Runtime.getRuntime().exec执行阻塞问题解决

上篇博文中CallMaxentThreadPoolTask类直接使用Runtime.getRuntime().exec方法调用cmd命令，结果今天在测试时发现当cmd命令执

 

行出现错误或警告时，主控程序的waitfor方法会被阻塞一直等待下去，查了查资料发现是Runtime.getRuntime().exec方法需要自己处理

 

stderr 及stdout流，而解决方法即是将它们导出用别的thread处理。

 

会造成阻塞的代码：

 

Process p = Runtime.getRuntime().exec(cmd); p.waitFor();

 

解决方法：

Process p = Runtime.getRuntime().exec(cmd); StreamGobbler errorGobbler = new StreamGobbler(p.getErrorStream(), "ERROR"); // kick off stderr errorGobbler.start(); StreamGobbler outGobbler = new StreamGobbler(p.getInputStream(), "STDOUT"); // kick off stdout outGobbler.start(); p.waitFor();

 

其中StreamGobbler类的代码：

 package com.sdc.callmaxent.socket; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.OutputStream; import java.io.PrintWriter; import com.sdc.callmaxent.util.FileUtil; /** * 用于处理Runtime.getRuntime().exec产生的错误流及输出流 * @author shaojing * */ public class StreamGobbler extends Thread { InputStream is; String type; OutputStream os; StreamGobbler(InputStream is, String type) { this(is, type, null); } StreamGobbler(InputStream is, String type, OutputStream redirect) { this.is = is; this.type = type; this.os = redirect; } public void run() { InputStreamReader isr = null; BufferedReader br = null; PrintWriter pw = null; try { if (os != null) pw = new PrintWriter(os); isr = new InputStreamReader(is); br = new BufferedReader(isr); String line=null; while ( (line = br.readLine()) != null) { if (pw != null) pw.println(line); System.out.println(type + ">" + line); } if (pw != null) pw.flush(); } catch (IOException ioe) { ioe.printStackTrace(); } finally{ FileUtil.close(pw); FileUtil.close(br); FileUtil.close(isr); } } }

 

感谢http://faq.csdn.net/read/200584.html中提到的各位。