javaEE OGNL表达式，对象视图导航语言

jar包下载：https://pan.baidu.com/s/1jJbXWYHAsyH32h6bVJbrJA 密码：7gly

OGNL：对象视图导航语言。${user.addr.name}这种写法就叫对象视图导航。
OGNL不仅仅可以视图导航，而且支持比EL表达式更加丰富的功能。

Demo.java（测试类）：

package cn.xxx.ognl;

import java.util.HashMap;
import java.util.Map;

import org.junit.Test;

import cn.xxx.bean.User;
import ognl.Ognl;
import ognl.OgnlContext;
import ognl.OgnlException;

//学习OGNL语法
public class Demo {
	@Test
	//准备工作
	public void fun1() throws Exception{
		//准备OGNLContext
		//准备Root
		User rootUser = new User("tom",18);
		//准备Context
		Map<String,User> context = new HashMap<String,User>();
		context.put("user1", new User("jack",18));
		context.put("user2", new User("rose",22));
		OgnlContext oc = new OgnlContext();
		//将rootUser作为root部分
		oc.setRoot(rootUser);
		//将context这个Map作为Context部分
		oc.setValues(context);
		
		//二、书写OGNL
		Ognl.getValue("XXX", oc, oc.getRoot());
	}
	
	@Test
	//基本语法演示
	//取出root中的属性值
	public void fun2() throws Exception{
		//一、准备OGNLContext
		User rootUser = new User("tom",18);
		Map<String,User> context = new HashMap<String,User>();
		context.put("user1", new User("jack",18));
		context.put("user2", new User("rose",22));
		OgnlContext oc = new OgnlContext();
		oc.setRoot(rootUser);
		oc.setValues(context);
		
		//二、书写OGNL
		//取出root中user对象的name属性
		String name = (String) Ognl.getValue("name", oc, oc.getRoot());
		Integer age = (Integer) Ognl.getValue("age", oc, oc.getRoot());
		System.out.println(name);
		System.out.println(age);
	}
	@Test
	//基本语法演示
	//取出context中的属性值
	public void fun3() throws Exception{
		//一、准备OGNLContext
		User rootUser = new User("tom",18);
		Map<String,User> context = new HashMap<String,User>();
		context.put("user1", new User("jack",18));
		context.put("user2", new User("rose",22));
		OgnlContext oc = new OgnlContext();
		oc.setRoot(rootUser);
		oc.setValues(context);
		
		//二、书写OGNL
		//取出context中键为user1对象的name属性
		String name = (String) Ognl.getValue("#user1.name", oc, oc.getRoot()); // #表示从Context中取值
		Integer age = (Integer) Ognl.getValue("#user2.age", oc, oc.getRoot());
		System.out.println(name);
		System.out.println(age);
	}
	
	@Test
	//基本语法演示
	//为属性赋值
	public void fun4() throws Exception{
		//一、准备OGNLContext
		User rootUser = new User("tom",18);
		Map<String,User> context = new HashMap<String,User>();
		context.put("user1", new User("jack",18));
		context.put("user2", new User("rose",22));
		OgnlContext oc = new OgnlContext();
		oc.setRoot(rootUser);
		oc.setValues(context);
		
		//二、书写OGNL
		//为root中的user对象的name属性赋值
		Ognl.getValue("name='jerry'", oc, oc.getRoot());
		String name = (String) Ognl.getValue("name", oc, oc.getRoot());
		
		//为Context中的user1键对应的值赋值
		String name2 = (String) Ognl.getValue("#user1.name='张三',#user1.name", oc, oc.getRoot()); //可以用逗号,串联多个表达式;返回最后一个表达式的值。 
		System.out.println(name);  // jerry
		System.out.println(name2);  // 张三
	}
	
	@Test
	//基本语法演示
	//调用方法
	public void fun5() throws Exception{
		//一、准备OGNLContext
		User rootUser = new User("tom",18);
		Map<String,User> context = new HashMap<String,User>();
		context.put("user1", new User("jack",18));
		context.put("user2", new User("rose",22));
		OgnlContext oc = new OgnlContext();
		oc.setRoot(rootUser);
		oc.setValues(context);
		
		//二、书写OGNL
		//调用root中user对象的setName方法
		Ognl.getValue("setName('lilei')", oc, oc.getRoot());
		String name = (String) Ognl.getValue("getName()", oc, oc.getRoot());
		
		//调用Context中user1键对应值的setName方法
		String name2 = (String) Ognl.getValue("#user1.setName('lucy'),#user1.getName()", oc, oc.getRoot());
		
		System.out.println(name);
		System.out.println(name2);
	}
	
	
	@Test
	//基本语法演示
	//调用静态方法
	public void fun6() throws Exception{
		//一、准备OGNLContext
		User rootUser = new User("tom",18);
		Map<String,User> context = new HashMap<String,User>();
		context.put("user1", new User("jack",18));
		context.put("user2", new User("rose",22));
		OgnlContext oc = new OgnlContext();
		oc.setRoot(rootUser);
		oc.setValues(context);
		
		//二、书写OGNL
		//调用静态类的静态方法
		String name = (String) Ognl.getValue("@cn.itheima.a_ognl.DemoUtils@demoMethod('参数')", oc, oc.getRoot());
		//获取静态类的静态属性值
		Double pi = (Double) Ognl.getValue("@java.lang.Math@PI", oc, oc.getRoot());
		//Double pi = (Double) Ognl.getValue("@@PI", oc, oc.getRoot()); // Math类是OGNL内置对象,可以省略。
		System.out.println(name);
		System.out.println(pi);
	}
	
	@Test
	//基本语法演示
	//ognl创建对象-list|map
	public void fun7() throws Exception{
		//一、准备OGNLContext
		User rootUser = new User("tom",18);
		Map<String,User> context = new HashMap<String,User>();
		context.put("user1", new User("jack",18));
		context.put("user2", new User("rose",22));
		OgnlContext oc = new OgnlContext();
		oc.setRoot(rootUser);
		oc.setValues(context);
		
		//二、书写OGNL
		//创建list对象
		Integer size = (Integer) Ognl.getValue("{'tom','jerry','jack','rose'}.size()", oc, oc.getRoot());
		String name = (String) Ognl.getValue("{'tom','jerry','jack','rose'}[0]", oc, oc.getRoot());
		String name2 = (String) Ognl.getValue("{'tom','jerry','jack','rose'}.get(0)", oc, oc.getRoot());
	
		/*System.out.println(size);
		System.out.println(name);
		System.out.println(name2);*/
		
		//创建Map对象
		Integer size2 = (Integer) Ognl.getValue("#{'name':'tom','age':18}.size()", oc, oc.getRoot()); // #表示创建的对象是Map集合。
		String name3  = (String) Ognl.getValue("#{'name':'tom','age':18}['name']", oc, oc.getRoot());
		Integer age  = (Integer) Ognl.getValue("#{'name':'tom','age':18}.get('age')", oc, oc.getRoot());
		System.out.println(size2);
		System.out.println(name3);
		System.out.println(age);
	}

}

User.java（用到的JavaBean对象）：

package cn.xxx.bean;

public class User {
	private String name;
	private Integer age;
	
	public User() {
		super();
		// TODO Auto-generated constructor stub
	}
	
	
	public User(String name, Integer age) {
		super();
		this.name = name;
		this.age = age;
	}

	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public Integer getAge() {
		return age;
	}
	public void setAge(Integer age) {
		this.age = age;
	}


	@Override
	public String toString() {
		return "User [name=" + name + ", age=" + age + "]";
	}
	
}