struts2 ognl表达式

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OGNL对象图导航语言

Object Graphic Navigation Language.

可以单独使用获取关系复杂的数据

eg:

Person p=new Person();

p.setName("张三");

p.setAddress(new Address("上海中兴区","rar"));

ognl.Ognl.setValue("Address.addr", p, "上海交通大学");

String name=(String) ognl.Ognl.getValue("Address.addr", p);

System.out.println(name);

源于ognl.jar工具包.其作用如下:

(1)对属性获取和设置

(2)调用对象方法

(3)调用静态属性和方法

(4)对集合进行过滤

(5)支持Java中的运算符,操作符

(6)定义List常量 {"tom","sun"}

(7)定义Map常量 #{"M":"男","F","女"}

struts2标签

(1) struts2使用OGNL来访问ValueStack中的信息.

a. 访问context区域内容语法以"#key"开始

b. 访问root区域内容语法为"属性名"

(2)struts2提供了很多标签,有些标签属性需要指定OGNL表达式.

a. 通用标签

debug,property,date,if...else,iterator

bean,push,action,set

b. 表单标签

form,textfield,password,checkbox,checkboxlist,radio,select,optgroup

思考

EL表达式为什么能获取Action对象的属性?

HttpServletRequest request;

request = new StrutsRequestWrapper(request);

request.getAttribute("user");

public class StrutsRequestWrapper extends HttpServletRequestWrapper{

public Object getAttribute(String key){

//先去request对象中寻找信息

Object obj = super.getAttribute(key);

//如果在原request中找不到,去valuestack中查找

if(obj == null){

ValueStack vs = ActionContext.getContext().getValueStack();

obj = vs.findValue(key);//"name"充当OGNL表达式,从而访问了root区域的Action对象

}

return obj;

}

<s:iterator value="list.{?#this.age>=18}">满足年龄大于18的子集

<s:property value="@java.lang.Math@PI" />

代码：

package testvaluestack;

import java.util.ArrayList;

import java.util.Date;

import java.util.List;

import java.util.Map;

import org.apache.struts2.ServletActionContext;

import bean.Address;

import bean.Person;

import com.opensymphony.xwork2.ActionContext;

import com.opensymphony.xwork2.ActionSupport;

import com.opensymphony.xwork2.util.ValueStack;

public class teststack extends ActionSupport

{

private Date date;

private List list;

private int price;

private String sex;

public String getSex() {

return sex;

}

public void setSex(String sex) {

this.sex = sex;

}

public int getPrice() {

return price;

}

public void setPrice(int price) {

this.price = price;

}

public List getList() {

return list;

}

public void setList(List list) {

this.list = list;

}

public Date getDate() {

return date;

}

public void setDate(Date date) {

this.date = date;

}

@Override

public String execute() {

// TODO Auto-generated method stub

date=new Date();

Map session=ActionContext.getContext().getSession();

session.put("ses", "haha");

Map request=(Map) ActionContext.getContext().get("request");

request.put("res", "request获取");

list=new ArrayList<Address>();

for(int i=0;i<10;i++)

{

Address address=new Address("海淀区"+i+"号","33260"+i);

list.add(address);

}

price=100000;

sex="男";

Person person=new Person();

person.setAddress(new Address("上海","332600"));

person.setName("王五");

person.setPrice(500);

//存放在栈顶的Person对象可以直接通过price获取,重名情况不好获取

ActionContext.getContext().getValueStack().push(person);

* 存放在栈顶的Map 通过person.price获取

* ActionContext.getContext.getValueStack().set("person",person);

* */

System.out.println("hello");

return SUCCESS;

}

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<%@taglib prefix="s" uri="/struts-tags"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

<head>

</head>

<body>

<s:property value="person.name"/>

<s:date name="date" format="yyyy-MM-dd hh:mm"/>

ses:<s:property value="#session.ses"/>

res:<s:property value="#request.res"/>

<ul>

<s:iterator value="list" var="er" status="status">

</s:iterator>

</ul>

<s:property value="price"/>

<s:if test="price>100000">太贵了</s:if>

<s:else>太便宜了</s:else>

<s:if test='sex.equals("男")'>男性</s:if>

<s:else>女性</s:else>

<s:property value="address.addr"/>

<s:debug></s:debug>

</body>

</html>

<s:form action="form" namespace="/" theme="simple">//不需要是form提供的主题

用户名:<s:textfield name="name"></s:textfield>

密码:<s:password name="passwd" showPassword="true"></s:password>//回显时默认是不显示密码的

年龄:<s:textfield name="age"></s:textfield>

Email:<s:textfield name="Email"></s:textfield>

性别:<s:radio list='#{"M":"男","FM":"女"}' name="sex"></s:radio> //list还可以是Map List（后面跟listkey和listvalue List<Sex> ）

爱好:<s:checkboxlist list="#request.likes" name="mylikes"></s:checkboxlist> //封装成数组交给bean数据库存字符串

兴趣:<s:select headerKey="-1" headerValue="--请选择--"list="#request.likes" name="dds"></s:select>

<s:submit value="提交"></s:submit>

</s:form>

<s:form action="sample02" theme="simple">

<s:bean name="tarena.action.ModelBean" var="data"></s:bean>

请选择朋友:<s:select name="friend" list="{}">

<s:optgroup label="男性" list="#data.males" listKey="name" listValue="name"></s:optgroup>//带分组的选择

<s:optgroup label="女性" list="#data.females" listKey="name" listValue="name"></s:optgroup>

</s:select>

姓名:<s:textfield name="name"></s:textfield>

密码:<s:password name="pwd" showPassword="true"></s:password>

年龄:<s:textfield name="age"></s:textfield>

Email:<s:textfield name="email"></s:textfield>

性别:<s:radio list='#{"M":"男","F":"女"}' name="sex"></s:radio>

是否已婚:<s:checkbox name="marry"></s:checkbox>

个人爱好:<s:checkboxlist name="myloves" list="#data.loves" listKey="key" listValue="value"></s:checkboxlist>

<s:radio name="mylove" list="#data.loves" listKey="key" listValue="value"></s:radio>

爱好:

<s:select name="mylove" emptyOption="true" headerKey="-1" headerValue="--请选择--" list="#data.loves" listKey="key" listValue="value">

</s:select>

</s:form>