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利用JSP实现Web与数据库的连接:
(1).完成环境设置，导入java.sql包，命令如下：
import java.sql.*
(2).载入驱动器
(3).连接到数据库
(4).语句接口
(5).获得结果集
1. 测试环境：
windows 2003
j2sdk1.4.2_06
Tomcat 5.0
mysql-4.0.23-win
mm.mysql-2.0.4-bin.jar
2. 建立数据库及表
在Mysql中建个publish数据库，并建个book表。在book中添加id，title，price
3. JavaBean的代码： dbconn.java
package Border;
import java.sql.*; //完成环境设置，导入java.sql包
public class dbconn {
public dbconn()
{
}
//declare variable
private Connection conn = null;
private ResultSet rs = null;
private String server = "127.0.0.1"; // Can't use localhost , you must use IP or CNAME
private String port = "3306"; //change to your port
private String db = "publish"; //change to your db name
private String user = "root"; //change to your username
private String pass = "root"; //change to your password
private String drivername="org.gjt.mm.mysql.Driver"; //mysql driver
private String URL="jdbc:mysql://"+server+":"+port+"/"+db+"?useUnicode=true&characterEncoding=GBK&user="+user+"&password="+pass;
public Connection getConn(){ //get database connection
try{
Class.forName(drivername).newInstance(); //载入驱动器
conn = DriverManager.getConnection(URL); //连接到数据库
}
catch(Exception e){
e.printStackTrace();
}
return conn ;
}
public ResultSet executeSQL(String str) {
try{
Statement stmt = conn.createStatement(); //语句接口
rs = stmt.executeQuery(str); //获得结果集
}
catch(Exception e){
e.printStackTrace();
}
return rs;
}
}
编译javac dbconn.java,将编译后的文件dbconn.class放到目录 "你的项目"\WEB-INF\classes\Border\下
4. 调用Java Bean的JSP文件test.jsp
<%@ page contentType="text/html;charset=GBK" import="java.sql.*"%>
<jsp:useBean id="Border" scope="page" class="Border.dbconn" />
<%
ResultSet rs = null;
Connection conn = null;
conn = Border.getConn() ;
rs = Border.executeSQL("select * from book");
%>
<html>
<body>
<br>
<h2 align="center" > My first Jsp JavaBean Mysql </h2>
<br>
<table border="1" align="center">
<tr>
<th>
id
</th>
<th>
title
</th>
<th>
price
</th>
</tr>
<%
while(rs.next()) {
%>
<tr>
<th>
<%=rs.getString("id")%>
</th>
<th>
<%=rs.getString("title")%>
</th>
<th>
<%=rs.getString("price")%>
</th>
</tr>
<%}%>
<%
rs.close();
conn.close();
%>
</table>
<form name="form1" method="post" action="update.jsp">
<table width="210" border="1" align="center" cellpadding="0" cellspacing="0">
<tr>
<td width="77">title:</td>
<td width="127"><label>
<input name="Title" type="text" id="Title">
</label></td>
</tr>
<tr>
<td>price:</td>
<td><label>
<input name="Price" type="text" id="Price">
</label></td>
</tr>
<tr>
<td><div align="right">
<label>
<input type="submit" name="Submit" value="提交">
</label>
</div></td>
<td><label>
<input type="reset" name="Submit2" value="重置">
</label></td>
</tr>
</table>
</form>
</body>
</html>
5. update.jsp 写入数据库
<%@ page contentType="text/html;charset=GBK" import="java.sql.*"%>
<% request.setCharacterEncoding("GBK"); %>
<jsp:useBean id="Border" scope="page" class="Border.text" />
<%
Connection conn = null;
conn = Border.getConn() ;
String tit=request.getParameter("Title");
String prc=request.getParameter("Price");
Statement stmt = conn.createStatement();
stmt.executeUpdate("INSERT INTO book (title,price) VALUES ('"+tit+"','"+prc+"')");
%>
<jsp:forward page="text.jsp" />
6. 提供几个函数：
(1). getConnection
public static Connection getConnection(String url,
String user,
String password)
throws SQLException
Attempts to establish a connection to the given database URL. The DriverManager attempts to select an appropriate driver from the set of registered JDBC drivers.
Parameters:
url - a database url of the form jdbc:subprotocol:subname
user - the database user on whose behalf the connection is being made
password - the user's password
Returns:
a connection to the URL
Throws:
SQLException - if a database access error occurs
(2). createStatement
public Statement createStatement()
throws SQLException
Creates a Statement object for sending SQL statements to the database. SQL statements without parameters are normally executed using Statement objects. If the same SQL statement is executed many times, it may be more efficient to use a PreparedStatement object.
Result sets created using the returned Statement object will by default be type TYPE_FORWARD_ONLY and have a concurrency level of CONCUR_READ_ONLY.
Returns:
a new default Statement object
Throws:
SQLException - if a database access error occurs
(3). executeQuery
public ResultSet executeQuery(String sql)
throws SQLException
Executes the given SQL statement, which returns a single ResultSet object.
Parameters:
sql - an SQL statement to be sent to the database, typically a static SQL SELECT statement
Returns:
a ResultSet object that contains the data produced by the given query; never null
Throws:
SQLException - if a database access error occurs or the given SQL statement produces anything other than a single ResultSet object
(4). getString
public String getString(String columnName)
throws SQLException
Retrieves the value of the designated column in the current row of this ResultSet object as a String in the Java programming language.
Parameters:
columnName - the SQL name of the column
Returns:
the column value; if the value is SQL NULL, the value returned is null
Throws:
SQLException - if a database access error occurs
(5). next
public boolean next()
throws SQLException
Moves the cursor down one row from its current position. A ResultSet cursor is initially positioned before the first row; the first call to the method next makes the first row the current row; the second call makes the second row the current row, and so on.
If an input stream is open for the current row, a call to the method next will implicitly close it. A ResultSet object's warning chain is cleared when a new row is read.
Returns:
true if the new current row is valid; false if there are no more rows
Throws:
SQLException - if a database access error occurs
7. ok! Now game is over~~
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