chatbean.java

《jsp网站开发技术》中的源代码(清华大学出版社)

package chat;
import java.sql.*;
import java.util.*;
import java.io.*;
import javax.servlet.http.*;
import javax.servlet.*;

public class  ChatBean{
String sDBDriver = "sun.jdbc.odbc.JdbcOdbcDriver";
String sConnStr = "jdbc:odbc:chatreg";
Connection conn = null;
ResultSet rs = null;
HttpSession session;
HttpServletRequest request;
static String defaultString="defaultstring";
/**
*create a chat bean
*/
public ChatBean() {
	try {
		Class.forName(sDBDriver); 
	}
	catch(java.lang.ClassNotFoundException e) {
		System.err.println("ChatBean(): " + e.getMessage());
	}
}
/**
*set servlet context of this chat bean
*@param request the HttpServletRequest to be set 
*@param session the HttpSession to be set
*/
public void setContext(HttpServletRequest request,HttpSession session)
{
	this.request=request;
	this.session=session;
}
/**
*exexute a sql query
*@param sql the sql query string
*@return the ResultSet
*/
public synchronized ResultSet executeQuery(String sql) {
	rs = null;
	try {
	conn = DriverManager.getConnection(sConnStr); 
	Statement stmt = conn.createStatement();
	rs = stmt.executeQuery(sql);
	} 
	catch(SQLException ex) { 
		System.err.println("aq.executeQuery: " + ex.getMessage());
	}
	return rs;
}
/**
*exexute a sql update command, such as INSERT,DELETE and UPDATE
*@param sql the sql update string
*@return the records that have been effected by the update command
*/
public synchronized int executeUpdate(String sql) {
	int record = -1;
	try {
	conn = DriverManager.getConnection(sConnStr); 
	Statement stmt = conn.createStatement();
	record = stmt.executeUpdate(sql);
	} 
	catch(SQLException ex) { 
		System.err.println("aq.executeQuery: " + ex.getMessage());
	}
	return record;
}
/**
*parse string to Chinese Charator in order to 
*display it correctly
*@param in the source string to be parsed
*@return parsed String
*/
public String parseChinese(String in)
{
   String s = null;       
   byte temp [];               
   if (in == null)
   {
   	 System.out.println("Warn:Chinese null founded!");
   	 return new String("");
   }
   try
   {
   temp=in.getBytes("iso-8859-1");
    s = new String(temp);
   }catch(UnsupportedEncodingException e)
   {
   System.out.println (e.toString()); 
   }
    return s;
}
/**
*get session value with the specified name
*@param name the key string of session
*@return a string value of the key
*/
public String getSessionValue(String name)
{
	if(session!=null&&session.getValue(name)!=null){
		return (String)session.getValue(name);
	}
	return defaultString;
}
/**
*get request parameter
*@param name parameter name
*@return the parameter value 
*/
public String getRequestParam(String name)
{
	if(request!=null){
		if(request.getParameter(name)!=null&&!request.getParameter(name).equals(""))
		return this.parseChinese(request.getParameter(name));
	}
	return defaultString;
}
/**
*compare session value and request parameter value with the same key.<br>
*if the request value does not equal to the session value,<br>
*set the session value to the request value
*@return if reseted return true,else return false
*/
public boolean reset(String key)
{
	String rev=getRequestParam(key);
	String sev=getSessionValue(key);
	if(!rev.equals("")&&!rev.equals(sev)){
		if(session!=null){
			session.putValue(key,rev);
			return true;
		}
	}
	return false;
}

}//~~~~~~~~~class ChatBean~~~~~~~~~~~