El表示式獲取資料
<h1>獲取常量</h1>
${"奧運會"}${2008 } ${true}
<h1>獲取域中的變數</h1>
<%
String name="huzi";
pageContext.setAttribute("name", name);
%>
${name }
<h1>獲取域中的陣列</h1>
<%
String [] names= {"小明","小黃","小新"};
pageContext.setAttribute("names", names);
%>
${names[2]}
<h1>獲取map中的資料</h1>
<%
Map<String,String> map = new HashMap();
map.put("age", "47");
pageContext.setAttribute("map", map);
%>
${map["name"]} ${map["age"]}
<h1>獲取域中集合中資料</h1>
<%
List<String> list = new ArrayList<String>();
list.add("南山南");
list.add("北上北");
list.add("張磊");
session.setAttribute("list", list);
%>
${list[0] }
<h1>獲取javabean中的屬性</h1>
<%
Person p = new Person(); //使用"alt+/"來匯出包; 在jsp頁面中shift+ctrl+o不管用的;
p.setName("習大大");
p.setAge(50);
application.setAttribute("p", p);
%>
${p.name }${p.age } <!--當p.時, El會自動去該類中呼叫對應的get**方法 -->
Tips:
1.EL表示式能獲取的屬性必須是儲存在四大作用域中的;
2.EL表示式只能獲取值不能設定資料;
3.能獲取陣列中的資料,但不能遍歷陣列;
<h1>獲取javabean中的屬性</h1>
<%Person p = new Person(); //使用"alt+/"來匯出包; 在jsp頁面中shift+ctrl+o不管用的;
p.setName("習大大");
p.setAge(50);
application.setAttribute("p", p);
%>
${p.name }${p.age } <!--當p.時, El會自動去該類中呼叫對應的get**方法 -->
<!-- p.xxx (物件.屬性) -->
當p.xxx時,(物件.屬性)
El會自動去該類中呼叫對應的get***方法 ,
xxx並非是屬性,只是p物件中get方法的名字而已(自稱為:偽屬性),即:getXxx()(get後首字母大寫)
demo:
public class User {
private String username;
private String realname;
private String gender;
private String pwd;
public User() {
super();
// TODO Auto-generated constructor stub
}
public User(String username, String realname, String gender, String pwd) {
super();
this.username = username;
this.realname = realname;
this.gender = gender;
this.pwd = pwd;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getRealname() {
return realname;
}
public void setRealname(String realname) {
this.realname = realname;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
public String getPwd() {
return pwd;
}
public void setPwd(String pwd) {
this.pwd = pwd;
}
@Override
public String toString() {
return "User [username=" + username + ", realname=" + realname
+ ", gender=" + gender + ", pwd=" + pwd + "]";
}
//自定義get方法
public String getHello() {
return "Hello World !";
}
}
${user.hello}----------輸出為:Hello World !