struts2 ognl

Map<String , Object> context = new HashMap<String , Object>();

Person person1 = new Person();
person1.setName("zhangsan");

Department dep = new Department();
dep.setName("xx");
person1.setDep(dep);

Person person2 = new Person();
person2.setName("lisi");

Person person3 = new Person();
person3.setName("wangwu");

context.put("p1", person1);
context.put("p2", person2);
context.put("p3", person3);

oc.put("name", person3);
String name="";
try {
//    name = (String)Ognl.getValue("name", context,person1);
//    name = (String)Ognl.getValue("dep.name", person1);
name = (String)Ognl.getValue("#root.name",context, person1);
} catch (OgnlException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println(name);
}

进入getValue：
public static Object getValue(String expression, Map context, Object root)
throws OgnlException
{
return getValue(expression, context, root, null);
}

public static Object getValue(String expression, Map context, Object root, Class resultType)
throws OgnlException
{
return getValue(parseExpression(expression), context, root, resultType);
}

public static Object getValue(Object tree, Map context, Object root, Class resultType)
throws OgnlException
{
OgnlContext ognlContext = (OgnlContext)addDefaultContext(root, context);
Node node = (Node)tree;
Object result;
if(node.getAccessor() != null)
result = node.getAccessor().get(ognlContext, root);
else
result = node.getValue(ognlContext, root);
if(resultType != null)
result = getTypeConverter(context).convertValue(context, root, null, null, result, resultType);
return result;
}

OgnlContext ognlContext = (OgnlContext)addDefaultContext(root, context);

public static Map addDefaultContext(Object root, Map context)
{
return addDefaultContext(root, null, null, null, context);
}

public static Map addDefaultContext(Object root, ClassResolver classResolver, TypeConverter converter, MemberAccess memberAccess, Map context)
{
OgnlContext result;
if(!(context instanceof OgnlContext))
{
result = new OgnlContext();
result.setValues(context);
} else
{
result = (OgnlContext)context;
}
if(classResolver != null)
result.setClassResolver(classResolver);
if(converter != null)
result.setTypeConverter(converter);
if(memberAccess != null)
result.setMemberAccess(memberAccess);
result.setRoot(root);
return result;
}

name = (String)Ognl.getValue("#root.name",context, person1);

大概流程是：如果context不是OgnlContext，就新建一个OgnlContext再将此context设置其中
：

result = new OgnlContext();
result.setValues(context);

如果context是OgnlContext，直接转换成OgnlContext，然后设置OgnlContext的root：

result.setRoot(root);