java陷阱-------用java 打开一个 .exe文件

public class Test {
	public static void main(String[] args) {
		Runtime rt = Runtime.getRuntime();
		try {
			Process proc = rt.exec("C:\\Program Files\\Internet Explorer\\iexplore.exe");
			int exitVal = proc.exitValue();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}

但是这样允许会出现一个异常：
Exception in thread "Main Thread" java.lang.IllegalThreadStateException: process has not exited
问题原因：
因为程序还没有退出，所以proc.exitValue();程序退出的值当然没有啦。。

怎么改呢。。。

public class Test {
	public static void main(String[] args) {
		Runtime rt = Runtime.getRuntime();
		try {
			Process proc = rt.exec("C:\\Program Files\\Internet Explorer\\iexplore.exe");
			int exitVal = proc.waitFor();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}

这里主要是要学习用运行时对象来执行外面的程序。。。

下面换成javac试试
public class Test {
	public static void main(String[] args) {
		Runtime rt = Runtime.getRuntime();
		int exitVal = 0;
		try {
			Process proc = rt.exec("javac");
			exitVal = proc.waitFor();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		System.out.println(exitVal);
	}
}

允许后发现javac死在这里了，因为proc.waitFor一直在等待关闭，而现在javac这样调用的语法有问题，所以这个程序会先输出错误信息再输出退出的val，但是这时候它想输出错误信息都输不出来，所以程序一直挂在这里。。。改的方法就是让错误信息先输出来呀~~~~~~~

public class Test {
	public static void main(String[] args) {
		Runtime rt = Runtime.getRuntime();
		int exitVal = 0;
		try {
			Process proc = rt.exec("javac");
			exitVal = proc.waitFor();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		System.out.println(exitVal);
	}
}
//我改

public class Test {
	public static void main(String[] args) {
		Runtime rt = Runtime.getRuntime();
		int exitVal = 0;
		try {
			Process proc = rt.exec("javac");
			InputStream es = proc.getErrorStream();
			InputStreamReader reader = new InputStreamReader(es);
			BufferedReader br = new BufferedReader(reader);
			StringBuffer sb = new StringBuffer();
			String l = "";
			while((l = br.readLine()) != null){
				sb.append(l+"\n");
			}
			System.out.println(sb.toString());
			exitVal = proc.waitFor();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		System.out.println(exitVal);
	}
}


* 永远要在调用waitFor()方法之前读取数据流
  * 永远要先从标准错误流中读取，然后再读取标准输出流

于是将waitFor()方法放在读取数据流后调用，目前没有发现什么问题。


正好解决了我心中的疑问，非常感谢！

我们的程序一开始就是exec完了接着waitFor()，但bat文件执行不完整：

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

后面的build中在waitFor()之前读取了数据流，bat文件就可以完整执行了：

Process proc = Runtime.getRuntime().exec(cmd);
  StreamGobbler errorGobbler = new StreamGobbler(proc.getErrorStream(), "Error");   
  StreamGobbler outputGobbler = new StreamGobbler(proc.getInputStream(), "Output");
  errorGobbler.start();
  outputGobbler.start();

  proc.waitFor();

class StreamGobbler extends Thread {
 InputStream is;

 String type;

 StreamGobbler(InputStream is, String type) {
  this.is = is;
  this.type = type;
 }

 public void run() {
  try {
  InputStreamReader isr = new InputStreamReader(is);
  BufferedReader br = new BufferedReader(isr);
  String line = null;
  while ((line = br.readLine()) != null) {
  if (type.equals("Error"))
  LogManager.logError(line);
  else
  LogManager.logDebug(line);
  }
  } catch (IOException ioe) {
  ioe.printStackTrace();
  }
 }
}