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javaweb_实现增删改查操作

程序员文章站 2022-07-10 10:19:10
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花了几天的时间,终于实现了这些操作。利用博客来梳理下自己关于javaweb的知识点。


一:准备工作

    1:test01文件夹(里面有所需的页面资源),我完成的是在里面添加增删改查操作

    2:myeclipse(版本没什么要求)  eclipse也行

    3:数据库 MySQL

    4:需要了解到的知识点:

                                        servlet

                                        EL与JSTL表达式

                                      项目的基本框架搭建(javaweb经典三层框架)

    5:在myeclipse中建立对应的包结构

    javaweb_实现增删改查操作


二:项目的基本框架搭建

    所谓三层框架分别为表述层(WEB层)、业务逻辑层()、数据访问层()。

  •     web层(action):包含JSP和Servlet等与web相关的内容,负责与浏览器的响应和请求;
  •     业务层(service):只关心业务逻辑;
  •     数据层(dao):封装了对数据库的访问细节,数据操作类;

关系:web层依赖业务层    业务层依赖数据层(这个关系很重要)


ps:除了以上三层框架是我们在写一个javaweb项目必须的外,还需要一个实体类(entity)。

三:实现数据库的连接

    需要在MySQL中创建所需数据库,并将表建好。

    

  •     数据库相关设计

1数据库名为db_examsystem。

2项目信息表名为tb_subject,表结构见表1,其中subjectID为自增长主键,增量为1。

1 试题信息表(tb_subject)

javaweb_实现增删改查操作


3、在表tb_subject中插入记录,见表2

2试题信息表中的数据

javaweb_实现增删改查操作


  • 连接数据库

在dao下新建一个DBConn类用来处理对数据进行连接。 这是MySQL的连接方式

package dao;

import java.sql.*;


public class DBConn {
	static Connection conn = null;
	//连接数据库,返回Connection conn;
	public static Connection getConn () {
		String driverClassName = "com.mysql.jdbc.Driver";
		String url = "jdbc:mysql://localhost:3306/db_examsystem";
		String username = "root";
		String password = "123";
		
	try {
		Class.forName(driverClassName);
		conn = DriverManager.getConnection(url, username, password);
	} catch (Exception e) {
		e.printStackTrace();
	}
	return conn;
	
	}
	
}



四:建立实体类

在entity包下创建Subject实体类(实体类中的对象对应数据库表中的字段数据)

package entity;

public class Subject {
private int subjectID;
private String subjectTitle;
private String subjectOptionA;
private String subjectOptionB;
private String subjectOptionC;
private String subjectOptionD;
private String subjectAnswer;
private String subjectParse;


public int getSubjectID() {
	return subjectID;
}
public void setSubjectID(int subjectID) {
	this.subjectID = subjectID;
}
public String getSubjectTitle() {
	return subjectTitle;
}
public void setSubjectTitle(String subjectTitle) {
	this.subjectTitle = subjectTitle;
}
public String getSubjectOptionA() {
	return subjectOptionA;
}
public void setSubjectOptionA(String subjectOptionA) {
	this.subjectOptionA = subjectOptionA;
}
public String getSubjectOptionB() {
	return subjectOptionB;
}
public void setSubjectOptionB(String subjectOptionB) {
	this.subjectOptionB = subjectOptionB;
}
public String getSubjectOptionC() {
	return subjectOptionC;
}
public void setSubjectOptionC(String subjectOptionC) {
	this.subjectOptionC = subjectOptionC;
}
public String getSubjectOptionD() {
	return subjectOptionD;
}
public void setSubjectOptionD(String subjectOptionD) {
	this.subjectOptionD = subjectOptionD;
}
public String getSubjectAnswer() {
	return subjectAnswer;
}
public void setSubjectAnswer(String subjectAnswer) {
	this.subjectAnswer = subjectAnswer;
}
public String getSubjectParse() {
	return subjectParse;
}
public void setSubjectParse(String subjectParse) {
	this.subjectParse = subjectParse;
}




}


五:实现增删改查方法


创建方法类,这里有两种方法

1:在dao包中创建一个StudentDao接口,里面写增删改查的方法,再在dao中创建StudentDaoImpl类来实现接口,并实现之中的方法。

StudentDao接口:

package dao;

import java.util.List;

import entity.Subject;

public interface SubjectDao {
	/*
	 * 1.添加数据
	 * 2.查看数据,返回信息
	 * 3.修改
	 * 4.删除
	 * 
	 * */
	
	
	public boolean add(Subject subject);
	public List<Subject> selectall();
	public boolean update(String subjectTitle,String subjectOptionA,String subjectOptionB,
			String subjectOptionC,String subjectOptionD,String subjectAnswer,String subjectParse);
	public boolean delete(int subjectID);
	public List<Subject> selectByID(String string);
}


StudentDaoImpl类(包含增删改查操作):

package dao;

import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import com.mysql.jdbc.Connection;

import entity.Subject;

public class SubjectDaoImpl implements SubjectDao {
	
	Connection conn = (Connection) DBConn.getConn();

	
	@Override
	public boolean add(Subject subject) {
		boolean flag = false;
		
		
		try {
			String sql="insert tb_subject values('"+subject.getSubjectID()+"','"
					 +subject.getSubjectTitle()+"','"
				     +subject.getSubjectOptionA()+"','"
					 +subject.getSubjectOptionB()+"','"
					 +subject.getSubjectOptionC()+"','"
				     +subject.getSubjectOptionD()+"','"
				     +subject.getSubjectAnswer()+"','"
				     +subject.getSubjectParse()+"')";
			PreparedStatement pstmt = conn.prepareStatement(sql);
			int i = pstmt.executeUpdate();
			pstmt.close();
			conn.close();
			if(i>0) {
				flag = true;
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return flag;
	}


	@Override
	public List<Subject> selectall() {
		List<Subject> list = new ArrayList<Subject>();
		try {
			String sql = "select * from tb_subject";
			PreparedStatement pstmt = conn.prepareStatement(sql);
			ResultSet rs = pstmt.executeQuery();
			while(rs.next()) {
				Subject subject = new Subject();
				subject.setSubjectID(rs.getInt("subjectID"));
				subject.setSubjectTitle(rs.getString("subjectTitle"));
				subject.setSubjectOptionA(rs.getString("subjectOptionA"));
				subject.setSubjectOptionB(rs.getString("subjectOptionB"));
				subject.setSubjectOptionC(rs.getString("subjectOptionC"));
				subject.setSubjectOptionD(rs.getString("subjectOptionD"));
				subject.setSubjectAnswer(rs.getString("subjectAnswer"));
				subject.setSubjectParse(rs.getString("subjectParse"));
				list.add(subject);
			}
			rs.close();
			pstmt.close();
			conn.close();
			
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return list;
	}
	
	@Override
	public List<Subject> selectByID(String subjectID) {
		List<Subject> list = new ArrayList<Subject>();
		try {
			String sql = "select * from tb_subject where subjectID=?";
			PreparedStatement pstmt = conn.prepareStatement(sql);
			pstmt.setString(1,subjectID );
			ResultSet rs = pstmt.executeQuery();
			while(rs.next()) {
				Subject subject = new Subject();
				subject.setSubjectID(rs.getInt("subjectID"));
				subject.setSubjectTitle(rs.getString("subjectTitle"));
				subject.setSubjectOptionA(rs.getString("subjectOptionA"));
				subject.setSubjectOptionB(rs.getString("subjectOptionB"));
				subject.setSubjectOptionC(rs.getString("subjectOptionC"));
				subject.setSubjectOptionD(rs.getString("subjectOptionD"));
				subject.setSubjectAnswer(rs.getString("subjectAnswer"));
				subject.setSubjectParse(rs.getString("subjectParse"));
				list.add(subject);
			}
			rs.close();
			pstmt.close();
			conn.close();
		} catch (SQLException e) {
			e.printStackTrace();
		}
		
		return list;
	}

	@Override
	public boolean update( String subjectTitle,
			String subjectOptionA, String subjectOptionB,
			String subjectOptionC, String subjectOptionD, String subjectAnswer,
			String subjectParse) {
		boolean flag = false;
		try {
			String sql = "update tb_subject set subjectOptionA = '"+subjectOptionA+"',subjectOptionB = '"+subjectOptionB+"',subjectOptionC = '"+subjectOptionC+
					"',subjectOptionD = '"+subjectOptionD+"',subjectAnswer = '"+subjectAnswer+"',subjectParse = '"+subjectParse+"' where subjectTitle = '"+subjectTitle+"'";
			
			PreparedStatement pstmt = conn.prepareStatement(sql);
			int i = pstmt.executeUpdate();
			pstmt.close();
			conn.close();
			if(i>0)flag = true;
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return flag;
	}

	@Override
	public boolean delete(int subjectID) {
		boolean flag = false;
		
		try {
			String sql = "delete from tb_subject where subjectID = '"+subjectID+"'";
			PreparedStatement pstmt = conn.prepareStatement(sql);
			int i = pstmt.executeUpdate();
			pstmt.close();
			conn.close();
			if(i>0) flag = true;
		} catch (SQLException e) {
			System.out.println("删除失败!");
			e.printStackTrace();
		}
		
		return flag;
	}


	



}

2:在service包中创建StudentService类,在dao包中创建StudentDao类来实现StudentService类中的方法。(具体操作以后更新)

六:实现servlet和对应jsp(html)页面

Servlet有两种方式创建,一种手工创建。另一种程序自动生成。前者自己创建java类,实现Servlet具体内容,然后需要去WEB_INF下的web.xml去配置servlet  . 而后者则直接由程序替我们配置好了Servlet

1:增

  • 创建SubjectAddServlet
package action;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.SQLException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import dao.SubjectDao;
import dao.SubjectDaoImpl;
import entity.Subject;

public class SubjectServlet extends HttpServlet {

	@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		request.setCharacterEncoding("utf-8");
		response.setContentType("text/html;charset=utf-8");
		
		String subjectTitle=request.getParameter("subjectTitle");
		String subjectOptionA=request.getParameter("subjectOptionA");
		String subjectOptionB=request.getParameter("subjectOptionB");
		String subjectOptionC=request.getParameter("subjectOptionC");
		String subjectOptionD=request.getParameter("subjectOptionD");
		String subjectAnswer=request.getParameter("subjectAnswer");
		String subjectParse=request.getParameter("subjectParse");
		Subject Subject =new Subject();
		Subject.setSubjectTitle(subjectTitle);
		Subject.setSubjectOptionA(subjectOptionA);
		Subject.setSubjectOptionB(subjectOptionB);
		Subject.setSubjectOptionC(subjectOptionC);
		Subject.setSubjectOptionD(subjectOptionD);
		Subject.setSubjectAnswer(subjectAnswer);
		Subject.setSubjectParse(subjectParse);
		
		SubjectDao sd = new SubjectDaoImpl();
		try{
			sd.add(Subject);
		}catch(Exception e){
			System.out.println("添加失败");
			e.printStackTrace();
		}
		
	}
   
}

注意:

ps:因为在设计数据库中我们设置的subjectID为自增长,所以这里添加数据的时候不用添加subjectID这一字段。

request.getParameterr("xxx"):
request.getParameter("name");//得到request域的参数信息(得到jsp页面传过来的参数)

getParameter表示接收参数,参数为页面提交的参数,包括:表单提交的参数、URL重写(就是xxx?id=1中的id)传的参数等,因此这个并没有设置参数的方法(没有setParameter),而且接收参数返回的不是Object,而是String类型


  • subjectAdd页面部分
<div id="addSubjectForm" align="center"><!--录入试题表单-->
				<form action="SubjectAddServlet" method="post">
				<table border="0" cellspacing="10" cellpadding="0">
				  <tr>
					<td colspan="2"><FONT color="red"><s:actionerror/></FONT></td>
				  </tr>
				  <tr>
					<td>试题题目:</td>
					<td><input type="text" name="subjectTitle" size="80" ></td>
				  </tr>
				  <tr>
					<td>选项A:</td>
					<td><input type="text" name="subjectOptionA" size="20" ></td>
				  </tr>
				   <tr>
					<td>选项B:</td>
					<td><input type="text" name="subjectOptionB" size="20" ></td>
				  </tr>
				   <tr>
					<td>选项C:</td>
					<td><input type="text" name="subjectOptionC" size="20" ></td>
				  </tr>
				   <tr>
					<td>选项D:</td>
					<td><input type="text" name="subjectOptionD" size="20" ></td>
				  </tr>
				   <tr>
					<td>答案:</td>
					<td>
						<input name="subjectAnswer" type="radio" value="A" checked>A
						<input name="subjectAnswer" type="radio" value="B">B
						<input name="subjectAnswer" type="radio" value="C">C
						<input name="subjectAnswer" type="radio" value="D">D
					</td>
				  </tr>
				  <tr>
					<td valign="top">试题解析:</td>
					<td>
						<textarea name="subjectParse" cols="76" rows="10"></textarea>
					</td>
				  </tr>
				  <tr>
				  	<td colspan="2"><div align="center">
				  	  <input type="submit" value="录入">				  	  
				  	  <input type="reset" value="重置">
			  	  </div>
				</td>
				  </tr>
			</table>
			</form>


注意:

action=“SubjectAddServlet”为SubjectAddServlet在web.xml中的URL目录
当在servlet中完成的操作需要获取页面表单等的数据时,需要在页面中指向对应的servlet。


2:删

  • 创建SubjectDeleteServlet
package action;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import dao.SubjectDao;
import dao.SubjectDaoImpl;
import entity.Subject;

public class SubjectDeleteServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doPost(request, response);
	}

	
	@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		request.setCharacterEncoding("utf-8");
		response.setContentType("text/html;charset=utf-8");
		
		String subjejctID = (String) request.getParameter("subjectID");
		int userSubjectID = Integer.parseInt(subjejctID);
		
		SubjectDao sd = new SubjectDaoImpl();
		sd.delete(userSubjectID);
	}

}

注意:doGet(),doPost()

当需要获取页面中的数据时,用doPost。

当用到URL重写(就是xxx?id=1中的id)传的参数时,用doGet()。

或者是把具体方法写到doPost中,在doGet()方法中调用doPost方法。


  • subjectDelete.jsp部分页面
<div id="manageSubject" align="center"><!--删除试题-->
			<table width="95%" cellspacing="10">
				  <tr align="center">
					<td>试题编号</td>
					<td>试题标题</td>
					<td>正确答案</td>
					<td>查看试题</td>
						 </tr>
				  
				  	 
					  
					<c:forEach var="s" items="${list }">
						<tr align="center">
							<td>${s.subjectID }</td>
							<td align="left">${s.subjectTitle }</td>
							<td>${s.subjectAnswer }</td>
							<td><a href="SubjectShowServlet?subjectID=${s.subjectID }">查看</a></td>
							<td><a href="SubjectDeleteServlet?subjectID=${s.subjectID }">删除</a></td>
						</tr>
					</c:forEach>
				 
			</table>
		</div>
注意:

删除页面和查询页面是公用一个页面

${list }:EL表达式  获取request域中名为list的值

页面使用的到JSTL表达式 即c标签。使用c标签需要引入头文件<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%> 。

需要注意的的是El标签配合JSTl标签的使用,<c:forEach var="s" items="${list }"  >   例子forEach标签的遍历内容即为EL表达式获取的${list }

而且当指定别名后var="s"  ,别名可以随便起,为了方便一般是小写类名命名。  

C标签内遍历的属性也是需要用${  }获取。此时别名s即为当前集合中的Subject对象,想得到属性只需要用 ${ s.属性名 }     即可



3:改


  • 创建SubjectUpdateServlet
package action;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import dao.SubjectDao;
import dao.SubjectDaoImpl;
import entity.Subject;

public class SubjectUpdateServlet 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.setContentType("text/html;charset=utf-8");
		
		String subjectID = request.getParameter("subjectID");
		String subjectTitle=request.getParameter("subjectTitle");
		String subjectOptionA=request.getParameter("subjectOptionA");
		String subjectOptionB=request.getParameter("subjectOptionB");
		String subjectOptionC=request.getParameter("subjectOptionC");
		String subjectOptionD=request.getParameter("subjectOptionD");
		String subjectAnswer=request.getParameter("subjectAnswer");
		String subjectParse=request.getParameter("subjectParse");
		
		
		SubjectDao sd = new SubjectDaoImpl();
		try{
		sd.update( subjectTitle, subjectOptionA, subjectOptionB, subjectOptionC,
				subjectOptionD, subjectAnswer, subjectParse);
		}catch(Exception e) {
			System.out.println("修改失败!");
			e.printStackTrace();
		}
		
	}

}

注意:

request.getParameter("")获取页面参数

<div id="updateSubjectForm" align="center"><!--更新试题表单-->
				<form action="SubjectUpdateServlet" method="post">
				<table border="0" cellspacing="10" cellpadding="0">
					<tr>
						<td colspan="2"><s:actionmessage/></td>
					</tr>
				  <tr>
					<td>试题题目:</td>
					<td>
						<input name="subjectID" type="hidden" >
						<input name="subjectTitle" type="text" size="80"  >
					</td>
				  </tr>
				  <tr>
					<td>选项A:</td>
					<td><input type="text" name="subjectOptionA" size="20" ></td>
				  </tr>
				   <tr>
					<td>选项B:</td>
					<td><input type="text" name="subjectOptionB" size="20" ></td>
				  </tr>
				   <tr>
					<td>选项C:</td>
					<td><input type="text" name="subjectOptionC" size="20" ></td>
				  </tr>
				   <tr>
					<td>选项D:</td>
					<td><input type="text" name="subjectOptionD" size="20" ></td>
				  </tr>
				   <tr>
					<td>答案:</td>
					<td>
				<input type="text" name="subjectAnswer" size="20" value="">
					</td>
				  </tr>
				  <tr>
					<td valign="top">答案解析:</td>
					<td>
						<textarea name="subjectParse" cols="76" rows="10" ></textarea>
					</td>
				  </tr>
				  <tr>
				  	<td colspan="2"><div align="center">
				  	  <input type="submit" value="更新">				  	  
				  	  <input type="reset" value="重置">
			  	  </div>
				</td>
				  </tr>
			</table>
			</form>	
			</div>

注意:

action=“SubjectUpdateServlet”为SubjectUpdateServlet在web.xml中的URL目录
当在servlet中完成的操作需要获取页面表单等的数据时,需要在页面中指向对应的servlet。

4:查

这里需要完成两个查询(查询返回列表;查询返回列表详细)

  • 查询返回列表

创建SubjectListServlet:

package action;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import dao.SubjectDao;
import dao.SubjectDaoImpl;
import entity.Subject;

public class SubjectListServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		request.setCharacterEncoding("utf-8");
		response.setContentType("text/html;charset=utf-8");
		
		SubjectDao sd = new SubjectDaoImpl();
		List<Subject> list = sd.selectall();
		request.setAttribute("list", list);
		request.getRequestDispatcher("/subjectList.jsp").forward(request, response);//转发到指定页面    
	}

	
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}

}

注意:当不需要页面的参数时,页面由servlet引出

转发(request.getRequestDispatcher().forward();)和重定向(response.sendRedirect();)区别:

(1).重定向的执行过程:Web服务器向浏览器发送一个http响应--》浏览器接受此响应后再发送一个新的http请求到服务器--》服务器根据此请求寻找资源并发送给浏览器。它可以重定向到任意URL,不能共享request范围内的数据。
(2).重定向是在客户端发挥作用,通过新的地址实现页面转向。
(3).重定向是通过浏览器重新请求地址,在地址栏中可以显示转向后的地址。
(4).转发过程:Web服务器调用内部方法在容器内部完成请求和转发动作--》将目标资源发送给浏览器,它只能在同一个Web应用中使用,可以共享request范围内的数据。
(5).转发是在服务器端发挥作用,通过forward()方法将提交信息在多个页面间进行传递。
(6).转发是在服务器内部控制权的转移,客户端浏览器的地址栏不会显示出转向后的地址。


subjectList.jsp部分页面:

<div id="manageSubject" align="center"><!--查看试题-->
			<table width="95%" cellspacing="10">
				  <tr align="center">
					<td>试题编号</td>
					<td>试题标题</td>
					<td>正确答案</td>
					<td>查看试题</td>
						 </tr>
				  
				  	 
					  
					<c:forEach var="u" items="${list }">
						<tr align="center">
							<td>${u.subjectID }</td>
							<td align="left">${u.subjectTitle }</td>
							<td>${u.subjectAnswer }</td>
							<td><a href="SubjectShowServlet?subjectID=${u.subjectID }">查看</a></td>
							<td><a href="SubjectDeleteServlet?subjectID=${u.subjectID }">删除</a></td>
						</tr>
					</c:forEach>
				 
			</table>
		</div>

注意:

这里的顺序是,先访问的是SubjectListServlet,在转发到此页面,此页面的查看和删除又通过对应的servlet来实现对应的功能。


  • 查询返回列表详细

创建SubjectShowServlet:

package action;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import dao.SubjectDao;
import dao.SubjectDaoImpl;
import entity.Subject;

public class SubjectShowServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		request.setCharacterEncoding("utf-8");
		response.setContentType("text/html;charset=utf-8");
		
		SubjectDao sd = new SubjectDaoImpl();
		List<Subject> list = sd.selectByID(request.getParameter("subjectID"));
		request.setAttribute("list", list);
		request.getRequestDispatcher("/subjectShow.jsp").forward(request, response);
	}

	
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
		
	}

}

注意:

这个查询方法需要通过限制条件subjectID来查询,不然显示出来的是所有的数据


subjectShow.jsp部分页面

<div id="showSubject" align="center"><!--显示试题-->
			<table border="0" cellspacing="10" cellpadding="0">
				  <c:forEach var="u" items="${list }">
				  <tr>
				    <td>试题编号:</td>
				    <td>${u.subjectID }</td>
			    </tr>
				  <tr>
					<td>试题题目:</td>
					<td>${u.subjectTitle }</td>
				  </tr>
				  <tr>
					<td>选项A:</td>
					<td>${u.subjectOptionA }</td>
				  </tr>
				   <tr>
					<td>选项B:</td>
					<td>${u.subjectOptionB }</td>
				  </tr>
				   <tr>
					<td>选项C:</td>
					<td>${u.subjectOptionC }</td>
				  </tr>
				   <tr>
					<td>选项D:</td>
					<td>${u.subjectOptionD }</td>
				  </tr>
				   <tr>
					<td>答案:</td>
					<td>${u.subjectAnswer }</td>
				  </tr>
				  <tr>
					<td valign="top">答案解析:</td>
					<td valign="top">${u.subjectParse }</td>
				  </tr>
				  </c:forEach>
			</table>
			</div>

注意:

页面同样运用的是EL和jstl表达式


七:总结

在学习的道路上,一昧的看视频是没有用的,当看完一个阶段的视频后,要对该阶段写一个小项目,这样才能将视频中的知识点融会贯通。


项目源码(页面):点击打开链接

建议保留页面相关代码,servlet及jsp相关代码自己敲。