OGNL（Object-Graph Navigation Language）：对象视图导航语言
${user.addr.name}这样的写法就叫对象视图导航
OGNL不仅可以视图导航，支持EL表达式更加丰富的功能
EL表达式取值要从11个内置对象中取：requestScope、sessionScope、applicationScope、pageScope、 pageContext、params、paramValues、header、headerValues、cookie、initParams
OGNL表达式取值要从OGNLContext中取值，在Ognl上下文中有Root部分和Context部分，Root部分放置任何对象作为root都可以，Context部分必须是Map类型
使用OGNL准备工作
导包->struts2的包中已经包含了，所以不需要导入额外的jar包
书写代码
@Test
//准备工作
public void fun1() throws Exception{
//准备ONGL Context
//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 在双引号里写OGNL表达式即可
Ognl.getValue("", oc, oc.getRoot());
}
OGNL基本语法演示 取出root的值
@Test
//基本语法演示
//取出oot中的属性值
public void fun2() throws OgnlException{
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);
//书写OGNL
//取出root中user对象的name属性
String name = (String) Ognl.getValue("name", oc, oc.getRoot());
String age = (String) Ognl.getValue("age", oc, oc.getRoot());
System.out.println(name+" "+age);
}
tom 18
OGNL取出Context的值
@Test
//基本语法演示
//取出context中的属性值
public void fun3() throws OgnlException{
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);
//书写OGNL
String name = (String) Ognl.getValue("#user1.name", oc, oc.getRoot());
String name2 = (String) Ognl.getValue("#user2.name", oc, oc.getRoot());
String age = (String) Ognl.getValue("#user2.age", oc, oc.getRoot());
System.out.println(name);
System.out.println(name2);
System.out.println(age);
}
jack
rose
22
OGNL赋值语法
@Test
//赋值
public void fun4() throws OgnlException{
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); Ognl.getValue("name='jerry'", oc, oc.getRoot());
String name = (String) Ognl.getValue("name", oc, oc.getRoot());
//书写OGNL
String name2 = (String) Ognl.getValue("#user1.name='zao',#user1.name", oc, oc.getRoot());
System.out.println(name);
System.out.println(name2);
}
jerry
zao
OGNL方法调用
@Test
//调用方法
public void fun5() throws OgnlException{
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);
//书写OGNL
Ognl.getValue("setName('lilei')", oc, oc.getRoot());
String name = (String) Ognl.getValue("getName()", oc, oc.getRoot()); String name2 = (String) Ognl.getValue("#user1.setName('lucy'),#user1.getName()", oc, oc.getRoot());
System.out.println(name);
System.out.println(name2);
}
lilei
lucy
OGNL调用静态方法和静态常量
注意下面表达式
@全类名@方法名('传参')
@全类名@常量名
@@常量名
@Test
public void fun6() throws OgnlException{
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);
//书写OGNL
String name = (String) Ognl.getValue("@cn.itheima.a_ognl.HahaUtils@echo('hello shijie')", oc, oc.getRoot());
Double pi = (Double) Ognl.getValue("@java.lang.Math@PI", oc, oc.getRoot());
Double pi1 = (Double) Ognl.getValue("@@PI", oc, oc.getRoot());
System.out.println(name);
System.out.println(pi);
System.out.println(pi1);
}
hello shijie
3.141592653589793
3.141592653589793
OGNL创建 list map集合
@Test
public void fun7() throws OgnlException{
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);
//书写OGNL
//创建list对象
Integer size = (Integer) Ognl.getValue("{'tom','jerr','jack'}.size()", oc, oc.getRoot());
String name = (String) Ognl.getValue("{'tom','jerr','jack'}[0]", oc, oc.getRoot());
String name2 = (String) Ognl.getValue("{'tom','jerr','jack'}.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);
}
3
tom
jerr
2
tom
18