Java执行cmd命令的举例与注意事项

public static void execCommand() {
    try {
        Runtime runtime = Runtime.getRuntime();
        // 打开任务管理器，exec方法调用后返回 Process 进程对象
        Process process = runtime.exec("cmd.exe /c taskmgr");
        // 等待进程对象执行完成，并返回“退出值”，0 为正常，其他为异常
        int exitValue = process.waitFor();
        System.out.println("exitValue: " + exitValue);
        // 销毁process对象
        process.destroy();
    } catch (IOException | InterruptedException e) {
        e.printStackTrace();
    }
}

public static void execCommandAndGetOutput() {
    try {
        Runtime runtime = Runtime.getRuntime();
        Process process = runtime.exec("cmd.exe /c ipconfig");
        // 输出结果，必须写在 waitFor 之前
        String outStr = getStreamStr(process.getInputStream());
        // 错误结果，必须写在 waitFor 之前
        String errStr = getStreamStr(process.getErrorStream());
        int exitValue = process.waitFor(); // 退出值 0 为正常，其他为异常
        System.out.println("exitValue: " + exitValue);
        System.out.println("outStr: " + outStr);
        System.out.println("errStr: " + errStr);
        process.destroy();
    } catch (IOException | InterruptedException e) {
        e.printStackTrace();
    }
}

public static String getStreamStr(InputStream is) throws IOException {
    BufferedReader br = new BufferedReader(new InputStreamReader(is, "GBK"));
    StringBuilder sb = new StringBuilder();
    String line;
    while ((line = br.readLine()) != null) {
        sb.append(line);
        sb.append("\n");
    }
    br.close();
    return sb.toString();
}

public static void main(String[] args) {
 /*获取cmd命令*/
 try {
    Process pro = Runtime.getRuntime().exec("cmd /c calc"); //添加要进行的命令，"cmd  /c calc"中calc代表要执行打开计算器，如何设置关机请自己查找cmd命令
    BufferedReader br = new BufferedReader(new InputStreamReader(pro
      .getInputStream())); //虽然cmd命令可以直接输出，但是通过IO流技术可以保证对数据进行一个缓冲。
    String msg = null;
    while ((msg = br.readLine()) != null) {
     System.out.println(msg);
    }
   } catch (IOException exception) {
   } 
 /*cmd /c dir 是执行完dir命令后关闭命令窗口
 cmd /k dir 是执行完dir命令后不关闭命令窗口
 cmd /c start dir  会打开一个新窗口后执行dir命令，原窗口会关闭
 cmd /k start dir  会打开一个新窗口后执行dir命令，原窗口不会关闭
 cmd /?  查看帮助信息*/
 }