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移动架构12_责任链模式

2017-10-05 21:51 281 查看
一、定义

使多个对象都有机会处理请求,从而避免了请求的发送者和接受者之间的耦合关系,将这些对象形成一条链,并沿着这条链传递该请求,直到有对象处理它为止。

二、使用场景

多个对象能够处理同一请求,具体处理则在运行时动态确定

在请求矗立者不明确的时候向多个对象提交同一个请求

需要动态制定一组对象处理请求

三、Demo
1.请求抽取:
public abstract class AbstractRequest {
private Object object;
public AbstractRequest(Object object)
{
this.object=object;
}
/**
* 具体的内容对象
* @return
*/
public Object getContent()
{
return object;
}
/**
* 获取请求级别
*/
public abstract int getRequestLevel();
}

2、处理抽取
public abstract class Handler {

public Handler nextHandler;

public void handleRequest(AbstractRequest abstractRequest){
if(getHandleLevel() == abstractRequest.getRequestLevel()){
handle(abstractRequest);
}else{
if(nextHandler != null){
nextHandler.handleRequest(abstractRequest);
}else{
System.out.println("->所有的处理对象都不能处理它");
}
}
}

/**
* 每个处理对象的具体处理方式
* @param abstractRequest
*/
public abstract void handle(AbstractRequest abstractRequest);

/**
* 每个对象处理的级别
* @return
*/
public abstract int getHandleLevel();
}

3、定义多个具体处理
public class Handler1 extends Handler {

@Override
public void handle(AbstractRequest abstractRequest) {
System.out.println("---handle1 处理请求:"+abstractRequest.getRequestLevel());
}

@Override
public int getHandleLevel() {
return 1;
}

}
public class Handler2 extends Handler {

@Override
public void handle(AbstractRequest abstractRequest) {
System.out.println("---handle2 处理请求:"+abstractRequest.getRequestLevel());
}

@Override
public int getHandleLevel() {
return 2;
}

}
public class Request3 extends AbstractRequest{

public Request3(Object object) {
super(object);
}

@Override
public int getRequestLevel() {
return 3;
}

}

4、定义几个具体请求
public class Request1 extends AbstractRequest{

public Request1(Object object) {
super(object);
}

@Override
public int getRequestLevel() {
return 1;
}

}
public class Request2 extends AbstractRequest{

public Request2(Object object) {
super(object);
}

@Override
public int getRequestLevel() {
return 2;
}

}
public class Request3 extends AbstractRequest{

public Request3(Object object) {
super(object);
}

@Override
public int getRequestLevel() {
return 3;
}

}

5使用
public class Client {
public static void main(String[] args){
Handler handler1 = new Handler1();
Handler handler2 = new Handler2();
Handler handler3 = new Handler3();
handler1.nextHandler = handler2;
handler2.nextHandler = handler3;

AbstractRequest request3 = new Request3("请求3");
handler1.handleRequest(request3);
}
}
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