Question

由于我是Xamarin的新手，如果有人能用最简单的例子使用Xamarin Forms解释如何使用RESTful服务（返回JSON数据），我将非常感激。

Answer 1

您可以使用JSON.net和HTTP请求，这里有一个如何使用电影数据库的快速示例，这是一个免费的电影数据库GET和POST示例，希望这有帮助：

const string _baseUrl = "http://api.themoviedb.org/3/";
const string _pageString = "&page=";

//GET Example
public static async Task<ObservableCollection<Movie>> GetTopRatedMoviesAsync(int page = 1)
{
    HttpClient client = new HttpClient();
    //_apiKey = themoviedb api key, page = page size 1 = first 20 movies;
    string topRatedUrl = _baseUrl + "movie/top_rated?" + _apiKey + _pageString + page;
    HttpResponseMessage result = await client.GetAsync (topRatedUrl, CancellationToken.None);

    if (result.IsSuccessStatusCode) {
        try{
            string content = await result.Content.ReadAsStringAsync ();
            ObservableCollection<Movie> MovieList = GetJsonData(content);
            //return a ObservableCollection to fill a list of top rated movies
            return MovieList;

        }catch(Exception ex){
            //Model Error
            Console.WriteLine (ex);
            return null;
        }
    }
    //Server Error or no internet connection.
    return null;
}


static ObservableCollection<Movie> GetJsonData(string content){

    JObject jresponse = JObject.Parse (content);
    var jarray = jresponse ["results"];
    ObservableCollection<Movie> movieList = new ObservableCollection<Movie> ();

    foreach (var jObj in jarray) {
        Movie newMovie = new Movie();
        newMovie.Title = (string)jObj["title"];
        newMovie.PosterPath = _baseImgUrl + (string)jObj["poster_path"];
        newMovie.HighResPosterPath = _baseImgUrl + (string)jObj["poster_path"];
        newMovie.Id = (int)jObj["id"];
        newMovie.Overview = (string)jObj["overview"];
        newMovie.VoteCount = (double)jObj["vote_count"];
        newMovie.ReleaseDate = (DateTime)jObj["release_date"];
        newMovie.VoteAverage = (float)jObj["vote_average"];
        movieList.Add(newMovie);
    }
    return movieList;
}

//POST Example:
public static async Task<bool> PostFavoriteMovieAsync(Movie movie)
{
    try 
    {
        HttpClient client = new HttpClient();
        //_sessionId = string with the movie database session.
        string tokenUrl = _baseUrl + "account/id/favorite?" + _apiKey + _sessionId;
        string postBody = JsonConvert.SerializeObject(new Favorite{
            favorite = !movie.Favorite,
            media_id = movie.Id,
        });

        client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
        HttpResponseMessage response = await client.PostAsync (tokenUrl, 
            new StringContent (postBody, Encoding.UTF8, "application/json"));

        if(response.IsSuccessStatusCode)
            return true;
        else
            return false;   
    }
    catch(Exception ex){
        Console.WriteLine (ex.Message);
        return false;
    }
}

如何在Xamarin.Forms中使用RESTful服务来获取JSON数据

1 个答案: