Java同步调用external app

我们可以根据Runtime和Process类在Java中调用外部程序。
更多资料参见：
http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html
http://java.sun.com/j2se/1.4.2/docs/api/java/lang/Process.html
try {
Process process = Runtime.getRuntime().exec("start a.doc");
int exitVal = process.waitfor( ); 
System.out.println("Process exitValue: " + exitVal);
} catch (IOException e) {
e.printStackTrace();
}
} catch (InterruptedException e) {
e.printStackTrace();
}
} catch (Throwable t) {
t.printStackTrace();
}

可以使用下面代码显示子进程的输出内容：
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(process.getInputStream());
String line = null;
while ( (line=bufferedReader.readLine()) != null)
System.out.println(line);