Active Object 模式
0. 描述了什么事？
该章节为前几章节的综合运用。
1. 程序示例
1. Main.java
package active.object;
public class Main {
public static void main(String[] args) {
ActiveObject activeObject = ActiveObjectFactory.createActiveObject();
new MakerClientThread("Alice", activeObject).start();
new MakerClientThread("Bob", activeObject).start();
new DisplayClientThread("Chris", activeObject).start();
}
}
2. ActivationQueue.java
package active.object;
public class ActivationQueue {
private static final int MAX_COUNT = 100;
private final MethodRequest[] requests = new MethodRequest[MAX_COUNT];
private int tail, head, count;
public ActivationQueue() {
tail = 0;
head = 0;
count = 0;
}
public synchronized void putRequest(MethodRequest request) {
while (count >= MAX_COUNT) {
try {
wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
requests[tail] = request;
tail = (tail + 1) % MAX_COUNT;
count++;
notifyAll();
}
public synchronized MethodRequest takeRequest() {
while (count <= 0) {
try {
wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
MethodRequest request = requests[head];
head = (head + 1) % MAX_COUNT;
count--;
notifyAll();
return request;
}
}
3. ActiveObject.java
package active.object;
public interface ActiveObject {
Result makeString(int count, char fillchar);
void displayString(String content);
}
4. ActiveObjectFactory.java
package active.object;
public class ActiveObjectFactory {
public static ActiveObject createActiveObject() {
Servant servant = new Servant();
ActivationQueue queue = new ActivationQueue();
SchedulerThread scheduler = new SchedulerThread(queue);
Proxy proxy = new Proxy(scheduler, servant);
scheduler.start();
return proxy;
}
}
5. DisplayClientThread.java
package active.object;
public class DisplayClientThread extends Thread {
private final ActiveObject activeObject;
public DisplayClientThread(String name, ActiveObject activeObject) {
super(name);
this.activeObject = activeObject;
}
@Override
public void run() {
try {
for (int i = 0; true; i++) {
// 没有返回值的调用
String string = Thread.currentThread().getName() + " " + i;
activeObject.displayString(string);
Thread.sleep(200);
}
} catch (InterruptedException e) {
}
}
}
6. DisplayStringRequest.java
package active.object;
public class DisplayStringRequest extends MethodRequest 7. FutureResult.java
package active.object;
public class FutureResult extends Result {
private Result result;
private boolean ready;
public synchronized void setResult(Result result) {
if (ready) return;
this.result = result;
ready = true;
notifyAll();
}
@Override
public synchronized T getResultValue() {
while (!ready) {
try {
wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
return result.getResultValue();
}
}
8. MakerClientThread.java
package active.object;
public class MakerClientThread extends Thread {
private final ActiveObject activeObject;
private final char fillchar;
public MakerClientThread(String name, ActiveObject activeObject) {
super(name);
this.activeObject = activeObject;
this.fillchar = name.charAt(0);
}
@Override
public void run() {
try {
for (int i = 0; true; i++) {
// 有返回值的调用
Result result = activeObject.makeString(i, fillchar);
Thread.sleep(10);
String value = result.getResultValue();
System.out.println(Thread.currentThread().getName() + " : value = " + value);
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
9. MakeStringRequest.java
package active.object;
public class MakeStringRequest extends MethodRequest {
private final int count;
private final char fillchar;
protected MakeStringRequest(Servant servant, FutureResult futureResult, int count, char fillchar) {
super(servant, futureResult);
this.count = count;
this.fillchar = fillchar;
}
@Override
public void execute() {
Result result = servant.makeString(count, fillchar);
futureResult.setResult(result);
}
}
10. MethodRequest.java
package active.object;
public abstract class MethodRequest {
protected final Servant servant;
protected final FutureResult futureResult;
protected MethodRequest(Servant servant, FutureResult futureResult) {
this.futureResult = futureResult;
this.servant = servant;
}
public abstract void execute();
}
11. Proxy.java
package active.object;
public class Proxy implements ActiveObject {
private final SchedulerThread scheduler;
private final Servant servant;
public Proxy(SchedulerThread scheduler, Servant servant) {
this.scheduler = scheduler;
this.servant = servant;
}
public Result makeString(int count, char fillchar) {
FutureResult future = new FutureResult<>();
scheduler.invoke(new MakeStringRequest(servant, future, count, fillchar));
return future;
}
public void displayString(String string) {
scheduler.invoke(new DisplayStringRequest(servant, string));
}
}
12. RealResult.java
package active.object;
public class RealResult extends Result {
private final T resultValue;
public RealResult(T resultValue) {
this.resultValue = resultValue;
}
@Override
public T getResultValue() {
return this.resultValue;
}
}
13. Result.java
package active.object;
public abstract class Result {
public abstract T getResultValue();
}
14. SchedulerThread.java
package active.object;
public class SchedulerThread extends Thread {
private final ActivationQueue queue;
public SchedulerThread(ActivationQueue queue) {
this.queue = queue;
}
public void invoke(MethodRequest request) {
queue.putRequest(request);
}
public void run() {
while (true) {
MethodRequest request = queue.takeRequest();
request.execute();
}
}
}
15 Servant.java
package active.object;
public class Servant implements ActiveObject {
@Override
public Result makeString(int count, char fillchar) {
char[] buffer = new char[count];
for (int i = 0; i < count; i++) {
buffer[i] = fillchar;
try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
return new RealResult<>(new String(buffer));
}
@Override
public void displayString(String content) {
try {
System.out.println("Display String : " + content);
Thread.sleep(10);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}