一個簡單的網絡客戶端

2019-11-18 16:17:45

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A simple network client

/*
* Copyright (c) 2000-2001 Sun Microsystems, Inc. All Rights Reserved.
*/

import java.lang.*;
import java.io.*;
import java.util.*;
import javax.microedition.io.*;
import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;

/**
* A simple network client.
*
* This MIDlet shows a simple use of the HTTP
* networking interface. It opens a HTTP POST
* connection to a server, authenticates using
* HTTP Basic Authentication and writes a string
* to the connection. It then reads the
* connection and displays the results.
*/
public class NetClientMIDlet extends MIDlet
    implements CommandListener {

    PRivate Display display;  // handle to the display
    private Form mainScr;     // main screen
    private Command cmdOK;    // OK command
    private Command cmdExit;  // EXIT command
    private Form dataScr;     // for display of results

    /**
     * ConstrUCtor.
     *
     * Create main screen and commands. Main
     * screen shows simple instructions.
     */
    public NetClientMIDlet() {
        display = Display.getDisplay(this);
        mainScr = new Form("NetClient");
        mainScr.append("Hit OK to make network connection");
        mainScr.append(" ");
        mainScr.append("Hit EXIT to quit");
        cmdOK = new Command("OK", Command.OK, 1);
        cmdExit = new Command("Exit", Command.EXIT, 1);
        mainScr.addCommand(cmdOK);
        mainScr.addCommand(cmdExit);
        mainScr.setCommandListener(this);
    }

    /**
     * Called by the system to start our MIDlet.
     * Set main screen to be displayed.
     */
    protected void startApp() {
        display.setCurrent(mainScr);
    }

    /**
     * Called by the system to pause our MIDlet.
     * No actions required by our MIDLet.
     */
    protected void pauseApp() {}

    /**
     * Called by the system to end our MIDlet.
     * No actions required by our MIDLet.
     */
    protected void destroyApp(boolean unconditional) {}

    /**
     * Gets data from server.
     *
     * Open a connection to the server, set a
     * user and passWord to use, send data, then
     * read the data from the server.
     */
    private void genDataScr() {
        ConnectionManager h = new ConnectionManager();

        // Set message to send, user, password
        h.setMsg("Esse quam videri");
        h.setUser("book");
        h.setPassword("bkpasswd");
        byte[] data = h.Process();

        // create data screen
        dataScr = new Form("Data Screen");
        dataScr.addCommand(cmdOK);
        dataScr.addCommand(cmdExit);
        dataScr.setCommandListener(this);
        if (data == null  data.length == 0) {
            // tell user no data was returned
            dataScr.append("No Data Returned!");
        } else {
            // loop trough data and extract strings
            // (delimited by '/n' characters
            StringBuffer sb = new StringBuffer();
            for (int i = 0; i < data.length; i++) {
                if (data[i] == (byte)'/n') {
                    dataScr.append(sb.toString());
                    sb.setLength(0);
                } else {
                    sb.append((char)data[i]);
                }
            }
        }
        display.setCurrent(dataScr);
    }

    /**
     * This method implements a state machine that drives
     * the MIDlet from one state (screen) to the next.
     */
    public void commandAction(Command c,
                              Displayable d) {
        if (c == cmdOK) {
            if (d == mainScr) {
                genDataScr();
            } else {
                display.setCurrent(mainScr);
            }
        } else if (c == cmdExit) {
            destroyApp(false);
            notifyDestroyed();
        }
    }
}

/*
* Copyright (c) 2000-2001 Sun Microsystems, Inc. All Rights Reserved.
*/

/**
* This class encodes a user name and password
* in the format (base 64) that HTTP Basic
* Authorization requires.
*/

class BasicAuth {
    // make sure no one can instantiate this class
    private BasicAuth() {}

    // conversion table
    private static byte[] cvtTable = {
        (byte)'A', (byte)'B', (byte)'C', (byte)'D', (byte)'E',
        (byte)'F', (byte)'G', (byte)'H', (byte)'I', (byte)'J',
        (byte)'K', (byte)'L', (byte)'M', (byte)'N', (byte)'O',
        (byte)'P', (byte)'Q', (byte)'R', (byte)'S', (byte)'T',
        (byte)'U', (byte)'V', (byte)'W', (byte)'X', (byte)'Y',
        (byte)'Z',
        (byte)'a', (byte)'b', (byte)'c', (byte)'d', (byte)'e',
        (byte)'f', (byte)'g', (byte)'h', (byte)'i', (byte)'j',
        (byte)'k', (byte)'l', (byte)'m', (byte)'n', (byte)'o',
        (byte)'p', (byte)'q', (byte)'r', (byte)'s', (byte)'t',
        (byte)'u', (byte)'v', (byte)'w', (byte)'x', (byte)'y',
        (byte)'z',
        (byte)'0', (byte)'1', (byte)'2', (byte)'3', (byte)'4',
        (byte)'5', (byte)'6', (byte)'7', (byte)'8', (byte)'9',
        (byte)'+', (byte)'/'
    };

    /**
     * Encode a name/password pair appropriate to
     * use in an HTTP header for Basic Authentication.
     *    name     the user's name
     *    passwd   the user's password
     *    returns  String   the base64 encoded name:password
     */
    static String encode(String name,
                         String passwd) {
        byte input[] = (name + ":" + passwd).getBytes();
        byte[] output = new byte[((input.length / 3) + 1) * 4];
        int ridx = 0;
        int chunk = 0;

        /**
         * Loop through input with 3-byte stride. For
         * each 'chunk' of 3-bytes, create a 24-bit
         * value, then extract four 6-bit indices.
         * Use these indices to extract the base-64
         * encoding for this 6-bit 'character'
         */
        for (int i = 0; i < input.length; i += 3) {
            int left = input.length - i;

            // have at least three bytes of data left
            if (left > 2) {
                chunk = (input[i] << 16)
                        (input[i + 1] << 8)
                         input[i + 2];
                output[ridx++] = cvtTable[(chunk&0xFC0000)>>18];
                output[ridx++] = cvtTable[(chunk&0x3F000) >>12];
                output[ridx++] = cvtTable[(chunk&0xFC0)   >> 6];
                output[ridx++] = cvtTable[(chunk&0x3F)];
            } else if (left == 2) {
                // down to 2 bytes. pad with 1 '='
                chunk = (input[i] << 16)
                        (input[i + 1] << 8);
                output[ridx++] = cvtTable[(chunk&0xFC0000)>>18];
                output[ridx++] = cvtTable[(chunk&0x3F000) >>12];
                output[ridx++] = cvtTable[(chunk&0xFC0)   >> 6];
                output[ridx++] = '=';
            } else {
                // down to 1 byte. pad with 2 '='
                chunk = input[i] << 16;
                output[ridx++] = cvtTable[(chunk&0xFC0000)>>18];
                output[ridx++] = cvtTable[(chunk&0x3F000) >>12];
                output[ridx++] = '=';
                output[ridx++] = '=';
            }
        }
        return new String(output);
    }
}

/*
* Copyright (c) 2000-2001 Sun Microsystems, Inc. All Rights Reserved.
*/

/**
* Manages network connection.
*
* This class established an HTTP POST connection
* to a server defined by baseurl.
* It sets the following HTTP headers:
* User-Agent: to CLDC and MIDP version strings
* Accept-Language: to microedition.locale or
*                  to "en-US" if that is null
* Content-Length:  to the length of msg
* Content-Type:    to text/plain
* Authorization:   to "Basic" + the base 64 encoding of
*                  user:password
*/
class ConnectionManager {
    private HttpConnection con;
    private InputStream is;
    private OutputStream os;
    private String ua;
    private final String baseurl =
        "http://127.0.0.1:8080/Book/netserver";
    private String msg;
    private String user;
    private String password;

    /**
     * Set the message to send to the server
     */
    void setMsg(String s) {
        msg = s;
    }

    /**
     * Set the user name to use to authenticate to server
     */
    void setUser(String s) {
        user = s;
    }
    /**
     * Set the password to use to authenticate to server
     */
    void setPassword(String s) {
        password = s;
    }

    /**
     * Open a connection to the server
     */
    private void open() throws IOException {
        int status = -1;
        String url = baseurl;
        String auth = null;
        is = null;
        os = null;
        con = null;

        // Loop until we get a connection (in case of redirects)
        while (con == null) {
            con = (HttpConnection)Connector.open(url);
            con.setRequestMethod(HttpConnection.POST);
            con.setRequestProperty("User-Agent", ua);
            String locale =
                System.getProperty("microedition.locale");
            if (locale == null) {
                locale = "en-US";
            }
            con.setRequestProperty("Accept-Language", locale);
            con.setRequestProperty("Content-Length",
                                   "" + msg.length());
            con.setRequestProperty("Content-Type", "text/plain");
            con.setRequestProperty("Accept", "text/plain");
            if (user != null && password != null) {
                con.setRequestProperty("Authorization",
                                       "Basic " +
                                       BasicAuth.encode(user,
                                                     password));
            }

            // Open connection and write message
            os = con.openOutputStream();
            os.write(msg.getBytes());
            os.close();
            os = null;

            // check status code
            status = con.getResponseCode();
            switch (status) {
            case HttpConnection.HTTP_OK:
                // Success!
                break;
            case HttpConnection.HTTP_TEMP_REDIRECT:
            case HttpConnection.HTTP_MOVED_TEMP:
            case HttpConnection.HTTP_MOVED_PERM:
                // Redirect: get the new location
                url = con.getHeaderField("location");
                os.close();
                os = null;
                con.close();
                con = null;
                break;
            default:
                // Error: throw exception
                os.close();
                con.close();
                throw new IOException("Response status not OK:"+
                                      status);
            }
        }
        is = con.openInputStream();
    }

    /**
     * Constructor
    * Set up HTTP User-Agent header string to be the
     * CLDC and MIDP version.
     */
    ConnectionManager() {
        ua = "Profile/" +
            System.getProperty("microedition.profiles") +
            " Configuration/" +
            System.getProperty("microedition.configuration");
    }

    /**
     * Process an HTTP connection request
     */
    byte[] Process() {
        byte[] data = null;

        try {
            open();
            int n = (int)con.getLength();
            if (n != 0) {
                data = new byte[n];
                int actual = is.read(data);
            }
        } catch (IOException ioe) {
        } finally {
            try {
                if (con != null) {
                    con.close();
                }
                if (os != null) {
                    os.close();
                }
                if (is != null) {
                    is.close();
                }
            } catch (IOException ioe) {}
            return data;
        }
    }
}