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[Java教程]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");      }    }  }}

  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