使用Servlet和Java Bean访问MySQL

运行环境: JDK 5.0 + Tomcat 5.5.4

JDK安装路径: D:\Java\jdk1.5.0_01

Tomcat安装路径:D:\Tomcat 5.5

设置环境变量(控制面板->系统->高级):

java_home=D:\Java\jdk1.5.0_01

path=%JAVA_HOME%\bin

classpath=.;D:\Java\jdk1.5.0_01\lib\dt.jar;D:\Java\jdk1.5.0_01\lib\tools.jar;D:\Tomcat 5.5\common\lib\servlet-api.jar;D:\Tomcat 5.5\common\lib\mysql-connector-java-3.1.6-bin.jar;

其中D:\Tomcat 5.5\common\lib\servlet-api.jar为Tomcat的servlet API实现,一定要加上,不如无法编译servlet

D:\Tomcat 5.5\common\lib\mysql-connector-java-3.1.6-bin.jar;是MySQL的JDBC驱动,connect/J 3.1.6,可到MySQL官方网站下载

Tomcat5.5虚拟目录设定:

D:\Tomcat 5.5\conf\Catalina\localhost下新加一test.XML

内容如下:

<Context path="/test" docBase="d:/www" reloadable="true" crossContext="true" debug="0" >

</Context>

d:\www路径将是我们测试网站的根目录,通过http://localhost:8080/test访问该虚拟目录

d:\www下建有目录Web-INF,下有web.xml设置文件(可参考D:\Tomcat 5.5\webapps\ROOT\WEB-INF\web.xml),classes目录和lib目录

//连接数据库的Java Bean文件名dbconn.java

package NinGoo;

import java.sql.*;

public class dbconn {

public dbconn() {

}

//declare variable

private Connection conn = null;

ResultSet rs = null;

private String server = "127.0.0.1";

private String port = "3306";

private String db = "test";

private String user = "root";

private String pass = "password";

private String drivername="com.mysql.jdbc.Driver";

private String URL="jdbc:mysql://"+server+":"+port+"/"+db+"?user="+user+"&password="+pass;

public Connection getConn(){//get database connection

try{

Class.forName(drivername).newInstance();

conn = DriverManager.getConnection(URL);

}

catch(Exception e){

e.printStackTrace();

}

return this.conn ;

}

public ResultSet executeSQL(String str) {

try{

Statement stmt = conn.createStatement();

rs = stmt.executeQuery(str);

}

catch(Exception e){

e.printStackTrace();

}

return this.rs;

}

}

编译javac welcome.java,将编译后的文件welcome.class放到目录D:\www\WEB-INF\classes\NinGoo\下

//调用Java Bean的servlet welcome.java

import java.io.*;

import javax.servlet.*;

import javax.servlet.http.*;

import java.sql.*;