Web API 简单示例

一、RESTful和Web API

　　Representational State Transfer (REST) is a software architecture style consisting of guidelines and best practices for creating scalable web services. REST is a coordinated set of constraints applied to the design of components in a distributed hypermdedia system that can lead to a more performant and maintainable architecture. 　-- wikipedia　

　　ASP.NET Web API is a framework that makes it easy to build HTTP services that reach a broad range of clients, including browsers and mobile devices. ASP.NET Web API is an ideal platform for building RESTful applications on the .NET Framework.

　　原来RESTful是一种软件架构风格（REST是一种设计风格，而不是一种标准），而ASP.NET Web API是其在.NET平台的一种标准/实现。目前在三种主流的Web Services实现方案中，因为REST模式与复杂的SOAP和XML -PRC相比更加简洁，越来越多的web服务开始采用REST风格设计和实现。

　　ASP.NET整体框架结构如下图。可以看出，Web API支持JSON和XML，面向的是多种客户终端，包括多浏览器和各种移动设备。

二、简单示例

　　新建ASP.NET Web Application，命名NBAApp

　　选择Empty模板，下面选择Web API，更改Authentication为No Authentication

　　新建一个Model - Player

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace NBAApp.Models
{
    public class Player
    {
        public int Id { get; set; }
        public int No { get; set; }
        public string Name { get; set; }
        public string Position { get; set; }
        public string Team { get; set; }
    }
}

　　新建Controller - PlayersController，模板选择Web API 2 Controller - Empty

　　编辑代码如下

using NBAApp.Models;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web.Http;

namespace NBAApp.Controllers
{
    public class PlayersController : ApiController
    {
        Player[] players = new Player[] {
            new Player { Id = 1, No = 3, Name = "Chris Paul", Position = "Point Guard", Team = "Los Angeles Clippers" },
            new Player { Id = 2, No = 3, Name = "Dwyane Wade", Position = "Shooting Guard", Team = "Miami Heat" },
            new Player { Id = 3, No = 23, Name = "LeBron James", Position = "Forward", Team = "Cleveland Cavaliers" },
            new Player { Id = 4, No = 21, Name = "Tim Duncan", Position = "Power forward", Team = "San Antonio Spurs" },
            new Player { Id = 5, No = 33, Name = "Marc Gasol", Position = "Center", Team = "Memphis Grizzlies" }
        };

        public IEnumerable<Player> GetAllPlayers()
        {
            return players;
        }

        public IHttpActionResult GetPlayer(int id)
        {
            var player = players.FirstOrDefault<Player>(p => p.Id == id);
            if (player == null)
            {
                return NotFound();
            }
            return Ok(player);
        }
    }
}

　　添加Html - Index.html页面

　　编辑代码如下

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>NBA App</title>
</head>
<body>

    <div>
        <h2>All Players</h2>
        <ul id="players" />
    </div>
    <div>
        <h2>Search by ID</h2>
        <input type="text" id="prodId" size="5" />
        <input type="button" value="Search" onclick="find();" />
        <p id="player" />
    </div>

    <script src="http://ajax.aspnetcdn.com/ajax/jQuery/jquery-2.0.3.min.js"></script>
    <script>
        var uri = ‘api/players‘;

        $(document).ready(function () {
            // Send an AJAX request
            $.getJSON(uri)
                .done(function (data) {
                    // On success, ‘data‘ contains a list of players.
                    $.each(data, function (key, item) {
                        // Add a list item for the player.
                        $(‘<li>‘, { text: formatItem(item) }).appendTo($(‘#players‘));
                    });
                });
        });

        function formatItem(item) {
            return item.Id + ": " + item.Name + "(" + item.No + ‘)‘ + " - " + item.Team + "(" + item.Position + ")";
        }

        function find() {
            var id = $(‘#prodId‘).val();
            $.getJSON(uri + ‘/‘ + id)
                .done(function (data) {
                    $(‘#player‘).text(formatItem(data));
                })
                .fail(function (jqXHR, textStatus, err) {
                    $(‘#player‘).text(‘Error: ‘ + err);
                });
        }
    </script>
</body>
</html>

　　执行效果如下（Chrome浏览器）