一、从网页给数据库添加数据（添加，修改，删除）

package holle;

import java.io.IOException;
import java.sql.SQLException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.dbutils.QueryRunner;

import utils.C3P0Utils;

public class Demo_03 extends HttpServlet{

	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		//处理编码格式
		//使用网页给数据库添加数据
		//数据库链接
		QueryRunner qu = new QueryRunner(C3P0Utils.getDataSource());
		//预编译方法
		String sql = "insert into product(PNAME,PRICE) VALUES(?,?)";
		//index的值！通过网页的name和password值进入数据库
		String name = req.getParameter("name");
		String password = req.getParameter("password");
		//异常最大化
		try {
			//把name和password放进o对象内，
			Object[] o = {name,password};
			//把sql添加数据，在把o网页上输出的内容给数据库（qu）
			qu.update(sql,o);
			System.out.println("添加成功");
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		//跳转链接
		req.getRequestDispatcher("index.jsp").forward(req, resp);
	}
}

　　

package holle3;

import java.io.IOException;
import java.sql.SQLException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.dbutils.QueryRunner;

import utils.C3P0Utils;

public class Demo_01 extends HttpServlet{

	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		// 通过网页修改一条数据
		QueryRunner qu = new QueryRunner(C3P0Utils.getDataSource());
		//要修改的数据格式
		String sql = "update product set  PNAME=?,PRICE=? WHERE PID=?";
		//jsp的属性值
		String name = req.getParameter("name");
		String password = req.getParameter("password");
		String pid = req.getParameter("pid");

		//异常的最大化
		try {
			//把属性值放进对象中
			Object [] o = {name,password,pid};
			//网页输入的内容放入数据库
			qu.update(sql,o);
			System.out.println("修改成功");
		} catch (SQLException e) {
			// TODO Auto-generated catch 
			e.printStackTrace();
		}
		//跳转的链接
		req.getRequestDispatcher("update.jsp").forward(req, resp);
	}
}

　　

@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
/*从网页中删除一条数据*/
QueryRunner qu = new QueryRunner(C3P0Utils.getDataSource());
String sql = "delete from product where pid=?";
String pid = req.getParameter("pid");

try {
Object o[] = {pid};
qu.update(sql,o);
System.out.println("删除成功");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
req.getRequestDispatcher("delete.jsp").forward(req, resp);
}