HTTP 知识总结(四) OkHttp3 的使用

参考链接：

square:  http://square.github.io/okhttp/

github: https://github.com/square/okhttp

Okhttp是square推出的一个支持Http1.1和Http2.0的客户端（不知道支持1.0不，抽时间确认一下）。打开上面的链接，就可以看到square官方的简短介绍，然后后面给了示例代码。okhttp支持同步和异步请求。HttpURLConnection和Httpclient本身是没有对异步的支持的，需要的话可以自己封装。Android之前推出的Volley是对httpclient和httpurlconnection的封装。（根据不同的版本选择使用HttpClient还是 HttpURLConnection).

个人认为，OkHttp3最大的好处就是接口使用方便，官方文档里也这么说了：

Using OkHttp is easy. Its request/response API is designed with fluent builders and immutability. It supports both synchronous blocking calls and async calls with callbacks.

然后，okhttp支持 Android 2.3及以上，以及java1.7及以上。

下面把官方的使用例子贴出来.例子中使用的是同步方法，异步方法调用equeue把call扔进队列，然后设置callback即可，与其他异步机制使用大同小异。

GET:

package okhttp3.guide;

import java.io.IOException;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public class GetExample {
  OkHttpClient client = new OkHttpClient();

  String run(String url) throws IOException {
    Request request = new Request.Builder()
        .url(url)
        .build();

    try (Response response = client.newCall(request).execute()) {
      return response.body().string();
    }
  }

  public static void main(String[] args) throws IOException {
    GetExample example = new GetExample();
    String response = example.run("https://raw.github.com/square/okhttp/master/README.md");
    System.out.println(response);
  }
}

POST:

package okhttp3.guide;

import java.io.IOException;
import okhttp3.MediaType;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;

public class PostExample {
  public static final MediaType JSON = MediaType.get("application/json; charset=utf-8");

  OkHttpClient client = new OkHttpClient();

  String post(String url, String json) throws IOException {
    RequestBody body = RequestBody.create(JSON, json);
    Request request = new Request.Builder()
        .url(url)
        .post(body)
        .build();
    try (Response response = client.newCall(request).execute()) {
      return response.body().string();
    }
  }

  String bowlingJson(String player1, String player2) {
    return "{'winCondition':'HIGH_SCORE',"
        + "'name':'Bowling',"
        + "'round':4,"
        + "'lastSaved':1367702411696,"
        + "'dateStarted':1367702378785,"
        + "'players':["
        + "{'name':'" + player1 + "','history':[10,8,6,7,8],'color':-13388315,'total':39},"
        + "{'name':'" + player2 + "','history':[6,10,5,10,10],'color':-48060,'total':41}"
        + "]}";
  }

  public static void main(String[] args) throws IOException {
    PostExample example = new PostExample();
    String json = example.bowlingJson("Jesse", "Jake");
    String response = example.post("http://www.roundsapp.com/post", json);
    System.out.println(response);
  }
}