java 调用 linux 命令行 +使用管道、awk等命令进行数据处理的方法

这里用 sh -c "命令" 的方式是因为java里只能这么用，管道这边java处理不了，所以只能一次执行一条命令，但是在linux里用 sh -c 的方式返回的awk处理过的结果是有问题的，比如下面：

[root@192 ~]# sh -c  "ping www.baidu.com -c 3 | awk -F '[ ]+' 'NR==8 {print $4}'"
rtt min/avg/max/mdev = 3.514/3.778/4.232/0.329 ms

但是在java代码里却能够成功执行所需要的功能，可能是java执行后产生的是下面这样的效果：

[root@192 ~]# ping www.baidu.com -c 3 | awk -F '[ ]+' 'NR==8 {print $4}'
2.586/4.436/6.657/1.683

下面的java代码能够在 CentOS Linux release 7.6.1810 (Core) 下实现效果（取得ms值）：

package com.kinome.surveillance.detect.connectivity;

public class UpDateConnectivity {

    public static String upDateConnectivity(int rid, String ptLink) {

        String targetUrl = FilterHttpHeader.filterHttpHeader(ptLink);
        String canPingTargetUrl = ConnectionTimeMatchHandler.getFilteredResult(targetUrl, "(.*?)/");
//        String TimeLine = RunCmdGetConnectionTimeHandler.getAverageTimeLine(canPingTargetUrl);
//        String connectTime = ConnectionTimeMatchHandler.getFilteredResult(TimeLine, "平均 = (.*?)ms").toString();
        String avg1 = RunCmdGetConnectionTimeHandler.fetchAvg1(canPingTargetUrl);
        String connectTime = RunCmdGetConnectionTimeHandler.fetchAvg2(avg1);
        System.out.println("avg = " + connectTime + " ms");
        return connectTime;
    }
}

public static String fetchAvg1(String targetUrl) {
        BufferedReader br = null;
        String result = null;
        try {
            List<String> cmds = new LinkedList<String>();
            cmds.add("sh");
            cmds.add("-c");
            cmds.add("ping " + targetUrl + " -c 3 | awk -F '[ ]+' 'NR==8 {print $4}'");
            ProcessBuilder pb = new ProcessBuilder(cmds);
            pb.redirectErrorStream(true);
            Process p = pb.start();
            p.waitFor(3, TimeUnit.SECONDS);
            br = new BufferedReader(new InputStreamReader(p.getInputStream()));
            StringBuffer sb = new StringBuffer();
            String line;
            while ((line = br.readLine()) != null) {
                sb.append(line);
            }
            result = sb.toString();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (br != null) {
                try {
                    br.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
        return result;
    }

    public static String fetchAvg2(String avg1) {
        BufferedReader br = null;
        String result = null;
        try {
            List<String> cmds = new LinkedList<String>();
            cmds.add("sh");
            cmds.add("-c");
            cmds.add("echo " + avg1 + " | awk  -F '[/]+' '{print $2}'");
            ProcessBuilder pb = new ProcessBuilder(cmds);
            pb.redirectErrorStream(true);
            Process p = pb.start();
            p.waitFor(3, TimeUnit.SECONDS);
            br = new BufferedReader(new InputStreamReader(p.getInputStream()));
            StringBuffer sb = new StringBuffer();
            String line;
            while ((line = br.readLine()) != null) {
                sb.append(line);
            }
            result = sb.toString();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (br != null) {
                try {
                    br.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
        return result;
    }