web开发 mysql数据库操作之分页技术

来源：互联网发布：centos安装nodejs 编辑：程序博客网时间：2024/05/17 02:20

在之前登陆界面的基础上，三个文件 Login，Verify，Welome。登陆界面操作数据库项目代码：点击打开链接

然后为了验证大数据量处理，通过 insert into users (username,passwd,grade) select username,passwd,grade from users 来让表自我复制，我们最好让表数量超过10w。

package com.busymonkey;    import java.io.IOException;  import java.io.PrintWriter;    import javax.servlet.ServletException;  import javax.servlet.http.HttpServlet;  import javax.servlet.http.HttpServletRequest;  import javax.servlet.http.HttpServletResponse;    /**  * Servlet implementation class ServletDemo  */  public class Login extends HttpServlet {      private static final long serialVersionUID = 1L;               public Login() {          super();      }        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {          try {              PrintWriter pw = response.getWriter();              pw.println("<html>");              pw.println("<body>");              pw.println("<h1>Login</h1>");              pw.println("<form action=verify method=post>");              pw.println("UserName:<input type=text name=username><br>");              pw.println("PassWord:<input type=password name=passwd><br>");              pw.println("<input type=submit value=loging><br>");              pw.println("</form>");              pw.println("</body>");              pw.println("</html>");          }          catch (Exception ex) {              ex.printStackTrace();          }      }        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {          this.doGet(request, response);      }  }

package com.busymonkey;import javax.servlet.ServletException;import javax.servlet.http.*;import java.io.*;import java.sql.*;public class Verify extends HttpServlet {    private static final long serialVersionUID = 1L;           public Verify() {        super();    }    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {    Connection ct = null;    Statement sm = null;    ResultSet rs = null;    try {        String u=request.getParameter("username");        String p=request.getParameter("passwd");                //数据库连接        Class.forName("com.mysql.jdbc.Driver");        //得到连接        ct = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/db_hou", "root", "123456");        //创建Statement        sm = ct.createStatement();        rs = sm.executeQuery("select * from users where username='"+u+"' and passwd='"+p+"'");                if (rs.next()) {//next能进来说明用户是存在的        String dbPasswd = rs.getString("passwd");        if (dbPasswd.equals(p)) {        HttpSession hs = request.getSession(true);        hs.setMaxInactiveInterval(20);        hs.setAttribute("pass", "ok");        response.sendRedirect("welcome?uname=" + u + "&upass=" + p);         }        else        {        response.sendRedirect("login");        }        }        else {        response.sendRedirect("login");        }        }        catch (Exception ex) {        ex.printStackTrace();        }finally{        try {        if (rs!=null) rs.close();        if (sm!=null) sm.close();        if (ct!=null) ct.close();        }        catch (Exception ex) {        ex.printStackTrace();        }        }    }    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        this.doGet(request, response);    }}

package com.busymonkey;import javax.servlet.ServletException;import javax.servlet.http.*;import java.io.*;import java.sql.*;public class WelCome extends HttpServlet {    private static final long serialVersionUID = 1L;           public WelCome() {        super();    }    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        Connection ct = null;        PreparedStatement ps = null;        ResultSet rs = null;            HttpSession hs = request.getSession(true);        String val = (String) hs.getAttribute("pass");//非法登陆返回空        if ( val == null )        {        try {        response.sendRedirect("login");        }        catch (Exception ex) {        ex.printStackTrace();        }        }    String u = request.getParameter("uname");        String p = request.getParameter("upass");    try {    //分页技术    int pageSize = 3;//每页条数    int pageCurrent = 1;//当前页数    int rowCount = 0;//总条数    int pageCount = 0;//总页数    PrintWriter pw = response.getWriter();    //动态接收pageCurrent    String sPageCurrent = request.getParameter("pageCurrent");    if (sPageCurrent != null) {    pageCurrent = Integer.parseInt(sPageCurrent);    }    //得到rowCount        Class.forName("com.mysql.jdbc.Driver");        ct = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/db_hou", "root", "123456");        ps = ct.prepareStatement("select count(*) from users");        rs = ps.executeQuery();        if (rs.next()) {        rowCount = rs.getInt(1);        }        //计算pageCount        if (rowCount%pageSize == 0) {        pageCount = rowCount/pageSize;        }        else {        pageCount = rowCount/pageSize + 1;        }                ps = ct.prepareStatement("select * from users limit ?,?");        //给？赋值        ps.setInt(1, pageSize*(pageCurrent-1));        ps.setInt(2, pageSize);        rs = ps.executeQuery();                pw.println("<body><center>");        pw.println("<img src=./imgs/1.GIF ><br>");        pw.println("Welcome!!!! " + u + " pass=" + p);        //表数据显示        pw.println("<table border=1>");        pw.println("<tr><th>ID</th><th>NAME</th><th>PASSWD</th><th>GRADE</th></tr>");        while (rs.next()) {        pw.println("<tr>");        pw.println("<td>"+rs.getInt("userId")+"</td>");        pw.println("<td>"+rs.getString("username")+"</td>");        pw.println("<td>"+rs.getString("passwd")+"</td>");        pw.println("<td>"+rs.getInt("grade")+"</td>");        pw.println("</tr>");        }        pw.println("</table>");                //上一页        if (pageCurrent != 1)        pw.println("<a href=welcome?pageCurrent="+(pageCurrent-1)+">Prepage</a>");        //显示超链接        for (int i = pageCurrent; i <= pageCurrent+5; i ++) {        pw.println("<a href=welcome?pageCurrent="+i+">"+i+"</a>");        }        //下一页        if (pageCurrent != pageCount)        pw.println("<a href=welcome?pageCurrent="+(pageCurrent+1)+">Nextpage</a>");                pw.println("</center></body>");        }        catch (Exception ex) {        ex.printStackTrace();        }    }    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        this.doGet(request, response);    }}

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web开发 mysql数据库操作 之 分页技术

web开发 mysql数据库操作之分页技术