使用Java Runtime.getRunTime.exec（）的交互式命令

Question

如何使用Runtime.getRunTime.exec（）发送和接收多个输入。

例如，如果我想运行诸如openSSL之类的东西来生成一个csr，它将询问诸如州，城市，公用名..之类的东西。

Process p = Runtime.getRuntime().exec(cmd);
OutputStream out = p.getOutputStream();
//print stuff p.getInputStream(); 
//Now i want to send some inputs 
out.write("test".getBytes()); 
//flush and close??? don't know what to do here
//print what ever is returned
//Now i want to send some more inputs 
out.write("test2".getBytes());
//print what ever is returned.. and so on until this is complete

为什么不使用p.getInputStream（）来读取需要发送的内容，而使用out.write（）来相应地发送数据呢？

Process p = Runtime.getRuntime().exec(cmd);
OutputStream out = p.getOutputStream();
//print stuff p.getInputStream();
out.write("test".getBytes()); 
out.close(); //if i don't close, it will just sit there 
//print stuff p.getInputStream();
out.write("test".getBytes()); // I can no longer write at this point, maybe because the outputstream was closed? 

Answer 1

为什么不使用p.getInputStream().read()来读取需要发送的内容，而使用out.write()来相应地发送数据呢？

这是一个取自以下示例： http : //www.rgagnon.com/javadetails/java-0014.html

String line;
OutputStream stdin = null;
InputStream stderr = null;
InputStream stdout = null;

  // launch EXE and grab stdin/stdout and stderr
  Process process = Runtime.getRuntime ().exec ("/folder/exec.exe");
  stdin = process.getOutputStream ();
  stderr = process.getErrorStream ();
  stdout = process.getInputStream ();

  // "write" the parms into stdin
  line = "param1" + "\n";
  stdin.write(line.getBytes() );
  stdin.flush();

  line = "param2" + "\n";
  stdin.write(line.getBytes() );
  stdin.flush();

  line = "param3" + "\n";
  stdin.write(line.getBytes() );
  stdin.flush();

  stdin.close();

  // clean up if any output in stdout
  BufferedReader brCleanUp =
    new BufferedReader (new InputStreamReader (stdout));
  while ((line = brCleanUp.readLine ()) != null) {
    //System.out.println ("[Stdout] " + line);
  }
  brCleanUp.close();

  // clean up if any output in stderr
  brCleanUp =
    new BufferedReader (new InputStreamReader (stderr));
  while ((line = brCleanUp.readLine ()) != null) {
    //System.out.println ("[Stderr] " + line);
  }
  brCleanUp.close();