Java Socket编程 文件传输（客户端从服务器下载一个文件）

服务器（Server）

[java] view plaincopy
package com.socket.sample; 
 
import java.io.BufferedInputStream; 
import java.io.DataInputStream; 
import java.io.DataOutputStream; 
import java.io.File; 
import java.io.FileInputStream; 
import java.net.ServerSocket; 
import java.net.Socket; 
 
public class ServerTest { 
    int port = 8821; 
 
    void start() { 
        Socket s = null; 
        try { 
            ServerSocket ss = new ServerSocket(port); 
            while (true) { 
                // 选择进行传输的文件 
                String filePath = "D:\\lib.rar"; 
                File fi = new File(filePath); 
 
                System.out.println("文件长度:" + (int) fi.length()); 
 
                // public Socket accept() throws 
                // IOException侦听并接受到此套接字的连接。此方法在进行连接之前一直阻塞。 
 
                s = ss.accept(); 
                System.out.println("建立socket链接"); 
                DataInputStream dis = new DataInputStream( 
                        new BufferedInputStream(s.getInputStream())); 
                dis.readByte(); 
 
                DataInputStream fis = new DataInputStream( 
                        new BufferedInputStream(new FileInputStream(filePath))); 
                DataOutputStream ps = new DataOutputStream(s.getOutputStream()); 
                // 将文件名及长度传给客户端。这里要真正适用所有平台，例如中文名的处理，还需要加工，具体可以参见Think In Java 
                // 4th里有现成的代码。 
                ps.writeUTF(fi.getName()); 
                ps.flush(); 
                ps.writeLong((long) fi.length()); 
                ps.flush(); 
 
                int bufferSize = 8192; 
                byte[] buf = new byte[bufferSize]; 
 
                while (true) { 
                    int read = 0; 
                    if (fis != null) { 
                        read = fis.read(buf); 
                        // 从包含的输入流中读取一定数量的字节，并将它们存储到缓冲区数组 b 
                        // 中。以整数形式返回实际读取的字节数。在输入数据可用、检测到文件末尾 (end of file) 
                        // 或抛出异常之前，此方法将一直阻塞。 
                    } 
 
                    if (read == -1) { 
                        break; 
                    } 
                    ps.write(buf, 0, read); 
                } 
                ps.flush(); 
                // 注意关闭socket链接哦，不然客户端会等待server的数据过来， 
                // 直到socket超时，导致数据不完整。 
                fis.close(); 
                s.close(); 
                System.out.println("文件传输完成"); 
            } 
 
        } catch (Exception e) { 
            e.printStackTrace(); 
        } 
    } 
 
    public static void main(String arg[]) { 
        new ServerTest().start(); 
    } 
} 
客户端工具（SocketTool）
[java] view plaincopy
package com.socket.sample; 
 
import java.io.BufferedInputStream; 
import java.io.DataInputStream; 
import java.io.DataOutputStream; 
import java.net.Socket; 
 
public class ClientSocket { 
    private String ip; 
 
    private int port; 
 
    private Socket socket = null; 
 
    DataOutputStream out = null; 
 
    DataInputStream getMessageStream = null; 
 
    public ClientSocket(String ip, int port) { 
        this.ip = ip; 
        this.port = port; 
    } 
 
    /** */ 
    /**
     * 创建socket连接
     * 
     * @throws Exception
     *             exception
     */ 
    public void CreateConnection() throws Exception { 
        try { 
            socket = new Socket(ip, port); 
        } catch (Exception e) { 
            e.printStackTrace(); 
            if (socket != null) 
                socket.close(); 
            throw e; 
        } finally { 
        } 
    } 
 
    public void sendMessage(String sendMessage) throws Exception { 
        try { 
            out = new DataOutputStream(socket.getOutputStream()); 
            if (sendMessage.equals("Windows")) { 
                out.writeByte(0x1); 
                out.flush(); 
                return; 
            } 
            if (sendMessage.equals("Unix")) { 
                out.writeByte(0x2); 
                out.flush(); 
                return; 
            } 
            if (sendMessage.equals("Linux")) { 
                out.writeByte(0x3); 
                out.flush(); 
            } else { 
                out.writeUTF(sendMessage); 
                out.flush(); 
            } 
        } catch (Exception e) { 
            e.printStackTrace(); 
            if (out != null) 
                out.close(); 
            throw e; 
        } finally { 
        } 
    } 
 
    public DataInputStream getMessageStream() throws Exception { 
        try { 
            getMessageStream = new DataInputStream(new BufferedInputStream( 
                    socket.getInputStream())); 
            return getMessageStream; 
        } catch (Exception e) { 
            e.printStackTrace(); 
            if (getMessageStream != null) 
                getMessageStream.close(); 
            throw e; 
        } finally { 
        } 
    } 
 
    public void shutDownConnection() { 
        try { 
            if (out != null) 
                out.close(); 
            if (getMessageStream != null) 
                getMessageStream.close(); 
            if (socket != null) 
                socket.close(); 
        } catch (Exception e) { 
 
        } 
    } 
} 

客户端（Client）

[java] view plaincopy
package com.socket.sample; 
 
import java.io.BufferedOutputStream; 
import java.io.DataInputStream; 
import java.io.DataOutputStream; 
import java.io.FileOutputStream; 
 
public class ClientTest { 
    private ClientSocket cs = null; 
 
    private String ip = "localhost";// 设置成服务器IP 
 
    private int port = 8821; 
 
    private String sendMessage = "Windows"; 
 
    public ClientTest() { 
        try { 
            if (createConnection()) { 
                sendMessage(); 
                getMessage(); 
            } 
 
        } catch (Exception ex) { 
            ex.printStackTrace(); 
        } 
    } 
 
    private boolean createConnection() { 
        cs = new ClientSocket(ip, port); 
        try { 
            cs.CreateConnection(); 
            System.out.print("连接服务器成功!" + "\n"); 
            return true; 
        } catch (Exception e) { 
            System.out.print("连接服务器失败!" + "\n"); 
            return false; 
        } 
 
    } 
 
    private void sendMessage() { 
        if (cs == null) 
            return; 
        try { 
            cs.sendMessage(sendMessage); 
        } catch (Exception e) { 
            System.out.print("发送消息失败!" + "\n"); 
        } 
    } 
 
    private void getMessage() { 
        if (cs == null) 
            return; 
        DataInputStream inputStream = null; 
        try { 
            inputStream = cs.getMessageStream(); 
        } catch (Exception e) { 
            System.out.print("接收消息缓存错误\n"); 
            return; 
        } 
 
        try { 
            // 本地保存路径，文件名会自动从服务器端继承而来。 
            String savePath = "E:\\"; 
            int bufferSize = 8192; 
            byte[] buf = new byte[bufferSize]; 
            int passedlen = 0; 
            long len = 0; 
 
            savePath += inputStream.readUTF(); 
            DataOutputStream fileOut = new DataOutputStream( 
                    new BufferedOutputStream(new FileOutputStream(savePath))); 
            len = inputStream.readLong(); 
 
            System.out.println("文件的长度为:" + len + "\n"); 
            System.out.println("开始接收文件!" + "\n"); 
 
            while (true) { 
                int read = 0; 
                if (inputStream != null) { 
                    read = inputStream.read(buf); 
                } 
                passedlen += read; 
                if (read == -1) { 
                    break; 
                } 
                // 下面进度条本为图形界面的prograssBar做的，这里如果是打文件，可能会重复打印出一些相同的百分比 
                System.out.println("文件接收了" + (passedlen * 100 / len) + "%\n"); 
                fileOut.write(buf, 0, read); 
            } 
            System.out.println("接收完成，文件存为" + savePath + "\n"); 
 
            fileOut.close(); 
        } catch (Exception e) { 
            System.out.println("接收消息错误" + "\n"); 
            return; 
        } 
    } 
 
    public static void main(String arg[]) { 
        new ClientTest().getMessage(); 
    } 
} 

测试是成功的，在DOS命令行下编译~~~