Java调用外部程序

Java web开发调用外部 ffmpeg或mencoder转码...

遇到的问题是ffmpeg或mencoder进程阻塞, 需要停掉tomcat--javaw.exe进程之后才能执行ffmpeg.exe或mencoder.exe

问题的原因: getErrorStream 和 getInputStream 缓冲区没有清空

解决的方法: 同时清空getErrorStream 和 getInputStream 的缓冲区

代码如下:

       ProcessBuilder builder = new ProcessBuilder();
       builder.command(commend);
       Process process = builder.start();
       final InputStream is1 = process.getInputStream();
       new Thread( new Runnable() {
             public void run() {
                     BufferedReader br = new BufferedReader( new InputStreamReader(is1));    
             try {
               while(br.readLine() != null) ;
             } catch (IOException e) {
               e.printStackTrace();
             }
             }
       }).start(); // 启动单独的线程来清空process.getInputStream()的缓冲区
       InputStream is2 = process.getErrorStream();
       BufferedReader br2 = new BufferedReader( new InputStreamReader(is2));    
       StringBuilder buf = new StringBuilder(); // 保存输出结果流
       String line = null;
       while((line = br2.readLine()) != null) buf.append(line);