JSP作业和例子：map，put，EL表达式，下拉框selected，单选框checked【诗书画唱】
1、创建一个商品类，包含商品名称和商品价格两个属性，在a.jsp页面创建一个<String,Product>类型的map，添加三样商品，跳转到show.jsp页面中通过EL表达式显示map中所有商品的名称和价格信息。
package com.SSHC;
public class Product {
private String name;
private Double price;
private String type;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Double getPrice() {
return price;
}
public void setPrice(Double price) {
this.price = price;
}
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
}
<%@page import="com.SSHC.Product"%>
<%@page import="java.util.HashMap"%>
<%@page import="java.util.Map"%>
<%@ page language="java" contentType="text/html;
charset=UTF-8" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"
+request.getServerName()+":"+request.getServerPort()+path+"/";
Map<String,Product>m = new HashMap<String,Product>();
Product P = new Product();
P.setName("诗书画唱");
P.setPrice(66.6);
m.put("Key", P);
request.setAttribute("m", m);
request.getRequestDispatcher("b.jsp").forward(request, response);
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base hreff="<%=basePath%>">
<title></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>
</body>
</html>
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<%request.getAttribute("m");
%>
<!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=ISO-8859-1">
<title>Insert title here</title></head>
<body>
<h1>${m["Key"].name }</h1>
<h1>${m["Key"]["price"] }</h1>
</body>
</html>
2、创建一个Person类，包含姓名，性别，学历三个属性，在b.jsp页面创建一个Person对象，跳转到result.jsp页面后通过EL表达式显示姓名，性别和学历（注意：学历是一个下拉框）
<select>
<option>初中</option>
<option>高中</option>
<option>大专</option>
<option>本科</option>
</select>
package com.SSHC;
public class Person {
private String name;
private Integer age;
private String xueLi;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public String getXueLi() {
return xueLi;
}
public void setXueLi(String xueLi) {
this.xueLi = xueLi;
}
}
<%@page import="java.util.Date"%>
<%@page import="com.SSHC.Person"%>
<%@ page language="java" contentType="text/html;
charset=UTF-8" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"
+request.getServerName()+":"+request.getServerPort()+path+"/";
Person s = new Person();
s.setName("诗书画唱");
s.setSex("男");
s.setXueLi("本科");
request.setAttribute("KeyS",s);
request.getRequestDispatcher("result.jsp").forward(request, response);
%>
<%@ page language="java" contentType="text/html;
charset=UTF-8" pageEncoding="UTF-8"%>
<%
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 hreff="<%=basePath%>">
<title></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>
<form action="" method="post">
<label>姓名：</label><input type=
"text" value="${KeyS.name }" />
<br>
<label>性别：</label>
<input type="radio" name="ssex" value="男"
${KeyS.sex=="男" ? "checked":"" } />男
<input type="radio" name="ssex" value="女"
${KeyS.sex=="女" ? "checked":"" } />女
<br>
<label>学历：</label>
<select>
<option ${KeyS.xueLi=="初中" ? "selected":"" }>初中</option>
<option ${KeyS.xueLi=="高中" ? "selected":"" }>高中</option>
<option ${KeyS.xueLi=="大专" ? "selected":"" }>大专</option>
<option ${KeyS.xueLi=="本科" ? "selected":"" }>本科</option>
</select> <br>
</form> </body></html>
3、创建一个Cat类，包含名字和毛色，在c.jsp创建一个Cat对象，跳转到my.jsp页面，通过EL表达式显示出Cat的名字和毛色。
package com.SSHC;
public class Cat {
private String name;
private String maoSe;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getMaoSe() {
return maoSe;
}
public void setMaoSe(String maoSe) {
this.maoSe = maoSe;
}
}
<%@page import="java.util.Date"%>
<%@page import="com.SSHC.Cat"%>
<%@ page language="java" contentType="text/html;
charset=UTF-8" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"
+request.getServerName()+":"+request.getServerPort()+path+"/";
Cat s = new Cat();
s.setName("诗书画唱的可爱猫猫");
s.setMaoSe("白色");
request.setAttribute("KeyS",s);
request.getRequestDispatcher("my.jsp").forward(request, response);
%>
<%@ page language="java" contentType="text/html;
charset=UTF-8" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"
+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base hreff="<%=basePath%>">
<title></title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content=
"keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
</head>
<body>
<form action="" method="post">
<label>姓名：</label><input type=
"text" value="${KeyS.name }" />
<br>
<label>毛色：</label><input type=
"text" value="${KeyS.maoSe }" />
<br>
</form> </body></html>
——————————————————————
例子（含自己写的题目内容）：
声明Map<String,String>map， Student 类，把内容放进去，之后用EL表达式打印出来（request.setAttribute("fruitMap", map);， map.put("4号", "石榴");
中的"fruitMap"就像钥匙，用${fruitMap["4号"] }“打开”（打印）"石榴"（map的值）这扇门：
<%@page import="com.SSHC.Student"%>
<%@page import="java.util.HashMap"%>
<%@page import="java.util.Map"%>
<%@ page language="java" contentType="text/html;
charset=UTF-8" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"
+request.getServerName()+":"+request.getServerPort()+path+"/";
Map<String,String>map = new HashMap<String,String>();
map.put("1号", "苹果");
map.put("2号", "火龙果");
map.put("4号", "石榴");
map.put("7号", "西梅");
request.setAttribute("fruitMap", map);
Map<String,Student>m = new HashMap<String,Student>();
Student s1 = new Student();
s1.setSname("张三");
m.put("20190001", s1);
request.setAttribute("m", m);
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base hreff="<%=basePath%>">
<title></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>
<h1>${fruitMap["4号"] }</h1>
<h1>${m["20190001"].sname }</h1>
<h1>${m["20190001"]["sname"] }</h1>
</body>
</html>
package com.SSHC;
import java.util.Date;
public class Student {
private String sname;
private String hobby;
private Date birth;
private char ssex;
private String scls;
public Student(){
}
public String getSname() {
return sname;
}
public void setSname(String sname) {
this.sname = sname;
}
public String getHobby() {
return hobby;
}
public void setHobby(String hobby) {
this.hobby = hobby;
}
public Date getBirth() {
return birth;
}
public void setBirth(Date birth) {
this.birth = birth;
}
public char getSsex() {
return ssex;
}
public void setSsex(char ssex) {
this.ssex = ssex;
}
public String getScls() {
return scls;
}
public void setScls(String scls) {
this.scls = scls;
}
public Student(String sname, String hobby,
Date birth, char ssex, String scls) {
super();
this.sname = sname;
this.hobby = hobby;
this.birth = birth;
this.ssex = ssex;
this.scls = scls;
}
@Override
public String toString() {
return "Student [sname=" + sname +
", hobby=" + hobby + ", birth=" + birth
+ ", ssex=" + ssex + ", scls=" + scls + "]";
}
}
用上
request.setAttribute("stu", s);
request.setAttribute("prop", "ssex");，通过 ${stu[prop] }获取 "ssex"的内容
<%@page import="java.util.Date"%>
<%@page import="java.text.SimpleDateFormat"%>
<%@page import="com.SSHC.Student"%>
<%@ page language="java" contentType="text/html;
charset=UTF-8" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"
+request.getServerName()+":"+request.getServerPort()+path+"/";
Student s = new Student();
s.setSname("Kite");
s.setHobby("唱歌，跳舞");
String strBirth = "2000-11-20";
//将strBirth字符串转换成日期对象
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
Date birth = sdf.parse(strBirth);
s.setBirth(birth);
s.setSsex('女');
s.setScls("J190802");
request.setAttribute("stu", s);
request.setAttribute("prop", "ssex");
//跳转到result.jsp
request.getRequestDispatcher("result.jsp").
forward(request, response);
%>
<%@ page language="java" contentType="text/html;
charset=UTF-8" pageEncoding="UTF-8"%>
<%
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 hreff="<%=basePath%>">
<title></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>
${stu[prop] }
</body>
</html>
用上页面跳转，要求把改为String sex（这里用char的话容易报错）的Student的内容跳转并打印到别的界面，性别用单选框显示：
package com.SSHC;
import java.util.Date;
public class Student {
private String sname;
private String hobby;
private Date birth;
private String ssex;
private String scls;
public Student(){
}
public String getSname() {
return sname;
}
public void setSname(String sname) {
this.sname = sname;
}
public String getHobby() {
return hobby;
}
public void setHobby(String hobby) {
this.hobby = hobby;
}
public Date getBirth() {
return birth;
}
public void setBirth(Date birth) {
this.birth = birth;
}
public String getSsex() {
return ssex;
}
public void setSsex(String ssex) {
this.ssex = ssex;
}
public String getScls() {
return scls;
}
public void setScls(String scls) {
this.scls = scls;
}
}
<%@page import="java.util.Date"%>
<%@page import="com.SSHC.Student"%>
<%@ page language="java" contentType="text/html;
charset=UTF-8" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"
+request.getServerName()+":"+request.getServerPort()+path+"/";
Student s = new Student();
s.setSname("诗书画唱");
s.setHobby("当UP主");
s.setBirth(new Date());
s.setSsex("男");
s.setScls("诗书画唱班");
request.setAttribute("stu",s);
request.getRequestDispatcher("update.jsp").forward(request, response);
%>
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%
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 hreff="<%=basePath%>">
<title></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>
<form action="" method="post">
<label>姓名：</label><input type=
"text" value="${stu.sname }" />
<br>
<label>爱好：</label><input type=
"text" value="${stu.hobby }" />
<br>
<label>性别：</label>
<input type="radio" name="ssex" value="男"
${stu.ssex=="男" ? "checked":"" } />男
<input type="radio" name="ssex" value="女"
${stu.ssex=="女" ? "checked":"" } />女
<br>
<label>生日：</label>
<input type="text" value="${stu.birth }" />
</form>
</body>
</html>
用SimpleDateFormat显示日期到网页：
<%@page import="java.util.Date"%>
<%@page import="java.text.SimpleDateFormat"%>
<%@page import="com.SSHC.Student"%>
<%@ page language="java" contentType="text/html;
charset=UTF-8" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+
"://"+request.getServerName()+
":"+request.getServerPort()+path+"/";
Student s = new Student();
s.setSname("Kite");
s.setHobby("唱歌，跳舞");
String strBirth = "2000-11-20 8:43:28";
//将strBirth字符串转换成日期对象
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
Date birth = sdf.parse(strBirth);
s.setBirth(birth);
s.setSsex("女");
s.setScls("J190802");
request.setAttribute("stu", s);
request.setAttribute("br", strBirth);
Date now = new Date();
//将日期对象转换成字符串
String str = sdf.format(now);
System.out.println(str);
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base hreff="<%=basePath%>">
<title></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>
<label>姓名：</label><h1>${stu.sname }</h1>
<label>生日：</label><h1>${br }</h1>
</body>
</html>
