[英]Java how to wait until a command has completed?
I have the following script: 我有以下脚本:
Connection con = new Connection("host",80);
ByteBuffer loginbb = ByteBuffer.allocate(300);
<snip>
loginbb.flip();
byte[]login = new byte[loginbb.remaining()];
loginbb.get(login);
ByteBuffer headerbb = ByteBuffer.allocate(7);
<snip>
headerbb.flip();
byte[]header = new byte[headerbb.remaining()];
headerbb.get(header);
con.run(login, header);
try {
Thread.sleep(1000);
} catch(InterruptedException ex) {
Thread.currentThread().interrupt();
}
long pid = Long.parseLong(request.getParameter("player"));
PrintWriter out = response.getWriter();
ByteBuffer bb = ByteBuffer.allocate(100);
bb.putLong(pid);
bb.putLong(pid);
bb.put((byte) 0x00);
bb.flip();
byte[] payload = new byte[bb.remaining()];
bb.get(payload);
ByteBuffer headerbb2 = ByteBuffer.allocate(7);
<snip>
headerbb2.flip();
byte[]header2 = new byte[headerbb2.remaining()];
headerbb2.get(header2);
con.send(payload, header2);
try {
Thread.sleep(700);
} catch(InterruptedException ex) {
Thread.currentThread().interrupt();
}
Gson gson = new GsonBuilder().setPrettyPrinting().create();
JsonParser jp = new JsonParser();
JsonElement je = jp.parse(Avatar.getJson().toString());
String json = gson.toJson(je);
out.flush();
out.println(json);
out.flush();
Notice the following? 请注意以下内容?
try {
Thread.sleep(700);
} catch(InterruptedException ex) {
Thread.currentThread().interrupt();
}
and this: 和这个:
try {
Thread.sleep(1000);
} catch(InterruptedException ex) {
Thread.currentThread().interrupt();
}
So that is pausing my script for some time but I don't want it like that as the script may take longer or less time. 所以这会暂停我的脚本一段时间,但是我不希望这样,因为脚本可能会花费更长或更短的时间。 That would be a waste of some time D:
那会浪费一些时间D:
What I want to happen is that it just waits for the stuff to finish. 我想发生的是,它只是等待内容完成。
con.run basically does an initial task and then a con.send. con.run基本上会执行初始任务,然后进行协商。
con.send basically runs this: con.send基本上运行以下命令:
private void sendToServer(byte[] message, int length, byte[]header) {
byte[]payload = outrc4.encrypt(message,false);
byte[] data = new byte[header.length+payload.length];
System.arraycopy(header,0,data,0,header.length);
System.arraycopy(payload,0,data,header.length,payload.length);
try {
out.write(data);
} catch (IOException e) {
System.out.println("Error!");
}
}
It just sends the packet to the server. 它只是将数据包发送到服务器。
From here, on the con.run I get multiple packets back. 从这里,在con.run上,我得到了多个数据包。 I can catch the ID of the packet and in the loop that receives and parses the packet I can add an if statement which checks if the loginDone packet is received.
我可以捕获数据包的ID,并在接收和解析数据包的循环中添加一个if语句,该语句检查是否已收到loginDone数据包。
void receive() {
try {
while (in.available() > -1) {
int type = in.readUnsignedShort();
int size = in.readUnsignedByte();
size <<= 8;
size |= in.readUnsignedByte();
size <<= 8;
size |= in.readUnsignedByte();
int version = in.readUnsignedShort();
byte array[] = new byte[7];
array[0] = (byte)((type >>> 8) & 0xFF);
array[1] = (byte)(type & 0xFF);
array[2] = (byte)((size >>> 16) & 0xFF);
array[3] = (byte)((size >>> 8) & 0xFF);
array[4] = (byte)(size & 0xFF);
array[5] = (byte)((version >>> 8) & 0xFF);
array[6] = (byte)(version & 0xFF);
final byte[] reply = new byte[size];
in.readFully(reply,0,size);
byte[] data = new byte[array.length + reply.length];
System.arraycopy(array, 0, data, 0, array.length);
System.arraycopy(reply, 0, data, array.length, reply.length);
byte[] decryptedPayload = inrc4.encrypt(reply,false);
if(type == 20000){
updateKeys(decryptedPayload);
}
if(type == 24411){
//this one means that the 1st packet that uses con.run is done
System.out.println("Logged In!");
}
if(type == 24334){
//this one means that the 2nd packet that uses con.send is done
InputStream myis = new ByteArrayInputStream(decryptedPayload);
new Avatar(myis);
t.interrupt();
}
}
} catch (Exception e) {}
}
Take not of these comments: //this one means that the 2nd packet that uses con.send is done and //this one means that the 1st packet that uses con.run is done 不接受这些注释://这表示使用con.send的第二个数据包已完成,//这表示使用con.run的第一个数据包已完成
This is as far as I have got. 据我所知。 Does anyone have any idea on what I should do from here?
有谁知道我应该从这里做什么?
If your server and client are in the same java process, use a CountDownLatch to do that, or thread.join() . 如果您的服务器和客户端在同一个Java进程中,请使用CountDownLatch或thread.join() 。 If they are different machines, read the EDIT part.
如果它们是不同的机器,请阅读EDIT部分。
class Foo extends Thread {
CountDownLatch latch;
public Foo(CountDownLatch latch) {
this.latch = latch;
}
@Override
public synchronized void start() {
try {
sleep(1000);
latch.countDown(); // in every call latch decrease one, when it reach to zero, every thread that is waiting the latch will continue.
sleep(100);
} catch (InterruptedException e) {
}
}
}
class FooBar {
public static void main(String[] args) throws InterruptedException {
CountDownLatch latch = new CountDownLatch(1);
new Foo(latch).start();
latch.await(); // wait latch reach to zero. BE CAREFUL, IT'S NOT WAIT(),
// IT'S AWAIT()
System.out.println("done");
}
}
EDIT I will keep the code above for the purposes of simplicity. 编辑为了简单起见,我将保留上面的代码。 I think it's very self-explanatory, could help the others.
我认为这很不言自明,可以帮助其他人。
Ok, if you want to wait until receive()
method is completely, you need to develop a way that the server can say to the client that method is completed, or you can develop a way that your client keeps checking a some state in the server, like isTaskCompleted()
. 好的,如果您要等到
receive()
方法完全完成,则需要开发一种方法,使服务器可以对客户端说该方法已完成,或者可以开发一种方法,使您的客户端不断检查客户端中的某些状态。服务器,例如isTaskCompleted()
。 I don't know how dificult is your situation to make the server send a packet to the client. 我不知道您的情况如何使服务器向客户端发送数据包。 I will describe basically two approaches to this situation, I will use others name of class and variables, so try to adapt to your code.
我将基本上描述两种解决这种情况的方法,我将使用其他名称的类和变量,因此请尝试适应您的代码。
public class WaitServer extends Thread {
synchronized void serverCompleted() {
// when server completes
notify();
}
@Override
public synchronized void start() {
try {
wait(); // waits the server
} catch (InterruptedException e) {
}
}
}
class ClientSide {
void doSomething() {
// ... some stuff ....
sendToServer();
new WaitServer().join();
// continues execution
}
}
class ServerSide {
void received() {
// ... do some stuff .....
if (someStuff) {
sendSignalToClient();
}
// .. others stuff
}
void sendSignalToClient() {
// here of course you need to send in the way that you are sending today, this is "pseudocode"
client.serverCompleted()
}
}
Another approach is to make your client checking the server until task is completed, simply create a Thread the send a verification of the job, if not completed sleep for some time. 另一种方法是让您的客户端检查服务器,直到任务完成为止,只需创建一个线程即可发送作业验证,如果一段时间未完成睡眠。 When you want to make a thread to wait another use
join()
. 当您想让一个线程等待另一个时,请使用
join()
。 If you want a thread to wait some part of the processing inside another, use CountDownLatch
. 如果希望线程在另一个内部等待处理的某些部分,请使用
CountDownLatch
。
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