定义
责任链模式为请求创建了一个接收者对象的链。这种模式给予请求的类型，对请求的发送者和接收者进行解耦。
避免请求发送者与接收者耦合在一起，让多个对象都有可能接收请求
实现
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
| public abstract class AbstractLogger{
public static int INFO = 1;
public static int DEBUG = 2;
public static int ERROR = 3;
protected int level;
protected AbstractLogger nextLogger;
public void setNextLogger(AbstractLogger logger){
this.nextLogger = logger;
}
public void log(int level, String msg){
if(this.level <= level){
write(msg);
}
if(nextLogger != null){
nextLogger.log(level, msg);
}
}
abstract protected void write(String msg);
}
public class ConsoleLogger extends AbstractLogger{
public ConsoleLogger(int level){
this.level = level;
}
@Override
protected void write(String msg){
System.out.println(""+msg);
}
}
public class ErrorLogger extends AbstractLogger{
public ErrorLogger(int level){
this.level = level;
}
@Override
protected void write(String msg){
System.out.println(""+msg);
}
}
public class FileLogger extends AbstractLogger{
public FileLogger(int level){
this.level = level;
}
@Override
protected void write(String msg){
System.out.println(""+msg);
}
}
public class Demo{
public static void main(String[] args){
ConsoleLogger logger1 = new ConsoleLogger(AbstractLogger.INFO);
FileLogger logger2 = new FileLogger(AbstractLogger.DEBUG);
ErrorLogger logger3 = new ErrorLogger(AbstractLogger.ERROR);
logger2.setNextLogger(logger1);
logger3.setNextLogger(logger2);
logger3.log(AbstractLogger.INFO,"这是info级别的日志");
logger3.log(AbstractLogger.DEBUG,"这是debug级别的日志");
logger3.log(AbstractLogger.ERROR,"这是error级别的日志");
}
}
|
优点
1、降低耦合度，请求的发送者和接收者解耦
2、简化对象，对象不需要知道链的结构
3、增强灵活性，可以改变顺序，增删成员改变链内对象的顺序或存在
4、增加新的处理方式很容易
缺点
1、不能保证请求一定能被处理（或许必须要做一个兜底处理者）
2、链式调用，性能会有影响
3、不容易观察运行时的特征