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.*;