[Java] 文件上传下载项目（详细注释）

先上代码，最上方注释是文件名称(运行时要用到)

FTServer.java

 /*
     FTServer.java
 */

 import java.util.*;
 import java.io.*;

 public class FTServer {

     public static File share = null;

     public static void main(String[] args) throws Exception  {

         int port = ;

         //加载配置文件
         Properties p = new Properties();
         p.load(FTServer.class.getClassLoader().getResourceAsStream("server.properties"));

         //获取服务器的存储路径
         share = new File(p.getProperty("share"));

         if(!share.isDirectory()) {
             System.out.println("share directory not exists or isn't a directory");
             System.exit(-);
         }

         //读取服务器与客户机交互的端口号
         port = Integer.parseInt(p.getProperty("port"));

         FTProtocol protocol = new FTProtocol();
         AdvancedSupport as = new AdvancedSupport(protocol);
         NwServer nw = new NwServer(as,port);

     }

 }

FTClient.java

 /*
     FTClient.java
 */

 import java.net.*;
 import java.io.*;
 import java.util.*;

 public class FTClient {

     Socket s = null;
     DataInputStream dis = null;
     DataOutputStream dos = null;

     String[] args = null;

     public void start(String server, int port) throws Exception {
         s = establish(server, port);//new一个socket
         dis = new DataInputStream(s.getInputStream());
         dos = new DataOutputStream(s.getOutputStream());

         if (args[].equals("get")) {//获取文件
             dos.writeInt();//执行command为3的操作，对应FTProtocol中的case 3
             dos.flush();//清空缓冲区数据
             int files = dis.readInt();//得到目录中文件数量
             if (files == ) {//目录中文件为空
                 System.out.println("no files available on the FTServer");
                 s.close();//关闭套接字
                 System.exit(-);//退出程序
             }
             String[] filenames = new String[files];
             for (int i = ; i < files; i++) {
                 filenames[i] = dis.readUTF();//读取FTProtocol中通过writeUTF(files[i])发来的文件名
                 System.out.println(i +  + "\t\t" + filenames[i]);//输出序号和文件名
             }

             System.out.print("please input your choice:");

             BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
             String c = br.readLine();//读取输入的命令选项

             if (c.equalsIgnoreCase("q")) {//若输入'Q'或'q'则退出程序
                 s.close();//关闭套接字
                 System.exit();//退出程序
             }

             if (c.equalsIgnoreCase("a")) {//若输入'A'或'a'则下载全部文件
                 for (int i = ; i < filenames.length; i++) {
                     System.out.println("filenames[i] = " + filenames[i]);
                     download(filenames[i]);//循环下载每一个文件
                 }
                 s.close();
                 System.exit();
             }
             int choice = ;
             try {
                 choice = Integer.parseInt(c);//将字符串转换成整形
             } catch (NumberFormatException e) {
                 System.out.println("your input is wrong");
                 s.close();
                 System.exit(-);
             }

             //输入文件对应序号则下载该文件
             if (choice >=  && choice <= filenames.length) {
                 download(filenames[choice - ]);
             } else {
                 System.out.println("your input is wrong");
                 s.close();
                 System.exit(-);
             }
             s.close();
             System.exit();
         } else if (args[].equals("put")) {//上传文件
             File f = new File("C:/_Client/" + args[]);//args[2]为文件名
             if (f.isFile()) {
                 upload("C:/_Client/" + args[]);
             } else if (f.isDirectory()) {//如果上传的是一个目录
                 String[] filenames = f.list();//将目录中所有文件存入filenames数组
                 if (filenames.length == ) {
                     s.close();
                     System.out.println("no files available in the directory");
                     System.exit(-);
                 }
                 for (int i = ; i < filenames.length; i++) {//将目录中的文件列表显示
                     System.out.println(i +  + "\t\t" + filenames[i]);
                 }
                 System.out.print("please input your choice:");
                 BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
                 String c = br.readLine();

                 if (c.equalsIgnoreCase("q")) {//若输入'Q'或'q'则退出程序
                     s.close();//关闭套接字
                     System.exit();//退出程序
                 }

                 if (c.equalsIgnoreCase("a")) {//若输入'A'或'a'则上传全部文件
                     for (int i = ; i < filenames.length; i++) {
                         String dir = f.getCanonicalPath();//获取文件路径
                         String tf = null;
                         if (dir.endsWith(File.separator)) {//如果以分隔符结尾，则直接加上文件名
                             tf = dir + filenames[i];
                         } else {//否则加上分隔符再加文件名
                             tf = dir + File.separator + filenames[i];
                         }
                         //此时tf为文件的绝对路径
                         if(new File(tf).isDirectory()) continue;
                         upload(tf);
                     }
                     s.close();
                     System.exit();
                 }
                 int choice = ;
                 try {
                     choice = Integer.parseInt(c);
                 } catch (NumberFormatException e) {
                     System.out.println("your input is wrong");
                     s.close();
                     System.exit(-);
                 }
                 //上传第choice个文件
                 if (choice >=  && choice <= filenames.length) {
                     String dir = f.getCanonicalPath();
                     if (dir.endsWith(File.separator)) {
                         upload(dir + filenames[choice - ]);
                     } else {
                         upload(dir + File.separator + filenames[choice - ]);
                     }

                 } else {
                     System.out.println("your input is wrong");
                     s.close();
                     System.exit(-);
                 }

             } else {
                 s.close();
                 System.out.println(args[] + " not exists");
                 System.exit(-);
             }

             s.close();
             System.exit();

         }

     }

     public Socket establish(String server, int port) {
         try {
             Socket s = new Socket(server, port);
             return s;
         } catch (Exception e) {
             e.printStackTrace();
             return null;
         }
     }

     public void upload(String filename) throws Exception {

         File f = new File(filename);

         if (!f.exists() || !f.isFile()) {
             System.out.println("it's wrong, maybe it is not a file or not exists");
             System.exit(-);
         }

         byte[] buffer = new byte[];
         int rr = ;

         dos.writeInt();//执行FTProtocol中的上传命令
         dos.writeUTF(f.getName());//将文件名传递给FTProtocol
         dos.writeLong(f.length());//将文件长度传递给FTProtocol
         dos.flush();//清空缓存

         FileInputStream fis = new FileInputStream(f);
         BufferedInputStream bis = new BufferedInputStream(fis);

         while ((rr = bis.read(buffer)) != -) {
             dos.write(buffer, , rr);
             dos.flush();
         }

         bis.close();
         fis.close();

     }

     public void download(String filename) throws Exception {
         dos.writeInt();//执行FTProtocol中的下载命令
         dos.writeUTF(filename);//将要下载的文件名传递给FTProtocol
         dos.flush();

         //filename = dis.readUTF();
         long len = dis.readLong();//获得文件长度

         byte[] buffer = new byte[];
         long r = ;
         int rr = ;

         //将先下载后的文件输出到C盘的_Client文件夹
         FileOutputStream fos = new FileOutputStream("C:/_Client/" + filename);
         BufferedOutputStream bos = new BufferedOutputStream(fos);

         while (r < len) {
             if (len - r >= buffer.length) {//若文件未传输的部分大于buffer的长度则每次传输buffer.length的字节
                 rr = dis.read(buffer, , buffer.length);
             } else {//将剩余(小于buffer.length)的数据传输
                 rr = dis.read(buffer, , (int) (len - r));
             }
             r = r + rr;
             bos.write(buffer, , rr);//将下次传输可接收的字节传递给FTProtocol,rr=-1则传输结束
         }

         bos.close();
         fos.close();

         System.out.println("download Finished!");

     }

     public static void main(String[] args) throws Exception {
         if(args.length==) {
             System.out.println("Usage:");
             System.out.println("java FTClient host get");
             System.out.println("java FTClient host put afile");
             System.exit();

         }
         FTClient ftc = new FTClient();
         ftc.args = args;
         ftc.start(args[], );//args[0]为host
     }
 }

FTProtocol.java

 import java.net.Socket;
 /*
     FTProtocol.java
 */

 import java.io.*;
 import java.util.*;

 //与AdvancedSupport都implements IOStrategy，都重写了service()函数
 public class FTProtocol implements IOStrategy {

     @Override
     public void service(Socket socket) {
         String client = socket.getInetAddress().getHostName() + "(" + socket.getInetAddress().getHostAddress() + ")";

         try {
             InputStream is = socket.getInputStream();
             OutputStream os = socket.getOutputStream();
             DataInputStream dis = new DataInputStream(is);
             DataOutputStream dos = new DataOutputStream(os);

             String filename = null;
             long len = ;
             byte[] buffer = new byte[];
             long r = ;
             int rr = ;

             while (true) {
                 int command = dis.readInt(); // 读取FTClient中通过writeInt()传来的命令
                 switch (command) {
                 case : // file upload
                     filename = dis.readUTF();//接收文件名
                     len = dis.readLong();//接收文件长度

                     //将用户上传文件存到FTServer.share目录中
                     FileOutputStream fos = new FileOutputStream(new File(FTServer.share, filename));
                     BufferedOutputStream bos = new BufferedOutputStream(fos);
                     r = ;
                     rr = ;

                     while (r < len) {
                         if (len - r >= buffer.length) {
                             rr = dis.read(buffer, , buffer.length);
                         } else {
                             rr = dis.read(buffer, , (int) (len - r));
                         }

                         r = r + rr;
                         bos.write(buffer, , rr);
                     }

                     bos.close();
                     fos.close();
                     break;
                 case : // file download
                     filename = dis.readUTF();
                     //dos.writeUTF(filename);
                     File t = new File(FTServer.share, filename);
                     //System.out.println("FTServer.share = " + FTServer.share);
                     dos.writeLong(t.length());//将文件长度传递给FTClient
                     dos.flush();//清空缓存
                     FileInputStream fis = new FileInputStream(t);
                     BufferedInputStream bis = new BufferedInputStream(fis);

                     while ((rr = bis.read(buffer)) != -) {//接收到下次可发送的字节数,-1结束
                         dos.write(buffer, , rr);
                         dos.flush();
                     }

                     bis.close();
                     fis.close();
                     break;

                 case : // list files
                     String[] files = FTServer.share.list();//将share目录下所有文件名存入files数组
                     List<String> list = new LinkedList<String>();
                     for(int i=;i<files.length;i++) {
                         if(new File(FTServer.share, files[i]).isDirectory())
                             continue;//如果是一个目录则不显示
                         list.add(files[i]);
                     }

                     files = list.toArray(new String[]);//将List<String>转换成String[]

                     dos.writeInt(files.length);//将文件数量传给FTClient
                     dos.flush();//清空缓存
                     for (int i = ; i < files.length; i++) {
                         dos.writeUTF(files[i]);//将每一个文件名传给FTClient
                     }
                     dos.flush();//清空缓存
                     break;
                 }
             }
         } catch (Exception e) {
             if (e instanceof EOFException) {
                 System.out.println(client + " disconnected");
             } else {
                 e.printStackTrace();
             }

         }
     }
 }

AdvancedSupport.java

 /*
     AdvancedSupport.java
 */

 import java.net.*;
 import java.io.*;
 import java.util.*;

 //与FTProtocol都implements IOStrategy，都重写了service()函数
 public class AdvancedSupport implements IOStrategy {
     private ArrayList threads = new ArrayList();//开线程数组
     private final int INIT_THREADS = ;//初始线程数
     private final int MAX_THREADS = ;//最大线程数
     private IOStrategy ios = null;//初始化

     //构造函数
     public AdvancedSupport(IOStrategy ios) {
         this.ios = ios;

         for (int i = ; i < INIT_THREADS; i++) {
             IOThread t = new IOThread(ios);
             t.start();
             threads.add(t);
         }
         try {
             Thread.sleep();
         } catch (Exception e) {
         }
     }

     public void service(Socket socket) {
         IOThread t = null;
         boolean found = false;

         //顺序找到线程中第一个等待的IOThread，将found置为true并退出循环
         for (int i = ; i < threads.size(); i++) {
             t = (IOThread) threads.get(i);
             if (t.isIdle()) {
                 found = true;
                 break;
             }
         }

         //若Thread中不存在等待的线程，则新建一个线程并启动
         if (!found) {
             t = new IOThread(ios);
             t.start();
             try {
                 Thread.sleep();
             } catch (Exception e) {
             }
             //将新建线程添加到threads数组中
             threads.add(t);
         }

         //将socket赋值为传来的socket参数
         t.setSocket(socket);
     }
 }

 class IOThread extends Thread {
     private Socket socket = null;
     private IOStrategy ios = null;

     public IOThread(IOStrategy ios) {
         this.ios = ios;
     }

     public boolean isIdle() {
         return socket == null;
     }

     public synchronized void setSocket(Socket socket) {
         this.socket = socket;
         notify();//唤醒
     }

     public synchronized void run() {
         while (true) {
             try {
                 wait();//等待到setSocket执行notify()后，调用service()
                 ios.service(socket);
                 socket = null;//service()结束后，套接字置为空
             } catch (Exception e) {
                 e.printStackTrace();
             }
         }
     }
 };

IOStrategy.java

 /*
     IOStrategy.java
 */

 import java.net.*;

 /*
     提供协议策略定义
 */

 public interface IOStrategy
 {
     public void service(Socket socket);
 }

NwServer.java

 /*
     NwServer.java
 */

 import java.net.*;

 /*
     实现网络通信，可以服务于任何应用，没有提供协议，
     也就是说NwServer可以适用于任何协议。
 */

 public class NwServer
 {
     private int port = ;  //没有处理端口

     public NwServer(IOStrategy io, int port) throws Exception {
         //它只负责接受客户端的连接请求，建立网络建立（socket连接）
         //然后将连接提交给协议处理程序。

         this.port = port;

         ServerSocket server = new ServerSocket(port);
         System.out.println("FTServer is ready");

         while(true)
         {
             //接受客户端的连接请求
             Socket socket = server.accept();

             //获取客户端地址
             InetAddress ia = socket.getInetAddress();
             System.out.println(ia.getHostName() + "(" + ia.getHostAddress() + ") connected."); 

             //将连接提交给协议处理程序
             io.service(socket);
         }
     }
 }

server.properties配置文件：

 share=C:\\_Server
 port=

效果展示：

首先看一下客户端和服务器端的存储空间内的文件：

服务器：

客户端：

1.编译

2.再开一个窗口，分别运行FTServer和FTClient

（1）get命令，得到服务器中的全部文件列表显示(文件夹不显示)

（2）·choice输入文件序号则下载对应文件

　　·choice输入a或A则下载全部文件

　　·choice输入q或Q则退出

（3）put命令，客户端向服务器上传文件（若是一个文件夹则显示文件夹中内容）

·直接上传文件名

·上传文件夹

choice选项基本和下载时一样：

输入a或A则上传全部文件，输入q或Q则退出，输入文件序号则上传对应文件，不再截图。