职责链模式

概念：使多个对象都有机会处理请求，从而避免请求的发送者和接受者之间的耦合关系。将这个对象连成一条链，并沿着这条链传递该请求，知道有一个特对象处理他位置。

java代码：

public class HandlerTest {
    public static void main(String[] args) {
        ConcreteHandler concreteHandler = new ConcreteHandler();
        ConcreteHandler2 concreteHandler2 = new ConcreteHandler2();
        concreteHandler.setSuccessor(concreteHandler2);
        concreteHandler.HandleRequest(100);
    }
}
//处理器抽象类
public abstract class Handler {
    public Handler successor;
    public void setSuccessor(Handler handler){
        successor = handler;
    }
    public abstract void HandleRequest(int request);
}
//处理器1
public class ConcreteHandler extends Handler {
    @Override
    public void HandleRequest(int request) {
        if (request < 5){
            System.out.println("处理器1处理");
        }
        if (successor != null){
            successor.HandleRequest(request);
        }
    }
}
//处理器2
public class ConcreteHandler2 extends Handler {
    @Override
    public void HandleRequest(int request) {
        if (request > 5){
            System.out.println("处理器2处理");
        }
        if (successor != null){
            successor.HandleRequest(request);
        }
}