发布日期：2021-05-14 00:18:16 浏览次数：14 分类：博客文章

本文共 21003 字，大约阅读时间需要 70 分钟。

1、获取指定主机的IP地址

如何使用 InetAddress 类的 InetAddress.getByName() 方法来获取指定主机（网址）的IP地址？

package Java_Learn.File;import java.net.InetAddress;import java.net.UnknownHostException;public class Main1 {    public static void main(String[] args) {        System.out.println(getIp("www.baidu.com"));    }    public static String getIp(String nds)    {        InetAddress address=null;        try {            address=InetAddress.getByName(nds);        } catch (UnknownHostException e) {            System.exit(2);        }        return  address.getHostName()+"="+address.getHostAddress();    }}

结果：

"C:\Program Files\Java\jdk1.8.0_221\bin\java.exe" "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\lib\idea_rt.jar=52053:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_221\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\rt.jar;C:\app\WorkSpace\target\classes;C:\Program Files (x86)\scala\lib\scala-actors-2.11.0.jar;C:\Program Files (x86)\scala\lib\scala-actors-migration_2.11-1.1.0.jar;C:\Program Files (x86)\scala\lib\scala-library.jar;C:\Program Files (x86)\scala\lib\scala-parser-combinators_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-reflect.jar;C:\Program Files (x86)\scala\lib\scala-swing_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-xml_2.11-1.0.1.jar;C:\repository\org\scala-lang\scala-library\2.11.0\scala-library-2.11.0.jar" Java_Learn.File.Main1www.baidu.com=163.177.151.109Process finished with exit code 0

2、判断端口是否可用

package Java_Learn.File;import java.io.IOException;import java.net.InetSocketAddress;import java.net.Socket;import java.net.SocketAddress;import java.net.SocketTimeoutException;public class Main1 {    public static void main(String[] args) {        printLog(isSocketAliveUitlitybyCrunchify("localhost",80));        printLog(isSocketAliveUitlitybyCrunchify("localhost",8080));        // 检测本地 8081 端口        printLog(isSocketAliveUitlitybyCrunchify("localhost", 8081));        // 检测 runoob.com 的 80 端口        printLog(isSocketAliveUitlitybyCrunchify("runoob.com", 80));        // 检测 runoob.com 的 443 端口        printLog(isSocketAliveUitlitybyCrunchify("runoob.com", 443));        // 检测 runoob.com 的 81 端口        printLog(isSocketAliveUitlitybyCrunchify("runoob.com", 81));    }    public static boolean isSocketAliveUitlitybyCrunchify(String hostname,int port)    {        boolean isAlive=false;        SocketAddress socketAddress=new InetSocketAddress(hostname,port);        Socket socket=new Socket();        int timeout=2000;        printLog("hostName: " + hostname + ", port: " + port);        try {            socket.connect(socketAddress,timeout);            socket.close();            isAlive=true;        }        catch (SocketTimeoutException ex)        {            System.out.println("SocketTimeoutException " + hostname + ":" + port + ". " + ex.getMessage());        }        catch (IOException e) {            System.out.println(                    "IOException - 不能连接 " + hostname + ":" + port + ". " + e.getMessage());        }        return isAlive;    }    public  static void printLog(String str)    {        System.out.println(str);    }    public static void printLog(Boolean isAlive)    {        System.out.println("是否真正在使用:"+isAlive+"\n");    }}

结果：

"C:\Program Files\Java\jdk1.8.0_221\bin\java.exe" "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\lib\idea_rt.jar=52421:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_221\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\rt.jar;C:\app\WorkSpace\target\classes;C:\Program Files (x86)\scala\lib\scala-actors-2.11.0.jar;C:\Program Files (x86)\scala\lib\scala-actors-migration_2.11-1.1.0.jar;C:\Program Files (x86)\scala\lib\scala-library.jar;C:\Program Files (x86)\scala\lib\scala-parser-combinators_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-reflect.jar;C:\Program Files (x86)\scala\lib\scala-swing_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-xml_2.11-1.0.1.jar;C:\repository\org\scala-lang\scala-library\2.11.0\scala-library-2.11.0.jar" Java_Learn.File.Main1hostName: localhost, port: 80IOException - 不能连接 localhost:80. Connection refused: connect是否真正在使用:falsehostName: localhost, port: 8080IOException - 不能连接 localhost:8080. Connection refused: connect是否真正在使用:falsehostName: localhost, port: 8081IOException - 不能连接 localhost:8081. Connection refused: connect是否真正在使用:falsehostName: runoob.com, port: 80是否真正在使用:truehostName: runoob.com, port: 443SocketTimeoutException runoob.com:443. connect timed out是否真正在使用:falsehostName: runoob.com, port: 81SocketTimeoutException runoob.com:81. connect timed out是否真正在使用:falseProcess finished with exit code 0

3、

如何使用 InetAddress 类的 InetAddress.getByName() 方法来获取指定主机（网址）的IP地址

package Java_Learn.File;import java.net.InetAddress;import java.net.UnknownHostException;public class Main1 {    public static void main(String[] args) {        getIpAndHostname("本机信息");    }    private static void getIpAndHostname(String hostname)    {        try {            InetAddress address =InetAddress.getLocalHost();            System.out.println("本机地址："+address.getHostAddress()+"\n"+"本机机名:"+address.getHostName());        } catch (UnknownHostException e) {            e.printStackTrace();        }    }}

结果：

Local HostAddress: 192.168.1.4Local host name: harsh

4、获取远程文件大小

如何获取远程文件的大小？

package Java_Learn.File;import java.io.IOException;import java.net.*;public class Main1 {    public static void main(String[] args) {        getRemoteFileSize("http://www.runoob.com/wp-content/themes/runoob/assets/img/newlogo.png");    }    private static void getRemoteFileSize(String str)    {        int size;        try {            URL url=new URL(str);            URLConnection conn=url.openConnection();            size=conn.getContentLength();            if(size<0)            {                System.out.println("无法获取文件的大小");            }            else            {                System.out.println("文件大小为："+size+"bytes");            }            conn.getInputStream().close();        } catch (MalformedURLException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }    }}

结果：

"C:\Program Files\Java\jdk1.8.0_221\bin\java.exe" "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\lib\idea_rt.jar=53125:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_221\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\rt.jar;C:\app\WorkSpace\target\classes;C:\Program Files (x86)\scala\lib\scala-actors-2.11.0.jar;C:\Program Files (x86)\scala\lib\scala-actors-migration_2.11-1.1.0.jar;C:\Program Files (x86)\scala\lib\scala-library.jar;C:\Program Files (x86)\scala\lib\scala-parser-combinators_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-reflect.jar;C:\Program Files (x86)\scala\lib\scala-swing_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-xml_2.11-1.0.1.jar;C:\repository\org\scala-lang\scala-library\2.11.0\scala-library-2.11.0.jar" Java_Learn.File.Main1文件大小为：278bytesProcess finished with exit code 0

5、Socket 实现多线程服务器程序

如何使用 Socket 类的 accept() 方法和 ServerSocket 类的 MultiThreadServer(socketname) 方法来实现多线程服务器程序？

package Java_Learn.File;import java.io.IOException;import java.io.PrintStream;import java.net.ServerSocket;import java.net.Socket;public class Main1 implements Runnable{    Socket socket;    public Main1(Socket socket) {        this.socket = socket;    }    @Override    public void run() {        try {            PrintStream printStream=new PrintStream(socket.getOutputStream());            for(int i=100;i>=0;i--)            {                printStream.println(i+" bottles of beer on the wall");            }            printStream.close();            socket.close();        } catch (IOException e) {            System.out.println(e.getMessage());        }    }    private static void getThread(int port)    {        try {            ServerSocket serverSocket=new ServerSocket(port);            System.out.println("开始监听");            while (true)            {                Socket socket=serverSocket.accept();                System.out.println("已经连接上");                new Thread(new Main1(socket)).start();            }        } catch (IOException e) {            e.printStackTrace();        }    }    public static void main(String[] args) {        getThread(1234);    }}

结果：

ListeningConnected

6、查看主机指定文件的最后修改时间

如何查看主机指定文件的最后修改时间？

import java.net.URL;import java.net.URLConnection;import java.util.Date;import java.text.SimpleDateFormat; public class Main {    public static void main(String[] argv) throws Exception {        URL u = new URL("http://127.0.0.1/test/test.html");        URLConnection uc = u.openConnection();        SimpleDateFormat ft = new SimpleDateFormat ("yyyy-MM-dd hh:mm:ss");        uc.setUseCaches(false);        long timestamp = uc.getLastModified();        System.out.println("test.html 文件最后修改时间 :" + ft.format(new Date(timestamp)));    }}

结果：

test.html 文件最后修改时间 :2018-09-06 10:06:04

7、使用 Socket 连接到指定主机

如何使用 net.Socket 类的 getInetAddress() 方法来连接到指定主机

import java.net.InetAddress;import java.net.Socket; public class WebPing {    public static void main(String[] args) {        try {            InetAddress addr;            Socket sock = new Socket("www.runoob.com", 80);            addr = sock.getInetAddress();            System.out.println("连接到 " + addr);            sock.close();        } catch (java.io.IOException e) {            System.out.println("无法连接 " + args[0]);            System.out.println(e);        }    }}

结果：

连接到 http:/www.runoob.com/222.73.134.120

8、网页抓取

如何使用 net.URL 类的 URL() 构造函数来抓取网页？

package Java_Learn.File;import java.io.*;import java.net.MalformedURLException;import java.net.URL;public class Main1{    public static void main(String[] args) {        getWeb("http://www.runoob.com");    }private static void getWeb(String webSite){    try {        URL url=new URL(webSite);        BufferedReader reader=new BufferedReader(new InputStreamReader(url.openStream()));        BufferedWriter writer=new BufferedWriter(new FileWriter("data.html"));        String line;        while ((line = reader.readLine()) != null)        {            System.out.println(line);            writer.write(line);            writer.newLine();        }        reader.close();        writer.close();    } catch (MalformedURLException e) {        e.printStackTrace();    } catch (IOException e) {        e.printStackTrace();    }}}

结果：

"C:\Program Files\Java\jdk1.8.0_221\bin\java.exe" "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\lib\idea_rt.jar=53619:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_221\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\rt.jar;C:\app\WorkSpace\target\classes;C:\Program Files (x86)\scala\lib\scala-actors-2.11.0.jar;C:\Program Files (x86)\scala\lib\scala-actors-migration_2.11-1.1.0.jar;C:\Program Files (x86)\scala\lib\scala-library.jar;C:\Program Files (x86)\scala\lib\scala-parser-combinators_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-reflect.jar;C:\Program Files (x86)\scala\lib\scala-swing_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-xml_2.11-1.0.1.jar;C:\repository\org\scala-lang\scala-library\2.11.0\scala-library-2.11.0.jar" Java_Learn.File.Main1301 Moved Permanently

301 Moved Permanently

The requested resource has been assigned a new permanent URI.

9、获取 URL响应头的日期信息

如何使用 HttpURLConnection 的 httpCon.getDate() 方法来获取 URL响应头的日期信息？

import java.net.HttpURLConnection;import java.net.URL;import java.util.Date; public class Main{   public static void main(String args[])    throws Exception {      URL url = new URL("http://www.runoob.com");      HttpURLConnection httpCon =       (HttpURLConnection) url.openConnection();      long date = httpCon.getDate();      if (date == 0)      System.out.println("无法获取信息。");      else      System.out.println("Date: " + new Date(date));   }}

结果：

Date: Mon May 04 11:57:06 CST 2015

10、获取 URL 响应头信息

如何获取指定 URL 的响应头信息？

import java.io.IOException;import java.net.URL;import java.net.URLConnection;import java.util.Map;import java.util.Set; public class Main {    public static void main(String[] args) throws IOException{        URL url = new URL("http://www.runoob.com");        URLConnection conn = url.openConnection();                Map headers = conn.getHeaderFields();        Set
    
      keys = headers.keySet();        for( String key : keys ){            String val = conn.getHeaderField(key);            System.out.println(key+"    "+val);        }        System.out.println( conn.getLastModified() );    }}

结果：

Transfer-Encoding    chunkednull    HTTP/1.1 200 OKServer    Tengine/1.3.0Connection    keep-aliveVary    CookieDate    Mon, 04 May 2015 03:54:05 GMTX-Pingback    http://www.runoob.com/xmlrpc.phpX-Powered-By    PHP/5.3.15Content-Type    text/html; charset=UTF-8

11、解析URL

如何使用 net.URL 类的 url.getProtocol() ,url.getFile() 等方法来解析 URL 地址？

import java.net.URL; public class Main {   public static void main(String[] args)    throws Exception {      URL url = new URL("http://www.runoob.com/html/html-tutorial.html");      System.out.println("URL 是 " + url.toString());      System.out.println("协议是 " + url.getProtocol());      System.out.println("文件名是 " + url.getFile());      System.out.println("主机是 " + url.getHost());      System.out.println("路径是 " + url.getPath());      System.out.println("端口号是 " + url.getPort());      System.out.println("默认端口号是 "       + url.getDefaultPort());   }}

结果：

URL 是 http://www.runoob.com/html/html-tutorial.html协议是 http文件名是 /html/html-tutorial.html主机是 www.runoob.com路径是 /html/html-tutorial.html端口号是 -1默认端口号是 80

12、ServerSocket 和 Socket 通信实例

如何实现客户端发送消息到服务器，服务器接收到消息并读取输出，然后写出到客户端客户端接收到输出。

1、建立服务器端

服务器建立通信ServerSocket

服务器建立Socket接收客户端连接

建立IO输入流读取客户端发送的数据

建立IO输出流向客户端发送数据消息

服务器端代码:

Server.java 文件

import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.IOException;import java.io.InputStreamReader;import java.io.OutputStreamWriter;import java.net.ServerSocket;import java.net.Socket; public class Server {   public static void main(String[] args) {      try {         ServerSocket ss = new ServerSocket(8888);         System.out.println("启动服务器....");         Socket s = ss.accept();         System.out.println("客户端:"+s.getInetAddress().getLocalHost()+"已连接到服务器");                  BufferedReader br = new BufferedReader(new InputStreamReader(s.getInputStream()));         //读取客户端发送来的消息         String mess = br.readLine();         System.out.println("客户端："+mess);         BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));         bw.write(mess+"\n");         bw.flush();      } catch (IOException e) {         e.printStackTrace();      }   }}

以上代码运行输出结果为：

启动服务器....

2、建立客户端

创建Socket通信，设置通信服务器的IP和Port

建立IO输出流向服务器发送数据消息

建立IO输入流读取服务器发送来的数据消息

客户端代码:

Client.java 文件

import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import java.io.OutputStream;import java.io.OutputStreamWriter;import java.net.Socket;import java.net.UnknownHostException; public class Client {   public static void main(String[] args) {      try {         Socket s = new Socket("127.0.0.1",8888);                  //构建IO         InputStream is = s.getInputStream();         OutputStream os = s.getOutputStream();                  BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(os));         //向服务器端发送一条消息         bw.write("测试客户端和服务器通信，服务器接收到消息返回到客户端\n");         bw.flush();                  //读取服务器返回的消息         BufferedReader br = new BufferedReader(new InputStreamReader(is));         String mess = br.readLine();         System.out.println("服务器："+mess);      } catch (UnknownHostException e) {         e.printStackTrace();      } catch (IOException e) {         e.printStackTrace();      }   }}