1月17日      Simba.Hua         Create
 * ****************************************************************************
 * </pre>
 * @author Simba.Hua
 */
public class ResourceBean {
	private FileOutputStream fos;
	private File file;
	public void init() {
		System.out.println("ResourceBean初始化");
		System.out.println("ResourceBean載入資源，做一些預操作");
		try {
			this.fos = new FileOutputStream(file);
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		}
	}
	
	public void destroy() {
		System.out.println("ResourceBean銷燬");
		System.out.println("ResourceBean釋放資源，進行一些清理操作");
		try {
			fos.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	public FileOutputStream getFos() {
		return fos;
	}

	public void setFos(FileOutputStream fos) {
		this.fos = fos;
	}

	public File getFile() {
		return file;
	}

	public void setFile(File file) {
		this.file = file;
	}
	
	
}
 

<!-- 測試depends-on -->
	<bean id="resourceBean" class="com.shux.springsource.depends.on.ResourceBean" init-method="init" destroy-method="destroy">
		<property name="file" value="D:/test.txt"></property>
	</bean>
	<bean id="dependentBean" class="com.shux.springsource.depends.on.DependentBean" init-method="init" destroy-method="destroy" depends-on="resourceBean">
		<property name="resourceBean" ref="resourceBean"></property>
	</bean>
 

 @Test
    public void testDependsOn() {
    	ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("mybeans.xml");
    	context.registerShutdownHook();
    	DependentBean dependentBean = context.getBean("dependentBean",DependentBean.class);
    	try {
			dependentBean.write("hello,是我正在寫入哦\r\n");
		} catch (IOException e) {
			e.printStackTrace();
		}
    }

look-up 用於解決當一個單例的bean的屬性中存在一個prototype的屬性bean，如果用set,get注入
 * 則prototype的屬性也會跟單例bean的生命週期一樣，即屬性bean只會產生一個例項bean，這不是我們想要的，
 * 我們想要的是可以產生不同的例項，而look-up就是解決這一問題的，用look-up即使宿主bean是單例的，只要屬性bean是
 * prototype型別的，就可以產生多個例項.

如下例子，例子來自http://jinnianshilongnian.iteye.com/blog/1415461

package com.shux.springsource.lookup;
/**
 * 描述：
 * 
 * <pre>HISTORY
 * ****************************************************************************
 *  ID   DATE           PERSON          REASON
 *  1    2018年1月18日      Simba.Hua         Create
 * ****************************************************************************
 * </pre>
 * @author Simba.Hua
 */
public interface HelloApi {

	void sayHello();

}

package com.shux.springsource.lookup;
/**
 * 描述：
 * 
 * <pre>HISTORY
 * ****************************************************************************
 *  ID   DATE           PERSON          REASON
 *  1    2018年1月18日      Simba.Hua         Create
 * ****************************************************************************
 * </pre>
 * @author Simba.Hua
 */
public class Printer {
	private int counter;
	public void print(String type) {
		System.out.println(type + "  printer " + counter ++);
	}
}

package com.shux.springsource.lookup;
/**
 * 
 * <pre>HISTORY
 * ****************************************************************************
 *  ID   DATE           PERSON          REASON
 *  1    2018年1月18日      Simba.Hua         Create
 * ****************************************************************************
 * </pre>
 * @author Simba.Hua
 */
public abstract class HelloImpl implements HelloApi{
	private Printer printer;
	@Override
	public void sayHello() {
		printer.print("setter");
		createPrototypePrinter().print("prototype");
		createSingletonPrinter().print("singleton");
	}
	public abstract Printer createPrototypePrinter();
	public Printer createSingletonPrinter() {
		System.out.println("該方法不會被執行，如果執行了就出錯了");
		return new Printer();
	}
	
	public void setPrinter(Printer printer) {
		this.printer = printer;
	}
}

	<!-- 測試look-up -->
	<bean id="prototypePrinter" class="com.shux.springsource.lookup.Printer" scope="prototype"></bean>
	
	<bean id="singletonPrinter" class="com.shux.springsource.lookup.Printer" scope="singleton"></bean>
	
	<bean id="prototypeHelloApi" class="com.shux.springsource.lookup.HelloImpl" scope="prototype">
		<property name="printer" ref="prototypePrinter"></property>
		<lookup-method name="createPrototypePrinter" bean="prototypePrinter"/>
		<lookup-method name="createSingletonPrinter" bean="singletonPrinter"/>
	</bean>
	
	<bean id="singletonHelloApi" class="com.shux.springsource.lookup.HelloImpl" scope="singleton">
		<property name="printer" ref="prototypePrinter"></property>
		<lookup-method name="createPrototypePrinter" bean="prototypePrinter"/>
		<lookup-method name="createSingletonPrinter" bean="singletonPrinter"/>
	</bean>

@Test
    public void testLookUp() {
    	ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("mybeans.xml");
    	System.out.println("------------Singleton sayHello-----------");
    	HelloApi singletonHelloApi = context.getBean("singletonHelloApi", HelloApi.class);
    	singletonHelloApi.sayHello();
    	singletonHelloApi = context.getBean("singletonHelloApi", HelloApi.class);
    	singletonHelloApi.sayHello();
    	System.out.println("------------Prototype sayHello-----------");
    	HelloApi prototypeHelloApi = context.getBean("prototypeHelloApi", HelloApi.class);
    	prototypeHelloApi.sayHello();
    	prototypeHelloApi = context.getBean("prototypeHelloApi", HelloApi.class);
    	prototypeHelloApi.sayHello();
    }

------------Singleton sayHello-----------
setter  printer 0
prototype  printer 0
singleton  printer 0
setter  printer 1
prototype  printer 0
singleton  printer 1
------------Prototype sayHello-----------
setter  printer 0
prototype  printer 0
singleton  printer 2
setter  printer 0
prototype  printer 0
singleton  printer 3