struts2[3.1]OGNL表达式介绍和准备和OGNL表达式语句

1.介绍和准备

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，支持EL表达式更加丰富的功能。(在使用OGNL表达式之前需要导入相应的jar包)

                                                                  图1、OGNL表达式（EL为复习内容，与OGNL无关）

                                                                                           图2、项目结构

2.测试

2.1取出root中的user对象的name属性（@Test需要引入import org.junit.Test;然后在运行时直接点击Run as JUnit Test）

	@Test
	public void fun1() throws OgnlException {
		//准备OGNLContext
			//准备Root
			User rootUser1 = new User("tom",18);
			//准备Context
			Map<String,User> context = new HashMap<String,User>();
			context.put("user1", new User("isleiyi",18));
			context.put("user2", new User("Rose",19));
		
		OgnlContext oc = new OgnlContext();
		oc.setRoot(rootUser1);
		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());
		System.out.println(name);
	}

输出：tom

2.2取出root中的属性值

@Test
	//取出root中的属性值
	public void fun2() throws OgnlException {
		//准备OGNLContext
			//准备Root
			User rootUser1 = new User("tom",18);
			//准备Context
			Map<String,User> context = new HashMap<String,User>();
			context.put("user1", new User("isleiyi",18));
			context.put("user2", new User("Rose",19));
		
		OgnlContext oc = new OgnlContext();
		oc.setRoot(rootUser1);
		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+age);
	}

输出：tom18

2.3取出context中的属性值

@Test
	//取出context中的属性值
	public void fun3() throws OgnlException {
		//准备OGNLContext
			//准备Root
			User rootUser1 = new User("tom",18);
			//准备Context
			Map<String,User> context = new HashMap<String,User>();
			context.put("user1", new User("isleiyi",18));
			context.put("user2", new User("Rose",19));
		
		OgnlContext oc = new OgnlContext();
		oc.setRoot(rootUser1);
		oc.setValues(context);
		//书写OGNl
		//取出root中user对象的name属性
		//#从context中取值，user1从contextMap中取出user1这个键对应的值(user1这个对象的属性)
		String name1 = (String) Ognl.getValue("#user1.name", oc, oc.getRoot());
		Integer age1 = (Integer) Ognl.getValue("#user1.age", oc, oc.getRoot());
		String name2 = (String) Ognl.getValue("#user2.name", oc, oc.getRoot());
		Integer age2 = (Integer) Ognl.getValue("#user2.age", oc, oc.getRoot());
		
		System.out.println(name1+age1);
		System.out.println(name2+age2);
	}

输出：

isleiyi18
Rose19

2.4为属性赋值

@Test
	//为属性赋值
	public void fun4() throws OgnlException {
		//准备OGNLContext
			//准备Root
			User rootUser1 = new User("tom",18);
			//准备Context
			Map<String,User> context = new HashMap<String,User>();
			context.put("user1", new User("isleiyi",18));
			context.put("user2", new User("Rose",19));
		
		OgnlContext oc = new OgnlContext();
		oc.setRoot(rootUser1);
		oc.setValues(context);
		//书写OGNl
		//取出root中user对象的name属性
		//#从context中取值，user1从contextMap中取出user1这个键对应的值(user1这个对象的属性)
		Ognl.getValue("name='isqian'", oc, oc.getRoot());
		String name1 = (String) Ognl.getValue("name", oc, oc.getRoot());
		
		String name2 = (String) Ognl.getValue("#user1.name='qianqian'", oc, oc.getRoot());
		
		System.out.println(name1);
		System.out.println(name2);
	}

输出：isqian
qianqian

2.5调用getName()方法

@Test
	//调用方法
	public void fun5() throws OgnlException {
		//准备OGNLContext
			//准备Root
			User rootUser1 = new User("tom",18);
			//准备Context
			Map<String,User> context = new HashMap<String,User>();
			context.put("user1", new User("isleiyi",18));
			context.put("user2", new User("Rose",19));
		
		OgnlContext oc = new OgnlContext();
		oc.setRoot(rootUser1);
		oc.setValues(context);
		//书写OGNl
		//取出root中user对象的name属性
		//#从context中取值，user1从contextMap中取出user1这个键对应的值(user1这个对象的属性)
		
		String name = (String) Ognl.getValue("getName()", oc, oc.getRoot());
		
		System.out.println(name);
	}

输出：tom

2.6调用setName()方法

@Test
	//调用方法
	public void fun6() throws OgnlException {
		//准备OGNLContext
			//准备Root
			User rootUser1 = new User("tom",18);
			//准备Context
			Map<String,User> context = new HashMap<String,User>();
			context.put("user1", new User("isleiyi",18));
			context.put("user2", new User("Rose",19));
		
		OgnlContext oc = new OgnlContext();
		oc.setRoot(rootUser1);
		oc.setValues(context);
		//书写OGNl
		//取出root中user对象的name属性
		//#从context中取值，user1从contextMap中取出user1这个键对应的值(user1这个对象的属性)
		Ognl.getValue("setName('李雷')", oc, oc.getRoot());
		String name1 = (String) Ognl.getValue("getName()", oc, oc.getRoot());
		
		String name2 = (String) Ognl.getValue("#user1.setName('lucy'),#user1.getName()", oc, oc.getRoot());
		
		System.out.println(name1);
		System.out.println(name2);
	}

输出：

李雷
lucy
2.7调用静态方法、调用Math的PI

@Test
	//调用静态方法
	public void fun7() throws OgnlException {
		//准备OGNLContext
			//准备Root
			User rootUser1 = new User("tom",18);
			//准备Context
			Map<String,User> context = new HashMap<String,User>();
			context.put("user1", new User("isleiyi",18));
			context.put("user2", new User("Rose",19));
		
		OgnlContext oc = new OgnlContext();
		oc.setRoot(rootUser1);
		oc.setValues(context);
		//书写OGNl
		//取出root中user对象的name属性
		//#从context中取值，user1从contextMap中取出user1这个键对应的值(user1这个对象的属性)
		String name1 = (String) Ognl.getValue("@com.aisino.a_ognl.TestUtils@echo('hello leiyi')", oc, oc.getRoot());
		Double PI1 = (Double) Ognl.getValue("@java.lang.Math@PI", oc, oc.getRoot());
		Double PI2 = (Double) Ognl.getValue("@@PI", oc, oc.getRoot());
		System.out.println(name1);
		System.out.println(PI1);
		System.out.println(PI2);
	}

输出：

hello leiyi
3.141592653589793
3.141592653589793