一、值栈简介：
值栈是对应每个请求对象的一套内存数据的封装，Struts2 会给每个请求创建一个新的值栈。
值栈能够线程安全地为每个请求提供公共的数据存取服务。
二、OGNL引入：
OGNL 是对象图导航语言 Object-Graph Navigation Language 的缩写，它是一种功能强大的表达式语言。
OGNL 访问 ValueStack 数据
<s:property value=”account” />
OGNL 访问 ActionContext 数据
访问某个范围下的数据要用#
#parameters 请求参数 request.getParameter(...)；
#request 请求作用域中的数据 request.getAttribute(...)；
#session 会话作用域中的数据 session.getAttribute(...)；
#application 应用程序作用域中的数据 application.getAttribute(...)；
#attr 按照 page request session application 顺序查找值
om.cy.action.HelloAction.java:
package com.cy.action;
import java.util.Map;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport;
import com.opensymphony.xwork2.util.ValueStack;
public class HelloAction extends ActionSupport{
private static final long serialVersionUID = 1L;
@Override
public String execute() throws Exception {
ActionContext actionContext = ActionContext.getContext();
ValueStack valueStack = actionContext.getValueStack();
valueStack.set("name", "张三(valueStack)");
valueStack.set("age", 11);
Map<String, Object> session = actionContext.getSession();
session.put("name", "王五(session)");
session.put("age", 13);
Map<String, Object> application = actionContext.getApplication();
application.put("name", "赵六(application)");
application.put("age", 14);
return SUCCESS;
}
}
struts.xml:
<struts>
<package name="manage" namespace="/" extends="struts-default">
<action name="hello" class="com.cy.action.HelloAction">
<result name="success">success.jsp</result>
</action>
</package>
</struts>
success.jsp:
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@taglib prefix="s" uri="/struts-tags" %>
<!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>
<%
request.setAttribute("name", "李四(request)");
request.setAttribute("age", 12);
// pageContext.setAttribute("name", "小沛(page)");
//pageContext.setAttribute("age", "18");
%>
</head>
<body>
获取狭义上的值栈数据：<s:property value="name"/>
<s:property value="age"/><br>
请求参数：<s:property value="#parameters.name"/>
<s:property value="#parameters.age"/><br>
request：<s:property value="#request.name"/>
<s:property value="#request.age"/><br>
session：<s:property value="#session.name"/>
<s:property value="#session.age"/><br>
application：<s:property value="#application.name"/>
<s:property value="#application.age"/><br>
attr取值：<s:property value="#attr.name"/>
<s:property value="#attr.age"/><br>
</body>
</html>
测试结果：
说明如果不注释掉
ActionContext actionContext = ActionContext.getContext(); ValueStack valueStack = actionContext.getValueStack();
valueStack.set("name", "张三(valueStack)");
valueStack.set("age", 11);这段代码的attr取值为张三(valueStack)，11
然后不注释掉
pageContext.setAttribute("name", "小沛(page)");
pageContext.setAttribute("age", "18");这段代码的话attr取值位小沛(page)，18
三、OGNL访问复杂对象：
1，访问 javaBean 对象；
2，访问集合对象；
3，访问 Map 对象
第四节：OGNL 访问静态方法和属性
1，访问静态属性；
2，访问静态方法；<constant name="struts.ognl.allowStaticMethodAccess" value="true"></constant>
success.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@taglib prefix="s" uri="/struts-tags" %>
<!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>
<%
request.setAttribute("name", "李四(request)");
request.setAttribute("age", "12");
%>
</head>
<body>
获取狭义上的值栈数据：<s:property value="name"/>
<s:property value="age"/><br/>
请求参数：<s:property value="#parameters.name"/>
<s:property value="#parameters.age"/><br/>
request：<s:property value="#request.name"/>
<s:property value="#request.age"/><br/>
session：<s:property value="#session.name"/>
<s:property value="#session.age"/><br/>
application：<s:property value="#application.name"/>
<s:property value="#application.age"/><br/>
attr取值：<s:property value="#attr.name"/>
<s:property value="#attr.age"/><br/>
ognl访问javaBean对象：<s:property value="student.name"/>
<s:property value="student.age"/><br/>
ognl访问List集合：<s:property value="students[0].name"/>
<s:property value="students[0].age"/><br/>
<s:property value="students[1].name"/>
<s:property value="students[1].age"/><br/>
ognl访问Map：<s:property value="studentMap['goodStudent'].name"/>
<s:property value="studentMap['goodStudent'].age"/><br/>
<s:property value="studentMap['badStudent'].name"/>
<s:property value="studentMap['badStudent'].age"/><br/>
</body>
</html>
struts.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd">
<struts>
<constant name="struts.ognl.allowStaticMethodAccess" value="true"></constant>
<package name="manage" namespace="/" extends="struts-default">
<action name="hello" class="com.java1234.action.HelloAction">
<result name="success" >success.jsp</result>
</action>
</package>
</struts>
Student.java
package com.java1234.model;
public class Student {
private String name;
private int age;
public Student() {
super();
// TODO Auto-generated constructor stub
}
public Student(String name, int age) {
super();
this.name = name;
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
}
HelloAction.java
package com.java1234.action;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import com.java1234.model.Student;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport;
import com.opensymphony.xwork2.util.ValueStack;
public class HelloAction extends ActionSupport{
/**
*
*/
private static final long serialVersionUID = 1L;
private Student student;
private List<Student> students;
private Map<String,Student> studentMap;
public Map<String, Student> getStudentMap() {
return studentMap;
}
public void setStudentMap(Map<String, Student> studentMap) {
this.studentMap = studentMap;
}
public List<Student> getStudents() {
return students;
}
public void setStudents(List<Student> students) {
this.students = students;
}
public Student getStudent() {
return student;
}
public void setStudent(Student student) {
this.student = student;
}
@Override
public String execute() throws Exception {
ActionContext actionContext=ActionContext.getContext();
// 获取狭义上的值栈
ValueStack valueStack=actionContext.getValueStack();
valueStack.set("name", "张三(valueStack)");
valueStack.set("age", 11);
Map<String, Object> session=actionContext.getSession();
session.put("name", "王五(session)");
session.put("age", 13);
Map<String, Object> application=actionContext.getApplication();
application.put("name", "赵六(application)");
application.put("age", 14);
student=new Student("小扒", 12);
students=new ArrayList<Student>();
students.add(new Student("老九",13));
students.add(new Student("老十",14));
studentMap=new HashMap<String,Student>();
studentMap.put("goodStudent", new Student("学霸",20));
studentMap.put("badStudent", new Student("学渣",19));
return SUCCESS;
}
}
输出结果
struts.xml配置，开启ognl允许访问静态方法：
<constant name="struts.ognl.allowStaticMethodAccess" value="true"></constant>
package com.java1234.common;
public class MyStatic {
public static final String str="Java知识分享网";
public static String printUrl(){
System.out.println("http://www.java1234.com");
return "http://www.java1234.com";
}
}
ognl_static.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@taglib prefix="s" uri="/struts-tags" %>
<!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>
</head>
<body>
访问静态属性： <s:property value="@[email protected]"/><br/>
访问静态方法：<s:property value="@[email protected]()"/>
</body>
</html>
直接在下面的网址中输入下面的url