Java网络编程

1.通过InetAddress获取IP地址

public class IPDemo {    public static void main(String[] args) throws Exception    {        //获取本机的IP地址        InetAddress i=InetAddress.getLocalHost();        System.out.println(i.toString());        System.out.println("address:"+i.getHostAddress());//主要方式，速度快        System.out.println("name:"+i.getHostName());        //域名下映射多个ip获取方式        InetAddress[] ias=InetAddress.getAllByName("www.baidu.com");        for(InetAddress i:ias){            System.out.println(i.toString());        }        InetAddress ia=InetAddress.getByName("www.baidu.com");        System.out.println(ia.toString());//默认获得第一个IP地址     }}

2.udp方式发送和接收数据

• 发送端

public class UdpSend2 {    public static void main(String[] args) throws Exception     {        DatagramSocket ds=new DatagramSocket(6666);        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));        String line=null;        while((line=br.readLine())!=null){            if(line.equals("886")){                break;            }            byte[] buf=line.getBytes();            DatagramPacket dp=new DatagramPacket(buf,     buf.length,InetAddress.getByName("192.168.XXX.XX"),10001);            ds.send(dp);        }        ds.close();    }}

• 接收端

public class UpdReceive2 {    public static void main(String[] args) throws Exception {        DatagramSocket ds =new DatagramSocket(10001);        while(true){            byte[] buf=new byte[1024];            DatagramPacket dp=new DatagramPacket(buf, buf.length);            ds.receive(dp);//阻塞式方法            String ip=dp.getAddress().getHostAddress();            String data=new String(dp.getData(),0,dp.getLength());            System.out.println(ip+":"+data);        }//      ds.close();    }}

注意：运行时先开启接收端，再开启发送端

• 多线程聊天小程序

class Send implements Runnable{    private DatagramSocket ds;    public Send(DatagramSocket ds){        this.ds=ds;    }    public void run() {        try {            BufferedReader br=new BufferedReader(new InputStreamReader(System.in));            String line=null;            while((line=br.readLine())!=null){                byte[] buf=line.getBytes();                DatagramPacket dp=new DatagramPacket(buf, buf.length,InetAddress.getByName("192.168.XXX.XXX"),10002);                ds.send(dp);            }           } catch (Exception e) {            throw new RuntimeException("发送端失败!");        }    }}class Receive implements Runnable{    private DatagramSocket ds;    public Receive(DatagramSocket ds){        this.ds=ds;    }    public void run() {        try {            while(true){                byte[] buf=new byte[1024];                DatagramPacket dp=new DatagramPacket(buf, buf.length);                ds.receive(dp);                String ip=dp.getAddress().getHostAddress();                String data=new String(dp.getData(),0,dp.getLength());                System.out.println(ip+":"+data);            }        } catch (Exception e) {            throw new RuntimeException("接收端失败!");        }    }}public class ChatDemo {    public static void main(String[] args) throws Exception {        DatagramSocket sendDs=new DatagramSocket();        DatagramSocket receiveDs=new DatagramSocket(10002);        new Thread(new Receive(receiveDs)).start();        new Thread(new Send(sendDs)).start();    }}

3.tcp方式接收和发送数据

• 客户端

public class TcpClient{    public static void main(String[] args) throws Exception {        //创建客户端的socket服务，指定目的主机和端口        Socket s=new Socket("169.254.X.X",10003);        //为了发送数据，应该获取socket流中的输出流        OutputStream out=s.getOutputStream();        out.write("TCP哥们来了".getBytes());        s.close();    }}

• 服务端

class TcpServer{    public static void main(String[] args) throws Exception {        //建立服务端socket服务。并监听一个端口        ServerSocket ss=new ServerSocket(10003);        //通过accept方法获取链接过来的客户端对象        Socket s=ss.accept();        String ip=s.getInetAddress().getHostAddress();        System.out.println(ip+".....connected");        //获取客户端发送过来的数据，使用输入流来读取        InputStream in=s.getInputStream();        byte[] buf=new byte[1024];        int len=in.read(buf);        System.out.println(new String(buf,0,len));        s.close();        ss.close();    }}

• 大小写转换案例

//客户端public class TransClient {    public static void main(String[] args) throws Exception {        Socket s=new Socket("169.254.X.X", 10004);        //获取键盘输入        BufferedReader br =new BufferedReader(new InputStreamReader(System.in));        //定义一个读取流，读取服务端返回的大写字母        BufferedReader bufIn=new BufferedReader(new InputStreamReader(s.getInputStream()));        //将数据写到输出流发送到服务端//      BufferedWriter bufOut=new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));        //或者        PrintWriter pw=new PrintWriter(s.getOutputStream(),true);        String line=null;        while((line=br.readLine())!=null){            if("over".equals(line))                break;//          bufOut.write(line);//          bufOut.newLine();//          bufOut.flush();            pw.println(line);            String str=bufIn.readLine();            System.out.println("server:"+str);        }        br.close();        s.close();    }}//服务端public class TransServer {    public static void main(String[] args) throws Exception{        ServerSocket ss=new ServerSocket(10004);        Socket s=ss.accept();        String ip=s.getInetAddress().getHostAddress();        System.out.println(ip+"......connected");        //读取客户端键盘录入的字母        BufferedReader bufIn=new BufferedReader(new InputStreamReader(s.getInputStream()));//      BufferedWriter bufOut=new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));        PrintWriter pw =new PrintWriter(s.getOutputStream(), true);        String line=null;        while((line=bufIn.readLine())!=null){//          bufOut.write(line.toUpperCase());//          bufOut.newLine();//          bufOut.flush();            pw.println(line.toUpperCase());        }        s.close();        ss.close();    }

• 上传文件案例

//客户端public class TextClient {    public static void main(String[] args) throws Exception {        Socket s=new Socket("169.254.x.x",10005);        BufferedReader bufr=new BufferedReader(new FileReader("F:\\工作区\\APIs\\sql注入.txt"));        PrintWriter out=new PrintWriter(s.getOutputStream(),true);        String line=null;        while((line=bufr.readLine())!=null){            out.println(line);        }        s.shutdownOutput();//关闭客户端的输出流，相当于给流中加入了结束标记-1        BufferedReader bufIn=new BufferedReader(new InputStreamReader(s.getInputStream()));        String str=bufIn.readLine();        System.out.println(str);//接收服务端传过来的上传成功字样        bufr.close();        s.close();    }}//服务端public class TextServer {    public static void main(String[] args) throws Exception {        ServerSocket ss=new ServerSocket(10005);        Socket s=ss.accept();        String ip=s.getInetAddress().getHostAddress();        System.out.println(ip+"....connected");        BufferedReader buIn=new BufferedReader(new InputStreamReader(s.getInputStream()));        PrintWriter out=new PrintWriter(new FileWriter("D:\\1.txt"),true);        String line = null;        while((line=buIn.readLine())!=null){            out.println(line);        }        PrintWriter pw =new PrintWriter(s.getOutputStream(),true);        pw.println("上传成功！");        out.close();        s.close();        ss.close();    }}

• 上传图片案例

//客户端public class PicClient {    public static void main(String[] args) throws Exception {        Socket  s=new Socket("192.168.x.x", 10006);        FileInputStream fis=new FileInputStream("E:\\图片\\b9.jpg");        OutputStream out=s.getOutputStream();        byte[] buf=new byte[1024];        int len=0;        while((len=fis.read(buf))!=-1){            out.write(buf,0,len);        }        //告诉服务器数据已写完        s.shutdownOutput();        byte[] str=new byte[1024];        InputStream in=s.getInputStream();        int num=in.read(str);        System.out.println(new String(str,0,num));        fis.close();        s.close();    }}//服务端public class PicServer {    public static void main(String[] args) throws Exception{        ServerSocket ss=new ServerSocket(10006);        Socket s=ss.accept();        String ip=s.getInetAddress().getHostAddress();        System.out.println(ip+"......connected");        InputStream in=s.getInputStream();        FileOutputStream fos=new FileOutputStream("d:\\1.jpg");        int len=0;        byte[] buf =new byte[1024];        while((len=in.read(buf))!=-1){            fos.write(buf,0,len);        }        OutputStream out=s.getOutputStream();        out.write("上传成功".getBytes());        fos.close();        s.close();        ss.close();    }}