JSP網站開發基礎總結《六》

2019-11-14 23:21:35

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jsp網站開發基礎總結《六》

　　對于本篇需要總結的內容，量估計有點大，大家好好看哈，絕對全是干貨，代碼的已經運行測試，不存在問題，大家可以參考學習，下面開始本篇的內容。

　1、添加數據到數據庫：

　　如何用戶在JSP頁面的填寫的信息輸入到MySQL數據庫呢？其實原理很簡單，就是我們在JSP頁面里添加一個form表單標簽，需要注意的是這里的action值填我們的用于與數據庫庫交互的select的地址，method標簽有兩個值可選：get和post，get方式的數據傳輸，不安全，傳輸的數據在地址欄可以看到，而post方式的傳輸就相對安全些，用戶填寫的數據不會顯式讓用戶看到。設置好form表單標簽后，當用戶填寫完表達后，點擊提交，用戶的填寫的表單數據將會傳輸給我們的select，這樣我們的select獲得到數據后，通過調用我們之前編輯好的添加數據方法，便可以把用戶的填寫的數據添加到數據庫。

　　jsp頁面代碼：

<%@ 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>添加數據</title>        <meta http-equiv="Words" content="添加數據">    <meta http-equiv="descr　　對于的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);//調用doPsot()方法，把使用get方式傳輸的數據用doPost()方向接收    }    public void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        request.setCharacterEncoding("utf-8");//設置編碼方式        response.setCharacterEncoding("utf-8");//設置編碼方式                //這里使用了一個登錄驗證        String manager_name = (String)request.getsession().getAttribute("name");//獲得登錄用戶的用戶名        String manager_password = (String)request.getSession().getAttribute("password");//獲得登錄用戶的密碼        ManagerMaImp mmi = new ManagerMaImp();        boolean login = mmi.getByName(manager_name, manager_password);//驗證是否正確        if(!login){            request.setAttribute("news", "您還未登錄，請先登錄再進行操作");            request.getRequestDispatcher("Login.jsp").forward(request, response);//不正確跳轉到登錄頁        }else{            String name = request.getParameter("name");//獲得用戶填寫的姓名            String sex_ = request.getParameter("sex");//獲得用戶選擇的性別            int sex = 1;            if(sex_.equals("女")){                sex = 0;            }            int year = Integer.parseInt(request.getParameter("year"));//獲得用戶填寫的年齡信息            String from = request.getParameter("from");//獲得用戶填寫的故鄉信息            String school = request.getParameter("school");//獲得用戶填寫的學校信息            //生成一個學生對象            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);//調用添加方法，將數據添加到數據庫            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");            }        }    }}
　　對于向數據庫添加信息，就為大家總結完畢，加上前幾篇，我想大家應該已經明白如何通過JSP來做動態網站了吧。對于這里提到的是否登錄驗證，下面單獨聊一下。
　3、登錄驗證：
　　這個功能大家應該遇到過很多，一般當我們在一些網站下載資料時，會有一個會員是否登錄驗證，只有你登錄了才能下載，這個小功能很簡單，但比較實用。下面我們就一起學習一下，這里用到了一個關鍵字：session，我們只需要在用戶登錄成功后，將用戶的賬戶和密碼通過requset方式進行一下聲明，之后我們就可以在任何頁面或select中得到。
　　聲明代碼：
request.getSession().setAttribute("name",name);            request.getSession().setAttribute("password", password);
　　調用代碼：
String manager_name = (String)request.getSession().getAttribute("name");//獲得登錄用戶的用戶名        String manager_password = (String)request.getSession().getAttribute("password");//獲得登錄用戶的密碼
　4、遍歷數據庫：
　　添加數據我們已經學會了，下面我們一起學一下，如何把數據庫中的所有數據遍歷后，通過JSP頁面為用戶顯示出來。
　　后臺select代碼：
　　　　　　　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頁面：
<%@ 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>遍歷數據庫</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>遍歷數據庫中的數據</h1>        <hr/>        <form action="get" method="post">            <table width="80%">                <tr>                    <td><a href="Add.jsp">添加</a></td><td>&nbsp;</td><td>精確查找:<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>性別</td><td>年齡</td><td>家鄉</td><td>學校</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() %>">刪除</a></td></tr>            <%                    }                }             %>        </table>    </center>  </body></html>
　　界面效果：
　　
　5、刪除數據：
　　既然是刪除操作，也就沒有界面了，但我們點擊刪除后，select接到我們發送過去的數據信息，根據這些信息調用我們之前寫好的刪除方法，完成刪除操作。
　　select代碼：
public class del extends HttpServlet {    public void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        doPost(request, response);//刪除操作，發送數據的方式便是get方式，我們可以在地址欄看到我們發送過來的數據信息    }    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", "您還未登錄，請先登錄再進行操作");            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：
　　學完了添加、刪除、遍歷操作后，接下來我們一起來學習一下更新操作。
　　更新操作的JSP頁面：
<%@ 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>修改數據</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="修改數據">    <meta http-equiv="description" content="修改數據到數據庫">  </head>    <body>  <%Student student = (Student)request.getAttribute("student"); %>    <center>        <h1>修改數據到mysql數據庫</h1>        <hr/>        <form action="update" method="post" >            <table>                <tr>                    <!--  disabled="disabled":銷毀的，select無法得到它的值   -->                    <!--  readonly="readonly":只讀的，select可以讀出值  -->                    <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>性別：</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>年齡：</td><td><input type="text" name="year" value="<%=student.getYear() %>"/></td>                </tr>                <tr>                    <td>家鄉：</td><td><input type="text" name="from" value="<%=student.getFrom() %>"/></td>                </tr>                <tr>                    <td>學校：</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，我們需要首先通過select獲得需要更新信息的對象，然后將對象數據發送給JSP頁面，代碼：
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);    }}
　　用戶接收用戶修改的數據，并進行數據更新的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", "您還未登錄，請先登錄再進行操作");            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，到這里對于通過JSP實現對數據庫的增、刪、改、遍歷操作，就為大家總結完畢。下一篇：JSP頁面精確搜索、模糊搜索