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  • JSP网站开发基础总结《六》

      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"><input type="radio" name="sex" value="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="mohu"/><%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){ %><%}else{ %><%} %></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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  • 原文地址:https://www.cnblogs.com/AndroidJotting/p/4347457.html
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