javefpclient.c

经典－Java版本的FTP和Telnet源程序

import java.net.*;
import java.awt.*;
import java.io.*;
import java.lang.*;
public class Telnet extends java.applet.Applet
{
        String hoststr, portstr;        // parameters giving host & port
        Panel controls;
        TelnetClient tn;                // telnet component
        TextField hostfield;
        TextField portfield;
        Button connect, disconnect;

        public void init()
        {
        // Create interface
        setLayout(new BorderLayout());
        add("Center",tn = new TelnetClient());
        add("North",controls = new Panel());
        controls.setLayout(new FlowLayout());
        controls.add(new Label("Host"));
        controls.add(hostfield = new TextField());
        controls.add(new Label("Port"));
        controls.add(portfield = new TextField(5));
        controls.add(connect = new Button("Connect"));
        controls.add(disconnect = new Button("Disconnect"));

        // Parse parameters
        String hoststr = getParameter("host");
        String portstr = getParameter("port");
        if (hoststr == null) return;
        if (portstr == null) portstr = "23";
        hostfield.setText(hoststr);
        portfield.setText(portstr);
        }

        public void start()
        {
        tn.disconnect();
        tn.connect(hostfield.getText(), Integer.parseInt(portfield.getText()));
        }

        public void stop()
        {
        tn.disconnect();
        }

        public boolean action(Event e, Object arg)
        {
        if (e.target == connect)
                start();
        else if (e.target == disconnect)
                stop();
        return true;
        }
}


// TelnetClient
// An AWT component that makes a telnet connection to a given host and port
class TelnetClient extends java.awt.Canvas implements Runnable
{
        boolean debug = false;
        String host;                    // remote host
        int port;                       // remote port
        Socket s;                       // connection to remote host
        InputStream in;                 // data from other end
        OutputStream out;               // data to other end
        Thread th;                      // thread for reading data
        Font fn;                        // current font
        Image back;                     // backing image
        int x, y;                       // cursor position (in chars)
        int chw,chh;                    // size of a char (in pixels)
        int chd;                        // offset of char from baseline
        int width,height;               // size of applet (in pixels)
        int w,h;                        // size of applet (in chars)
        char ch[][];                    // array of characters on display
        Graphics gr,bgr;                // front and back graphics

        String term = "dumb";           // what this terminal claims to be
        boolean echo;                   // echo keys sent?

        // reshape
        // Called to resize the telnet component
        public void reshape(int nx, int ny, int nw, int nh)
        {
        if (nw != width || nh != height) {
                width = nw;
                height = nh;

                // Open font
                gr = getGraphics();
                gr.setColor(Color.black);
                fn = new Font("Courier",Font.PLAIN,10);
                if (fn != null) gr.setFont(fn);
                FontMetrics fnm = gr.getFontMetrics();
                chw = fnm.getMaxAdvance();
                chh = fnm.getHeight();
                chd = fnm.getDescent();

                // work out size of drawing area
                h = nh / chh;
                w = nw / chw;
                ch = new char [w][h];

                // setup backing image
                back = createImage(width, height);
                bgr = back.getGraphics();
                bgr.setFont(fn);
                bgr.setColor(Color.black);
                clearch();
                }
        super.reshape(nx,ny,nw,nh);
        }

        // connect
        // Connect to the given host and port
        void connect(String givenhost, int givenport)
        {
        host = givenhost; port = givenport;

        if (debug) System.out.println("Height = "+String.valueOf(h));
        if (debug) System.out.println("Width  = "+String.valueOf(w));

        // reset display
        clearch();
        echo = true;
        requestFocus();

        // Open connection
        try {
                try {
                        if ((s = new Socket(host,port)) == null) {
                                display("Failed to connect to host "+host+"\n");
                                return;
                                }
                        }
                catch(UnknownHostException e) {
                        display("Host " + host + " not found\n");
                        return;
                        }
                }
        catch(IOException e) {
                display("Failed to connect to host "+host+"\n");
                return;
                }
        try {
                in = s.getInputStream();
                out = s.getOutputStream();
                }
        catch(IOException e) {
                if (debug) System.out.println("Failed to get stream from socket");
                System.exit(5);
                }
        display("Connected to "+host+"\n");
        if (debug) System.out.println("Connected to host");

        // Begin thread for reading data
        th = new Thread(this);
        th.start();
        }

        // disconnect
        // Close the connection 
        void disconnect()
        {
        if (th != null) {
                display("\nDisconnected from "+host+"\n");
                th.stop();
                th = null;
                s = null; in = null; out = null;
                }
        }

        // clearch
        // Clear the backing array of characters and reset the cursor
        void clearch()
        {
        int i,j;
        for(i=0; i<w; i++)
                for(j=0; j<h; j++)
                        ch[i][j] = ' ';
        x = y = 0;
        bgr.setColor(Color.white);
        bgr.fillRect(0, 0, width, height);
        paint(gr);
        }

        // keyDown
        // Called on keypress
        public boolean keyDown(Event e, int k)
        {
        if (out != null) {
                int kp = e.key;
                if (debug) System.out.println("Pressed key " + String.valueOf(kp));
                transmitch((char)kp);
                if (echo) {
                        if (debug) System.out.println("Echo'd "+String.valueOf(kp));
                        displaych((char)kp);
                        }
                }
        return true;
        }

        // mouseDown
        // Called when the user clicks in the telnet window, to get the focus
        public boolean mouseDown(Event e, int x, int y)
        {
        requestFocus();
        return true;
        }

        // paint
        // Blit the back image to the front
        public void paint(Graphics g)
        {
        gr.drawImage(back,0,0,this);
        }

        // renderchar
        // draw the given character at the given character position
        void renderchar(char c, int x, int y, boolean back)
        {
        gr.setColor(Color.white);
        gr.fillRect(x*chw, y*chh, chw, chh);
        gr.setColor(Color.black);
        gr.drawString(String.valueOf(c), x*chw, (y+1)*chh-chd);

        if (back) {
                bgr.setColor(Color.white);
                bgr.fillRect(x*chw, y*chh, chw, chh);
                bgr.setColor(Color.black);
                bgr.drawString(String.valueOf(c), x*chw, (y+1)*chh-chd);
                }
        }

        // run
        // Loop forever, reading and displaying characters
        public void run()
        {
        while(true)
                displaych(readch());
        }

        // readch
        // Read one char from other end, or die
        char readch()
        {
        int c = 0;
        try
        {        c = in.read(); }
        catch(IOException e)
        {        shutdown();}
        if (c == -1) shutdown();
        if (debug) System.out.println("Got char "+String.valueOf(c)+" = "+String.valueOf((char)c));
        return (char)c;
        }

        // shutdown
        // Terminate connection
        void shutdown()
        {
        display("\nConnection closed\n");
        s = null; in = null; out = null;
        Thread.currentThread().stop();
        }

        // display
        // Display a string in the telnet window
        void display(String str)
        {
        int i;
        for(i=0; i<str.length(); i++)
                displaych(str.charAt(i));
        }

        // displaych
        // Display one character at the current cursor position
        void displaych(char c)
        {
        if (c == '\n') {
                // Newline
                renderchar(ch[x][y], x, y, false);      // erase cursor
                x = 0;
                if (y == h-1) {
                        gr.copyArea(0, chh, w*chw, (h-1)*chh, 0, -chh);
                        gr.setColor(Color.white);
                        gr.fillRect(0, (h-1)*chh, width, chh);
                        bgr.copyArea(0, chh, w*chw, (h-1)*chh, 0, -chh);
                        bgr.setColor(Color.white);
                        bgr.fillRect(0, (h-1)*chh, width, chh);
                        int i,j;
                        for(i=0; i<w; i++) {
                                for(j=0; j<h-1; j++)
                                        ch[i][j] = ch[i][j+1];
                                ch[i][h-1] = ' ';
                                }
                        }
                else
                        y++;
                }
        else if (c == '\t') {
                // Tab
                int i;
                for(i=8; i>x%8; i--)
                        displaych(' ');
                }
        else if (c == (char)8) {
                // Backspace
                renderchar(ch[x][y], x, y, false);      // erase cursor
                if (x != 0) x--;
                }
        else if (c >= 32 && c < 127) {
                // Some printable character
                renderchar(c, x, y, true);
                ch[x][y] = c;
                if (x == w-1)
                        displaych('\n');
                else
                        x++;
                }
        else if (c == 255) {
                // Telnet IAC
                char cmd = readch();
                char opt = readch();

                switch(opt) {
                        case 1:         // echo
                        if (cmd == 251) echo = false;
                        else if (cmd == 252) echo = true;
                        break;

                        case 3:         // supress go-ahead
                        break;

                        case 24:        // terminal type
                        if (cmd == 253) {
                                // IAC WILL terminal-type
                                transmitch((char)255);
                                transmitch((char)251);
                                transmitch((char)24);
                                // IAC SB terminal-type IS <term> IAC SE
                                transmitch((char)255);
                                transmitch((char)250);
                                transmitch((char)24);
                                transmitch((char)0);
                                transmit(term);
                                transmitch((char)255);
                                transmitch((char)240);
                                }
                        else if (cmd == 250) {
                                while(readch() != 240)
                                        ;
                                }
                        break;

                        default:        // some other command
                        if (cmd == 253) {
                                // IAC DONT whatever
                                transmitch((char)255);
                                transmitch((char)252);
                                transmitch((char)opt);
                                }
                        break;
                        }
                }
        renderchar('_', x, y, false);   // draw cursor
        }

        void transmit(String str)
        {
        int i;

        for(i=0; i<str.length(); i++)
                transmitch(str.charAt(i));
        }

        void transmitch(char c)
        {
        if (c == '\n') transmitch('\r');
        try {
                out.write((int)c);
                out.flush();
                }
        catch(IOException e){ };
     
        if (debug) System.out.println("Sent char " + String.valueOf((int)c) + " = " + String.valueOf(c));
        }
}