欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识!
您现在的位置是: 首页  >  Java

Java基础入门之网络编程教程

程序员文章站 2022-04-28 12:38:39
...
TCP 网络编程

-- tcp 分为客户端和服务端

-- 客户端对应的对象是 Socket

-- 服务端对应的对象是 ServerSocket

-- 如果客户端先启动,则出现 connection refused 异常 //refused 拒绝

客户端创建Socket 对象时,就可以连接服务器,连接成功后,即形成通路,进行数据交换

import java.net.*;import java.io.*;        //TCP客户端class TClient{public static void main(String [] args) throws Exception
            {
                Socket socket=new Socket("127.0.0.1",9000);                //取得 Socket 中的输出流OutputStream out =socket.getOutputStream();
                out.write("这是客户端向主机输出的数据".getBytes());                //取得服务端发回的数据InputStream in=socket.getInputStream();byte [] buff=new byte[1024];int len =in.read(buff);
                String str=new String(buff,0,len);
                System.out.println("服务端返回的数是:"+str);
                
                out.close();
                in.close();
                socket.close();
            }
        }
//TCP服务端/* 1 创建ServerSocket ,指定要监听的端口
         2 通过 ServerSocket 的 accept 方法 (它是阻塞模式的) 取得连接上来的客户端对象
         3 与客户端连通后,就可以得到客户端对象,并使用客户端对象读取流来取得数据
         4 如果有必要,释放资源*/import java.io.*;import java.net.*;class TServer
        {public static void main(String [] args) throws Exception
            {
                ServerSocket serverSocket=new ServerSocket(9000);  //指定监听的端口Socket clientSocket=serverSocket.accept();                //通过客户端的Socket对象可以取得信息String clientIp=clientSocket.getInetAddress().getHostAddress();int clientPort=clientSocket.getPort();
                
                System.out.println(clientIp+":"+clientPort +"连接成功");
                
                InputStream in= clientSocket.getInputStream();byte[] buff=new byte[1024];int len=in.read(buff);  //len 表示读了多少个字节   注意,这个read 是阻塞的                
                String msg=new String(buff,0,len);
                
                System.out.println(msg);                //往回发送数据OutputStream out=clientSocket.getOutputStream();
                out.write("小样的客户端,你竞敢骂人?,我也能".getBytes()); */
                out.close();
                in.close();
                serverSocket.close();
                clientSocket.close();
        
            }
        }

例子 从客户端向服务端发字母,变成大写后反回

/*客户端:
            1 建立服务
            2 获取键盘录入
            3 将数入的数据发给服务端
            4 接收服务端返回的大写字母
            5 关闭资源
            备注: 使用带缓冲的字符流进行操作 */import java.io.*;import java.net.*;class TransClient
        {public static void main(String [] args) throws Exception
            {
                    Socket socket=new Socket("127.0.0.1",8000);                    //定义输入流,读取键盘数据BufferedReader br=new BufferedReader(new InputStreamReader(System.in));                    //定义输出流对象(用于将键盘数据写入到输出流中)BufferedWriter bw=new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));                    //定义一个socket 读取流,读取服务器返回的大写字母BufferedReader brResult=new BufferedReader(new InputStreamReader(socket.getInputStream()));
                    
                    String str=null;while((str=br.readLine())!=null){ //从键盘开始读取bw.write(str);  //向服务端输出                        bw.newLine();
                        bw.flush(); //千万别忘了                        
                      System.out.println("服务端返回的数据是"+brResult.readLine()); //取出变大写后的字符串                    }
                    
                    socket.close();
                    br.close();
                    bw.close();
                    brResult.close();        
            }
        }
//服务端  import java.net.*;import java.io.*;class TransServer
        {public static void main(String [] args) throws Exception
                {
                     ServerSocket serverSocket=new ServerSocket(8000);
                     Socket clientSocket=serverSocket.accept();                     
                     //读取socket流中的数据(从客户端发过来的小写字母) BufferedReader br=new BufferedReader(new InputStreamReader( clientSocket.getInputStream()));                     
                     //创建输出流对象,往clientSocket 的流中写入转换后的大写字母 BufferedWriter bw=new BufferedWriter(new OutputStreamWriter( clientSocket.getOutputStream()));
                     
                     String str=null;                     while((str=br.readLine())!=null)  //注意 readLine 的特性,它是要一直读取回车换行才返回                     {
                             bw.write(str.toUpperCase());
                             bw.newLine();
                             bw.flush(); //千万别忘了                     }
                     
                    br.close();
                    bw.close();
                    clientSocket.close();
                    serverSocket.close();
                }
        
        }

例子 上传文件

//客户端  import java.io.*;import java.net.*;class UPClient
        {public static void main(String [] args) throws Exception
            {
                    Socket socket=new Socket("127.0.0.1",7000);
                    BufferedReader br=new BufferedReader(new FileReader("C:\\作业\\名单.txt"));  //用来读文件的输入流BufferedWriter bw=new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));  //用来把文件往服务端传                    //往scoket中一行一行的写入数据String content=null;while((content=br.readLine())!=null){
                        bw.write(content);
                        bw.newLine();
                        bw.flush();
                    }
                    
                    socket.shutdownOutput(); //关闭客端的输出流同,当相于加入一个结束标记(-1),要不然服务端会不停的等                                //取出服务端返回的信息BufferedReader brResult=new BufferedReader(new InputStreamReader(socket.getInputStream())) ;
                    System.out.println(    brResult.readLine());
                        
                    bw.close();
                    br.close();
                    socket.close();
            }
        }
//服务端  import java.io.*;import java.net.*;class UPServer
        {public static void main(String [] args) throws Exception
            {
                    ServerSocket serverSocket=new ServerSocket(7000);
                    Socket clientSocket=serverSocket.accept();
                    
                    System.out.println(clientSocket.getInetAddress().getHostAddress()+"已经连接..."); //打印一下客户端连上的的信息                    //读取客户端发过的来的数据BufferedReader br=new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
                    BufferedWriter bw=new BufferedWriter(new FileWriter("e:/xxx.exe"));
                    
                    String str=null;while((str=br.readLine())!=null){  //如果客户端不发结束标记,它就不会返回                        bw.write(str);
                        bw.newLine();
                        bw.flush();
                    }                    //再向发送端返回一条提示息                    
                    BufferedWriter bwResult=new BufferedWriter(new OutputStreamWriter(clientSocket.getOutputStream()));
                    bwResult.write("文件上传成功");
                    bwResult.flush();
                    
                    serverSocket.close();
                    clientSocket.close();
                    bwResult.close();
                    bw.close();
                    br.close();
                        
            }

例子 上传图片

客户端import java.net.*;import java.io.*;class ImgClient
            {public static void main(String [] ars) throws Exception
                    {
                            Socket socket=new Socket("127.0.0.1",7000);
                            FileInputStream fis=new FileInputStream("C:\\image\\0.jpg");  //文件输入流OutputStream out=socket.getOutputStream();                            byte [] buff  =new byte[1024];int len=0;while((len=fis.read(buff))!=-1){  //一边读数据,一边传数据out.write(buff,0,len);    //字节流,不用flush, 和 newLine()                            }
                            
                            socket.shutdownOutput(); //加一个结束标记,表示输入流结束                            //取出服务端发过来的信息BufferedReader brResult=new BufferedReader(new InputStreamReader(socket.getInputStream()));
                            System.out.println(brResult.readLine());
                            
                            socket.close();
                            fis.close();
                    }
            }
服务端import java.net.*;import java.io.*;class ImgServer
            {public static void main(String [] args) throws Exception
                {
                        ServerSocket serverSocket=new ServerSocket(7000);
                        
                        Socket clientSocket=serverSocket.accept();
                        
                        System.out.println(clientSocket.getInetAddress().getHostAddress()+" 已连接");
                        
                        InputStream in=clientSocket.getInputStream(); //取数据用的流FileOutputStream fos=new FileOutputStream("e:\\xxx.jpg");                        byte [] buff=new byte[1024];int len=0;while((len=in.read(buff))!=-1){
                            fos.write(buff,0,len); //不用flush 因为是字节流                        }
                        
                        BufferedWriter br=new BufferedWriter(new OutputStreamWriter(clientSocket.getOutputStream()));
                        br.write("图片上传成功");
                        br.flush(); //别忘了                        
                        serverSocket.close();
                        clientSocket.close();
                        br.close();
                        fos.close();    
                }
            }

例子 多线程并发上传图片

服务端     import java.net.*;class PICServer
        {public static void main(String [] args) throws Exception 
                {
                    ServerSocket serverSocket=new ServerSocket(9000);                    while(true)
                    {
                            Socket clientSocket=serverSocket.accept();new Thread(new PICThread(clientSocket)).start();
                    }
                }
        }
import java.io.*;import java.net.*;class PICThread implements Runnable{private Socket clientSocket;public PICThread(Socket socket)
            {
                clientSocket=socket;
            }public void run()
            {try{
                    
                    String clientIp=clientSocket.getInetAddress().getHostAddress();
                    FileOutputStream fos=new FileOutputStream("e:\\"+clientIp);
                    InputStream in =clientSocket.getInputStream();  //从套接字中取出数据byte[] buff=new byte[1024];int len=0;while((len=in.read(buff))!=-1)  //把数据从流中读出,写入文件                    {
                         fos.write(buff,0,len);
                    }
                    
                    BufferedWriter br=new BufferedWriter(new OutputStreamWriter(clientSocket.getOutputStream()));
                    br.write("图片上传成功");
                    br.flush();
                    
                    
                    clientSocket.close();
                    fos.close();
                    in.close();
                    
                }catch(Exception ex){
                    System.out.println("出错了");
                }            
            }
        }
客户端        import java.io.*;import java.net.*;class PICClient{public static void main(String [] args) throws Exception
            {
                
                   String fileName=args[0];//String fileName="c:\\Image\\2.jpg";                
                    //进行验证File file=new File(fileName);if(!(file.exists()&&file.isFile()))  //验证文件是不是存在                    {
                        System.out.println("输入的文件名错误或是个目录");return;
                    }                    if( !file.getName().endsWith(".jpg")){
                        System.out.println("文件类型不正确");return ;
                    }                    if( file.length() >1024*1024){
                        System.out.println("你想干啥,整这么大的文件上来? 不行");return; 
                    }
                    
                  Socket socket=new Socket("127.0.0.1",9000);
                
                    FileInputStream fis=new FileInputStream(fileName);  //构建文件输入流OutputStream out=socket.getOutputStream(); //输出流byte [] buff=new byte[1024]; int len=0;while((len=fis.read(buff))!=-1)  //一边读入,一边往文件中写出                    {
                         out.write(buff,0,len);
                    }
                    
                    socket.shutdownOutput();                    //取出服务端发过来的信息BufferedReader brResult=new BufferedReader(new InputStreamReader(socket.getInputStream()));
                    System.out.println(brResult.readLine());
                    
                    socket.close();
                    fis.close();
                    brResult.close();
                    out.close();    
            }
        }

以上就是Java基础入门之网络编程教程的详细内容,更多请关注其它相关文章!