// by writing '{ id: '@id' }' we want the id to be taken from 'id' parameter in request data,hence the '@' sign. Note that this mechanism is available for non-GET RQs only:
var Notes = $resource('/notes/:id',{ id: '@id' });
 
var noteId = "my_note1";
// below we specify 'id' explicitly - has to be done for GET RQ:
// operations on our note are done inside callback function,just to make sure that the note is resolved:
var note = Notes.get({ id: noteId },function () {
 
    // let's make some changes:
    note.topic = "A brand new topic here!";
 
    // save using $resource "static" action (aka "class" action). 'id' is taken from data object:
    Notes.save(note);
    // We can overwrite 'id' just like this: 
    Notes.save({ id: "some_other_noteId" },note);
 
    // even more changes:
    note.body = "Blah blah blah,new boring body is here";
 
    // this time save using instance action. Again: 'id' is taken from data object:
    note.$save();
    // changing id with instance action? there you go:
    note.$save({ id: "yet_another_noteId" });
 
    // Naturally,we could just:
    note.id = "OMG_how_many_of_those_noteIds_has_he_left";
    Notes.save(note);
    // ... and with instance action:
    note.id = "OK_he_wins";
    note.$save();
});

即使自定义$资源操作(由您定义)也可以使用$-prefixed对等方,只要它们不是GET – 请参见http://docs.angularjs.org/api/ngResource.$resource#example_creating-a-custom-put-request.
而不是,并不是所有的动作都有实例方法版本.在实例上调用GET的要点是什么？从官方ngResource文档：

The action methods on the class object or instance object can be invoked with the following parameters:

• HTTP GET “class” actions: Resource.action([parameters],[success],[error])
• non-GET “class” actions: Resource.action([parameters],postData,[error])
• non-GET instance actions: instance.$action([parameters],[error])