db2rs.java

一个JAVA小程序！功能不小！

import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.Socket;
import java.net.ServerSocket;

import java.sql.*;

public class DB2RS {

  private int port = 4004;

  private ServerSocket serverSocket;

  static final String dbURL =
    "jdbc:mysql://localhost/j2mebook?" + 
    "user=j2meapps&password=bigsecret";

  private static final int ID_DOWNLOAD    = 0;
  private static final int ID_SYNCHRONIZE = 2;
  private static final int ID_EXIT        = 3;

  public DB2RS() throws ClassNotFoundException {
    Class.forName("org.gjt.mm.mysql.Driver");
  }

  public void acceptConnections() {

    try {
      serverSocket = new ServerSocket(port);
    }
    catch (IOException e) {
      System.err.println("ServerSocket instantiation failure");
      e.printStackTrace();
      System.exit(0);
    }

    while (true) {
      try {
        Socket newConnection = serverSocket.accept();
        ServerThread st = new ServerThread(newConnection);
        new Thread(st).start();
      }
      catch (IOException ioe) {
        System.err.println("server accept failed");
      }
    }
  }
    
  public static void main(String args[]) {

    DB2RS server = null;
    try {
      server = new DB2RS();
    }
    catch (ClassNotFoundException e) {
      System.out.println("unable to load JDBC driver");
      e.printStackTrace();
      System.exit(1);
    }

    server.acceptConnections();
  }

  class ServerThread implements Runnable {

    private Socket socket;
    private BufferedReader datain;
    private BufferedWriter dataout;

    public ServerThread(Socket socket) {
      this.socket = socket;
    }

    public void run() {
      String line = null;
      try {
        datain = new BufferedReader(new InputStreamReader
          (socket.getInputStream()));
        dataout = new BufferedWriter(new OutputStreamWriter
          (socket.getOutputStream()));
      }
      catch (IOException e) {
        return;
      }
      byte[] ba = new byte[1024];
      int op = -1;
      try {
        line = datain.readLine();
        op = Integer.parseInt(line);
        switch (op) {
          case ID_DOWNLOAD:
            String division = datain.readLine();
            download(dataout, division);
            break;
          case ID_SYNCHRONIZE:
            synchronize(datain);
            break;
          default:
            break;
        }
        socket.close();
      }
      catch (IOException ioe) {
      }
    }

    private void synchronize(BufferedReader br) 
        throws IOException {
      Connection dbConn = null;
      try {
        dbConn = DriverManager.getConnection(dbURL);

        String update = "UPDATE fundraiser SET amount =  " + 
                        " ? WHERE division = ? AND " +
                        " branch = ?";
        PreparedStatement stmt = 
          dbConn.prepareStatement(update);
        while (true) {
          String line = br.readLine();
          if (line.length() == 0) {
            break;
          }
          int ix = line.indexOf("\t");
          String division = line.substring(0,ix);
          line = line.substring(ix+1);
          ix = line.indexOf("\t");
          String branch = line.substring(0,ix);
          int amount = Integer.parseInt(line.substring(ix+1));
          stmt.setInt(1,amount);
          stmt.setString(2,division);
          stmt.setString(3,branch);
          stmt.executeUpdate();
        }
      }
      catch (SQLException e) {
        System.out.println(e);
      }
      finally {
        if (dbConn != null) {
          try {
            dbConn.close();
          }
          catch (SQLException e) {
          }
        }
      }
    }

    private void download(BufferedWriter bw, String division) 
        throws IOException {
      Connection dbConn = null;
      try {
        dbConn = DriverManager.getConnection(dbURL);

        Statement stmt = dbConn.createStatement();
        String query = "SELECT * " +
                       "FROM fundraiser " + "WHERE division = " + 
                       "'" + division + "'";
        ResultSet rs = stmt.executeQuery(query);
        while (rs.next()) {
          StringBuffer sb = new StringBuffer();
          sb.append(rs.getString(1));
          sb.append("\t");
          sb.append(rs.getString(2));
          sb.append("\t");
          sb.append(rs.getString(3));
          sb.append('\n');
          dataout.write(sb.toString());
        }
        dataout.write("\n");
        dataout.flush();
      }
      catch (SQLException e) {
        System.out.println(e.getMessage());
      }
      finally {
        if (dbConn != null) {
          try {
            dbConn.close();
          }
          catch (SQLException e) {
          }
        }
      }
    }
  }
}