Java设计模式-----Chain of Responsibility职责链模式

源自：http://www.blogjava.net/flustar/archive/2007/12/14/cor.html

Chain of Responsibility职责链模式：

为了避免请求的发送者和接收者之间的耦合关系，使多个接受对象都有机会处理请求。将这些对象连成一条链，并沿着这条链传递该请求，直到有一个对象处理它为止。

例子：

public class Boy {

private boolean hasCar; // 是否有车
private boolean hasHouse; // 是否有房
private boolean hasResponsibility; // 是否有责任心

public Boy() {
}

public Boy(boolean hasCar, boolean hasHouse, boolean hasResponsibility) {
this.hasCar = hasCar;
this.hasHouse = hasHouse;
this.hasResponsibility = hasResponsibility;
}

public boolean isHasCar() {
return hasCar;
}

public void setHasCar(boolean hasCar) {
this.hasCar = hasCar;
}

public boolean isHasHouse() {
return hasHouse;
}

public void setHasHouse(boolean hasHouse) {
this.hasHouse = hasHouse;
}

public boolean isHasResponsibility() {
return hasResponsibility;
}

public void setHasResponsibility(boolean hasResponsibility) {
this.hasResponsibility = hasResponsibility;
}
}

public interface Handler {
public void handleRequest(Boy boy);
}

public class HouseHandler implements Handler {

private Handler handler;

public HouseHandler(Handler handler) {

this.handler = handler;
}

public Handler getHandler() {
return handler;
}

public void setHandler(Handler handler) {
this.handler = handler;
}

public void handleRequest(Boy boy) {
if (boy.isHasHouse()) {
System.out.println("没想到吧，我还有房子");
} else {
System.out.println("我也没有房");
handler.handleRequest(boy);
}
}
}

public class CarHandler implements Handler {

private Handler handler;

public CarHandler(Handler handler) {
this.handler = handler;
}

public Handler getHandler() {
return handler;
}

public void setHandler(Handler handler) {
this.handler = handler;
}

public void handleRequest(Boy boy) {
if (boy.isHasCar()) {
System.out.println("呵呵，我有辆车");
} else {
System.out.println("我没有车");
handler.handleRequest(boy);
}
}
}

public class ResponsibilityHandler implements Handler {

private Handler handler;

public ResponsibilityHandler(Handler handler) {
this.handler = handler;
}

public Handler getHandler() {
return handler;
}

public void setHandler(Handler handler) {
this.handler = handler;
}

public void handleRequest(Boy boy) {
if (boy.isHasResponsibility()) {
System.out.println("我只有一颗带Responsibility的心");
} else {
System.out.println("更没有责任心");
handler.handleRequest(boy);
}
}
}

public class Girl {

public static void main(String[] args) {

Boy boy = new Boy(false, false, true);// 这个boy没有车，也没有房，不过很有责任心
Handler handler = new CarHandler(new HouseHandler(
new ResponsibilityHandler(null)));// 也可以使用setHanlder方法
handler.handleRequest(boy);
}
}