tomcat管道模式 pipeline与valve详解

public class BasicValve implements Valve {
protected Valve next = null; 
public Valve getNext() {
return next;
}
public void invoke(String handling) {
    handling=handling.replaceAll("aa", "bb");
System.out.println("基础阀门处理完后：" + handling);
}
public void setNext(Valve valve) {
this.next = valve;
}
}

④ 第二个阀门，将传入的字符串中”11”替换成”22”

public class SecondValve implements Valve {
protected Valve next = null; 
public Valve getNext() {
return next;
}
public void invoke(String handling) {
handling = handling.replaceAll("11", "22");
System.out.println("Second阀门处理完后：" + handling);
getNext().invoke(handling);
}
public void setNext(Valve valve) {
this.next = valve;
}
}

⑤ 第三个阀门，将传入的字符串中”zz”替换成”yy”

public class ThirdValve implements Valve {
protected Valve next = null; 
public Valve getNext() {
return next;
}
public void invoke(String handling) {
handling = handling.replaceAll("zz", "yy");
System.out.println("Third阀门处理完后：" + handling);
getNext().invoke(handling);
}
public void setNext(Valve valve) {
this.next = valve;
}
}

⑥ 管道，我们一般的操作是先通过setBasic设置基础阀门，接着按顺序添加其他阀门，执行时的顺序是：先添加进来的先执行，最后才执行基础阀门。

public class StandardPipeline implements Pipeline {
protected Valve first = null; 
protected Valve basic = null; 
public void addValve(Valve valve) {
if (first == null) {
first = valve;
valve.setNext(basic);
} else {
Valve current = first;
while (current != null) {
if (current.getNext() == basic) {
current.setNext(valve);
valve.setNext(basic);
break;
}
current = current.getNext();
}
}
}
public Valve getBasic() {
return basic;
}
public Valve getFirst() {
return first;
}
public void setBasic(Valve valve) {
this.basic = valve;
}
}

⑦ 测试类

public class Main {
public static void main(String[] args) {
String handling="aabb1122zzyy";
StandardPipeline pipeline = new StandardPipeline();
BasicValve basicValve = new BasicValve();
SecondValve secondValve = new SecondValve();
ThirdValve thirdValve = new ThirdValve();
pipeline.setBasic(basicValve);
pipeline.addValve(secondValve);
pipeline.addValve(thirdValve);
pipeline.getFirst().invoke(handling);
}
}

输出的结果如下：

Second阀门处理完后：aabb2222zzyy
Third阀门处理完后：aabb2222yyyy
基础阀门处理完后：bbbb2222yyyy

这就是管道模式，在管道中连接一个或多个阀门，每个阀门负责一部分逻辑处理，数据按规定的顺序往下流。此模式分解了逻辑处理任务，可方便对某任务单元进行安装拆卸，提高了流程的可扩展性、可重用性、机动性、灵活性。