【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");
}
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