Struts2学习笔记OGNL例子代码

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Struts2学习笔记OGNL例子代码

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OGNL是Object-Graph Navigation Language的缩写，它是一种功能强大的表达式语言（Expression Language，简称为EL），通过它简单一致的表达式语法，可以存取对象的任意属性，调用对象的方法，遍历整个对象的结构图，实现字段类型转化等功能。它使用相同的表达式去存取对象的属性。(摘自百度百科)

第一部分:OgnlAction类,继承自ActionSupport

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import cn.hxex.struts.core.ognl.bean.Student;

import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport;

@SuppressWarnings("serial")
public class OgnlAction extends ActionSupport {

    @SuppressWarnings("unchecked")
    public String execute() {

        Map sessionMap = ActionContext.getContext().getSession();
        sessionMap.put("userName", "David");

        List<Student> students = new ArrayList<Student>();
        students.add( new Student("Mike", 20) );
        students.add( new Student("Tom", 18) );
        students.add( new Student("Jack", 16) );
        students.add( new Student("White", 15) );
        setStudents( students );

        return SUCCESS;
    }

    private List<Student> students;

    public List<Student> getStudents() {
        return students;
    }

    public void setStudents(List<Student> students) {
        this.students = students;
    }
}
第二部分JSP页面
<%@ taglib prefix="s" uri="/struts-tags"%>
<html>
    <head>
        <title>Ognl</title>
    </head>
    <body>
        <h2>Access Action Context:</h2>
        session.userName: <s:property value="#session.userName" />
        <h2>Projection And Selection Operators:</h2>
        Mike age is:
        <s:property value="students.{?#this.name=='Mike'}.{age}[0]"/><br/>
        Students that larger than 17:
        <s:iterator value="students.{?#this.age > 17}">
            <li><s:property value="name" /> - <s:property value="age" /></li>
        </s:iterator>
        <h2>Construction Map:</h2>
        <s:set name="foobar" value="#{ 'foo' : 'foo value', 'bar' : 'bar value' }" />
        The value of key "foo" is <s:property value="#foobar['foo']" />
    </body>
</html>
第三部分运行调试:
请求页面的表单内容
    <s:form action="ognl">
        <s:submit value="submit"></s:submit>
    </s:form>

环境搭建:
struts.xml配置
<?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.enable.DynamicMethodInvocation" value="false" />
    <constant name="struts.devMode" value="false" />
    <package name="core" extends="struts-default">
        
        <action name="ognl" class="com.ognl.action.OgnlAction">
            
            <result>/ognl/ognl.jsp</result>
        </action>
    </package>
</struts>
web.xml配置
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
    http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
    <filter>
        <filter-name>ognl</filter-name>
        <filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>ognl</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
</web-app>
struts.properties配置(不写也可以,但是会出现警告)
struts.locale=en_GB