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ProcessBuilder调用外部命令 并返回结果

来源:网络 作者:佚名 点击: 时间:2017-11-14 05:59
[摘要] 在网上常见的用Java调用外部命令返回结果的方法是: process =runtime.exec(cmd) is = process.getInputStream(); isr=new InputStreamReader(is); br =new BufferedReader(isr); while( (line = br.readLine()) != null ) { out.println(line);

  在网上常见的用Java调用外部命令返回结果的方法是:
  
  process =runtime.exec(cmd)
  
  is = process.getInputStream();
  
  isr=new InputStreamReader(is);
  
  br =new BufferedReader(isr);
  
  while( (line = br.readLine()) != null )
  
  {
  
  out.println(line);
  
  out.flush();
  
  }
  
  这种方法在遇到像cvs checkout modules这样不能马上返回结果的命令来说是无效的,不仅得不到返回结果,进程也会终止。其原因是,process在没有来得及gegtInputStream是,调用了BufferedReader.readLine其返回结果是null,也就是说循环一开始就会停止。因此想要正常运行只能直接读取process.getInputStream(),如下:
  
  import java.io.*;
  
  /**
  
  *
  
  * @author tyrone
  
  *
  
  */
  
  public class CMDExecute
  
  {
  
  /**
  
  * @param cmd
  
  * @return
  
  * @throws IOException
  
  */
  
  public synchronized String run(String[] cmd,String workdirectory) throws IOException{
  
  String line=null; String result="";
  
  try {
  
  ProcessBuilder builder = new ProcessBuilder(cmd);
  
  //set working directory
  
  if (workdirectory!=null)
  
  builder.directory(new File(workdirectory));
  
  builder.redirectErrorStream(true);
  
  Process process = builder.start();
  
  InputStream in=process.getInputStream();
  
  byte[] re=new byte[1024];
  
  while (in.read(re)!= -1) {
  
  System.out.println(new String(re));
  
  result = result + new String(re);
  
  }
  
  in.close();
  
  } catch (Exception ex) {
  
  ex.printStackTrace();
  
  }
  
  return result;
  
  }
  
  /**
  
  * @param args=cvs log
  
  */ public static void main(String[] args){ String result=null;
  
  CMDExecute cmdexe=new CMDExecute();
  
  try {
  
  result= cmdexe.run(args,"D:\\MyProject\\colimas\\axis_c");
  
  System.out.println(result);
  
  }catch ( IOException ex ){  ex.printStackTrace();
  
  }
  
  }
  
  }
  
  经过测试,本方法可以运行返回大量结果的应用程序。
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