jsp标签和增删改查案列

1.标签语言的特点

2.自定义标签的使用步骤

3.JSP标签生命周期图

4.JSP标签实践

5.增删改查案列

1.主界面邦值servlet和index.jsp

2.增加servlet和主界面

3.修改servlet和主界面

4.删除servlet

案列思路

---------------------------------------------------------实际操作------------------------------------------------------------

1.标签语言的特点

了解标签结构
   <c:if test="true"> 开始标签
   true 标签提
   </c:if> 结束标签

   标签分类：控制标签，数据标签，UI标签
   没有标签体也能在网页中输出内容的标签，为UI标签

<c:if test="true">true</c:if>
	<c:if test="false">false</c:if>
	<c:set var="name" value="HZ"></c:set>
	<c:out value="${name }"></c:out>

-------------------------------------------------------------------------------------------------------------------------------

2.自定义标签的使用步骤

1.自定义标签库是与tld文件相关的

2.标签库中的标签与tld中的元素有关，也就是跟tag元素的助手类有关

<h:if test="true">true</h:if>
	<h:if test="false">false</h:if>
	<h:set var="name" value="HZ"></h:set>
	<h:out value="${name }"></h:out>

-------------------------------------------------------------------------------------------------------------------------------

3.JSP标签生命周期图

1.助手类

package com.hz.tag;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.BodyTagSupport;

/**
 * 助手类 必须继承bodytagSupport
 * @author Administrator
 *
 */
public class DemoTag1 extends BodyTagSupport{
	@Override
	public int doStartTag() throws JspException {
		System.out.println("========doStartTag========");
		return EVAL_BODY_INCLUDE;
	}
	
	@Override
	public int doAfterBody() throws JspException {
		System.out.println("=======doAfterBody=======");
		return super.doAfterBody();
//		return EVAL_BODY_AGAIN;

	}
	
	@Override
	public int doEndTag() throws JspException {
		System.out.println("==========doEndTag=========");
		return super.doEndTag();
//		return SKIP_PAGE;

	}
}

-------------------------------------------------------------------------------------------------------------------------------

4.JSP标签实践

package com.hz.tag;

import java.io.IOException;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.BodyTagSupport;
/**
 * servlet中后台代码前台输出内容    out.print
 * 将数据输出到前台，首先拿到输出流
 * @author Administrator
 *
 */
public class OutTag extends BodyTagSupport{
	private Object value;

	public Object getValue() {
		return value;
	}

	public void setValue(Object value) {
		this.value = value;
	}

	@Override
	public int doStartTag() throws JspException {
		JspWriter out=pageContext.getOut();
		try {
			out.print(value);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return super.doStartTag();
	}
}

package com.hz.tag;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.BodyTagSupport;

/**
 * 数据标签，存储数据的
 * 使用，pagecontext，request，session，applocation（servletContext）
 * 
 * 要存储数据，以健值对的方式进行存储，分析得来该标签有2个属性
 * @author Administrator
 *
 */
public class SetTag extends BodyTagSupport{
	private String var;
	private Object value;
	
	public String getVar() {
		return var;
	}

	public void setVar(String var) {
		this.var = var;
	}

	public Object getValue() {
		return value;
	}

	public void setValue(Object value) {
		this.value = value;
	}

	@Override
public int doStartTag() throws JspException {
//		 * 要存储数据，以健值对的方式进行存储，分析得来该标签有2个属性
		pageContext.setAttribute(var, value);
		return super.doStartTag();
}
}

-------------------------------------------------------------------------------------------------------------------------------

5.增删改查案列

1.主界面邦值servlet和index.jsp

servlet

package com.Hz.servlet;

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

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

import com.Hz.biz.ClassBiz;
import com.Hz.biz.HobbyBiz;
import com.Hz.biz.IClassBiz;
import com.Hz.biz.IHobbyBiz;
import com.Hz.biz.IStudentBiz;
import com.Hz.biz.ITeacherBiz;
import com.Hz.biz.StudentBiz;
import com.Hz.biz.TeacherBiz;
import com.Hz.entity.Class;
import com.Hz.entity.Hobby;
import com.Hz.entity.Student;
import com.Hz.entity.Teacher;

@WebServlet("/IndexServlet")
public class IndexServlet extends HttpServlet {
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doPost(request, response);
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//设置编码方式
		request.setCharacterEncoding("utf-8");
		response.setCharacterEncoding("utf-8");
		response.setContentType("text/html; charset=UTF-8");
		
		//定义页码页数
		int pageInde=1;
		int pageSize=4;
		//接收表单传值
		String ctr = request.getParameter("ctr");//班级
		String htr = request.getParameter("htr");//爱好
		System.out.println(htr);
		String str = request.getParameter("str");//教员
		if(str==null) {
			str="";
		}
		if(htr==null) {
			htr="";
		}
		if(ctr==null) {
			ctr="";
		}
		String pid=request.getParameter("pid");
		if(pid!=null) {
			pageInde=Integer.parseInt(pid);
		}
		IStudentBiz isb=new StudentBiz();
		int rows=isb.getRows("tb_student where cid like '%"+ctr+"%' and hid like '%"+htr+"%' and tid like '%"+str+"%'");
		int max=rows/pageSize;
		if(rows%pageSize!=0) {
			max++;
		}
		if(max==0) {
			max=1;
		}
		//查询所有的班级
		IClassBiz icb=new ClassBiz();
		List<Class> lc = icb.getAll();
		System.out.println(lc);
		//查询所有的教员
		ITeacherBiz itb=new TeacherBiz();
		List<Teacher> lt = itb.getAll();
		//查询所有的学生
//		List<Student> ls = isb.getAll();
		//带模糊查询的分页
		List<Student> ls = isb.getMH(ctr, htr, str, pageInde, pageSize);
		//查询所有的爱好
		IHobbyBiz ihb=new HobbyBiz();
		List<Hobby> lh = ihb.getAll();

		if(ls.size()!=0&&lt.size()!=0&&lc.size()!=0&&lh.size()!=0) {
			request.setAttribute("pageIndex", pageInde);
			request.setAttribute("ls", ls);
			request.setAttribute("la", lt);
			request.setAttribute("lc", lc);
			request.setAttribute("lh", lh);
			request.setAttribute("max", max);
			request.getRequestDispatcher("index.jsp").forward(request, response);
		}
		else {
			System.out.println("集合为空");
		}
	}

}

主界面

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
<!-- http://t.csdn.cn/tJGfj -->
</head>
<body>
	<center>
		<form method="post" action="IndexServlet">
			<c:if test="${empty la}">
				<jsp:forward page="IndexServlet"></jsp:forward>
			</c:if>
			<c:if test="${not empty la}">
				<select name="str">
					<c:forEach var="t" items="${la}">
						<option value="${t.tid}">${t.tname}</option>
					</c:forEach>
				</select>
			</c:if>
			<c:if test="${empty lc}">
				<jsp:forward page="IndexServlet"></jsp:forward>
			</c:if>
			<c:if test="${not empty lc}">
				<select name="ctr">
					<c:forEach var="c" items="${lc}">
						<option value="${c.cid}">${c.cname}</option>
					</c:forEach>
				</select>
			</c:if>
			<c:if test="${empty lh}">
				<jsp:forward page="IndexServlet"></jsp:forward>
			</c:if>
			<c:if test="${not empty lh}">
				<c:forEach items="${lh}" var="h">
					<input type="checkbox" name="htr" value="${h.hid},"/>${h.hname}
				</c:forEach>
			</c:if>
			<input type="submit" value="查询"/>
		</form>
		<c:if test="${empty ls}">
			<jsp:forward page="IndexServlet"></jsp:forward>
		</c:if>
		<c:if test="${not empty ls}">
			<table border="1px">
				<tr>
					<td>学生编号</td>
					<td>学生姓名</td>
					<td>学生的教员</td>
					<td>学生所在班级</td>
					<td>学生爱好</td>
					<td>操作&nbsp;<a href="add.jsp">增加</a></td>
				</tr>
				<c:forEach items="${ls}" var="s">
					<tr>
						<td>${s.sid}</td>
						<td>${s.sname}</td>
						<td>${s.t.tname}</td>
						<td>${s.c.cname}</td>
						<td>
							<c:forEach items="${s.ls}" var="sd">
								${sd.hname}
							</c:forEach>
						</td>
						<td>
							<a onclick="return confirm('你确定要删除吗？');" href="DeleteServlet?sid=${s.sid}">删除</a>
							<a href="PreUpdateServlet?sid=${s.sid}">修改</a>
						</td>
					</tr>
				</c:forEach>
				<tr>
					<td colspan="6">
						<a href="IndexServlet?pid=1">首页</a>
						<a href="IndexServlet?pid=${pageIndex>1?pageIndex-1:1}">上一页</a>
						[${pageIndex}/${max}]
						<a href="IndexServlet?pid=${pageIndex<max?pageIndex+1:max}">下一页</a>
						<a href="IndexServlet?pid=${max}">尾页</a>
					</td>
				</tr>
			</table>
		</c:if>
	</center>
</body>
</html>

主界面页面展示

---------------------------------------------------------------------------------------------------------------------------------

2.增加servlet和主界面

增加servlet

package com.Hz.servlet;

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

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

import com.Hz.biz.ClassBiz;
import com.Hz.biz.HobbyBiz;
import com.Hz.biz.IClassBiz;
import com.Hz.biz.IHobbyBiz;
import com.Hz.biz.IStudentBiz;
import com.Hz.biz.ITeacherBiz;
import com.Hz.biz.StudentBiz;
import com.Hz.biz.TeacherBiz;
import com.Hz.entity.Class;
import com.Hz.entity.Hobby;
import com.Hz.entity.Student;
import com.Hz.entity.Teacher;

@WebServlet("/AddServlet")
public class AddServlet extends HttpServlet {
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doPost(request, response);
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//设置编码方式
		request.setCharacterEncoding("utf-8");
		response.setCharacterEncoding("utf-8");
		response.setContentType("text/html; charset=UTF-8");
		
		//拿out
		PrintWriter out = response.getWriter();
		
		//接收表单传值
		String sname = request.getParameter("sname");
		String tid = request.getParameter("teacher");
		String cid = request.getParameter("class");
		String[] hobby = request.getParameterValues("aa");
		String ss="";
		for (String string : hobby) {
			ss+=string;
		}
		
		//调用业务逻辑层
		IStudentBiz isb=new StudentBiz();
		ITeacherBiz itb=new TeacherBiz();
		Teacher t = itb.getTeacher(Integer.parseInt(tid));
		IClassBiz icb=new ClassBiz();
		Class c = icb.getOne(Integer.parseInt(cid));
		Student stu=new Student(sname, t, c, ss);
		int n = isb.addStu(stu);
		if(n>0) {//加入成功
			out.print("<script>alert('增加成功');location.href='index.jsp';</script>");
		}
		else {//加入失败
			out.print("<script>alert('增加失败');location.href='add.jsp';</script>");
		}
	}

}

增加主界面

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
<script type="text/javascript">
	function myf(){
		location.href="index.jsp";
	}
</script>
</head>
<body>
	<center>
		<form action="AddServlet" method="post">
			<table border="1px">
				<tr>
					<td>学生姓名</td>
					<td><input type="text" name="sname"/></td>
				</tr>
				<tr>
					<td>教员</td>
					<td>
						<c:if test="${empty la}">
							<jsp:forward page="PreAddServlet"></jsp:forward>
						</c:if>
						<c:if test="${not empty la}">
							<select name="teacher">
								<c:forEach var="t" items="${la}">
									<option value="${t.tid}">${t.tname}</option>
								</c:forEach>
							</select>
						</c:if>
					</td>
				</tr>
				<tr>
					<td>班级</td>
					<td>
						<c:if test="${empty lc}">
							<jsp:forward page="PreAddServlet"></jsp:forward>
						</c:if>
						<c:if test="${not empty lc}">
							<select name="class">
								<c:forEach var="c" items="${lc}">
									<option value="${c.cid}">${c.cname}</option>
								</c:forEach>
							</select>
						</c:if>
					</td>
				</tr>
				<tr>
					<td>爱好</td>
					<td>
						<c:if test="${empty lh}">
							<jsp:forward page="PreAddServlet"></jsp:forward>
						</c:if>
						<c:if test="${not empty lh}">
							<c:forEach items="${lh}" var="h">
								<input type="checkbox" name="aa" value="${h.hid},"/>${h.hname}
							</c:forEach>
						</c:if>
					</td>
				</tr>
			</table>
			<input type="submit" value="增加"/>
			<input type="button" value="清空" onclick="myf()"/>
		</form>
	</center>
</body>
</html>

界面展示

---------------------------------------------------------------------------------------------------------------------------------

3.修改servlet和主界面

package com.Hz.servlet;

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

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

import com.Hz.biz.ClassBiz;
import com.Hz.biz.HobbyBiz;
import com.Hz.biz.IClassBiz;
import com.Hz.biz.IHobbyBiz;
import com.Hz.biz.IStudentBiz;
import com.Hz.biz.ITeacherBiz;
import com.Hz.biz.StudentBiz;
import com.Hz.biz.TeacherBiz;
import com.Hz.entity.Class;
import com.Hz.entity.Hobby;
import com.Hz.entity.Student;
import com.Hz.entity.Teacher;

@WebServlet("/PreUpdateServlet")
public class PreUpdateServlet extends HttpServlet {
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doPost(request, response);
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//设置编码方式
		request.setCharacterEncoding("utf-8");
		response.setCharacterEncoding("utf-8");
		response.setContentType("text/html; charset=UTF-8");
		
		//接收
		String sid = request.getParameter("sid");
		//调用业务逻辑层
		IStudentBiz isb=new StudentBiz();
		Student stu = isb.getStu(Integer.parseInt(sid));
		IHobbyBiz ihb=new HobbyBiz();
		IClassBiz icb=new ClassBiz();
		ITeacherBiz itb=new TeacherBiz();
		List<Hobby> lh = ihb.getAll();
		List<Class> lc = icb.getAll();
		List<Teacher> lt = itb.getAll();
		request.setAttribute("lh", lh);
		request.setAttribute("lc", lc);
		request.setAttribute("la", lt);
		request.setAttribute("stu", stu);
		request.getRequestDispatcher("update.jsp").forward(request, response);
	}

}

package com.Hz.servlet;

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

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

import com.Hz.biz.ClassBiz;
import com.Hz.biz.HobbyBiz;
import com.Hz.biz.IClassBiz;
import com.Hz.biz.IHobbyBiz;
import com.Hz.biz.IStudentBiz;
import com.Hz.biz.ITeacherBiz;
import com.Hz.biz.StudentBiz;
import com.Hz.biz.TeacherBiz;
import com.Hz.entity.Class;
import com.Hz.entity.Hobby;
import com.Hz.entity.Student;
import com.Hz.entity.Teacher;

@WebServlet("/PreUpdateServlet1")
public class PreUpdateServlet1 extends HttpServlet {
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doPost(request, response);
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//设置编码方式
		request.setCharacterEncoding("utf-8");
		response.setCharacterEncoding("utf-8");
		response.setContentType("text/html; charset=UTF-8");
		PrintWriter out = response.getWriter();
		
		
		//接收表单传值
		String sid = request.getParameter("sid");
		String sname = request.getParameter("sname");
		String tid = request.getParameter("teacher");
		String cid = request.getParameter("class");
		String[] hobby = request.getParameterValues("aa");
		String ss="";
		for (String string : hobby) {
			ss+=string;
		}
		
		//调用业务逻辑层
		IStudentBiz isb=new StudentBiz();
		ITeacherBiz itb=new TeacherBiz();
		Teacher t = itb.getTeacher(Integer.parseInt(tid));
		IClassBiz icb=new ClassBiz();
		Class c = icb.getOne(Integer.parseInt(cid));
		Student stu=new Student(sname, t, c, ss);
		int n = isb.updStu(Integer.parseInt(sid),stu);
		if(n>0) {//加入成功
			out.print("<script>alert('修改成功');location.href='index.jsp';</script>");
		}
		else {//加入失败
			out.print("<script>alert('修改成功');location.href='PreUpdateServlet?sid="+sid+"';</script>");
		}
	}

}

主界面

--------------------------------------------------------------------------------------------------------------------------------

4.删除servlet

package com.Hz.servlet;

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

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

import com.Hz.biz.IStudentBiz;
import com.Hz.biz.StudentBiz;

@WebServlet("/DeleteServlet")
public class DeleteServlet extends HttpServlet {
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doPost(request, response);
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//设置编码方式
		request.setCharacterEncoding("utf-8");
		response.setCharacterEncoding("utf-8");
		response.setContentType("text/html; charset=UTF-8");
		
		PrintWriter out = response.getWriter();
		//接收表单传值
		String sid = request.getParameter("sid");
		//调用业务逻辑层
		IStudentBiz isb=new StudentBiz();
		int n = isb.delStu(Integer.parseInt(sid));
		if(n>0) {
			out.print("<script>alert('删除成功');location.href='index.jsp';</script>");
		}
		else {
			out.print("<script>alert('删除失败');location.href='index.jsp';</script>");
		}
	}

}

原文链接：https://blog.csdn.net/csnbb/article/details/125374271