Struts2--OGNL语法详解（取值、赋值、调用普通方法、调用静态方法、创建List和Map）

创建项目并导包

创建一个User类

package cn.itheima.bean;

public class User {
	private String name;
	private Integer age;
	
	public User() {
		super();
	}
	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 + "]";
	}
}

准备工作

@Test
//准备工作
public void fun1() throws Exception{
	//准备ONGLContext
		//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);
	//书写OGNL
	Ognl.getValue("", oc, oc.getRoot());
}

取root中的属性值

@Test
//取出root中的属性值
public void fun2() throws Exception{
	//准备ONGLContext
		//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();
	oc.setRoot(rootUser);
	oc.setValues(context);
	//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);
}

运行Junit测试，控制台打印：

tom
18

取出context中的属性值

public void fun3() throws Exception{
	//准备ONGLContext
		//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();
	oc.setRoot(rootUser);
	oc.setValues(context);
	//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());
	String name2 = (String) Ognl.getValue("#user2.name", oc, oc.getRoot());
	Integer age = (Integer) Ognl.getValue("#user2.age", oc, oc.getRoot());
	System.out.println(name);
	System.out.println(name2);
	System.out.println(age);
}

运行Junit测试，控制台打印：

jack
rose
22

为属性赋值

@Test
//基本语法演示
//为属性赋值
public void fun4() throws Exception{
	//准备ONGLContext
		//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();
	oc.setRoot(rootUser);
	oc.setValues(context);
	//书写OGNL
	
	//将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());
	//将Context中的user对象的name属性赋值  
	//可以使用（,）将表达式进行串联执行，但是多个表达式串联，如果有多个返回值，只返回最后一个表达式的
	String name2 = (String) Ognl.getValue("#user1.name='二狗', #user1.name", oc, oc.getRoot());
	System.out.println(name);
	System.out.println(name2);
}

运行Junit测试，控制台打印：

jerry
二狗

调用方法

@Test
//调用方法
public void fun5() throws Exception{
	//准备ONGLContext
		//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();
	oc.setRoot(rootUser);
	oc.setValues(context);
	//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user对象的setName方法
	String name2 = (String) Ognl.getValue("#user1.setName('lucy'),#user1.getName()", oc, oc.getRoot());
	
	
	System.out.println(name);
	System.out.println(name2);
}

运行Junit测试，控制台打印：

lilei
lucy

调用静态方法

创建一个工具类，定义一个静态方法：

package pers.zhang.Utils;

public class HahaUtils {
	
	//回音方法
	public static Object echo(Object o){
		return o;
	}
}

@Test
//基本语法演示
//调用静态方法
public void fun6() throws Exception{
	//准备ONGLContext
		//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();
	oc.setRoot(rootUser);
	oc.setValues(context);
	//书写OGNL
	//@+完整类名+@+方法
	String name = (String) Ognl.getValue("@pers.zhang.Utils@echo('hello 强勇!')", oc, oc.getRoot());
	//Double pi = (Double) Ognl.getValue("@java.lang.Math@PI", oc, oc.getRoot());
	//访问Math的简写
	Double pi = (Double) Ognl.getValue("@@PI", oc, oc.getRoot());
	System.out.println(name);
	System.out.println(pi);
}

运行Junit测试，控制台打印：

hello 二狗
3.141592653589793

ognl创建对象（List，Map）

@Test
//基本语法演示
//ognl创建对象-list|map
public void fun7() throws Exception{
	//准备ONGLContext
		//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();
	oc.setRoot(rootUser);
	oc.setValues(context);
	//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(1)", 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());
	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);
}

运行Junit测试，控制台输出：

2
tom
18