一、套接字Socket
IP地址标志Internet上的计算机，端口号标志正在计算机上运行的进程（程序）。
端口号被规定为一个16位的0--65535之间的整数，其中，0--1023被预先定义的服务通信占用。
当两个程序需要通信时，可以通过Socket类建立套接字对象并连接在一起。（端口号与IP地址的组合得出的一个网络套接字）
二、示例
（1）客户端服务器端一对一；聊天
package mychat; import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.Socket;
import java.net.UnknownHostException; public class Client { /**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
Socket client = null;
//读服务器说的话
BufferedReader br = null;
//写个服务器
BufferedWriter bw = null;
//读键盘
BufferedReader input = null;
try {
client = new Socket("127.0.0.1",);
while(true)
{
//从键盘写
System.out.println("客户端说:");
input = new BufferedReader(new InputStreamReader(System.in));
String str = input.readLine();
//写给服务器
bw = new BufferedWriter(new OutputStreamWriter(client.getOutputStream()));
bw.write(str);
bw.newLine();
bw.flush();
//接受服务器信息
br = new BufferedReader(new InputStreamReader(client.getInputStream()));
String line =null;
line = br.readLine();
System.out.println("服务器说"+line);
} } catch (UnknownHostException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} } }
Client.java客户端
package mychat; 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) {
// TODO Auto-generated method stub
BufferedReader input = null;
BufferedWriter bw =null;
BufferedReader br = null;
Socket socket = null;
try {
ServerSocket server = new ServerSocket(); System.out.println("等待客户端响应");
socket = server.accept();
System.out.println("与客户端建立连接");
//读
br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
//写
bw = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
input = new BufferedReader(new InputStreamReader(System.in)); while(true)
{
String line = br.readLine();
System.out.println("客户端说:"+line);
//写 System.out.println("请输入服务器说的话");
String str = input.readLine();
bw.write(str);
bw.newLine();
bw.flush();
System.out.println("服务器说："+str);
} } catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
finally{
try {
br.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
bw.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
input.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
socket.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} }
} }
Server.java服务器端
（2）客户端上传文件（字符）
package loadzifu; import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.Socket;
import java.net.UnknownHostException; public class Client { /**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
Socket client = null;
//读文件名
BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
//读本地文件
File f=null;
BufferedReader brFile = null;
BufferedWriter bw = null;
try {
client = new Socket("127.0.0.1",);
bw = new BufferedWriter(new OutputStreamWriter(client.getOutputStream()));
System.out.println("请输入要上传的文件");
String fileName = input.readLine();
brFile = new BufferedReader(new FileReader(("src/chat/"+fileName)));
String line =null;
while((line= brFile.readLine())!=null)
{
//写个客户端
bw.write(line);
bw.newLine();
bw.flush(); } } catch (UnknownHostException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
finally{
try {
bw.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
brFile.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
input.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} } }
Client.java客户端
package loadzifu; import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.ServerSocket;
import java.net.Socket; public class Server { /**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
ServerSocket server = null;
Socket socket = null;
BufferedReader br =null;
BufferedWriter bwFile = null;
try {
server = new ServerSocket();
System.out.println("等待客户端连接");
socket = server.accept();
System.out.println("与客户端建立连接");
File f = new File("src/loadzifu/a.txt");
bwFile = new BufferedWriter(new FileWriter(f));
br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
String str = null;
while((str=br.readLine())!=null)
{
bwFile.write(str);
bwFile.newLine();
bwFile.flush();
} } catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
finally{
try {
br.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
bwFile.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
socket.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} } }
Server.java服务器端
（3）客户端上传文件（字节）
package loadzijie; import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.Socket;
import java.net.UnknownHostException; public class Client { public static void main(String[] args) {
// TODO Auto-generated method stub
Socket client = null;
//读文件
BufferedInputStream bisFile = null;
//源文件
File f = null;
//读键盘
BufferedReader input = null;
//写个服务器
BufferedOutputStream bos = null;
try {
client = new Socket("127.0.0.1",); System.out.println("请输入要复制的文件");
input = new BufferedReader(new InputStreamReader(System.in));
String fileName = input.readLine();
f = new File("src/chat/"+fileName);
//读文件
bisFile = new BufferedInputStream(new FileInputStream(f));
bos = new BufferedOutputStream(client.getOutputStream());
int len=;
byte bytes[] = new byte[];
while((len=bisFile.read(bytes))!=-)
{
bos.write(bytes,,len);
bos.flush();
} } catch (UnknownHostException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
try {
bos.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
client.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
bisFile.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} } }
Client.java客户端
package loadzijie; import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket; public class Server { public static void main(String[] args) {
// TODO Auto-generated method stub
ServerSocket server = null;
Socket socket = null;
File f = null;
BufferedInputStream bis = null;
BufferedOutputStream bosFile = null; try {
server = new ServerSocket();
System.out.println("等待客户端连接");
socket = server.accept();
System.out.println("与客户端建立连接");
f = new File("src/loadzijie/dd.bmp");
bis = new BufferedInputStream(socket.getInputStream());
bosFile = new BufferedOutputStream(new FileOutputStream(f));
int len =;
byte bytes[] = new byte[];
while((len = bis.read(bytes))!=-)
{
//写文件
bosFile.write(bytes,,len);
bosFile.flush(); }
System.out.println("上传成功"); } catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
finally{
try {
bis.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
bosFile.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
socket.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
} }
Server.java服务器端
（4）服务器端多线程接受客户端文件
package loadget; import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.Socket;
import java.net.UnknownHostException; public class Client { /**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
Socket client = null;
File f = null;
//读键盘
BufferedReader input = null;
//读文件
BufferedInputStream brFile = null;
//上传服务器
BufferedOutputStream bos = null;
try {
client = new Socket("127.0.0.1",);
System.out.println("请输入要上传的文件");
input = new BufferedReader(new InputStreamReader(System.in));
String fileName = input.readLine();
bos = new BufferedOutputStream(client.getOutputStream());
f = new File(("src/chat/"+fileName));
//读文件
brFile = new BufferedInputStream(new FileInputStream(f));
int len =;
byte bytes[]= new byte[];
while((len=brFile.read(bytes))!=-)
{
bos.write(bytes,,len);
bos.flush();
} } catch (UnknownHostException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
finally{
try {
bos.close();
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
try {
brFile.close();
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
try {
client.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} } }
Client.java客户端
package loadget; import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket; public class Server { /**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
ServerSocket server = null;
//接受文件 try {
server = new ServerSocket(); while(true)
{ System.out.println("等待与客户端连接");
final Socket sock = server.accept();
System.out.println("与客户端建立连接");
new Thread(new Runnable() {
BufferedInputStream bis = null;
//写文件
BufferedOutputStream bos =null;
@Override
public void run() {
// TODO Auto-generated method stub
try { bis = new BufferedInputStream(sock.getInputStream());
int a = (int)(Math.random()*+);
System.out.println("a:"+a);
File fileName = new File("src/loadget/a.txt");
bos = new BufferedOutputStream(new FileOutputStream(fileName));
int len =;
byte bytes[] = new byte[];
while((len=bis.read(bytes))!=-)
{
bos.write(bytes,,len);
bos.flush();
} } catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
finally{
try {
bos.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
bis.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
sock.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} }
}).start();
} } catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
Server.java服务器端