[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 = 4321;
        
        //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(-4);
        }
        
        //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[1].equals("get")) {//获取文件
            dos.writeInt(3);//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 == 0) {//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(-1);//退出程序
            }
            String[] filenames = new String[files];
            for (int i = 0; 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 + 1 + "		" + 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(0);//退出程序
            }

            if (c.equalsIgnoreCase("a")) {//若输入'A'或'a'则下载全部文件
                for (int i = 0; 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(0);
            }
            int choice = 0;
            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(-2);
            }
            
            //输入文件对应序号则下载该文件
            if (choice >= 1 && choice <= filenames.length) {
                download(filenames[choice - 1]);
            } else {
                System.out.println("your input is wrong");
                s.close();
                System.exit(-5);
            }
            s.close();
            System.exit(0);
        } else if (args[1].equals("put")) {//上传文件
            File f = new File("C:/_Client/" + args[2]);//args[2]为文件名
            if (f.isFile()) {
                upload("C:/_Client/" + args[2]);
            } 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 == 0) {
                    s.close();
                    System.out.println("no files available in the directory");
                    System.exit(-8);
                }
                for (int i = 0; i < filenames.length; i++) {//将目录中的文件列表显示
                    System.out.println(i + 1 + "		" + 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(0);//退出程序
                }

                if (c.equalsIgnoreCase("a")) {//若输入'A'或'a'则上传全部文件
                    for (int i = 0; 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(0);
                }
                int choice = 0;
                try {
                    choice = Integer.parseInt(c);
                } catch (NumberFormatException e) {
                    System.out.println("your input is wrong");
                    s.close();
                    System.exit(-2);
                }
                //上传第choice个文件
                if (choice >= 1 && choice <= filenames.length) {
                    String dir = f.getCanonicalPath();
                    if (dir.endsWith(File.separator)) {
                        upload(dir + filenames[choice - 1]);
                    } else {
                        upload(dir + File.separator + filenames[choice - 1]);
                    }

                } else {
                    System.out.println("your input is wrong");
                    s.close();
                    System.exit(-5);
                }

            } else {
                s.close();
                System.out.println(args[2] + " not exists");
                System.exit(-7);
            }

            s.close();
            System.exit(0);

        }

    }

    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(-6);
        }

        byte[] buffer = new byte[4096];
        int rr = 0;

        dos.writeInt(1);//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)) != -1) {
            dos.write(buffer, 0, rr);
            dos.flush();
        }

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

    }

    public void download(String filename) throws Exception {
        dos.writeInt(2);//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[4096];
        long r = 0;
        int rr = 0;
        
        //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, 0, buffer.length);
            } else {//将剩余(小于buffer.length)的数据传输
                rr = dis.read(buffer, 0, (int) (len - r));
            }
            r = r + rr;
            bos.write(buffer, 0, 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==0) {
            System.out.println("Usage:");
            System.out.println("java FTClient host get");
            System.out.println("java FTClient host put afile");
            System.exit(0);
            
        }
        FTClient ftc = new FTClient();
        ftc.args = args;
        ftc.start(args[0], 4321);//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 = 0;
            byte[] buffer = new byte[4096];
            long r = 0;
            int rr = 0;

            while (true) {
                int command = dis.readInt(); // 读取FTClient中通过writeInt()传来的命令
                switch (command) {
                case 1: // 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 = 0;
                    rr = 0;

                    while (r < len) {
                        if (len - r >= buffer.length) {
                            rr = dis.read(buffer, 0, buffer.length);
                        } else {
                            rr = dis.read(buffer, 0, (int) (len - r));
                        }

                        r = r + rr;
                        bos.write(buffer, 0, rr);
                    }

                    bos.close();
                    fos.close();
                    break;
                case 2: // 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)) != -1) {//接收到下次可发送的字节数,-1结束
                        dos.write(buffer, 0, rr);
                        dos.flush();
                    }

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

                case 3: // 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=0;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[0]);//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 = 0; 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 = 10;//初始线程数
    private final int MAX_THREADS = 100;//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 = 0; i < INIT_THREADS; i++) {
            IOThread t = new IOThread(ios);
            t.start();
            threads.add(t);
        }
        try {
            Thread.sleep(300);
        } 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 = 0; 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(30);
            } 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 = 4321;  //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=4321

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。