Struts2 OGNL
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2022-04-18 11:46:44
...
Person.java
package org.fool.ognl;
public class Person {
private String name;
private Dog dog;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Dog getDog() {
return dog;
}
public void setDog(Dog dog) {
this.dog = dog;
}
}
Dog.java
package org.fool.ognl;
public class Dog {
private String name;
private String[] friends;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String[] getFriends() {
return friends;
}
public void setFriends(String[] friends) {
this.friends = friends;
}
}
OgnlTest.java
package org.fool.ognl;
import java.util.ArrayList;
import java.util.List;
import ognl.Ognl;
import ognl.OgnlContext;
import ognl.OgnlException;
/**
* OGNL(Object Graph Navigation Language)对象导航语言
*
* OgnlContext(上下文对象)，存在唯一的叫做根的对象(root)， 可以通过程序设定上下文当中哪个对象作为根对象。
*
* 在OGNL中，如果表达式没有使用#号，那么OGNL会从根对象中寻找 该属性对应的get方法，如果寻找的不是根对象中的属性，
* 那么则需要以#号开头，告诉OGNL，去寻找你所指定的特定对象中的属性。
*/
public class OgnlTest {
public static void main(String[] args) throws OgnlException {
Person person = new Person();
person.setName("zhangsan");
Dog dog2 = new Dog();
dog2.setName("wangcai2");
person.setDog(dog2);
Dog dog = new Dog();
dog.setName("wangcai");
OgnlContext context = new OgnlContext();
context.put("person", person);
context.put("dog", dog);
context.setRoot(person); // 根对象
Object object = Ognl.parseExpression("name");
System.out.println(object);
Object object2 = Ognl.getValue(object, context, context.getRoot());
System.out.println(object2);
System.out.println("-----------");
Object object3 = Ognl.parseExpression("#person.name");
System.out.println(object3);
Object object4 = Ognl.getValue(object3, context, context.getRoot());
System.out.println(object4);
System.out.println("-----------");
Object object5 = Ognl.parseExpression("#dog.name");
System.out.println(object5);
Object object6 = Ognl.getValue(object5, context, context.getRoot());
System.out.println(object6);
System.out.println("-----------");
Object object7 = Ognl.parseExpression("#person.dog.name");
System.out.println(object7);
Object object8 = Ognl.getValue(object7, context, context.getRoot());
System.out.println(object8);
System.out.println("-----------");
Object object9 = Ognl.parseExpression("name.toUpperCase()");
System.out.println(object9);
Object object10 = Ognl.getValue(object9, context, context.getRoot());
System.out.println(object10);
System.out.println("-----------");
// 当使用OGNL调用静态方法的时候，需要按照如下语法编写表达式：
// @[email protected](parameter)
Object object11 = Ognl
.parseExpression("@[email protected](10)");
System.out.println(object11);
Object object12 = Ognl.getValue(object11, context, context.getRoot());
System.out.println(object12);
System.out.println("-----------");
// 对于OGNL来说，java.lang.Math是其的默认类，如果调用java.lang.Math的静态方法时，
// 无需指定类的名字，比如：@@min(4, 10)
Object object13 = Ognl.parseExpression("@@min(4, 10)");
System.out.println(object13);
Object object14 = Ognl.getValue(object13, context, context.getRoot());
System.out.println(object14);
System.out.println("-----------");
Object object15 = Ognl.parseExpression("new java.util.LinkedList()");
System.out.println(object15);
Object object16 = Ognl.getValue(object15, context, context.getRoot());
System.out.println(object16);
// 对于OGNL来说，数组与集合是一样的，都是通过下标索引来去访问的。构造集合的时候使用｛...｝形式
Object object17 = Ognl.getValue("{'aa', 'bb', 'cc', 'dd'}[3]", context,
context.getRoot());
System.out.println(object17);
System.out.println("-----------");
dog.setFriends(new String[] { "aa", "bb", "cc" });
Object object18 = Ognl.getValue("#dog.friends[0]", context,
context.getRoot());
System.out.println(object18);
System.out.println("-----OGNL操纵集合------");
List<String> list = new ArrayList<String>();
list.add("hello");
list.add("world");
list.add("hello world");
context.put("list", list);
System.out
.println(Ognl.getValue("#list[2]", context, context.getRoot()));
System.out.println("-----OGNL操纵映射------");
// 处理OGNL来处理映射(Map)的语法格式如下所示：
// #{'key1' : 'value1', 'key2' : 'value2', '...' : '...'}
System.out.println(Ognl.getValue(
"#{'key1' : 'value1', 'key2' : 'value2'}['key2']", context,
context.getRoot()));
System.out.println("-----过滤------");
// 过滤(filtering):collection.{? expression}
List<Person> persons = new ArrayList<Person>();
Person p1 = new Person();
Person p2 = new Person();
Person p3 = new Person();
p1.setName("zhangsan");
p2.setName("lisi");
p3.setName("wangwu");
persons.add(p1);
persons.add(p2);
persons.add(p3);
context.put("persons", persons);
System.out.println(Ognl.getValue(
"#persons.{? #this.name.length() > 4}.size()", context,
context.getRoot()));
System.out.println(Ognl.getValue(
"#persons.{? #this.name.length() > 4}.isEmpty()", context,
context.getRoot()));
// OGNL针对集合提供了一些伪属性(如size, isEmpty),让我们可以通过属性的方式来调用
// 方法(本质原因在与集合当中的很多方法并不符合JavaBean的命名规则),但我们依然可以通
// 过调用方法来实现与伪属性相同的目的。
System.out.println(Ognl.getValue(
"#persons.{? #this.name.length() > 4}.size", context,
context.getRoot()));
System.out.println(Ognl.getValue(
"#persons.{? #this.name.length() > 4}.isEmpty", context,
context.getRoot()));
System.out.println("-----------");
// 过滤(filtering):获取集合中的第一个元素collection.{^ expression}
System.out.println(Ognl.getValue(
"#persons.{^ #this.name.length() > 4}[0].name", context,
context.getRoot()));
// 过滤(filtering):获取集合中的最后一个元素collection.{$ expression}
System.out.println(Ognl.getValue(
"#persons.{$ #this.name.length() > 4}[0].name", context,
context.getRoot()));
System.out.println("-----投影------");
// 投影(projection):collection.{expression}
System.out.println(Ognl.getValue("#persons.{name}", context,
context.getRoot()));
System.out.println("-----------");
System.out.println(Ognl.getValue("#persons.{#this.name.length() <= 5 ? 'Hello World' : #this.name}",
context, context.getRoot()));
}
}
...
<dependencies>
<dependency>
<groupId>org.apache.struts</groupId>
<artifactId>struts2-core</artifactId>
<version>${struts-version}</version>
</dependency>
<dependency>
<groupId>org.apache.struts</groupId>
<artifactId>struts2-convention-plugin</artifactId>
<version>${struts-version}</version>
</dependency>
</dependencies>
...
... <filter> <filter-name>struts2</filter-name> <filter-class> org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter </filter-class> </filter> <filter-mapping> <filter-name>struts2</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> ...
<?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> <constant name="struts.devMode" value="true" /> <constant name="struts.enable.DynamicMethodInvocation" value="false" /> <constant name="struts.objectFactory" value="spring" /> <constant name="struts.i18n.reload" value="true" /> <constant name="struts.configuration.xml.reload" value="true" /> </struts>
Student.java
package org.fool.bean;
import java.util.Map;
public class Student {
private String name;
private int age;
private String address;
private String[] teachers;
private Cat cat;
private Map<String, String> map;
public Student() {
}
public Student(String name, int age, String address, String[] teachers,
Cat cat, Map<String, String> map) {
super();
this.name = name;
this.age = age;
this.address = address;
this.teachers = teachers;
this.cat = cat;
this.map = map;
}
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;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public String[] getTeachers() {
return teachers;
}
public void setTeachers(String[] teachers) {
this.teachers = teachers;
}
public Cat getCat() {
return cat;
}
public void setCat(Cat cat) {
this.cat = cat;
}
public Map<String, String> getMap() {
return map;
}
public void setMap(Map<String, String> map) {
this.map = map;
}
}
Cat.java
package org.fool.bean;
public class Cat {
private String name;
private int age;
private String color;
public Cat() {
}
public Cat(String name, int age, String color) {
this.name = name;
this.age = age;
this.color = color;
}
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;
}
public String getColor() {
return color;
}
public void setColor(String color) {
this.color = color;
}
}
OgnlAction.java
package org.fool.action;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.struts2.convention.annotation.Action;
import org.apache.struts2.convention.annotation.Namespace;
import org.apache.struts2.convention.annotation.Result;
import org.apache.struts2.interceptor.ApplicationAware;
import org.apache.struts2.interceptor.RequestAware;
import org.apache.struts2.interceptor.SessionAware;
import org.fool.bean.Cat;
import org.fool.bean.Student;
import com.opensymphony.xwork2.ActionSupport;
@Namespace("/")
@Result(name = "success", location = "ognl.jsp")
public class OgnlAction extends ActionSupport implements RequestAware,
SessionAware, ApplicationAware {
private String username;
private String password;
private Map<String, Object> requestMap;
private Map<String, Object> sessionMap;
private Map<String, Object> applicationMap;
private List<Student> list = new ArrayList<Student>();
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public List<Student> getList() {
return list;
}
public void setList(List<Student> list) {
this.list = list;
}
@Override
public void setApplication(Map<String, Object> application) {
this.applicationMap = application;
}
@Override
public void setSession(Map<String, Object> session) {
this.sessionMap = session;
}
@Override
public void setRequest(Map<String, Object> request) {
this.requestMap = request;
}
@Action(value = "ognlAction")
public String execute() throws Exception {
requestMap.put("hello", "groovy");
sessionMap.put("hello", "grails");
applicationMap.put("hello", "jquery");
Cat cat1 = new Cat("cat1", 20, "red");
Cat cat2 = new Cat("cat2", 30, "blue");
String[] teachers1 = { "hello1", "hello2", "hello3" };
String[] teachers2 = { "world1", "world2", "world3" };
Map<String, String> map1 = new HashMap<String, String>();
Map<String, String> map2 = new HashMap<String, String>();
map1.put("hello1", "hello1");
map1.put("hello2", "hello2");
map2.put("world1", "world1");
map2.put("world2", "world2");
Student student1 = new Student("zhangsan", 20, "beijing", teachers1,
cat1, map1);
Student student2 = new Student("lisi", 30, "shanghai", teachers2, cat2,
map2);
list.add(student1);
list.add(student2);
return SUCCESS;
}
}
ognl.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"%>
<%@ page import="com.opensymphony.xwork2.ActionContext" %>
<%@ page import="com.opensymphony.xwork2.util.ValueStack" %>
<%@ page import="org.fool.action.OgnlAction" %>
<%@ page import="java.util.Map" %>
<%@ taglib prefix="s" uri="/struts-tags" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>ognl.jsp</title>
</head>
<body>
username:<s:property value="username"/><br>
password:<s:property value="password"/><br>
<hr>
username:<s:property value="#parameters.username"/><br>
password:<s:property value="#parameters.password"/><br>
<hr>
request:<s:property value="#request.hello"/><br>
session:<s:property value="#session.hello"/><br>
application:<s:property value="#application.hello"/><br>
attr:<s:property value="#attr.hello"/><br>
<hr>
request:<%= ((Map) ActionContext.getContext().get("request")).get("hello") %><br>
session:<%= ActionContext.getContext().getSession().get("hello") %><br>
application:<%=ActionContext.getContext().getApplication().get("hello") %><br>
attr:<%= ((Map) ActionContext.getContext().get("attr")).get("hello")%>
<hr>
student1.address:<s:property value="list[0].address"/><br>
student2.age:<s:property value="list[1].age"/><br>
student1.cat.name:<s:property value="list[0].cat.name"/><br>
size:<s:property value="list.size"/><br>
isEmpty:<s:property value="list.isEmpty"/><br>
<hr>
student1.address:<%= ((OgnlAction) ActionContext.getContext().getValueStack().peek()).getList().get(0).getAddress() %><br>
student2.age:<%= ((OgnlAction) ActionContext.getContext().getValueStack().peek()).getList().get(1).getAge() %><br>
student1.cat.name:<%= ((OgnlAction) ActionContext.getContext().getValueStack().peek()).getList().get(0).getCat().getName() %><br>
<hr>
student2.friend:<s:property value="list[1].teachers[2]"/><br>
student2.friend:<%= ((OgnlAction) ActionContext.getContext().getValueStack().peek()).getList().get(1).getTeachers()[2] %><br>
<hr>
student2.map2:<s:property value="list[1].map['world2']"/><br>
<hr>
filtering:<s:property value="list.{? #this.name.length() > 2}[1].name"/><br>
<hr>
<s:iterator value="list.{? #this.name.length() > 2}">
<s:property value="name"/><br>
<s:property value="cat.color"/><br>
<s:property value="teachers[0]"/><br>
</s:iterator>
<hr>
projection:<br>
<s:iterator value="list.{age}">
<s:property/><br>
</s:iterator>
</body>
</html>