OGNL表达式

迷南。 2022-06-05 12:23 208阅读 0赞

OGNL表达式需要struts2标签的支持， 需要在jsp页面中增加 
<%@ taglib uri=”/struts-tags” prefix=”s” %>

* jsp页面通过ognl表达式取出内容
 * <body>
 pi:<s:property value="@java.lang.Math@PI"/> 
 random:<s:property value="@java.lang.Math@random()*100"/> 
 
 访问action类变量name:<s:property value="name"/> 
 访问action类变量pwd:<s:property value="pwd"/> 
 访问action类中对象属性user.uname:<s:property value="user.uname"/> 
 访问action类中对象属性user.age:<s:property value="user.age"/> 
 访问action类中对象方法user.fun():<s:property value="user.fun()"/> 
 
 访问action类中普通方法:<s:property value="actionFun()"/> 
 访问某个类的静态方法:<s:property value="@form.S@s"/> 
 访问某个类的静态属性:<s:property value="@form.S@fun()"/> 
 访问某个类的构造方法:<s:property value="new form.User()"/> 
 
 访问list集合:<s:property value="user_list"/> 
 访问list集和元素:<s:property value="user_list[0]"/> 
 
 访问Map集合:<s:property value="user_map"/> 
 访问Map集合指定key:<s:property value="user_map.k1"/> 
 访问Map集合所有key:<s:property value="user_map.keys"/> 
 访问Map集合所有value:<s:property value="user_map.values"/> 
 
 筛选list内容:<s:property value="user_list.{?#this.age==20}.{uname}"/> 
 筛选list内容:<s:property value="user_list.{^#this.age>1}.{uname}"/> 
 筛选list内容:<s:property value="user_list.{$#this.age>1}.{uname}"/> 
 <s:debug></s:debug>
 </body>
 * action类, 每个属性必须提供getter(),setter()
 * package form;
 
 import java.lang.reflect.Array;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
 import javax.servlet.ServletContext;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpSession;
 
 import org.apache.struts2.ServletActionContext;
 
 import com.opensymphony.xwork2.Action;
 import com.opensymphony.xwork2.ActionContext;
 import com.opensymphony.xwork2.ActionSupport;
 import com.opensymphony.xwork2.ModelDriven;
 import com.opensymphony.xwork2.util.ValueStack;
 
 public class Form1Action extends ActionSupport{ 
 String name;
 String pwd;
 
 User user;
 
 List<User> user_list;
 Map<String, Object> user_map;
 
 
 public List<User> getUser_list() {
 return user_list;
 }
 public void setUser_list(List<User> user_list) {
 this.user_list = user_list;
 }
 public Map<String, Object> getUser_map() {
 return user_map;
 }
 public void setUser_map(Map<String, Object> user_map) {
 this.user_map = user_map;
 }
 public User getUser() {
 return user;
 }
 public void setUser(User user) {
 this.user = user;
 }
 public String getPwd() {
 return pwd;
 }
 public void setPwd(String pwd) {
 this.pwd = pwd;
 }
 public String getName() {
 return name;
 }
 public void setName(String name) {
 this.name = name;
 }
 public Form1Action() {
 System.out.println("执行。。。");
 }
 public String execute() throws Exception {
 
 user_list = new ArrayList<User>();
 user_list.add(new User(19,"tom"));
 user_list.add(new User(20,"jack"));
 
 user_map = new HashMap<String, Object>();
 user_map.put("k1", new User(19,"tom2"));
 user_map.put("k2", new User(20,"jack2"));
 
 
 return Action.SUCCESS;
 }
 
 public String actionFun(){
 return "action类的fun方法";
 }
 }
 * User类
 * package form;
 
 public class User { 
 int age;
 String uname;
 
 public User(int age, String uname) {
 super();
 this.age = age;
 this.uname = uname;
 }
 public User() {
 
 }
 public int getAge() {
 return age;
 }
 public String getUname() {
 return uname;
 }
 public void setAge(int age) {
 this.age = age;
 }
 public void setUname(String uname) {
 this.uname = uname;
 }
 public String fun(){
 return "my name is"+uname;
 }
 @Override
 public String toString() {
 return "User [age=" + age + ", uname=" + uname + "]";
 }
 
 }
 * struts.xml
 * 
 <constant name="struts.ognl.allowStaticMethodAccess" value="true"></constant>
 
 <package name="default" namespace="/" extends="struts-default">
 <action name="demo" class="form.Form1Action">
 <result>/index.jsp</result>
 </action>
 </package>