Ognl的底层用法

今天学了下ognl的运用，在这里和大家分享一下。希望对大家有所帮助。

package com.hcj.test;import java.util.ArrayList;import java.util.List;import ognl.Ognl;import ognl.OgnlContext;import ognl.OgnlException;public class Test {public static void main(String[] args) throws OgnlException {Person p = new Person();p.setName("张三");Cat cat = new Cat();cat.setName("花猫");//创建ognl上下文OgnlContext ognlContext = new OgnlContext();ognlContext.put("person", p);ognlContext.put("cat", cat);//设置person根对象ognlContext.setRoot(p);//获取根对象Object root = ognlContext.getRoot();//获取根对象的属性Object obj1 = Ognl.parseExpression("name");System.out.println(obj1);Object value1 = Ognl.getValue(obj1, ognlContext, root);System.out.println(value1);System.out.println("==========");//访问非根对象的属性Object obj2 = Ognl.parseExpression("#cat.name");System.out.println(obj2);Object value2 = Ognl.getValue(obj2, ognlContext, root);System.out.println(value2);System.out.println("==========");//访问类的静态方法Object obj3 = Ognl.parseExpression("@java.lang.Math@PI");System.out.println(obj3);Object value3 = Ognl.getValue(obj3, ognlContext, root);System.out.println(value3);System.out.println("======");//访问math方法Object obj4 = Ognl.parseExpression("@@max(1,3)");System.out.println(obj4);Object value4 = Ognl.getValue(obj4, ognlContext, root);System.out.println(value4);System.out.println("======");//创建对象Object obj5 = Ognl.parseExpression("new com.hcj.test.Cat()");System.out.println(obj5);Object value5 = Ognl.getValue(obj5, ognlContext, root);System.out.println(value5);System.out.println("======");//创建list对象Object obj6 = Ognl.parseExpression("{'a','b','c'}");System.out.println(obj6);Object value6 = Ognl.getValue(obj6, ognlContext, root);System.out.println(value6);System.out.println("======");//访问list对象属性Object obj7 = Ognl.parseExpression("{'a','b','c'}[1]");System.out.println(obj7);Object value7 = Ognl.getValue(obj7, ognlContext, root);System.out.println(value7);System.out.println("======");//创建map对象Object obj8 = Ognl.parseExpression("#{'1':'aa', '2':'bb', '3':'cc'}");System.out.println(obj8);Object value8 = Ognl.getValue(obj8, ognlContext, root);System.out.println(value8);System.out.println("======");//访问map对象属性Object obj9 = Ognl.parseExpression("#{'1':'aa', '2':'bb', '3':'cc'}['3']");System.out.println(obj9);Object value9 = Ognl.getValue(obj9, ognlContext, root);System.out.println(value9);System.out.println("======");//选择,格式： collection.{? expression}List<Person> persons = new ArrayList<Person>();Person p1 = new Person();p1.setName("zz12345");Person p2 = new Person();p2.setName("aa121312");Person p3 = new Person();p3.setName("bb");persons.add(p1);persons.add(p2);persons.add(p3);//将persons放入ognl上下文中ognlContext.put("persons", persons);Object obj10 = Ognl.parseExpression("#persons.{? #this.name.length() > 2}");System.out.println(obj10);Object value10 = Ognl.getValue(obj10, ognlContext, root);System.out.println(value10);System.out.println("======");//投影,格式： collection.{? expression}Object obj11 = Ognl.parseExpression("#persons.{#this.name}");System.out.println(obj11);Object value11 = Ognl.getValue(obj11, ognlContext, root);System.out.println(value11);System.out.println("======");}}

输出结果：

name张三==========#cat.name花猫==========@java.lang.Math@PI3.141592653589793======@java.lang.Math@max(1, 3)3======new com.hcj.test.Cat()com.hcj.test.Cat@1dff3a2======{ 'a', 'b', 'c' }[a, b, c]======{ 'a', 'b', 'c' }[1]b======#{ '1' : "aa", '2' : "bb", '3' : "cc" }{1=aa, 2=bb, 3=cc}======#{ '1' : "aa", '2' : "bb", '3' : "cc" }['3']cc======#persons.{? (#this.name.length() > 2) }[com.hcj.test.Person@b988a6, com.hcj.test.Person@ba6c83]======#persons.{ #this.name }[zz12345, aa121312, bb]======