java如何测试网络连通性

 /**
 * test network
 * @param ip
 */
private void getnetworkstate(string ip) {
  runtime runtime = runtime.getruntime();
  try {
    log.info("=================正在测试网络连通性ip："+ip);
    process process = runtime.exec("ping " +ip);
    inputstream istream = process.getinputstream();
    inputstreamreader isreader = new inputstreamreader(istream,"utf-8");
    bufferedreader breader = new bufferedreader(isreader);
    string line = null;
    stringbuffer sb = new stringbuffer();
    while ((line = breader.readline()) != null) {
      sb.append(line);
    }
    istream.close();
    isreader.close();
    breader.close();
    string result = new string(sb.tostring().getbytes("utf-8"));
    log.info("ping result:"+result);
    if (!stringutils.isblank(result)) {
      if (result.indexof("ttl") > 0 || result.indexof("ttl") > 0) {
        log.info("网络正常，时间: " + timeutil.getcurdate("yyyy-mm-dd hh:mm:ss"));     
      } else {
        log.info("网络断开，时间 :" + timeutil.getcurdate("yyyy-mm-dd hh:mm:ss"));

      }
    }
  } catch (exception e) {
    log.error("网络异常："+e.getmessage());
    e.printstacktrace();
  }
}

package com.util.network;

import java.io.ioexception;
import java.net.inetaddress;
import java.net.inetsocketaddress;
import java.net.networkinterface;
import java.net.socket;
import java.net.socketaddress;
import java.net.socketexception;
import java.net.unknownhostexception;
import java.util.enumeration;

import org.apache.commons.lang.stringutils;
import org.slf4j.logger;
import org.slf4j.loggerfactory;

/**
 * 测试网络连通性
 * 
 * @author donald
 * 
 */
public class networkhelper {
  private static logger log = loggerfactory.getlogger(networkhelper.class);
  private static networkhelper instance = null;
  public static synchronized networkhelper getinstance(){
    if(instance == null){
      instance = new networkhelper();
    }
    return instance;

  }

  /**
   * 测试本地能否ping ip
   * 
   * @param ip
   * @return
   */
  public boolean isreachip(string ip) {
    boolean isreach = false;
    try {
      inetaddress address = inetaddress.getbyname(ip);// ping this ip

      if (address instanceof java.net.inet4address) {
        log.info(ip + " is ipv4 address");
      } else if (address instanceof java.net.inet6address) {
        log.info(ip + " is ipv6 address");
      } else {
        log.info(ip + " is unrecongized");
      }
      if (address.isreachable(5000)) {
        isreach = true;
        log.info("success - ping " + ip
            + " with no interface specified");
      } else {
        isreach = false;
        log.info("failure - ping " + ip
            + " with no interface specified");
      }
    } catch (exception e) {
      log.error("error occurs:" + e.getmessage());
    }
    return isreach;
  }

  /**
   * 测试本地所有的网卡地址都能ping通 ip
   * 
   * @param ip
   * @return
   */
  public boolean isreachnetworkinterfaces(string ip) {
    boolean isreach = false;
    try {
      inetaddress address = inetaddress.getbyname(ip);// ping this ip

      if (address instanceof java.net.inet4address) {
        log.info(ip + " is ipv4 address");
      } else if (address instanceof java.net.inet6address) {
        log.info(ip + " is ipv6 address");
      } else {
        log.info(ip + " is unrecongized");
      }
      if (address.isreachable(5000)) {
        isreach = true;
        log.info("success - ping " + ip
            + " with no interface specified");
      } else {
        isreach = false;
        log.info("failure - ping " + ip
            + " with no interface specified");
      }
      if (isreach) {
        log.info("-------trying different interfaces--------");
        enumeration<networkinterface> netinterfaces = networkinterface
            .getnetworkinterfaces();
        while (netinterfaces.hasmoreelements()) {
          networkinterface ni = netinterfaces.nextelement();
          log.info("checking interface, displayname:"
              + ni.getdisplayname() + ", name:" + ni.getname());
          if (address.isreachable(ni, 0, 5000)) {
            isreach = true;
            log.info("success - ping " + ip);
          } else {
            isreach = false;
            log.info("failure - ping " + ip);
          }
          enumeration<inetaddress> ips = ni.getinetaddresses();
          while (ips.hasmoreelements()) {
            log.info("ip: " + ips.nextelement().gethostaddress());
          }
          log.info("-----------------check now networkinterface is done--------------------------");
        }
      }
    } catch (exception e) {
      log.error("error occurs:" + e.getmessage());
    }
    return isreach;
  }

  /**
   * 获取能与远程主机指定端口建立连接的本机ip地址
   * @param remoteaddr
   * @param port
   * @return
   */
  public string getreachableip(inetaddress remoteaddr, int port) {
    string retip = null;
    enumeration<networkinterface> netinterfaces;
    try {
      netinterfaces = networkinterface.getnetworkinterfaces();
      while (netinterfaces.hasmoreelements()) {
        networkinterface ni = netinterfaces.nextelement();
        enumeration<inetaddress> localaddrs = ni.getinetaddresses();
        while (localaddrs.hasmoreelements()) {
          inetaddress localaddr = localaddrs.nextelement();
          if (isreachable(localaddr, remoteaddr, port, 5000)) {
            retip = localaddr.gethostaddress();
            break;
          }
        }
      }
    } catch (socketexception e) {
      log.error("error occurred while listing all the local network addresses:"
          + e.getmessage());
    }
    if (retip == null) {
      log.info("null reachable local ip is found!");
    } else {
      log.info("reachable local ip is found, it is " + retip);
    }
    return retip;
  }
  /**
   * 获取能与远程主机指定端口建立连接的本机ip地址
   * @param remoteip
   * @param port
   * @return
   */
  public string getreachableip(string remoteip, int port) {

    string retip = null;
    inetaddress remoteaddr = null;
    enumeration<networkinterface> netinterfaces;
    try {
      remoteaddr = inetaddress.getbyname(remoteip);
      netinterfaces = networkinterface.getnetworkinterfaces();
      while (netinterfaces.hasmoreelements()) {
        networkinterface ni = netinterfaces.nextelement();
        enumeration<inetaddress> localaddrs = ni.getinetaddresses();
        while (localaddrs.hasmoreelements()) {
          inetaddress localaddr = localaddrs.nextelement();
          if (isreachable(localaddr, remoteaddr, port, 5000)) {
            retip = localaddr.gethostaddress();
            break;
          }
        }
      }
    } catch (unknownhostexception e) {
      log.error("error occurred while listing all the local network addresses:"+ e.getmessage());
    }catch (socketexception e) {
      log.error("error occurred while listing all the local network addresses:"+ e.getmessage());
    }
    if (retip == null) {
      log.info("null reachable local ip is found!");
    } else {
      log.info("reachable local ip is found, it is " + retip);
    }
    return retip;
  }
  /**
   * 测试localinetaddr能否与远程的主机指定端口建立连接相连
   * 
   * @param localinetaddr
   * @param remoteinetaddr
   * @param port
   * @param timeout
   * @return
   */
  public boolean isreachable(inetaddress localinetaddr,
      inetaddress remoteinetaddr, int port, int timeout) {
    boolean isreachable = false;
    socket socket = null;
    try {
      socket = new socket();
      // 端口号设置为 0 表示在本地挑选一个可用端口进行连接
      socketaddress localsocketaddr = new inetsocketaddress(
          localinetaddr, 0);
      socket.bind(localsocketaddr);
      inetsocketaddress endpointsocketaddr = new inetsocketaddress(
          remoteinetaddr, port);
      socket.connect(endpointsocketaddr, timeout);
      log.info("success - connection established! local: "
          + localinetaddr.gethostaddress() + " remote: "
          + remoteinetaddr.gethostaddress() + " port" + port);
      isreachable = true;
    } catch (ioexception e) {
      log.error("failre - can not connect! local: "
          + localinetaddr.gethostaddress() + " remote: "
          + remoteinetaddr.gethostaddress() + " port" + port);
    } finally {
      if (socket != null) {
        try {
          socket.close();
        } catch (ioexception e) {
          log.error("error occurred while closing socket:"
              + e.getmessage());
        }
      }
    }
    return isreachable;
  }

  /**
   * 测试localip能否与远程的主机指定端口建立连接相连
   * 
   * @param localip
   * @param remoteip
   * @param port
   * @param timeout
   * @return
   */
  public boolean isreachable(string localip, string remoteip,
      int port, int timeout) {
    boolean isreachable = false;
    socket socket = null;
    inetaddress localinetaddr = null;
    inetaddress remoteinetaddr = null;
    try {
      localinetaddr = inetaddress.getbyname(localip);
      remoteinetaddr = inetaddress.getbyname(remoteip);
      socket = new socket();
      // 端口号设置为 0 表示在本地挑选一个可用端口进行连接
      socketaddress localsocketaddr = new inetsocketaddress(
          localinetaddr, 0);
      socket.bind(localsocketaddr);
      inetsocketaddress endpointsocketaddr = new inetsocketaddress(
          remoteinetaddr, port);
      socket.connect(endpointsocketaddr, timeout);
      log.info("success - connection established! local: "
          + localinetaddr.gethostaddress() + " remote: "
          + remoteinetaddr.gethostaddress() + " port" + port);
      isreachable = true;
    } catch (ioexception e) {
      log.error("failre - can not connect! local: "
          + localinetaddr.gethostaddress() + " remote: "
          + remoteinetaddr.gethostaddress() + " port" + port);
    } finally {
      if (socket != null) {
        try {
          socket.close();
        } catch (ioexception e) {
          log.error("error occurred while closing socket:"
              + e.getmessage());
        }
      }
    }
    return isreachable;
  }

  public static void main(string[] args) {
     if(networkhelper.getinstance().isreachip("192.168.126.128")){
       log.info("=======本机可以ping通ip："+"192.168.126.128");
     }
     else{
       log.info("=======本机ping不通ip："+"192.168.126.128");
     }
     if(networkhelper.getinstance().isreachnetworkinterfaces("192.168.126.128")){
       log.info("=======本机所有网卡可以ping通ip："+"192.168.126.128");
     }
     else{
       log.info("=======本机所有网卡ping不通ip："+"192.168.126.128");
     }
     string localip = networkhelper.getinstance().getreachableip("192.168.126.128",8081);
     if(!stringutils.isblank(localip)){
       log.info("=======本机可以与ip："+"192.168.126.128"+",port:"+8081+"建立连接的ip："+localip);
     }
     else{
       log.info("=======本机不能与ip："+"192.168.126.128"+",port:"+8081+"建立连接的ip");
     }
  }

}