JSP + JavaBean step-by-Step Tutorial (iv)

js| Tutorial JavaServer Pages+javabeans Database Operations Application

The above has said a simple JavaBean application of the counter example, of course, in the actual program process, involves more and database-related operations, so in this section we will focus on JavaServer pages and JavaBeans How to operate the database. Here we have selected a more representative and practical example, that is the user registration management, because this is used on the Internet more frequently, whether it is registered email, award-winning survey, purchase items or join the community, etc. will involve a user registration problem; On the other hand, it is more representative, Related to the database record increase, record display and other common operations, so we take the user registration surgery.

The program uses the Oracle Jdeveloper3.1 development, the operating environment is wiin2000+tomcat3.1, the database system uses the oracle8.16i.

First we set up a database Demodb, and the fields are as shown below

Username VARCHAR2 (20) User name
Password VARCHAR2 (20) password
Email VARCHAR2 (email address)
Homepage VARCHAR2 (50) Home
Signs VARCHAR2 (200) signature
Regtime Date Registration Time

Then we build several JavaBeans and JavaServer pages files

Db.java files (encapsulates database connections and some underlying operations)
Adduser.java files (for user data reading and adding operations)
newuser.jsp file (user new page, for entering user registration information)
donewuser.jsp files (add for user registration information)
listuser.jsp file (all registered user Information list)

In order to facilitate everyone to see the code, in many places have been detailed comments and explanations, as for JavaBean in the Java grammar structure of things, please refer to Java books.

Db.java file

Description: This JavaBean encapsulates database connections and some underlying operations, derived classes can call these methods directly, and provides a Tochinese method, which is mainly used for processing Chinese data.

Copyright (c) http://jspbbs.yeah.net
Package Lyf;
/**
* A class class.
* $#@60; p$#@62;
* @author Liuyufeng
*/

Declaring Class library files
Import oracle.jdbc.driver.*;
Import java.net.*;
Import java.sql.*;
Import java.lang.*;
Import java.io.*;
Import java.util.*;
public class DB Br>//member variable initialization
Connection conn = null; Database connection
ResultSet rs = null; Set of records
String username= ""; User name
String password= ""; Password
String email= ""; Email
String homepage= ""; Home
String signs= ""; Signature
DB Builder
Public db () {
try {
Registering Database Drivers for Oracle drivers
Class.forName (New Oracle.jdbc.driver.OracleDriver ());
}
catch (Java.lang.ClassNotFoundException e) {
This is written in order to facilitate debugging programs, error printing mydb () know where the error occurred
System.err.println ("MyDB ():" + e.getmessage ());
}
}

The ExecuteQuery method is used for logging query operations

The entry parameter is an SQL statement that returns the ResultSet object
Public ResultSet executequery (String sql) {
rs = null;
try {
Establish a database connection, using an Oracle thin connection, demo for the host name, Demodb for the database, followed by the two demo for username and password
conn = Drivermanager.getconnection ("Jdbc:oracle:thin: @demo: 1521:demodb", "Demo", "Demo");
Statement stmt = Conn.createstatement ();
Performing database query operations
rs = stmt.executequery (SQL);
}
catch (SQLException ex) {
System.err.println ("Db.executequery:" + ex.getmessage ());
}
Return RS;
}

The Executeupdate method is used to manipulate add or update records

The entry parameter is a SQL statement, returns true successfully, or false
public boolean executeupdate (String sql) {
Boolean bupdate=false;
rs = null;
try {
Set up a database connection, other parameter description same as above
conn = Drivermanager.getconnection ("Jdbc:oracle:thin: @demo: 1521:demodb", "Demo", "Demo");
Statement stmt = Conn.createstatement ();
int rowcount = stmt.executeupdate (SQL);
If it doesn't work, bupdate will return 0.
if (rowcount!=0) bupdate=true;
}
catch (SQLException ex) {
Print error messages
System.err.println ("db.executeupdate:" + ex.getmessage ());
}
return bupdate;
}

The Tochinese method is used to handle a string in Chinese

Otherwise it's going to be???. Such a string
public static string Tochinese (string strvalue) {
try{
if (strvalue==null)
{
return null;
}
Else
{
strvalue = new String (strvalue.getbytes ("Iso8859_1"), "GBK");
return strvalue;
}
}catch (Exception e) {
return null;
}
}

}