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">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="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){ %>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");}}}}