Java Process详解及实例

 /**   * 设置本地日期   * @param date yyyy-MM-dd格式   */  private static void setSystemDate(String date){    Process process = null;    String command1 = "cmd /c date "+date;    System.out.println(command1);    try {      process = Runtime.getRuntime().exec(command1);      //必须等待该进程结束，否则时间设置就无法生效      process.waitFor();    } catch (IOException | InterruptedException e) {      e.printStackTrace();    }finally{      if(process!=null){        process.destroy();      }    }  }

 /**   * @Purpose:采集网络带宽使用量   * @param args   * @return float,网络带宽已使用量   */  public static Double getNetworkThoughput() {     Double curRate = 0.0;    Runtime r = Runtime.getRuntime();    // 第一次采集流量数据    long startTime = System.currentTimeMillis();    long total1 = calculateThoughout(r);    // 休眠1秒后，再次收集    try {      Thread.sleep(1000);    } catch (InterruptedException e) {      e.printStackTrace();    }    // 第二次采集流量数据    long endTime = System.currentTimeMillis();    long total2 = calculateThoughout(r);    // 计算该段时间内的吞吐量：单位为Mbps(million bit per second)    double interval = (endTime-startTime)/1000;    curRate = (total2-total1)*8/1000000*interval;    System.out.println("收集网络带宽使用率结束，当前设备的网卡吞吐量为："+(curRate)+"Mbps.");    return curRate;  }  /**   * 计算某个时刻网卡的收发数据总量   * @param runtime   * @return   */  private static long calculateThoughout(Runtime runtime){    Process process = null;    String command = "cat /proc/net/dev";    BufferedReader reader = null;    String line = null;    long total = 0;    try {      process = runtime.exec(command);      reader = new BufferedReader(new InputStreamReader(process.getInputStream()));      while ((line = reader.readLine()) != null) {        line = line.trim();        // 考虑多网卡的情况        if (line.startsWith("eth")) {          log.debug(line);          line = line.substring(5).trim();          String[] temp = line.split("//s+");          total+=(Long.parseLong(temp[0].trim()));// Receive          total+=(Long.parseLong(temp[8].trim()));// Transmit        }      }    } catch (NumberFormatException | IOException e) {      e.printStackTrace();    } finally {      if (reader != null) {        try {          reader.close();        } catch (IOException e) {          // TODO Auto-generated catch block          e.printStackTrace();        }      }      if (process != null) {        process.destroy();      }    }    return total;  }