JSP网站开发基础总结《六》

2022-11-04 10:36:53

　　对于本篇需要总结的内容，量估计有点大，大家好好看哈，绝对全是干货，代码的已经运行测试，不存在问题，大家可以参考学习，下面开始本篇的内容。

　1、添加数据到数据库：

　　如何用户在JSP页面的填写的信息输入到mysql数据库呢？其实原理很简单，就是我们在JSP页面里添加一个form表单标签，需要注意的是这里的action值填我们的用于与数据库库交互的select的地址，method标签有两个值可选：get和post，get方式的数据传输，不安全，传输的数据在地址栏可以看到，而post方式的传输就相对安全些，用户填写的数据不会显式让用户看到。设置好form表单标签后，当用户填写完表达后，点击提交，用户的填写的表单数据将会传输给我们的select，这样我们的select获得到数据后，通过调用我们之前编辑好的添加数据方法，便可以把用户的填写的数据添加到数据库。

　　jsp页面代码：

<%@ page language="java" import="java.util.*" pageEncoding="utf-8" errorPage="error.html"%>

<%

String path = request.getContextPath();

String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

  <head>

    <base href="<%=basePath%>">

    <title>添加数据</title>

    <meta http-equiv="pragma" content="no-cache">

    <meta http-equiv="cache-control" content="no-cache">

    <meta http-equiv="expires" content="0">

    <meta http-equiv="keywords" content="添加数据">

    <meta http-equiv="description" content="添加数据到数据库">

  </head>

  <body>

    <center>

        <h1>添加数据到mysql数据库</h1>

        <hr/>

        <form action="add" method="post" id="form" name="form">

            <table>

                <tr>

                    <td>姓名：</td><td><input type="text" name="name" /></td>

                </tr>

                <tr>

                    <td>性别：</td><td><input type="radio" name="sex" value="男" checked="checked">男<input type="radio" name="sex" value="女">女</td>

                </tr>

                <tr>

                    <td>年龄：</td><td><input type="text" name="year" /></td>

                </tr>

                <tr>

                    <td>家乡：</td><td><input type="text" name="from" /></td>

                </tr>

                <tr>

                    <td>学校：</td><td><input type="text" name="school" /></td>

                </tr>

                <tr>

                    <td align="center"><input type="submit" value="提交" /></td><td align="center"><input type="reset" value="重置"></td>

                </tr>

            </table>

        </form>

    </center>

  </body>

</html>

　　对于的select：

package com.mysql.jsp.select;

import java.io.IOException;

import java.util.ArrayList;

import java.util.List;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import com.mysql.jsp.manager.ManagerMaImp;

import com.mysql.jsp.sever.StudentMaImp;

import com.mysql.jsp.student.Student;

public class add extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        doPost(request, response);//调用doPsot()方法，把使用get方式传输的数据用doPost()方向接收

    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        request.setCharacterEncoding("utf-8");//设置编码方式

        response.setCharacterEncoding("utf-8");//设置编码方式

        //这里使用了一个登录验证

        String manager_name = (String)request.getSession().getAttribute("name");//获得登录用户的用户名

        String manager_password = (String)request.getSession().getAttribute("password");//获得登录用户的密码

        ManagerMaImp mmi = new ManagerMaImp();

        boolean login = mmi.getByName(manager_name, manager_password);//验证是否正确

        if(!login){

            request.setAttribute("news", "您还未登录，请先登录再进行操作");

            request.getRequestDispatcher("Login.jsp").forward(request, response);//不正确跳转到登录页

        }else{

            String name = request.getParameter("name");//获得用户填写的姓名

            String sex_ = request.getParameter("sex");//获得用户选择的性别

            int sex = 1;

            if(sex_.equals("女")){

                sex = 0;

            }

            int year = Integer.parseInt(request.getParameter("year"));//获得用户填写的年龄信息

            String from = request.getParameter("from");//获得用户填写的故乡信息

            String school = request.getParameter("school");//获得用户填写的学校信息

            //生成一个学生对象

            Student student = new Student();

            student.setName(name);

            student.setSex(sex);

            student.setYear(year);

            student.setFrom(from);

            student.setSchool(school);

            StudentMaImp smi = new StudentMaImp();

            boolean flag = smi.add(student);//调用添加方法，将数据添加到数据库

            if(flag){

                List<Student> list = new ArrayList<Student>();

                list = smi.getAll();

                request.setAttribute("list", list);

                request.getRequestDispatcher("All.jsp").forward(request, response);

            }else{

                response.sendRedirect("Add.jsp");

            }

        }

    }

}

　　对于向数据库添加信息，就为大家总结完毕，加上前几篇，我想大家应该已经明白如何通过JSP来做动态网站了吧。对于这里提到的是否登录验证，下面单独聊一下。

　3、登录验证：

　　这个功能大家应该遇到过很多，一般当我们在一些网站下载资料时，会有一个会员是否登录验证，只有你登录了才能下载，这个小功能很简单，但比较实用。下面我们就一起学习一下，这里用到了一个关键字：session，我们只需要在用户登录成功后，将用户的账户和密码通过requset方式进行一下声明，之后我们就可以在任何页面或select中得到。

　　声明代码：

request.getSession().setAttribute("name",name);

            request.getSession().setAttribute("password", password);

　　调用代码：

String manager_name = (String)request.getSession().getAttribute("name");//获得登录用户的用户名

        String manager_password = (String)request.getSession().getAttribute("password");//获得登录用户的密码

　4、遍历数据库：

　　添加数据我们已经学会了，下面我们一起学一下，如何把数据库中的所有数据遍历后，通过JSP页面为用户显示出来。

　　后台select代码：

　　　　　　　StudentMaImp smi = new StudentMaImp();

            List<Student> list = new ArrayList<Student>();

            list = smi.getAll();

            request.setAttribute("list", list);

            request.getRequestDispatcher("All.jsp").forward(request, response);

　　JSP页面：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8" errorPage="error.html"%>

<%@page import="com.mysql.jsp.student.Student"%>

<%

String path = request.getContextPath();

String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

  <head>

    <base href="<%=basePath%>">

    <title>遍历数据库</title>

    <meta http-equiv="pragma" content="no-cache">

    <meta http-equiv="cache-control" content="no-cache">

    <meta http-equiv="expires" content="0">

    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">

    <meta http-equiv="description" content="This is my page">

  </head>

  <body>

  <% List<Student> list = (List<Student>)request.getAttribute("list"); %>

    <center>

        <h1>遍历数据库中的数据</h1>

        <hr/>

        <form action="get" method="post">

            <table width="80%">

                <tr>

                    <td><a href="Add.jsp">添加</a></td><td>&nbsp;</td><td>精确查找:<input type="text" name="queding"/><%if(request.getAttribute("new1")!=null){ %><span style="color: red"><%=request.getAttribute("new1")%></span><% } %></td><td>&nbsp;</td><td>模糊查找:<input type="text" name="*"/><%if(request.getAttribute("new2")!=null){ %><span style="color: red"><%=request.getAttribute("new2")%></span><% } %></td><td><input type="submit" value="搜索"/></td>

                </tr>

            </table>

        </form>

        <table border="1" width="80%">

            <TR>

                <TD>ID</TD><td>姓名</td><td>性别</td><td>年龄</td><td>家乡</td><td>学校</td><td colspan="2">操作</td>

            </TR>

            <%

                if(list.size()!=0){

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

                        Student student = list.get(i);

            %>

                    <tr><TD><%=student.getId() %></TD><td><%=student.getName() %></td><td><%if(student.getSex()==1){ %>男<%}else{ %>女<%} %></td><td><%=student.getYear() %></td><td><%=student.getFrom() %></td><td><%=student.getSchool() %></td><td><a href="getId?id=<%=student.getId() %>">修改</a></td><td><a href="del?id=<%=student.getId() %>">删除</a></td></tr>

            <%

                    }

                }

             %>

        </table>

    </center>

  </body>

</html>

　　界面效果：

　5、删除数据：

　　既然是删除操作，也就没有界面了，但我们点击删除后，select接到我们发送过去的数据信息，根据这些信息调用我们之前写好的删除方法，完成删除操作。

　　select代码：

public class del extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        doPost(request, response);//删除操作，发送数据的方式便是get方式，我们可以在地址栏看到我们发送过来的数据信息

    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        request.setCharacterEncoding("utf-8");

        response.setCharacterEncoding("utf-8");

        String manager_name = (String)request.getSession().getAttribute("name");

        String manager_password = (String)request.getSession().getAttribute("password");

        ManagerMaImp mmi = new ManagerMaImp();

        boolean login = mmi.getByName(manager_name, manager_password);

        if(!login){

            request.setAttribute("news", "您还未登录，请先登录再进行操作");

            request.getRequestDispatcher("Login.jsp").forward(request, response);

        }else{

            int id = Integer.parseInt(request.getParameter("id"));

            StudentMaImp smi = new StudentMaImp();

            boolean flag = smi.del(id);

            if(flag){

                List<Student> list = new ArrayList<Student>();

                list = smi.getAll();

                request.setAttribute("list", list);

                request.getRequestDispatcher("All.jsp").forward(request, response);

            }else{

                response.sendRedirect("error.html");

            }

        }

    }

}

　6、更新操作：

　　学完了添加、删除、遍历操作后，接下来我们一起来学习一下更新操作。

　　更新操作的JSP页面：

<%@ page language="java" import="java.util.*" pageEncoding="utf-8" errorPage="error.html"%>

<%@page import="com.mysql.jsp.student.Student"%>

<%

String path = request.getContextPath();

String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

  <head>

    <base href="<%=basePath%>">

    <title>修改数据</title>

    <meta http-equiv="pragma" content="no-cache">

    <meta http-equiv="cache-control" content="no-cache">

    <meta http-equiv="expires" content="0">

    <meta http-equiv="keywords" content="修改数据">

    <meta http-equiv="description" content="修改数据到数据库">

  </head>

  <body>

  <%Student student = (Student)request.getAttribute("student"); %>

    <center>

        <h1>修改数据到mysql数据库</h1>

        <hr/>

        <form action="update" method="post" >

            <table>

                <tr>

                    <!--  disabled="disabled":销毁的，select无法得到它的值   -->

                    <!--  readonly="readonly":只读的，select可以读出值  -->

                    <td>id:</td><td><input type="text" name="id" readonly="readonly" value="<%=student.getId() %>" /></td>

                </tr>

                <tr>

                    <td>姓名：</td><td><input type="text" name="name" value="<%=student.getName() %>"/></td>

                </tr>

                <tr>

                    <td>性别：</td><td><input type="radio" name="sex" value="男" <%if(student.getSex()==1){ %>checked="checked"<%} %> >男<input type="radio" name="sex" value="女" <%if(student.getSex()==0){ %>checked="checked"<%} %> >女</td>

                </tr>

                <tr>

                    <td>年龄：</td><td><input type="text" name="year" value="<%=student.getYear() %>"/></td>

                </tr>

                <tr>

                    <td>家乡：</td><td><input type="text" name="from" value="<%=student.getFrom() %>"/></td>

                </tr>

                <tr>

                    <td>学校：</td><td><input type="text" name="school" value="<%=student.getSchool() %>"/></td>

                </tr>

                <tr>

                    <td align="center"><input type="submit" value="更新" /></td><td align="center"><input type="reset" value="重置"></td>

                </tr>

            </table>

        </form>

    </center>

  </body>

</html>

　　既然是更新，我们需要首先通过select获得需要更新信息的对象，然后将对象数据发送给JSP页面，代码：

public class come extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        doPost(request, response);

    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        StudentMaImp smi = new StudentMaImp();

        List<Student> list = new ArrayList<Student>();

        list = smi.getAll();

        request.setAttribute("list", list);

        request.getRequestDispatcher("All.jsp").forward(request, response);

    }

}

　　用户接收用户修改的数据，并进行数据更新的select：

public class update extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        doPost(request, response);

    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        request.setCharacterEncoding("utf-8");

        response.setCharacterEncoding("utf-8");

        String manager_name = (String)request.getSession().getAttribute("name");

        String manager_password = (String)request.getSession().getAttribute("password");

        ManagerMaImp mmi = new ManagerMaImp();

        boolean login = mmi.getByName(manager_name, manager_password);

        if(!login){

            request.setAttribute("news", "您还未登录，请先登录再进行操作");

            request.getRequestDispatcher("Login.jsp").forward(request, response);

        }else{

            int id = Integer.parseInt(request.getParameter("id"));

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

            String sex_ = request.getParameter("sex");

            int sex = 1;

            if(sex_.equals("女")){

                sex = 0;

            }

            int year = Integer.parseInt(request.getParameter("year"));

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

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

            Student student = new Student();

            student.setId(id);

            student.setName(name);

            student.setSex(sex);

            student.setYear(year);

            student.setFrom(from);

            student.setSchool(school);

            StudentMaImp smi = new StudentMaImp();

            boolean flag = smi.update(student);

            if(flag){

                List<Student> list = new ArrayList<Student>();

                list = smi.getAll();

                request.setAttribute("list", list);

                request.getRequestDispatcher("All.jsp").forward(request, response);

            }else{

                response.sendRedirect("error.html");

            }

        }

    }

}

　　好了，到这里对于通过JSP实现对数据库的增、删、改、遍历操作，就为大家总结完毕。下一篇：JSP页面精确搜索、模糊搜索

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