行为类模式（一）：职责链（Chain Of Responsibility）

定义

UML

public class Main
{
public static void main(String[] args)
{
Handler h1 = new ProjectManager();
Handler h2 = new DepManager();
Handler h3 = new GeneralManager();
h1.setSuccessor(h2);
h2.setSuccessor(h3);

System.out.println(h1.handlerFeeRequest("小李", 300));
System.out.println(h1.handlerFeeRequest("小张", 300));

System.out.println(h1.handlerFeeRequest("小李", 800));
System.out.println(h1.handlerFeeRequest("小张", 800));

System.out.println(h1.handlerFeeRequest("小李", 3000));
System.out.println(h1.handlerFeeRequest("小张", 3000));
}

/**
* 责任处理对象
*/
public static abstract class Handler
{
/**
* 下一个处理请求的处理对象
*/
protected Handler successor;

/**
* 设置下一个处理对象
*/
public void setSuccessor(Handler successor)
{
this.successor = successor;
}

/**
* 处理聚餐费用的请求
*/
public abstract String handlerFeeRequest(String name, double fee);
}

public static class ProjectManager extends Handler
{
@Override
public String handlerFeeRequest(String name, double fee)
{
String str = "";
if(fee < 500)
{
//小于500元的可以处理
if("小李".equals(name))
{
str = "项目经理同意" + name + "的聚餐费用" + fee + "元的请求";
}
else
{
str = "项目经理不同意" + name + "的聚餐费用" + fee + "元的请求";
}
}
else
{
if(this.successor != null)
{
return this.successor.handlerFeeRequest(name, fee);
}
}
return str;
}
}

public static class DepManager extends Handler
{
@Override
public String handlerFeeRequest(String name, double fee)
{
String str = "";
if(fee < 1000)
{
//小于1000元的可以处理
if("小李".equals(name))
{
str = "部门经理同意" + name + "的聚餐费用" + fee + "元的请求";
}
else
{
str = "部门经理不同意" + name + "的聚餐费用" + fee + "元的请求";
}
}
else
{
if(this.successor != null)
{
return this.successor.handlerFeeRequest(name, fee);
}
}
return str;
}
}

public static class GeneralManager extends Handler
{
@Override
public String handlerFeeRequest(String name, double fee)
{
String str = "";
//可以处理任意金额
if("小李".equals(name))
{
str = "总经理同意" + name + "的聚餐费用" + fee + "元的请求";
}
else
{
str = "总经理不同意" + name + "的聚餐费用" + fee + "元的请求";
}
return str;
}
}
}