Struts2框架(三) ------ OGNL表达式

一  ognl基本语法

 1.核心思想

2.基本语法

    2.1 创建一个User类

public class User {
	private String name;
	private Integer 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;
	}
	public User(String name, Integer age) {
		super();
		this.name = name;
		this.age = age;
	}
	public User() {
		super();
	}

}

    2.2 创建一个工具类

public class StaticUtils {
	
	public static Object echo(Object o){
		return o;
	}

}

    2.3 通过构造函数获取属性的值

	@Test
	public void fun1() throws OgnlException{
		//1.初始化root
		User rootUser = new User("AMYSKY",3);
		//2.初始化ognlcontext
		Map<String,User> context = new HashMap<String,User>();
		context.put("user1",new User("tom",18));
		context.put("user2",new User("lucy",22));
		OgnlContext oc = new OgnlContext();
		//3.封装ognl中的root部分
		oc.setRoot(rootUser);
		//4.封装Context部分
		oc.setValues(context);
		//5.书写ognl表达式 获取root部分的值
		Object name = Ognl.getValue("name", oc, oc.getRoot());
		Object age = Ognl.getValue("age", oc, oc.getRoot());
		System.out.println("name ="+name+",age="+age);
		//6.获取context部分的值
		Object user1name = Ognl.getValue("#user1.name", oc, oc.getRoot());
		Object user1age = Ognl.getValue("#user1.age", oc, oc.getRoot());
		System.out.println("user1name ="+user1name+",user1age="+user1age);
	}

    2.4 为属性赋值

@Test
	public void fun2() throws OgnlException{
		//1.初始化root
		User rootUser = new User("AMYSKY",3);
		//2.初始化ognlcontext
		Map<String,User> context = new HashMap<String,User>();
		context.put("user1",new User("tom",18));
		context.put("user2",new User("lucy",22));
		OgnlContext oc = new OgnlContext();
		//3.封装ognl中的root部分
		oc.setRoot(rootUser);
		//4.封装Context部分
		oc.setValues(context);
		//5.书写ognl表达式 ，为root属性赋值
		Object name = Ognl.getValue("name='zhangsan'", oc, oc.getRoot());
		Object age = Ognl.getValue("age= 30", oc, oc.getRoot());
		System.out.println("name ="+name+",age="+age);
		//6.为context部分的属性先赋值后获取
		Object user1name = Ognl.getValue("#user1.name='天元陆兵',#user1.name", oc, oc.getRoot());
		Object user1age = Ognl.getValue("#user1.age=3,#user1.age", oc, oc.getRoot());
		System.out.println("user1name ="+user1name+",user1age="+user1age);
	}

    2.5 通过setxx()和getxx()方法为属性赋值

 

@Test
	public void fun3() throws OgnlException{
		//1.初始化root
		User rootUser = new User("AMYSKY",3);
		//2.初始化ognlcontext
		Map<String,User> context = new HashMap<String,User>();
		context.put("user1",new User("tom",18));
		context.put("user2",new User("lucy",22));
		OgnlContext oc = new OgnlContext();
		//3.封装ognl中的root部分
		oc.setRoot(rootUser);
		//4.封装Context部分
		oc.setValues(context);
		//5.书写ognl表达式 ，调用set()方法，为root属性赋值
		Ognl.getValue("setName('lisi')", oc, oc.getRoot());
		Object name = Ognl.getValue("getName()", oc, oc.getRoot());
		Ognl.getValue("setAge(20)", oc, oc.getRoot());
		Object age = Ognl.getValue("getAge()", oc, oc.getRoot());
		System.out.println("name ="+name+",age="+age);
		//6.为context部分的属性调用set()方法赋值
		Object user1name = Ognl.getValue("#user1.setName('天元神兵'),#user1.getName()", oc, oc.getRoot());
		Object user1age = Ognl.getValue("#user1.setAge(3),#user1.getAge()", oc, oc.getRoot());
		System.out.println("user1name ="+user1name+",user1age="+user1age);
	}

    2.6  使用静态方法赋值

@Test
	public void fun4() throws OgnlException{
		//1.初始化root
		User rootUser = new User("AMYSKY",3);
		//2.初始化ognlcontext
		Map<String,User> context = new HashMap<String,User>();
		context.put("user1",new User("tom",18));
		context.put("user2",new User("lucy",22));
		OgnlContext oc = new OgnlContext();
		//3.封装ognl中的root部分
		oc.setRoot(rootUser);
		//4.封装Context部分
		oc.setValues(context);
		//5.书写ognl表达式 ，使用静态方法为root属性赋值
		
		Object name = Ognl.getValue("@[e-mail]('乔峰')", oc, oc.getRoot());
		Object age = Ognl.getValue("@[e-mail](34)", oc, oc.getRoot());
		System.out.println("name ="+name+",age="+age);
		//6.为context部分的属性调用静态方法赋值 如果是Math类可以省略
		Object user1name = Ognl.getValue("@[e-mail]", oc, oc.getRoot());
		Object user1age = Ognl.getValue("@@PI", oc, oc.getRoot());
		System.out.println("user1name ="+user1name+",user1age="+user1age);
	}

    2.7 list和Map对象赋值

@Test
	public void fun5() throws OgnlException{
		//1.初始化root
		User rootUser = new User("AMYSKY",3);
		//2.初始化ognlcontext
		Map<String,User> context = new HashMap<String,User>();
		context.put("user1",new User("tom",18));
		context.put("user2",new User("lucy",22));
		OgnlContext oc = new OgnlContext();
		//3.封装ognl中的root部分
		oc.setRoot(rootUser);
		//4.封装Context部分
		oc.setValues(context);
		//5.书写ognl表达式 ，创建list对象
		Integer size = (Integer) Ognl.getValue("{'tom','jim','lilei','lucy','lili'}.size()", oc, oc.getRoot());
		String name = (String) Ognl.getValue("{'tom','jim','lilei','lucy','lili'}[3]", oc, oc.getRoot());
		String name1 = (String) Ognl.getValue("{'tom','jim','lilei','lucy','lili'}.get(1)", oc, oc.getRoot());
		System.out.println("size ="+size+",name="+name+",name1="+name1);
		//6.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 ="+size2+",name3="+name3+",age="+age);
	}

二.OGNL与Struct2结合

1.原理

2.属性驱动接收参数原理

3.对象驱动接收参数原理

4.模型驱动接收参数原理

/**
 * * 下面的两个接口在真正开发的时候我们只用其一就可以
 *   一般是实现ModelDrive接口
 */
public class Demo2Action extends ActionSupport implements Preparable,ModelDriven<User>{
	private User user = new User();
	
	public String execute() throws Exception {
		
		System.out.println(user);
		return SUCCESS;
	}
	/**
	 * 查看Preparable接口的源码可以现模型驱动方式接收数据需要我们手动压栈
	 */
	@Override
	public void prepare() throws Exception {
		//压入栈顶
				//1获得值栈
				ValueStack vs = ActionContext.getContext().getValueStack();
				//2将u压入栈顶
				vs.push(user);
	}
	/**
	 * ModelDriven的源码已经实现了压栈操作
	 * 我们只需返回就可以了。
	 * @return
	 */
	@Override
	public User getModel() {
		return user;
	}

}

5.配置文件中使用ognl表达式获取调转的动态参数

public class Demo3Action extends ActionSupport{
	private String name;

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String execute() throws Exception {
		
		name ="amysky";
		return SUCCESS;
	}
	
}

三.Struts2源码扩展

     request的查找顺序