Question

我想在java中使用下面给出的commnda。我用过RunTime。但是使用RunTime，我的所有时间都是null。

$ cut -d. -f2,3 <<< com.tata.titi.toto
tata.titi

java中使用的方法：

public  void tataName() {

    try {
        Process process = Runtime.getRuntime().exec(
                new String[] { "/bin/sh", "cut -d. -f2,3 <<< com.tata.titi.toto " });
        process.waitFor();
        BufferedReader reader = new BufferedReader(new InputStreamReader(
                process.getInputStream()));
        File f = new File(path+ "/taname.txt");
        PrintWriter writer = new PrintWriter(f, "UTF-8");
        String line = reader.readLine();
        while ((line != null)) {
            System.out.println(line);
            writer.println(line);
            line = reader.readLine();



        }

        writer.close();


    } catch (IOException | InterruptedException e1) {

    }

Answer 1

删除process.waitFor();。您正在运行进程，等待其终止，然后在为时已晚时尝试读取其输出。

如果删除此行，则执行该过程并读取其输出。我希望这会对你有所帮助。

顺便说一下，你为什么要这样做？您可以逐行读取文件并在java中拆分每一行。这很多更容易和跨平台。

Answer 2

http://www.rgagnon.com/javadetails/java-0014.html但是在单独的线程中进行错误流处理为什么 - 请参阅javadoc http://docs.oracle.com/javase/1.5.0/docs/api/java/lang/Process.html

因为某些本机平台仅提供有限的缓冲区大小标准输入和输出流，无法及时写入输入流或读取子进程的输出流可能会导致要阻止的子进程，甚至是死锁。

package utl;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileReader;    

public class ReadStreamAsync extends Thread {

    private BufferedReader is = null;
    private int toOut = 0;//0 none, 1 out, 2 err
    private boolean toSB = false;
    private StringBuffer sb = null;
    public ReadStreamAsync(BufferedReader is, int toOut, boolean toSB){
        if(is == null)throw new NullPointerException("stream is null");
        this.is = is;
        this.toSB = toSB;
        this.toOut = toOut;
        if(toSB)sb = new StringBuffer();
        start();
    }

    public void run(){
        try{
            int i;
            while((i = is.read()) > -1){
                if(toOut == 1){
                    System.out.print((char)i);
                }else if(toOut ==2){
                    System.err.print((char)i);
                }
                if(toSB)sb.append((char)i);
            }
        }catch(Exception e){
            e.printStackTrace();
        }finally{
                    try{
                            is.close();
                    }catch(Exception e){
                            e.printStackTrace();
                    }
                }
    }

    public String getRead(){
        return sb.toString();
    }

    /**
         * test code
     * @param args
     */
    public static void main(String[] args) {
        try{
            BufferedReader fis = new BufferedReader(new FileReader("c:/tmp/sample1.txt"));
            ReadStreamAsync t = new ReadStreamAsync(fis, 1, false);
            t.join(1000);
            System.out.println("\nAll :");
            fis = new BufferedReader(new FileReader("c:/tmp/sample1.txt"));
             t = new ReadStreamAsync(fis, 0, true);
            t.join(1000);
            System.out.println(t.getRead());

        }catch(Exception e){
            e.printStackTrace();
        }

    }

}

这就是你如何使用它

        Process proc = procBldr.start();
        //props is a java.util.properties that was previosly loaded from some stream
        System.out.println(" Cmd start f :" + cmdStartFolder);
        System.out.println(" Cmd  :" + lstCmds);
        BufferedReader isO = new BufferedReader (new InputStreamReader(proc.getInputStream()));
        BufferedReader isE = new BufferedReader (new InputStreamReader(proc.getErrorStream()));
        asynO = new com.enstage.commonutil.file.ReadStreamAsync(isO, 1, true);
        asynE = new com.enstage.commonutil.file.ReadStreamAsync(isE, 1, true);
        if("1".equals(props.getProperty("waitFor")){
            proc.waitFor();//maybe parameterize this not required everywhere only good for short processes 
        }
        String sleepAfterWait = props.getProperty("sleepAfterWait");
        try {
            Thread.sleep(500);//some sleep after telling windows to do things with files is good
            if(sleepAfterWait != null){
                int i = Integer.parseInt(sleepAfterWait);
                Thread.sleep(i);
            }
        } catch (Exception e) {
            System.out.println("sleep err :" + e );
            e.printStackTrace();
        }
        asynE.join();
        asynO.join();
        String checkString = props.getProperty("checkString");
        System.out.println("\n done " );
        //asynE.getRead();//if you want error out as a string
        if(checkString != null){
            System.out.println("checkString :" + checkString );
            String out = asynO.getRead();
            if(out.indexOf(checkString) > -1){
                System.out.println(" Check string found!" );
            }else{
                System.err.println(" *** Check string not found ***!" );
            }
        }

已成功使用它在.bat和其他短进程和长进程中调用xcopy

如何使用Runtime？

2 个答案: