读取java exec的输出

Question

您好，我对Java有一些疑问。这是我的代码：public static void main(String[] args) throws Exception {    Process pr = Runtime.getRuntime().exec("java -version");    BufferedReader in = new BufferedReader(new InputStreamReader(pr.getInputStream()));    String line;    while ((line = in.readLine()) != null) {        System.out.println(line);    }    pr.waitFor();    System.out.println("ok!");    in.close();    System.exit(0);}在该代码中，我尝试获取Java版本命令执行是可以的，但是我无法读取输出，只是返回null。为什么？

Answer 1

使用getErrorStream（）。

BufferedReader in = new BufferedReader(new InputStreamReader(pr.getErrorStream()));

编辑：

您可以使用ProcessBuilder（也可以阅读文档）

ProcessBuilder   ps=new ProcessBuilder("java.exe","-version");

//From the DOC:  Initially, this property is false, meaning that the 

//standard output and error output of a subprocess are sent to two 

//separate streams

ps.redirectErrorStream(true);

Process pr = ps.start();  

BufferedReader in = new BufferedReader(new InputStreamReader(pr.getInputStream()));

String line;

while ((line = in.readLine()) != null) {

    System.out.println(line);

}

pr.waitFor();

System.out.println("ok!");

in.close();

System.exit(0);