通过socket访问数据库

2/9/2008来源:Oracle教程人气:6561


  Tip:通过socket访问数据库,分 Clinet, Display,sqlServer三个类
  
  Client.java
  
  import java.awt.*;
  import java.io.*;
  import java.net.*;
  import java.applet.*;
  
  public class Client extends Applet
  {
  public TextArea chat_txt;
  PRivate TextField sql_txt;
  private Button connect,execute;
  private Socket soc= null;
  private PrintStream ps= null;
  Listen listen;
  
  public void init()
  {
  chat_txt= new TextArea();
  sql_txt= new TextField(20);
  connect= new Button("Connect");
  execute= new Button("Execute");
  execute.disable();
  
  Panel pp= new Panel();
  pp.setLayout(new FlowLayout());
  pp.add(sql_txt);
  pp.add(connect);
  pp.add(execute);
  
  add("North",pp);
  add("Center",chat_txt);
  }
  
  public boolean action(Event evt,Object obj)
  {
  if(evt.target instanceof Button)
  {
  String label= (String)obj;
  if(label.equals("Connect"))
  {
  
  try{
  soc= new Socket(InetAddress.getLocalHost(),4700);
  ps= new PrintStream(soc.getOutputStream());
  ps.println("HELLO");
  ps.flush();
  listen= new Listen(this,soc);
  listen.start();
  }catch(Exception e)
  {
  chat_txt.setText(e.toString());
  disconnect();
  }
  connect.setLabel("Disconnect");
  execute.enable();
  }else if(label.equals("Disconnect"))
  disconnect();
  else if(label.equals("Execute"))
  {
  if(sql_txt.getText()!= null)
  {
  ps.println("FIND");
  ps.flush();
  ps.println(sql_txt.getText());
  ps.flush();
  }
  }
  }
  return false;
  }
  
  public void disconnect()
  {
  if(soc!= null)
  {
  try{
  listen.stop();
  ps.println("QUIT");
  ps.flush();
  soc.close();
  }catch(Exception e){}
  finally{
  listen.stop();
  listen= null;
  soc= null;
  }
  execute.disable();
  connect.setLabel("Disconnect");
  }
  }
  }
  
  class Listen extends Thread
  {
  Socket socket= null;
  DataInputStream dis= null;
  Client parent= null;
  
  public Listen(Client p,Socket s)
  {
  parent= p;
  socket= s;
  try{
  dis= new DataInputStream(socket.getInputStream());
  }catch(Exception e){}
  }
  
  public void run()
  {
  String line= null;
  
  while(true)
  {
  try{
  line= dis.readLine();
  }catch(Exception e){}
  if(line!
= null)
  parent.chat_txt.appendText(line);
  }
  }
  }
  
  Display.java
  
  /********************************************
  格式化输出数据库记录,出自<<使用java进行SQL数据库程序设计>>
  返回值为格式化的字符串
  ********************************************/
  import java.sql.*;
  
  class Display extends Object
  {
  ResultSet theResultSet;
  String theResult;
  
  public void display()
  {}
  
  public void setResult(ResultSet result)
  {
  theResultSet= result;
  }
  
  public String getString()
  throws SQLException,NoClassDefFoundError
  {
  theResult= "";
  ResultSetMetaData metaData= theResultSet.getMetaData();
  int colcount = metaData.getColumnCount();
  int colSize[]= new int[colcount];
  String colLabel[]= new String[colcount];
  int colType[]= new int[colcount];
  String colTName[]= new String[colcount];
  int colPrec[]= new int[colcount];
  int colScale[]= new int[colcount];
  
  theResult +="\n";
  for(int i= 1;i<= colcount;i++)
  {
  colSize[i-1] = metaData.getColumnDisplaySize(i);
  colLabel[i-1]= metaData.getColumnLabel(i);
  colType[i-1] = metaData.getColumnType(i);
  colTName[i-1]= metaData.getColumnTypeName(i);
  colPrec[i-1] = metaData.getPrecision(i);
  colScale[i-1]= metaData.getScale(i);
  
  if(colSize[i-1]<1+ colLabel[i-1].length())
  colSize[i-1]= 1+colLabel[i-1].length();
  theResult+= rightPad(colLabel[i-1],colSize[i-1]);
  }
  
  theResult +="\n\n";
  int row= 0;
  
  while(theResultSet.next())
  {
  row++;
  for(int i=1;i<= colcount;i++)
  {
  String colvalue= theResultSet.getString(i);
  if(colvalue== null)
  colvalue="";
  theResult+= rightPad(colvalue,colSize[i-1]);
  }
  theResult+="\n";
  }
  theResult+="\n(" +row+ "rows included)\n";
  return theResult;
  }
  
  private String rightPad(String s,int len)
  {
  int curlen= s.length();
  if(curlen>len)
  return repString("*",len);
  return (s+repString(" ",(len-curlen)));
  }
  
  private String repString(String s,int times)
  {
  String result="";
  for(int i=0;i result+= s;
  return result;
  }
  }
  
  sqlServer.java
  
  import java.awt.*;
  import java.sql.*;
  import java.io.*;
  import java.net.*;
  import Display;
  
  public class sqlServer
  {
  public static void main(String[] args)
  {
  System.out.println("Waiting for connection");
  
  try{
  ServerSocket session= new ServerSocket(4700);
  handleRequests handler= null;
  System.out.println("Waiting for connection");
  while(true)
  {
  Socket socket= null;
  socket= session.accept();
  if(socket== null)
  continue;
  System.out.println("Connection made");
  handler= new handleRequests(socket);
  handler.start();
  }
  }catch(Exception e)
  {
  System.out.println("客户连接失败"+e);
  }
  }
  }
  
  class handleRequests extends Thread
  {
  private DataInputStream in= null;
  private PrintStream out= null;
  private Socket socket= null;
  
  Connection theConnection= null;
  Statement theStatement= null;
  ResultSet theResultSet= null;
  Display display= null;
  
  public handleRequests(Socket s)
  throws IOException
  {
  socket= s;
  in= new DataInputStream(socket.getInputStream());
  out= new PrintStream(socket.getOutputStream());
  }
  
  public void openConnection()
  {
  try{
  Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
  if(theConnection!
= null)
  theConnection.close();
  theConnection= DriverManager.getConnection("jdbc:odbc:test","admin","1234");
  theStatement= theConnection.createStatement();
  display= new Display();
  }catch(Exception e)
  {
  System.out.println(e);
  }
  }
  
  public void run()
  {
  openConnection();
  try{
  String line= null;
  while(true)
  {
  line = in.readLine();
  if(line!= null)
  line= line.trim();
  if(line.equals("FIND"))
  {
  line = in.readLine();
  line= line.trim();
  theResultSet= theStatement.executeQuery(line);
  display.setResult(theResultSet);
  out.print(display.getString());
  out.flush();
  }
  if(line.equals("QUIT"))
  break;
  if(line.equals("HELLO"))
  {
  out.println("Welcome to join us");
  out.flush();
  }
  }
  in.close();
  out.close();
  socket.close();