Android OkHttp完全解析 --zz

参考文章

https://github.com/square/okhttp
http://square.github.io/okhttp/
泡网OkHttp使用教程
Android OkHttp完全解析是时候来了解OkHttp了 - Hongyang - 博客频道 - CSDN.NET
http://blog.csdn.net/lmj623565791/article/details/47911083

一、概述

最近在群里听到各种讨论okhttp的话题，可见okhttp的口碑相当好了。再加上Google貌似在6.0版本里面删除了HttpClient相关API，对于这个行为不做评价。为了更好的在应对网络访问，学习下okhttp还是蛮必要的，本篇博客首先介绍okhttp的简单使用，主要包含：

一般的get请求
一般的post请求
基于Http的文件上传
文件下载
加载图片
支持请求回调，直接返回对象、对象集合
支持session的保持

最后会对上述几个功能进行封装，完整的封装类的地址见：https://github.com/hongyangAndroid/okhttp-utils

使用前，对于Android Studio的用户，可以选择添加:

compile 'com.squareup.okhttp:okhttp:2.4.0'

或者Eclipse的用户，可以下载最新的jar okhttp he latest JAR，添加依赖就可以用了。

注意:okhttp内部依赖okio，别忘了同时导入okio：

gradle: compile 'com.squareup.okio:okio:1.5.0'

最新的jar地址：okio the latest JAR

二、使用教程

（一）Http Get

对了网络加载库，那么最常见的肯定就是http get请求了，比如获取一个网页的内容。

//创建okHttpClient对象

OkHttpClient mOkHttpClient = new OkHttpClient();

//创建一个Request

final Request request = new Request.Builder()

                .url("https://github.com/hongyangAndroid")

                .build();

//new call

Call call = mOkHttpClient.newCall(request);

//请求加入调度

call.enqueue(new Callback()

        {

            @Override

            public void onFailure(Request request, IOException e)

            {

            }

            @Override

            public void onResponse(final Response response) throws IOException

            {

                    //String htmlStr =  response.body().string();

            }

        });

以上就是发送一个get请求的步骤，首先构造一个Request对象，参数最起码有个url，当然你可以通过Request.Builder设置更多的参数比如：header、method等。
然后通过request的对象去构造得到一个Call对象，类似于将你的请求封装成了任务，既然是任务，就会有execute()和cancel()等方法。
最后，我们希望以异步的方式去执行请求，所以我们调用的是call.enqueue，将call加入调度队列，然后等待任务执行完成，我们在Callback中即可得到结果。

看到这，你会发现，整体的写法还是比较长的，所以封装肯定是要做的，不然每个请求这么写，得累死。

ok，需要注意几点：

onResponse回调的参数是response，一般情况下，比如我们希望获得返回的字符串，可以通过response.body().string()获取；如果希望获得返回的二进制字节数组，则调用response.body().bytes()；如果你想拿到返回的inputStream，则调用response.body().byteStream()

看到这，你可能会奇怪，竟然还能拿到返回的inputStream，看到这个最起码能意识到一点，这里支持大文件下载，有inputStream我们就可以通过IO的方式写文件。不过也说明一个问题，这个onResponse执行的线程并不是UI线程。的确是的，如果你希望操作控件，还是需要使用handler等，例如：
```
@Override

public void onResponse(final Response response) throws IOException

{

      final String res = response.body().string();

      runOnUiThread(new Runnable()

      {

          @Override

          public void run()

          {

            mTv.setText(res);

          }

      });

}
```
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我们这里是异步的方式去执行，当然也支持阻塞的方式，上面我们也说了Call有一个execute()方法，你也可以直接调用call.execute()通过返回一个Response。

(二) Http Post 携带参数

看来上面的简单的get请求，基本上整个的用法也就掌握了，比如post携带参数，也仅仅是Request的构造的不同。

Request request = buildMultipartFormRequest(

        url, new File[]{file}, new String[]{fileKey}, null);

FormEncodingBuilder builder = new FormEncodingBuilder();

builder.add("username","张鸿洋");

Request request = new Request.Builder()

                   .url(url)

                .post(builder.build())

                .build();

 mOkHttpClient.newCall(request).enqueue(new Callback(){});

大家都清楚，post的时候，参数是包含在请求体中的；所以我们通过FormEncodingBuilder。添加多个String键值对，然后去构造RequestBody，最后完成我们Request的构造。

后面的就和上面一样了。

（三）基于Http的文件上传

接下来我们在介绍一个可以构造RequestBody的Builder，叫做MultipartBuilder。当我们需要做类似于表单上传的时候，就可以使用它来构造我们的requestBody。

File file = new File(Environment.getExternalStorageDirectory(), "balabala.mp4");

RequestBody fileBody = RequestBody.create(MediaType.parse("application/octet-stream"), file);

RequestBody requestBody = new MultipartBuilder()

     .type(MultipartBuilder.FORM)

     .addPart(Headers.of(

          "Content-Disposition",

              "form-data; name=\"username\""),

          RequestBody.create(null, "张鸿洋"))

     .addPart(Headers.of(

         "Content-Disposition",

         "form-data; name=\"mFile\";

         filename=\"wjd.mp4\""), fileBody)

     .build();

Request request = new Request.Builder()

    .url("http://192.168.1.103:8080/okHttpServer/fileUpload")

    .post(requestBody)

    .build();

Call call = mOkHttpClient.newCall(request);

call.enqueue(new Callback()

{

    //...

});

上述代码向服务器传递了一个键值对username:张鸿洋和一个文件。我们通过MultipartBuilder的addPart方法可以添加键值对或者文件。

其实类似于我们拼接模拟浏览器行为的方式，如果你对这块不了解，可以参考：从原理角度解析Android （Java） http 文件上传

ok，对于我们最开始的目录还剩下图片下载，文件下载；这两个一个是通过回调的Response拿到byte[]然后decode成图片；文件下载，就是拿到inputStream做写文件操作，我们这里就不赘述了。

关于用法，也可以参考泡网OkHttp使用教程

接下来我们主要看如何封装上述的代码。

三、封装

由于按照上述的代码，写多个请求肯定包含大量的重复代码，所以我希望封装后的代码调用是这样的：

（一）使用

一般的get请求

 OkHttpClientManager.getAsyn("https://www.baidu.com", new OkHttpClientManager.ResultCallback<String>()

        {

            @Override

            public void onError(Request request, Exception e)

            {

                e.printStackTrace();

            }

            @Override

            public void onResponse(String u)

            {

                mTv.setText(u);//注意这里是UI线程

            }

        });

对于一般的请求，我们希望给个url，然后CallBack里面直接操作控件。

文件上传且携带参数

我们希望提供一个方法，传入url,params,file,callback即可。

  OkHttpClientManager.postAsyn("http://192.168.1.103:8080/okHttpServer/fileUpload",//

    new OkHttpClientManager.ResultCallback<String>()

    {

        @Override

        public void onError(Request request, IOException e)

        {

            e.printStackTrace();

        }

        @Override

        public void onResponse(String result)

        {

        }

    },//

    file,//

    "mFile",//

    new OkHttpClientManager.Param[]{

            new OkHttpClientManager.Param("username", "zhy"),

            new OkHttpClientManager.Param("password", "123")}

        );

键值对没什么说的，参数3为file，参数4为file对应的name，这个name不是文件的名字；
对应于http中的

<input type="file" name="mFile" >

对应的是name后面的值，即mFile.

文件下载

对于文件下载，提供url，目标dir，callback即可。

OkHttpClientManager.downloadAsyn(

    "http://192.168.1.103:8080/okHttpServer/files/messenger_01.png",

    Environment.getExternalStorageDirectory().getAbsolutePath(),

new OkHttpClientManager.ResultCallback<String>()

    {

        @Override

        public void onError(Request request, IOException e)

        {

        }

        @Override

        public void onResponse(String response)

        {

            //文件下载成功，这里回调的reponse为文件的absolutePath

        }

});

展示图片

展示图片，我们希望提供一个url和一个imageview，如果下载成功，直接帮我们设置上即可。
```
 OkHttpClientManager.displayImage(mImageView,

     "http://images.csdn.net/20150817/1.jpg");
```
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内部会自动根据imageview的大小自动对图片进行合适的压缩。虽然，这里可能不适合一次性加载大量图片的场景，但是对于app中偶尔有几个图片的加载，还是可用的。

四、整合Gson

很多人提出项目中使用时，服务端返回的是Json字符串，希望客户端回调可以直接拿到对象，于是整合进入了Gson，完善该功能。

（一）直接回调对象

例如现在有个User实体类：

package com.zhy.utils.http.okhttp;

public class User {

    public String username ;

    public String password  ;

    public User() {

        // TODO Auto-generated constructor stub

    }

    public User(String username, String password) {

        this.username = username;

        this.password = password;

    }

    @Override

    public String toString()

    {

        return "User{" +

                "username='" + username + '\'' +

                ", password='" + password + '\'' +

                '}';

    }

}

服务端返回：

{"username":"zhy","password":"123"}

客户端可以如下方式调用：

 OkHttpClientManager.getAsyn("http://192.168.56.1:8080/okHttpServer/user!getUser",

new OkHttpClientManager.ResultCallback<User>()

{

    @Override

    public void onError(Request request, Exception e)

    {

        e.printStackTrace();

    }

    @Override

    public void onResponse(User user)

    {

        mTv.setText(u.toString());//UI线程

    }

});

我们传入泛型User，在onResponse里面直接回调User对象。
这里特别要注意的事，如果在json字符串->实体对象过程中发生错误，程序不会崩溃，onError方法会被回调。

注意：这里做了少许的更新，接口命名从StringCallback修改为ResultCallback。接口中的onFailure方法修改为onError。

(二) 回调对象集合

依然是上述的User类，服务端返回

[{"username":"zhy","password":"123"},{"username":"lmj","password":"12345"}]

则客户端可以如下调用：

OkHttpClientManager.getAsyn("http://192.168.56.1:8080/okHttpServer/user!getUsers",

new OkHttpClientManager.ResultCallback<List<User>>()

{

    @Override

    public void onError(Request request, Exception e)

    {

        e.printStackTrace();

    }

    @Override

    public void onResponse(List<User> us)

    {

        Log.e("TAG", us.size() + "");

        mTv.setText(us.get(1).toString());

    }

});

唯一的区别，就是泛型变为List<User> ，ok ，如果发现bug或者有任何意见欢迎留言。

源码

ok，基本介绍完了，对于封装的代码其实也很简单，我就直接贴出来了，因为也没什么好介绍的，如果你看完上面的用法，肯定可以看懂：

package com.zhy.utils.http.okhttp;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

import android.os.Handler;

import android.os.Looper;

import android.widget.ImageView;

import com.google.gson.Gson;

import com.google.gson.internal.$Gson$Types;

import com.squareup.okhttp.Call;

import com.squareup.okhttp.Callback;

import com.squareup.okhttp.FormEncodingBuilder;

import com.squareup.okhttp.Headers;

import com.squareup.okhttp.MediaType;

import com.squareup.okhttp.MultipartBuilder;

import com.squareup.okhttp.OkHttpClient;

import com.squareup.okhttp.Request;

import com.squareup.okhttp.RequestBody;

import com.squareup.okhttp.Response;

import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.lang.reflect.ParameterizedType;

import java.lang.reflect.Type;

import java.net.CookieManager;

import java.net.CookiePolicy;

import java.net.FileNameMap;

import java.net.URLConnection;

import java.util.HashMap;

import java.util.Map;

import java.util.Set;

/**

 * Created by zhy on 15/8/17.

 */

public class OkHttpClientManager

{

    private static OkHttpClientManager mInstance;

    private OkHttpClient mOkHttpClient;

    private Handler mDelivery;

    private Gson mGson;

    private static final String TAG = "OkHttpClientManager";

    private OkHttpClientManager()

    {

        mOkHttpClient = new OkHttpClient();

        //cookie enabled

        mOkHttpClient.setCookieHandler(new CookieManager(null, CookiePolicy.ACCEPT_ORIGINAL_SERVER));

        mDelivery = new Handler(Looper.getMainLooper());

        mGson = new Gson();

    }

    public static OkHttpClientManager getInstance()

    {

        if (mInstance == null)

        {

            synchronized (OkHttpClientManager.class)

            {

                if (mInstance == null)

                {

                    mInstance = new OkHttpClientManager();

                }

            }

        }

        return mInstance;

    }

    /**

     * 同步的Get请求

     *

     * @param url

     * @return Response

     */

    private Response _getAsyn(String url) throws IOException

    {

        final Request request = new Request.Builder()

                .url(url)

                .build();

        Call call = mOkHttpClient.newCall(request);

        Response execute = call.execute();

        return execute;

    }

    /**

     * 同步的Get请求

     *

     * @param url

     * @return 字符串

     */

    private String _getAsString(String url) throws IOException

    {

        Response execute = _getAsyn(url);

        return execute.body().string();

    }

    /**

     * 异步的get请求

     *

     * @param url

     * @param callback

     */

    private void _getAsyn(String url, final ResultCallback callback)

    {

        final Request request = new Request.Builder()

                .url(url)

                .build();

        deliveryResult(callback, request);

    }

    /**

     * 同步的Post请求

     *

     * @param url

     * @param params post的参数

     * @return

     */

    private Response _post(String url, Param... params) throws IOException

    {

        Request request = buildPostRequest(url, params);

        Response response = mOkHttpClient.newCall(request).execute();

        return response;

    }

    /**

     * 同步的Post请求

     *

     * @param url

     * @param params post的参数

     * @return 字符串

     */

    private String _postAsString(String url, Param... params) throws IOException

    {

        Response response = _post(url, params);

        return response.body().string();

    }

    /**

     * 异步的post请求

     *

     * @param url

     * @param callback

     * @param params

     */

    private void _postAsyn(String url, final ResultCallback callback, Param... params)

    {

        Request request = buildPostRequest(url, params);

        deliveryResult(callback, request);

    }

    /**

     * 异步的post请求

     *

     * @param url

     * @param callback

     * @param params

     */

    private void _postAsyn(String url, final ResultCallback callback, Map<String, String> params)

    {

        Param[] paramsArr = map2Params(params);

        Request request = buildPostRequest(url, paramsArr);

        deliveryResult(callback, request);

    }

    /**

     * 同步基于post的文件上传

     *

     * @param params

     * @return

     */

    private Response _post(String url, File[] files, String[] fileKeys, Param... params) throws IOException

    {

        Request request = buildMultipartFormRequest(url, files, fileKeys, params);

        return mOkHttpClient.newCall(request).execute();

    }

    private Response _post(String url, File file, String fileKey) throws IOException

    {

        Request request = buildMultipartFormRequest(url, new File[]{file}, new String[]{fileKey}, null);

        return mOkHttpClient.newCall(request).execute();

    }

    private Response _post(String url, File file, String fileKey, Param... params) throws IOException

    {

        Request request = buildMultipartFormRequest(url, new File[]{file}, new String[]{fileKey}, params);

        return mOkHttpClient.newCall(request).execute();

    }

    /**

     * 异步基于post的文件上传

     *

     * @param url

     * @param callback

     * @param files

     * @param fileKeys

     * @throws IOException

     */

    private void _postAsyn(String url, ResultCallback callback, File[] files, String[] fileKeys, Param... params) throws IOException

    {

        Request request = buildMultipartFormRequest(url, files, fileKeys, params);

        deliveryResult(callback, request);

    }

    /**

     * 异步基于post的文件上传，单文件不带参数上传

     *

     * @param url

     * @param callback

     * @param file

     * @param fileKey

     * @throws IOException

     */

    private void _postAsyn(String url, ResultCallback callback, File file, String fileKey) throws IOException

    {

        Request request = buildMultipartFormRequest(url, new File[]{file}, new String[]{fileKey}, null);

        deliveryResult(callback, request);

    }

    /**

     * 异步基于post的文件上传，单文件且携带其他form参数上传

     *

     * @param url

     * @param callback

     * @param file

     * @param fileKey

     * @param params

     * @throws IOException

     */

    private void _postAsyn(String url, ResultCallback callback, File file, String fileKey, Param... params) throws IOException

    {

        Request request = buildMultipartFormRequest(url, new File[]{file}, new String[]{fileKey}, params);

        deliveryResult(callback, request);

    }

    /**

     * 异步下载文件

     *

     * @param url

     * @param destFileDir 本地文件存储的文件夹

     * @param callback

     */

    private void _downloadAsyn(final String url, final String destFileDir, final ResultCallback callback)

    {

        final Request request = new Request.Builder()

                .url(url)

                .build();

        final Call call = mOkHttpClient.newCall(request);

        call.enqueue(new Callback()

        {

            @Override

            public void onFailure(final Request request, final IOException e)

            {

                sendFailedStringCallback(request, e, callback);

            }

            @Override

            public void onResponse(Response response)

            {

                InputStream is = null;

                byte[] buf = new byte[2048];

                int len = 0;

                FileOutputStream fos = null;

                try

                {

                    is = response.body().byteStream();

                    File file = new File(destFileDir, getFileName(url));

                    fos = new FileOutputStream(file);

                    while ((len = is.read(buf)) != -1)

                    {

                        fos.write(buf, 0, len);

                    }

                    fos.flush();

                    //如果下载文件成功，第一个参数为文件的绝对路径

                    sendSuccessResultCallback(file.getAbsolutePath(), callback);

                } catch (IOException e)

                {

                    sendFailedStringCallback(response.request(), e, callback);

                } finally

                {

                    try

                    {

                        if (is != null) is.close();

                    } catch (IOException e)

                    {

                    }

                    try

                    {

                        if (fos != null) fos.close();

                    } catch (IOException e)

                    {

                    }

                }

            }

        });

    }

    private String getFileName(String path)

    {

        int separatorIndex = path.lastIndexOf("/");

        return (separatorIndex < 0) ? path : path.substring(separatorIndex + 1, path.length());

    }

    /**

     * 加载图片

     *

     * @param view

     * @param url

     * @throws IOException

     */

    private void _displayImage(final ImageView view, final String url, final int errorResId)

    {

        final Request request = new Request.Builder()

                .url(url)

                .build();

        Call call = mOkHttpClient.newCall(request);

        call.enqueue(new Callback()

        {

            @Override

            public void onFailure(Request request, IOException e)

            {

                setErrorResId(view, errorResId);

            }

            @Override

            public void onResponse(Response response)

            {

                InputStream is = null;

                try

                {

                    is = response.body().byteStream();

                    ImageUtils.ImageSize actualImageSize = ImageUtils.getImageSize(is);

                    ImageUtils.ImageSize imageViewSize = ImageUtils.getImageViewSize(view);

                    int inSampleSize = ImageUtils.calculateInSampleSize(actualImageSize, imageViewSize);

                    try

                    {

                        is.reset();

                    } catch (IOException e)

                    {

                        response = _getAsyn(url);

                        is = response.body().byteStream();

                    }

                    BitmapFactory.Options ops = new BitmapFactory.Options();

                    ops.inJustDecodeBounds = false;

                    ops.inSampleSize = inSampleSize;

                    final Bitmap bm = BitmapFactory.decodeStream(is, null, ops);

                    mDelivery.post(new Runnable()

                    {

                        @Override

                        public void run()

                        {

                            view.setImageBitmap(bm);

                        }

                    });

                } catch (Exception e)

                {

                    setErrorResId(view, errorResId);

                } finally

                {

                    if (is != null) try

                    {

                        is.close();

                    } catch (IOException e)

                    {

                        e.printStackTrace();

                    }

                }

            }

        });

    }

    private void setErrorResId(final ImageView view, final int errorResId)

    {

        mDelivery.post(new Runnable()

        {

            @Override

            public void run()

            {

                view.setImageResource(errorResId);

            }

        });

    }

    //*************对外公布的方法************

    public static Response getAsyn(String url) throws IOException

    {

        return getInstance()._getAsyn(url);

    }

    public static String getAsString(String url) throws IOException

    {

        return getInstance()._getAsString(url);

    }

    public static void getAsyn(String url, ResultCallback callback)

    {

        getInstance()._getAsyn(url, callback);

    }

    public static Response post(String url, Param... params) throws IOException

    {

        return getInstance()._post(url, params);

    }

    public static String postAsString(String url, Param... params) throws IOException

    {

        return getInstance()._postAsString(url, params);

    }

    public static void postAsyn(String url, final ResultCallback callback, Param... params)

    {

        getInstance()._postAsyn(url, callback, params);

    }

    public static void postAsyn(String url, final ResultCallback callback, Map<String, String> params)

    {

        getInstance()._postAsyn(url, callback, params);

    }

    public static Response post(String url, File[] files, String[] fileKeys, Param... params) throws IOException

    {

        return getInstance()._post(url, files, fileKeys, params);

    }

    public static Response post(String url, File file, String fileKey) throws IOException

    {

        return getInstance()._post(url, file, fileKey);

    }

    public static Response post(String url, File file, String fileKey, Param... params) throws IOException

    {

        return getInstance()._post(url, file, fileKey, params);

    }

    public static void postAsyn(String url, ResultCallback callback, File[] files, String[] fileKeys, Param... params) throws IOException

    {

        getInstance()._postAsyn(url, callback, files, fileKeys, params);

    }

    public static void postAsyn(String url, ResultCallback callback, File file, String fileKey) throws IOException

    {

        getInstance()._postAsyn(url, callback, file, fileKey);

    }

    public static void postAsyn(String url, ResultCallback callback, File file, String fileKey, Param... params) throws IOException

    {

        getInstance()._postAsyn(url, callback, file, fileKey, params);

    }

    public static void displayImage(final ImageView view, String url, int errorResId) throws IOException

    {

        getInstance()._displayImage(view, url, errorResId);

    }

    public static void displayImage(final ImageView view, String url)

    {

        getInstance()._displayImage(view, url, -1);

    }

    public static void downloadAsyn(String url, String destDir, ResultCallback callback)

    {

        getInstance()._downloadAsyn(url, destDir, callback);

    }

    //****************************

    private Request buildMultipartFormRequest(String url, File[] files,

                                              String[] fileKeys, Param[] params)

    {

        params = validateParam(params);

        MultipartBuilder builder = new MultipartBuilder()

                .type(MultipartBuilder.FORM);

        for (Param param : params)

        {

            builder.addPart(Headers.of("Content-Disposition", "form-data; name=\"" + param.key + "\""),

                    RequestBody.create(null, param.value));

        }

        if (files != null)

        {

            RequestBody fileBody = null;

            for (int i = 0; i < files.length; i++)

            {

                File file = files[i];

                String fileName = file.getName();

                fileBody = RequestBody.create(MediaType.parse(guessMimeType(fileName)), file);

                //TODO 根据文件名设置contentType

                builder.addPart(Headers.of("Content-Disposition",

                                "form-data; name=\"" + fileKeys[i] + "\"; filename=\"" + fileName + "\""),

                        fileBody);

            }

        }

        RequestBody requestBody = builder.build();

        return new Request.Builder()

                .url(url)

                .post(requestBody)

                .build();

    }

    private String guessMimeType(String path)

    {

        FileNameMap fileNameMap = URLConnection.getFileNameMap();

        String contentTypeFor = fileNameMap.getContentTypeFor(path);

        if (contentTypeFor == null)

        {

            contentTypeFor = "application/octet-stream";

        }

        return contentTypeFor;

    }

    private Param[] validateParam(Param[] params)

    {

        if (params == null)

            return new Param[0];

        else return params;

    }

    private Param[] map2Params(Map<String, String> params)

    {

        if (params == null) return new Param[0];

        int size = params.size();

        Param[] res = new Param[size];

        Set<Map.Entry<String, String>> entries = params.entrySet();

        int i = 0;

        for (Map.Entry<String, String> entry : entries)

        {

            res[i++] = new Param(entry.getKey(), entry.getValue());

        }

        return res;

    }

    private static final String SESSION_KEY = "Set-Cookie";

    private static final String mSessionKey = "JSESSIONID";

    private Map<String, String> mSessions = new HashMap<String, String>();

    private void deliveryResult(final ResultCallback callback, Request request)

    {

        mOkHttpClient.newCall(request).enqueue(new Callback()

        {

            @Override

            public void onFailure(final Request request, final IOException e)

            {

                sendFailedStringCallback(request, e, callback);

            }

            @Override

            public void onResponse(final Response response)

            {

                try

                {

                    final String string = response.body().string();

                    if (callback.mType == String.class)

                    {

                        sendSuccessResultCallback(string, callback);

                    } else

                    {

                        Object o = mGson.fromJson(string, callback.mType);

                        sendSuccessResultCallback(o, callback);

                    }

                } catch (IOException e)

                {

                    sendFailedStringCallback(response.request(), e, callback);

                } catch (com.google.gson.JsonParseException e)//Json解析的错误

                {

                    sendFailedStringCallback(response.request(), e, callback);

                }

            }

        });

    }

    private void sendFailedStringCallback(final Request request, final Exception e, final ResultCallback callback)

    {

        mDelivery.post(new Runnable()

        {

            @Override

            public void run()

            {

                if (callback != null)

                    callback.onError(request, e);

            }

        });

    }

    private void sendSuccessResultCallback(final Object object, final ResultCallback callback)

    {

        mDelivery.post(new Runnable()

        {

            @Override

            public void run()

            {

                if (callback != null)

                {

                    callback.onResponse(object);

                }

            }

        });

    }

    private Request buildPostRequest(String url, Param[] params)

    {

        if (params == null)

        {

            params = new Param[0];

        }

        FormEncodingBuilder builder = new FormEncodingBuilder();

        for (Param param : params)

        {

            builder.add(param.key, param.value);

        }

        RequestBody requestBody = builder.build();

        return new Request.Builder()

                .url(url)

                .post(requestBody)

                .build();

    }

    public static abstract class ResultCallback<T>

    {

        Type mType;

        public ResultCallback()

        {

            mType = getSuperclassTypeParameter(getClass());

        }

        static Type getSuperclassTypeParameter(Class<?> subclass)

        {

            Type superclass = subclass.getGenericSuperclass();

            if (superclass instanceof Class)

            {

                throw new RuntimeException("Missing type parameter.");

            }

            ParameterizedType parameterized = (ParameterizedType) superclass;

            return $Gson$Types.canonicalize(parameterized.getActualTypeArguments()[0]);

        }

        public abstract void onError(Request request, Exception e);

        public abstract void onResponse(T response);

    }

    public static class Param

    {

        public Param()

        {

        }

        public Param(String key, String value)

        {

            this.key = key;

            this.value = value;

        }

        String key;

        String value;

    }

}

源码地址okhttp-utils，大家可以自己下载查看。