Two Implementations of the Chain Of Responsibility Pattern
Two Implementations of the Chain Of Responsibility Pattern
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The Chain of Responsibility design pattern is needed when a few processors should exist for performing an operation and a particular order should be defined for those processors. Also the changeability of the order of processors on runtime are important.
public abstract class Processor {
protected Processor next;
protected int threshold;
public void setNextProcessor(Processor p) {
next = p;
}
public void process(String data, int value) {
if (value <= threshold) {
process(data);
}
if (next != null) {
next.message(data, threshold);
}
}
abstract protected void processData(String data);
}
public class ProcessorA extends Processor {
public ProcessorA (int threshold) {
this.threshold = threshold;
}
protected void processData(String data) {
System.out.println("Processing with A: " + data);
}
}
public class ProcessorB extends Processor {
public ProcessorB (int threshold) {
this.threshold = threshold;
}
protected void writeMessage(String data) {
System.err.println("Processing with B: " + data);
}
}
public class Client {
public static void main(String[] args) {
Processor p, p1, p2;
p1 = p = new ProcessorA(2);
p2 = new ProcessorB(1);
p1.setNextProcessor(p2);
// Handled by ProcessorA
p.process("data1", 2);
// Handled by ProcessorA and ProcessorB
p.process("data2", 1);
}
}
public abstract class Processor {
protected Processor next;
protected int threshold;
public void setNextProcessor(Processor p) {
next = p;
}
abstract protected void processData(String data);
}
public class ProcessorA extends Processor {
public ProcessorA (int threshold) {
this.threshold = threshold;
}
protected void processData(String data, int value) {
System.out.println("Processing with A: " + data);
if (value >= threshold && next != null) {
next.processData(data, value);
}
}
}
public class ProcessorB extends Processor {
public ProcessorB (int threshold) {
this.threshold = threshold;
}
protected void processData(String data, int value) {
System.out.println("Processing with B: " + data);
if (value >= threshold && next != null) {
next.processData(data, value);
}
}
}
public class Client {
public static void main(String[] args) {
Processor p, p1, p2;
p1 = p = new ProcessorA(2);
p2 = new ProcessorB(1);
p1.setNextProcessor(p2);
// Handled by ProcessorA
p.processData("data1", 1);
// Handled by ProcessorA and ProcessorB
p.processData("data2", 2);
}
}
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