Question

我编写了一个java socket服务器程序，它连续监听端口。它为传入数据创建一个新的文本文件，但我想每隔30分钟创建一个新的文本文件。

有人可以帮我安排每30分钟一次吗？

谢谢。

@paul：我有以下代码：

import java.io.*;
import java.net.*;
import java.util.*;
import java.text.*;
import java.util.Timer;
import java.util.TimerTask;

public class DateServer extends Thread {

    static public String str;   

   public static void main(String args[]) {

       String pattern = "yyyyMMdd-hhmm"; 
        SimpleDateFormat format = new SimpleDateFormat (pattern); 
        str = format.format(new Date());
        int delay = 0;
        int period = 180000;
        Timer timer = new Timer();

        ServerSocket echoServer = null;
        String line = null;
        DataInputStream is;
        PrintStream os;
        Socket clientSocket = null;

        try {
           echoServer = new ServerSocket(3000);
        }
        catch (IOException e) {
           System.out.println(e);
        }   

        try {
           clientSocket = echoServer.accept();
           is = new DataInputStream(clientSocket.getInputStream());
           os = new PrintStream(clientSocket.getOutputStream());

           while (true) {
             line = is.readLine();
             os.println("From server: "+ line); 
             System.out.println(line);

             timer.scheduleAtFixedRate(new TimerTask() {
                 public void run(){
                     try{

        FileWriter fstream = new FileWriter("C://" +str+".txt",true);
        BufferedWriter out = new BufferedWriter(fstream);
        out.write(line);
        out.newLine();
        out.flush(); 
        out.close();
          }catch (Exception e){//Catch exception if any
                System.err.println("Error: " + e.getMessage());
                    }

                 }
             }}, delay, period);           
        }   
        catch (IOException e) {
           System.out.println(e);
    }        
    }
}

在“timer.scheduleAtFixedRate（new TimerTask（）”这行中它给出了以下错误：[找不到scheduleAtFixedRate（）的合适方法方法java.util.Timer.scheduleAtFixedRate（java.util.TimerTask，java.util.Date，long）不适用（实际和正式的参数列表长度不同）方法java.util.Timer.scheduleAtFixedRate（java.util.TimerTask，long，long）不适用（实际和正式的参数列表长度不同）]
at“line = is.readLine（）;”它给了我以下错误：[无法为最终变量行赋值]。

我是java的新手。我很遗憾这个可怕的缩进。请帮帮我。

Answer 1

您的服务器只需创建一个每30分钟触发一次的定时间隔并创建该文件。 See here for an example，Java docs和another example。

这是代码片段，其中包含一些针对您情况的mod：

int delay = 0;   // delay for - no delay
int period = 1800000;  // repeat every 1.8 mil milliseconds = 30 minutes
Timer timer = new Timer();

timer.scheduleAtFixedRate(new TimerTask() {
        public void run() {
            // Create file here
        }
    }, delay, period);

修正了代码：

import java.io.*;
import java.net.*;
import java.util.*;
import java.text.*;
import java.util.Timer;
import java.util.TimerTask;

public class DateServer extends Thread {
    public static void main(String args[]) {
        new Runner().go();
    }
}

class Runner {
    public static  LinkedList<String> data = new LinkedList<String>();

    public void go() {
        ServerSocket echoServer = null;

        MyTimerTask timerTask = new MyTimerTask();
        new Timer().scheduleAtFixedRate(timerTask, 0, 2000);

        try {
            echoServer = new ServerSocket(3000);
        }
        catch (IOException e) {
            System.out.println(e);
        }

        try {
            Socket clientSocket = echoServer.accept();
            DataInputStream is = new DataInputStream(clientSocket.getInputStream());
            PrintStream os = new PrintStream(clientSocket.getOutputStream());

            while (true) {
                String line = is.readLine();
                data.add(line);
                os.println("From server: "+ line);
                System.out.println(line);
            }
        }
        catch (IOException e) {
            System.out.println(e);
        }
    }
}

class MyTimerTask extends TimerTask {
    public void run() {
        SimpleDateFormat format = new SimpleDateFormat("yyyyMMdd-hhmm");
        String line = null;
        System.out.print(".");
        try {
            String str = format.format(new Date());
            FileWriter fstream = new FileWriter("C://" +str+".txt",true);
            BufferedWriter out = new BufferedWriter(fstream);
            while (Runner.data.size() > 0) out.write(Runner.data.getLast());
            out.newLine();
            out.flush();
            out.close();
        } catch (Exception e) {//Catch exception if any
            System.err.println("Error: " + e.getMessage() + e.getStackTrace()[0].toString());
        }
    }
}

Answer 2

如果在Windows上，请创建使用Windows计划程序安排的批处理文件。如果在unix / linux中，你用cron安排的bash脚本。这将是最简单和最可靠的，因为操作系统将完成所有工作。

Answer 3

有很多方法可以做到这一点。为了获得更大的灵活性，我会看一下Quartz-Scheduler

Answer 4

可以选择线程安排。如果您阅读线程文档。它提到它不保证在调用时调用线程，但它将被放入队列中。这仍然是可取的。

请勿使用操作系统级别的计划应用 从OS调用批处理应用程序会失去通过应用程序配置设置的灵活性。对于java程序员来说，这将是最糟糕的方法

最佳Quartz-Scheduler 最佳方法将由Gevorg使用Quartz-Scheduler

提及

Answer 5

您可以尝试将其用于基本调度目的。对于高级计划，您可以使用Quartz库。

ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(NTHREADS);
ScheduledFuture<?> result = scheduler.scheduleWithFixedDelay(
                                 Runnable, 0, 1800, TimeUnit.SECONDS);

0是初始延迟，1800是任务应该运行的后续时间段。

Answer 6

/* File Signature.java created by Daniel Hicks on Mon Jun 11 2001. */
import java.io.*;
import java.util.*;
public class Signature {
    public static void main(String args[]) throws Exception {

    ResourceBundle properties = ResourceBundle.getBundle("WebSignature");
    String sigName = properties.getString("sig.file");
    String protoName = properties.getString("proto.file");
    String sayingsList = properties.getString("sayings.list");
    long waitTime = Long.parseLong(properties.getString("delay.time"));
    int lineLength = Integer.parseInt(properties.getString("line.length"));
    long notFoundTime = Long.parseLong(properties.getString("file.not.found.time"));
    int notFoundRetries = Integer.parseInt(properties.getString("file.not.found.retries"));

    Vector proto = new Vector();

    BufferedReader protoReader = new BufferedReader(new FileReader(protoName));
    String protoLine = protoReader.readLine();
    while (protoLine != null) {
        proto.addElement(protoLine);
        protoLine = protoReader.readLine();
    }
    protoReader.close();

    Vector sayings = new Vector();

    BufferedReader sayingsReader = new BufferedReader(new FileReader(sayingsList));
    String sayingsLine = sayingsReader.readLine();
    while (sayingsLine != null) {
        sayings.addElement(sayingsLine);
        sayingsLine = sayingsReader.readLine();
    }
    sayingsReader.close();

    Random rand = new Random();

    int retryCount = notFoundRetries;  // Require first cycle to work

    while (true) {
        int randVal = rand.nextInt();
        randVal = Math.abs(randVal) % sayings.size();
        try {
        PrintWriter sigWriter = new PrintWriter(new FileWriter(sigName));
        for (int i = 0; i < proto.size(); i++) {
            sigWriter.println(proto.elementAt(i));
        }
        putSaying(sigWriter, (String) (sayings.elementAt(randVal)), lineLength);
        sigWriter.close();
        retryCount = 0;
        }
        // Catch I/O error due to AFS being offline.
        catch (java.io.FileNotFoundException ex) {
        retryCount++;
        if (retryCount > notFoundRetries) {
            throw ex;
        }
        // Sleep for a long time (eg, 30 minutes).
        Thread.sleep(notFoundTime);
        }
        Thread.sleep(waitTime);
    }
    }

    private static void putSaying(PrintWriter sigWriter, String saying, int lineLength) throws Exception {
    saying = saying.trim();
    java.text.BreakIterator lineIterator = java.text.BreakIterator.getLineInstance();
    lineIterator.setText(saying);
    int pos = 0;
    int last = lineIterator.last();
    while (pos < last) {
        int newPos = pos + lineLength;
        if (newPos >= last) {
        newPos = last;
        }
        else {
        newPos = lineIterator.preceding(newPos);
        if (newPos <= pos) {
            newPos = lineIterator.following(pos);
        }
        }
        sigWriter.println(saying.substring(pos, newPos));
        pos = newPos;
        while ((pos < saying.length() - 1) && Character.isWhitespace(saying.charAt(pos))) {
        pos++;
        }
    }
    }
}

安排一个java程序

6 个答案: