【使用jdbc和servlet实现阅览文章访问次数】

Java代码
package com.lm.org;

import java.io.IOException;

import java.io.PrintWriter;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import javax.servlet.ServletContext;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

/**

* Servlet implementation class Test

*/

public class Test extends HttpServlet {

private static final long serialVersionUID = 1L;

/**

*/

public Test() {

super();

}

/**

*/

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

this.doPost(request, response);

}

/**

*/

protected void doPost(HttpServletRequest request,

HttpServletResponse response) throws ServletException, IOException {

request.setCharacterEncoding("utf-8");

response.setCharacterEncoding("utf-8");

PrintWriter out = response.getWriter();

//HttpSession session = request.getSession();// 得到session

//ServletContext application = super.getServletContext();

//Integer accessCount = (Integer) application.getAttribute("accessCount");//数据库查询出来

Integer wiewsCount=null;

Connection connection = null;

String sql="select * from t_news where id=1 ";//wiewsCount

PreparedStatement ps=null;

ResultSet rs=null;

try {

connection=getConnection();

ps = connection.prepareStatement(sql);

rs = ps.executeQuery();

if(rs.next()){

wiewsCount = rs.getInt("wiewsCount");

if(wiewsCount==null){

wiewsCount = 1;

}else{

wiewsCount = wiewsCount + 1;

Connection cn =getConnection();

String sql1="update t_news set wiewsCount="+wiewsCount+" where id=1";

PreparedStatement prepareStatement = cn.prepareStatement(sql1);

int executeUpdate = prepareStatement.executeUpdate();

if(executeUpdate>0){

System.out.println("1");

}else{

System.out.println(2);

}

cn.close();

cn=null;

prepareStatement.close();

prepareStatement=null;

}

}

} catch (SQLException e) {

e.printStackTrace();

}finally{

try {

connection.close();

connection=null;

ps.close();

ps=null;

rs.close();

rs=null;

} catch (SQLException e) {

e.printStackTrace();

}

}

Integer ac;

try {

ac = accessCount(request, response);

out.println("模拟值="+ac+"\t数据库值="+wiewsCount);

} catch (Exception e) {

e.printStackTrace();

}

out.flush();

out.close();

}

public static Integer accessCount(HttpServletRequest request,HttpServletResponse response)throws Exception{

HttpServletRequest hs=(HttpServletRequest)request;

ServletContext application = hs.getServletContext();

Integer accessCount = (Integer) application.getAttribute("accessCount");//数据库查询出来

//if=null

if (accessCount == null) {

accessCount = 1;

application.setAttribute("accessCount", accessCount);

} else {

//else +1并修改数据库的值

accessCount = accessCount + 1;

application.setAttribute("accessCount", accessCount);

//update

}

return accessCount;

}

/**

* @return

*/

public static Connection getConnection() {

Connection conn = null;

try {

Class.forName(Driver);

conn = DriverManager.getConnection(Url, UserName, PassWord);

} catch (Exception e) {

e.printStackTrace();

}

return conn;

}

private static String Driver = "com.mysql.jdbc.Driver";// ConfigUtils.getProperty("jdbc.driver");

private static String Url = "jdbc:mysql://localhost:3306/test?characterEncoding=utf8";// ConfigUtils.getProperty("jdbc.url");

private static String UserName = "root";// ConfigUtils.getProperty("jdbc.userName");

private static String PassWord = "root";// ConfigUtils.getProperty("jdbc.passWord");

}