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当你想把短生命周期的对象(如: prototype)注入到长生命周期的对象(如：singleton)时需要特别注意，Spring 提供了如下的解决办法。

使用代理 aop:scoped-proxy/

package shangbo.spring.example29;public interface MessageService {	String getMessage();}

package shangbo.spring.example29;public class MessageServiceImpl implements MessageService {	private int times = 0;	public String getMessage() {		times++;		return "Hello World-" + times;	}}

package shangbo.spring.example29;public class MessagePrinter {    final private MessageService service;    public MessagePrinter(MessageService service) {        this.service = service;    }    public void printMessage() {        System.out.println(this.service.getMessage());    }}

package shangbo.spring.example29;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;public class App {	public static void main(String[] args) {		// 实例化 Spring IoC 容器		ApplicationContext context = new ClassPathXmlApplicationContext("example.xml", MessagePrinter.class);				// 从容器中获得 MessagePrinter 的实例		MessagePrinter printer1 = context.getBean(MessagePrinter.class);		printer1.printMessage();				// 再次在容器中获得 MessagePrinter 的实例		MessagePrinter printer2 = context.getBean(MessagePrinter.class);		printer2.printMessage();	}}

使用 lookup 方法

package shangbo.spring.example30;public interface MessageService {	String getMessage();}

package shangbo.spring.example30;public class MessageServiceImpl implements MessageService {	private int times = 0;	public String getMessage() {		times++;		return "Hello World-" + times;	}}

package shangbo.spring.example30;public abstract class MessagePrinter {    public void printMessage() {    	MessageService service = createMessageService();        System.out.println(service.getMessage());    }        // 注意，这是传说中的 lookup 方法    protected abstract MessageService createMessageService();}

package shangbo.spring.example30;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;import shangbo.spring.example29.MessagePrinter;public class App {	public static void main(String[] args) {		// 实例化 Spring IoC 容器		ApplicationContext context = new ClassPathXmlApplicationContext("example.xml", MessagePrinter.class);				// 从容器中获得 MessagePrinter 的实例		MessagePrinter printer1 = context.getBean(MessagePrinter.class);		printer1.printMessage();				// 再次在容器中获得 MessagePrinter 的实例		MessagePrinter printer2 = context.getBean(MessagePrinter.class);		printer2.printMessage();	}}

Spring 还提供了其他方法，如注入 ，或实现 ApplicationContextAware 接口，但是它们需要继承 Spring 的接口，与 Spring 耦合在一起，不推荐使用。

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