我有一个程序,我可以从我的代码中成功执行cmd命令,但我希望能够从cmd命令获取输出。我怎么能这样做?
到目前为止,我的代码是:
Second.java:
public class Second {
public static void main(String[] args) {
System.out.println("Hello world from Second.java");
}
}
和Main.java
public class Main {
public static void main(String[] args) {
String filename = args[1].substring(0, args[1].length() - 5);
String cmd1 = "javac " + args[1];
String cmd2 = "java " + filename;
Runtime r = Runtime.getRuntime();
Process p = r.exec(cmd1); // i can verify this by being able to see Second.class and running it successfully
p = r.exec(cmd2); // i need to see this output to see if
System.out.println("Done");
}
}
我可以通过检查Second.class来检查第一个命令是否成功,但是如果这个类产生了一些错误,我怎么能看到那个错误呢?
答案 0 :(得分:8)
你需要你的Process的OutputStream(InputStream)(你应该使用ProcessBuilder)......就像这样
public static void main(String[] args) {
String filename = args[1].substring(0, args[1].length() - 5);
String cmd1 = "javac " + args[1];
String cmd2 = "java " + filename;
try {
// Use a ProcessBuilder
ProcessBuilder pb = new ProcessBuilder(cmd1);
Process p = pb.start();
InputStream is = p.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(is));
String line = null;
while ((line = br.readLine()) != null) {
System.out.println(line);
}
int r = p.waitFor(); // Let the process finish.
if (r == 0) { // No error
// run cmd2.
}
} catch (Exception e) {
e.printStackTrace();
}
}
答案 1 :(得分:4)
从命令返回的一般示例是:
Process p = null;
try {
p = p = r.exec(cmd2);
p.getOutputStream().close(); // close stdin of child
InputStream processStdOutput = p.getInputStream();
Reader r = new InputStreamReader(processStdOutput);
BufferedReader br = new BufferedReader(r);
String line;
while ((line = br.readLine()) != null) {
//System.out.println(line); // the output is here
}
p.waitFor();
}
catch (InterruptedException e) {
...
}
catch (IOException e){
...
}
finally{
if (p != null)
p.destroy();
}
答案 2 :(得分:1)
看这里:Extracting a process's exit code in the case of ThreadInterrupted
你需要获得返回代码......你必须等待它。