先引用两个实体bean
package com.EL.bean;
public class person {
private String username;
private String password;
private Address address;
public person()
{
}
public person(String username) {
this.username = username;
}
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
package com.EL.bean;
public class Address {
private String city;
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
}
//--EL表达式是为了取值的，取出servlet域中(request,session,application)中的数据<br>
//${取值 }相当于pageContent.findAttribute("取值")<br>
//取值通过.或者[]
<%
// (servlet中产生数据，于普通方式转发到jsp),把数据存到域中。那么jsp取出servlet中的数据?
String data="jack";
request.setAttribute("data",data);
%>
${data} <br>
<%
//(servlet产生数据，将数据封装为javabean),在带给jsp页面，那么jsp页面怎么取值呢？
person p=new person();
p.setUsername("lucy");
request.setAttribute("person",p);
%>
${person.username} //相当于person类有个Getusername()方法
<%
//(servlet 复杂bean,将数据封装为复杂javabean)，在调用另一个javabean，jsp怎么取值呢？
person p1=new person();
Address a=new Address();
a.setCity("nanjing");
p1.setAddress(a);
request.setAttribute("person",p1);
%>
<br>${person.address.city}
<%
//servlet中产生数据，如多个人的集合对象list,那么jsp怎么取值呢
List list=new ArrayList();
list.add(new person("aaa"));
list.add(new person("bbb"));
list.add(new person("ccc"));
list.add(new person("ddd"));
request.setAttribute("listdata",list);
//list[0]表示第一个person对象
%>
<br>
${listdata[0].username}
<%
//servlet产生map数据，存在域中，jsp怎么取值呢？
Map map=new HashMap();
map.put("aa", new person("aaaaaaa"));
map.put("bb", new person("bbbbbbb"));
map.put("cc", new person("ccccccc"));
request.setAttribute("map", map);
// ${map.bb }表示找到了new person("bbbbb")这个对象，在通过name找出
%>
<br>
${map.bb.username}
<br>${pageContext.request.contextPath} //获得当前web应用名称
//jstl+El迭达集合中的数据
<br><br>
<%
List list1=new ArrayList();
list1.add(new person("aaa"));
list1.add(new person("bbb"));
list1.add(new person("ccc"));
list1.add(new person("ddd"));
request.setAttribute("listdata",list1);
//list[0]表示第一个person对象
%>
<c:forEach items="${listdata }" var="person">
${person.name }
</c:forEach>