Struts2中使用OGNL

Posted 2020-08-26 Andy 胡

　　链接：Struts标签库

OGNL（Object Graphic Navigatino Language）

OGNL称为对象图导航语言。以一个对象为根（起点），通过OGNL可以访问与这个对象关联的其它对象，正所谓“对象导航，顺藤摸瓜”

使用OGNL的jsp需要引入标签库：<%@taglib prefix="s" uri="/struts-tags"%>

struts.xml

<?xml version="1.0" encoding="UTF-8" ?>                                    
<!DOCTYPE struts PUBLIC                                    
    "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"                                
    "http://struts.apache.org/dtds/struts-2.3.dtd">

<struts>
    <package name="p1" namespace="/" extends="struts-default">
        <action name="m1Action" class="org.ah.s2.C1" method="m1">
            <result name="success" type="dispatcher">
                /inputMsg.jsp
            </result>
        </action>
    </package>
</struts>

模型层：来个两级模型

Model.java

package org.ah.s2;

public class Model {
    private String uname;
    private M2 m2;

    public Model(String uname, M2 m2) {
        this.uname = uname;
        this.m2 = m2;
    }

    public M2 getM2() {
        return m2;
    }

    public void setM2(M2 m2) {
        this.m2 = m2;
    }

    public String getUname() {
        return uname;
    }

    public void setUname(String uname) {
        this.uname = uname;
    }
}

M2.java

package org.ah.s2;

public class M2 {
    public M2(String name2) {
        this.name2 = name2;
    }

    private String name2;

    public String getName2() {
        return name2;
    }

    public void setName2(String name2) {
        this.name2 = name2;
    }
}

Action：C1.java

package org.ah.s2;

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

import org.apache.struts2.ServletActionContext;

import ognl.Ognl;
import ognl.OgnlException;

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

public class C1 extends ActionSupport {
    private Model m;
    private List<Model> lstM;

    // ------------------------------------------------------------------
    public Model getM() {
        return m;
    }

    public void setM(Model m) {
        this.m = m;
    }

    public List<Model> getLstM() {
        return lstM;
    }

    public void setLstM(List<Model> lstM) {
        this.lstM = lstM;
    }

    // ------------------------------------------------------------------
    public String m1() {
        ActionContext ac = ActionContext.getContext();
        // 放入值栈外围
        ac.put("msg", "out_value");

        // 放入值栈
        ValueStack valueStack = ac.getValueStack();
        valueStack.set("msg", "vStack_value");// OK

        // 放入Application
        ac.getApplication().put("msg", "hello application");
        // 放入session
        ac.getSession().put("msg", "hello session");

        // 放入request(上面的ActionContext ac搞不定，需要ServletActionContext)
        ServletActionContext.getRequest().setAttribute("msg", "hello request");

        // 放置对象
        m = new Model("吕布", new M2("方天画戟"));

        // 放置List
        Model m1 = new Model("关羽", new M2("青龙偃月刀"));
        Model m2 = new Model("张飞", new M2("丈八蛇矛枪"));
        Model m3 = new Model("赵云", new M2("龙胆亮银枪"));
        lstM = new ArrayList<Model>();
        lstM.add(m1);
        lstM.add(m2);
        lstM.add(m3);
        return "success";
    }

}

index.jsp核心代码

    <s:form action="m1Action" method="post">
        <s:textfield name="msg" value="my input"></s:textfield>
        <s:submit value="测试Struts控件传值"></s:submit>
    </s:form>

回显页inputMsg.jsp核心代码

    1.值栈中的值：
    <s:property value="msg" />
    <hr>
    2.值栈外围值：
    <s:property value="#msg" />
    <br> 3.
    <s:property value="#parameters.msg" />取表单提交值
    <br> 4.
    <s:property value="#application.msg" />
    <br> 5.
    <s:property value="#session.msg" />
    <br> 6.
    <s:property value="#request.msg" />
    <br> 7.
    <s:property value="#attr.msg" /> 按page > request > session > application顺序访问其属性,取page的值只能用这个<br> 8.取对象
    <s:property value="m.uname" />
    <s:property value="m.m2.name2" />
    <br> 9.取List
    <!-- 用listValue指定显示的内容 -->
    下拉列表：
    <s:select list="lstM" listValue="uname" headerValue="缺省值">
    </s:select>
    <br> 下拉列表（自定义List）：
    <s:select list="#{\'0\':\'男\',\'1\':\'女\'}" label="性别" headerValue="请选择性别" />
    <br>
    <br> 循环遍历：
    <br>
    <s:iterator value="lstM" var="per" status="sta">
        <s:property value="#per.uname" />
        <s:property value="#per.m2.name2" />
        <br>
        循环的次数为：<s:property value="#sta.count" />
        <br>
        循环的索引为：<s:property value="#sta.index" />
        <br>
        是否为奇数：<s:property value="#sta.odd" />
        <s:if test="#sta.count==1">No.1</s:if>
        <s:elseif test="#sta.count==2">No.2</s:elseif>
        <s:else>No.3</s:else>
        <br />
        
    </s:iterator>
    <br>
    遍历set集合：(自定义的字符串不能是字符！至少加一个空格)
    <br>
    <s:set name="set" value="{\'E \',\'ddddd\',\'ccccc\',\'bbbbb\',\'aaaaa\'}"></s:set>
    <s:iterator value="#set" var="o">
        <!-- ${o }<br/> -->
        <s:property value="o" />
        <br />
    </s:iterator>


    <s:debug></s:debug>

直接点击提交，查看运行结果：