struts OGNL数据标签

OGNL对象图导航语言,类似于el表达式,strut的底层就是用这个写的
在导入struts-core的时候会导入ognl.jar

public class Test {

    public static void main(String[] args) throws OgnlException {

    // ognl获取值 
        Address address = new Address();
        address.setId(200);
        address.setCity("北京");

        User user = new User();
        user.setAddress(address);
        user.setId(100);
        user.setName("zhangsan");

        System.out.println(Ognl.getValue("address.id", user));
        System.out.println(Ognl.getValue("name", user));




        //对map操作

        Address address = new Address();
        address.setId(200);
        address.setCity("北京");

        User user = new User();
        user.setAddress(address);
        user.setId(100);
        user.setName("zhangsan");

        Admin admin = new Admin();
        admin.setId(250);
        admin.setUsername("superadmin");
        admin.setPassword("44455666");

        Map<String, Object> map = new HashMap<String, Object>();
        map.put("u", user);
        map.put("a", admin);
        // (想要输出的)(上下文)(root) 
        System.out.println(Ognl.getValue("#root", map, user));
        // 放在map中的admin中的id值
        System.out.println(Ognl.getValue("id", map,admin));
        // map中的u的address的city值
        System.out.println(Ognl.getValue("#u.address.city", map,map));
        // 这里的#root就代表map 
        System.out.println(Ognl.getValue("#root.u.address.city", map,map));









        <!-- 对list的操作 -->

        Address address1 = new Address();
        address1.setId(100);
        address1.setCity("北京");

        Address address2 = new Address();
        address2.setId(200);
        address2.setCity("南京");


        Address address3 = new Address();
        address3.setId(300);
        address3.setCity("东京");

        List<Address> list = new ArrayList<Address>();
        list.add(address1);
        list.add(address2);
        list.add(address3);

        System.out.println(list.size());
        System.out.println(Ognl.getValue("#root[1].city", list));
        System.out.println(Ognl.getValue("size()", list));
        <!--运行这个方法,并获得返回值输出  -->
        System.out.println(Ognl.getValue("hello()", address1));

    }
}

valuestack 

public class OgnlAction {

    private String name;
    private String password;
    private List<Address> addressList;
    
    public String execute() {
        ActionContext actionContext = ActionContext.getContext();
        
        
        name = "Rose";
        password = "123123";
        
        User user = new User();
        user.setId(100);
        user.setName("jack");
        /*入栈,首先是把当前action的属性值放进去,然后再放入push的东西*/
        actionContext.getValueStack().push(user);
        <!-- 放入actionContext 跟入栈是两个不同的位置-->
        actionContext.put("k1", "v1");
        actionContext.put("k2", "v2");
        
        Address address1 = new Address();
        address1.setId(100);
        address1.setCity("北京");
        
        Address address2 = new Address();
        address2.setId(200);
        address2.setCity("南京");
        
        
        Address address3 = new Address();
        address3.setId(300);
        address3.setCity("东京1");
        Address address4 = new Address();
        address4.setId(300);
        address4.setCity("东京2");
        
        addressList = new ArrayList<Address>();
        addressList.add(address1);
        addressList.add(address2);
        addressList.add(address3);
        addressList.add(address4);
        
    
        
        
        
        return "success";
    }
}

jsp中要倒入标签

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

<h3>List: <s:property value="addressList"/></h3>
    <h3>List size:<s:property value="addressList.size"/> </h3>
    <h3>List first: <s:property value="addressList[0]"/></h3>
    <h3>city: <s:property value="addressList[0].city"/></h3>
    <h3>city: <s:property value="addressList.{city}[1]"/></h3>
    <h3>city: <s:property value="addressList.{?#this.id == 300}.{city}"/> </h3>
    <h3>city: <s:property value="addressList.{^#this.id == 300}.{city}"/> </h3>
    <h3>city: <s:property value="addressList.{$#this.id == 300}.{city}"/> </h3>
    <h3>list: <s:property value="{'aa','bb','cc'}"/> </h3>
    <h3>map: <s:property value="#{'k1':'v1','k2':'v2' }"/></h3>
    <h3></h3>

    <hr/>
    <!-- 首先是把当前action的属性值放进去,然后再放入push的东西 ,所以出栈的时候
        user是首先出来的,是root[0],然后root[1]指的是action的属性值-->
    <h3>name5: <s:property value="#root[1].name"/></h3>
    <h3>password: <s:property value="password"/> </h3>
    <h3>k1: <s:property value="#request.k1"/> </h3>
    <h3>k2: <s:property value="k2"/></h3>
    <h3>user id : <s:property value="id"/></h3>