Web jsp开发学习——连接数据库，数据的增加和删除

1.首先在newlist界面增加三个图表，带上事件

newlist.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"

    import="java.util.*,java.text.*,com.xx17.cys.entity.*"

    import="java.sql.*,org.apache.commons.dbcp2.*"

    import="javax.naming.*,javax.sql.*" pageEncoding="UTF-8"%>

<%

//List<News> newslist = new ArrayList<News>();

    List newslist = new ArrayList();

    News news;

    /*= new News(1,"今天是星期四","gfsggfsg",201,"2019-3-13",0);

    newslist.add(news);

    news = new News(2,"又可以上web课啦！","gfsggfshgffdhg",104,"2019-3-14",0);

    newslist.add(news);

    String newstitle[]={"今天是星期四！","又可以上web课啦！","下午公休，嘿嘿！","人生啊，如此艰难！","现在是上午9点20分"};

    String newsdate[]={"2019-3-13","2019-3-14","2019-3-15","2019-3-16","2019-3-17"};

    */

    /*数据库连接池*/

    /*BasicDataSource ds = new BasicDataSource();

    String url="jdbc:mysql://localhost:3306/bookstore?user=root&password=caiyishuai";

    url += "&useUnicode=true&characterEncoding=utf8";

    ds.setDriverClassName(url);

    ds.setUsername("root");

    ds.setPassword("caiyishuai");

    ds.setMaxTotal(30);

    ds.setMinIdle(5);

    ds.setMaxWaitMillis(10000);

    ds.setRemoveAbandonedTimeout(100);

    ds.setRemoveAbandonedOnBorrow(true);

    ds.setRemoveAbandonedOnMaintenance(true);

    */

    /*使用静态数据库连接池*/

    Context initContext = new InitialContext();

    Context envContext = (Context)initContext.lookup("java:/comp/env");

    DataSource ds = (DataSource)envContext.lookup("jdbc/bookstore");

    //建立连接池连接

    Connection conn = ds.getConnection();

    /*Class.forName("com.mysql.jdbc.Driver");  ////驱动程序名

    String url = "jdbc:mysql://localhost:3306/bookstore"; //数据库名

    String username = "root";  //数据库用户名

    String password = "caiyishuai";  //数据库用户密码

    Connection conn = DriverManager.getConnection(url, username, password);  //连接状态*/

    if(conn != null){

        out.print("数据库连接成功！");

        Statement stmt = conn.createStatement();

        //创建结果集合，集合与表的结构类似

        ResultSet rs = stmt.executeQuery("select * from t_news");

        //rs.last

        //out.println("记录数："+rs.getRow());

        while(rs.next()){

            //System.out.println("rs"+rs);

              news = new News(rs.getInt(1),rs.getString(2),rs.getString(3),rs.getInt(5),rs.getString(4),1);

              newslist.add(news);

        }

    }

    /*建立连接

    Connection conn = DriverManager.getConnection(url);

    创建语句环境

    Statement stmt = conn.createStatement();

    创建结果集合，集合与表的结构类似

    ResultSet rs = stmt.executeQuery("select * from t_news");

    rs.last

    out.println("记录数："+rs.getRow());

    Class.forName("com.mysql.jdbc.Driver").newInstance();

    com.mysql.jdbc.Driver d = new com.mysql.jdbc.Driver

    String url="jdbc:mysql://localhost:3306/bookstore?"

    +"user=root&password=caiyishuai&useUnicode=true&characterEncoding=utf8";

    List<News> newslist = new ArrayList<News>();

    News news;

    while(rs.next()){

        news = new News(1,rs.getString(1),rs.getString(2),rs.getInt(4),rs.getString(3),1);

        newslist.add(news);

    }*/

%>

<!DOCTYPE html>

<html>

<head>

<meta charset="UTF-8">

<title>新闻列表</title>

</head>

<body>

<link href="css/style.css" rel="stylesheet" type="text/css"/>

<jsp:include page="head.jsp?col=1"></jsp:include>

<div id="main" class="layout">

<%

    SimpleDateFormat formatter = new SimpleDateFormat("yyyy年MM月dd日");

    java.util.Date today = new java.util.Date();

    out.print(formatter.format(today));

    //out.print(today.toLocaleString());

    //int id =Integer.parseInt(str);

%>

<table width="1000" border="1" cellpadding="0" cellspacing="0" style="border-collapse:collapse;">

    <tr>

        <th>序号</th>

        <th>标题</th>

        <th>日期</th>

        <th>点击</th>

        <th></th>

    </tr>

    <% String[] color={"red","orange","yellow","green","blue","purple","pink","black","brown"};%>

    <% for(int font_size=1;font_size<7;font_size++) {%>

        <br>

        <font color="<%= color[font_size-1] %>" size="<%= font_size %>">

            智慧的帅帅，么么哒！

        </font>

    <%}

    News n;

    %>

    <% for(int i=0;i<newslist.size();i++){

        n=(News)newslist.get(i);%>

        <tr>

            <td><%=i+1%></td>

            <td><a href="news.jsp?nid=<%=n.getNews_id()%>">

            <%=n.getNews_title()%></a></td>

            <td><%=n.getNews_date()%></td>

            <td><%=n.getNews_read()%></td>

            <td>

                <a href="addnews.do?action=mod&nid=<%=n.getNews_id()%>">

                    <img src="data:images/mod.png" width=40 >

                </a>

                <a href="addnews.do?action=del&nid=<%=n.getNews_id()%>">

                    <img src="data:images/del.png" width=40>

                </a>

            </td>

        </tr>

    <%}    %>

</table>

    <a href="addnews.do?action=add"><img src="data:images/new.png" width=40 ></a>

</div>

<%@ include file="foot.jsp" %>

</body>

</html>

2.在NewsServlet,java里写判断条件等等

package com.xx17.cys.servlet;

import java.io.IOException;

import java.text.SimpleDateFormat;

import java.util.Date;

import javax.servlet.RequestDispatcher;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import com.xx17.cys.entity.News;

import com.xx17.cys.javabean.NewsBean;

/**

 * Servlet implementation class NewsServlet

 */

@WebServlet("/addnews.do")

public class NewsServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    /**

     * @see HttpServlet#HttpServlet()

     */

    public NewsServlet() {

        super();

        // TODO Auto-generated constructor stub

    }

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

        RequestDispatcher rd;

        rd = request.getRequestDispatcher("addNews.jsp");

        rd.forward(request, response);

    }

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

        String nid = request.getParameter("nid");

        NewsBean nb = new NewsBean();

        News news = nb.getNewsById(nid);

        request.setAttribute("news", news);

        RequestDispatcher rd;

        rd = request.getRequestDispatcher("modnews.jsp");

        rd.forward(request, response);

    }

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

        String nid = request.getParameter("nid");

        NewsBean nb = new NewsBean();

        nb.del(nid);

        RequestDispatcher rd;

        rd = request.getRequestDispatcher("newslist.jsp");

        rd.forward(request, response);

    }

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

    }

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

        String nt = request.getParameter("ntitle");

        String nc = request.getParameter("ncontent");

        String ntop = request.getParameter("ntop");

        Date now = new Date();

        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

        String nd = sdf.format(now);

        int nr = 100;

        NewsBean nb = new NewsBean();

        nb.add(nt,nc,nd,nr,ntop);

        response.sendRedirect("newslist.jsp");

        /*RequestDispatcher rd;

        rd = request.getRequestDispatcher("newslist.jsp");

        rd.forward(request, response);*/

    }

    /**

     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)

     */

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

        // TODO Auto-generated method stub

        String act = request.getParameter("action");

        if(act.equals("add")) {

            addNews(request, response);

        }else if(act.equals("mod")) {

            modNews(request, response);

        }else if(act.equals("del")) {

            delNews(request, response);

        }else if(act.equals("show")) {

            getNews(request, response);

        }else if(act.equals("save")) {

            insNews(request, response);

        }

    }

    /**

     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)

     */

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

        // TODO Auto-generated method stub

        doGet(request, response);

    }

}

3.增加新闻，点击后跳转到addNews.jsp界面

addNews.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!DOCTYPE html>

<html>

<head>

<meta charset="UTF-8">

<title>Insert title here</title>

</head>

<body>

<link href="css/style.css" rel="stylesheet" type="text/css"/>

<jsp:include page="head.jsp?col=1"></jsp:include>

<div style="width:1000px; margin:auto; heigth:500px;">

<form action="addnews.do?action=save" method="post">

<table width="1000" border="1" cellpadding="5">

    <tr>

        <td width="200">标题：</td>

        <td width="800"><input name="ntitle" size="80"></td>

    </tr>

    <tr>

        <td>内容：</td>

        <td><textarea name="ncontent" cols="80" rows="10"></textarea></td>

    </tr>

    <tr>

        <td></td>

        <td><input type="checkbox" name="ntop" value="1">置顶</td>

    </tr>

    <tr>

        <td align="center" colspan="2">

        <input type="submit" value="保存">

        <input type="button" value="返回" onclick="location.href='newslist.jsp'">

        </td>

    </tr>

</table>

</form>

</div>

</body>

<%@ include file="foot.jsp" %>

</html>

NewsBean.java

package com.xx17.cys.javabean;

import java.sql.ResultSet;

import com.xx17.cys.entity.News;

public class NewsBean {

    public void add(String nt, String nc, String nd, int nr, String ntop) {

        String sql = "insert into t_news(ntitle,ncontent,ndate,";

        sql += "nread,ntop) values('"+nt+"','"+nc+"','"+nd;

        sql += "',"+nr+","+ntop+")";

        System.out.println("here: "+sql);

        DBBean db = new DBBean();

        db.getConnection();

        db.executeUpdata(sql);

    }

    public News getNewsById(String nid) {

        News n = new News();

        String sql = "select * from t_news where nid="+nid;

        DBBean db = new DBBean();

        db.getConnection();

        ResultSet rs = db.executeQuery(sql);

        try {

            if(rs.next()) {

                n.setNews_id(rs.getInt(1));

                n.setNews_title(rs.getString(2));

                n.setNews_content(rs.getString(3));

                n.setNews_top(rs.getInt(6));

            }

        }catch(Exception e) {

            e.printStackTrace();

        }

        return n;

    }

    public void del(String nid) {

        String sql = "delete from t_news where nid="+nid;

        System.out.println("here: "+sql);

        DBBean db = new DBBean();

        db.getConnection();

        db.executeUpdata(sql);

    }

}

DBBean.java

package com.xx17.cys.javabean;

import java.sql.*;

import javax.naming.*;

import javax.sql.*;

public final class DBBean {

    private Connection conn;

    private Statement stmt;

    private ResultSet rs;

    public DBBean() {

    }

    //建立数据库连接

    public Connection getConnection() {

        try {

            /*使用静态数据库连接池*/

            Context initContext = new InitialContext();

            Context envContext = (Context)initContext.lookup("java:/comp/env");

            DataSource ds = (DataSource)envContext.lookup("jdbc/bookstore");

            //建立连接池连接

            conn = ds.getConnection();

        }catch(Exception e) {

            e.printStackTrace();

        }

        return conn;

    }

    // 提取SQL生成记录集

    public ResultSet executeQuery(String sql) {

        try {

            stmt = conn.createStatement();

            rs = stmt.executeQuery(sql);

            System.out.println("返回结果集");

        }catch(Exception e) {

            e.printStackTrace();

        }

        return rs;

    }

    // 提取SQL添加记录

    public int executeUpdata(String sql){

        int result = 0;

        try{

            stmt = conn.createStatement();

            System.out.println(sql);

            result = stmt.executeUpdate(sql);

        }catch(Exception e){

            e.printStackTrace();

        }

        return result;

    }

}

3.删除数据

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