Struts2 Learner03

OGNL
Object graphic Navgation language 对象图形的导航语言

org.zttc.itat.model下面三个class
Department.class
Role.class
User.class

package org.zttc.itat.model;
public class User//两个构造函数
{
private int id;
private String username;
private String nickname;
private Department dep;
//以上成员变量全部都有get和set方法

//method
public int sum(int a, int b)
{
return a + b;
}

public String hello(String word)
{
return "hello" + word;
}
}
----------------------------------------------------------------------------
package org.zttc.itat.model;
public class Department
{
private String name;
//get and set
}
}
-----------------------------------------------------------------------------
package org.zttc.itat.model;

/**
* Created by Melody on 2015/11/7.
*/
public class Role
{
private int id;
private String name;
//构造函数和get set方法
}
-----------------------------------------------------------------------------
Test
package org.zttc.itat.test;
import ognl.Ognl;
import ognl.OgnlException;
import org.junit.Test;
import org.zttc.itat.model.*;
import java.util.*;

public class TestOngl
{
@Test
public void test01() throws OgnlException
{
User u = new User(1, "tangseng", "唐僧");
Department dep = new Department("财务处");
u.setDep(dep);

//第二个参数是root
System.out.println(Ognl.getValue("nickname", u));//唐僧

//从u里面找dep dep里面找name
System.out.println(Ognl.getValue("dep.name", u));//财务处
}

@Test
public void test02() throws OgnlException
{
Map<String, Object> ctx = new HashMap<String, Object>();
User u = new User(1, "tangseng", "唐僧");
Department dep = new Department("财务处");
u.setDep(dep);

Role r = new Role(1, "Admin");
ctx.put("user", u);
ctx.put("role", r);

//想找根u里面的对象
//没加# 是在root中找 加了#是在ctx中找
System.out.println(Ognl.getValue("username", ctx, u));//唐僧

//想找ctx里面的对象 #user.username是在ctx这个map中找
//ctx是一个map{"user", u} (String, Object)
//ActionContext.getContext()是一个map 所以后面也要加#
System.out.println(Ognl.getValue("#user.username", ctx, u));//唐僧
System.out.println(Ognl.getValue("#role.name", ctx, u));//Admin

//Ogn其实就是一个最大的Context,根的key就是root 所以可以根据#root.***来取
//所有东西有个最大的根context(map)里面有个root里面放的是u
System.out.println(Ognl.getValue("#root.username", ctx, u));//
}

@Test
public void test03() throws OgnlException
{
List<User> users = new ArrayList<User>();
users.add(new User(1, "ts", "唐僧"));
users.add(new User(2, "ss", "沙僧"));
users.add(new User(3, "bj", "八戒"));
users.add(new User(4, "wk", "悟空"));

//如果要取list中的元素 需要通过#root[index] 来完成取值
System.out.println(Ognl.getValue("#root[1].nickname", users));//沙僧

//看到没有 ognl还可以完成方法的调用
System.out.println(Ognl.getValue("#root[0].sum(1, 3)", users));//沙僧

//访问了u的hello(Stirng) 方法 注意里面的String要加''
User u = new User();
System.out.println(Ognl.getValue("hello('world')", u));

//可以通过List(java的集合)中的中get()方法获取某个下标的对象 然后完成导航
System.out.println(Ognl.getValue("get(0).username", users));
/*
沙僧
4
helloworld
ts
*/
}

}