Android OkHttp完全解析是时候来了解OkHttp了

分手后的思念是犯贱 2022-05-10 14:06 142阅读 0赞

> 转载请标明出处：  
> [http://blog.csdn.net/lmj623565791/article/details/47911083][http_blog.csdn.net_lmj623565791_article_details_47911083]；  
> 本文出自:[【张鸿洋的博客】][Link 1]

### 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][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'
     
      
       1

或者Eclipse的用户，可以下载最新的jar [okhttp he latest 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 ][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();
                }
            });

1.  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。
2.  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。
3.  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);
              }
    
          });
    }

*  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][Android _Java_ http]
    
    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][OkHttp]
    
    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 ####
    
    1.  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");
         
            
             1
             2
    
    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"}
         
            
             1
    
    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
            }
        });
         
            
             1
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             10
             11
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             15
    
    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"}]
         
            
             1
    
    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());
            }
        });
         
            
             1
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             5
             6
             7
             8
             9
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             11
             12
             13
             14
             15
    
    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][https_github.com_hongyangAndroid_okhttp-utils]，大家可以自己下载查看。
    
    --------------------
    
    --------------------
    
    ### 参考文章 ###
    
     *  [https://github.com/square/okhttp][https_github.com_square_okhttp]
     *  [http://square.github.io/okhttp/][http_square.github.io_okhttp]
     *  [泡网OkHttp使用教程][OkHttp]

[http_blog.csdn.net_lmj623565791_article_details_47911083]: http://blog.csdn.net/lmj623565791/article/details/47911083
[Link 1]: http://blog.csdn.net/lmj623565791/
[https_github.com_hongyangAndroid_okhttp-utils]: https://github.com/hongyangAndroid/okhttp-utils
[okhttp he latest JAR]: https://search.maven.org/remote_content?g=com.squareup.okhttp&a=okhttp&v=LATEST
[okio the latest JAR]: https://search.maven.org/remote_content?g=com.squareup.okio&a=okio&v=LATEST
[Android _Java_ http]: http://blog.csdn.net/lmj623565791/article/details/23781773
[OkHttp]: http://www.jcodecraeer.com/a/anzhuokaifa/androidkaifa/2015/0106/2275.html
[https_github.com_square_okhttp]: https://github.com/square/okhttp
[http_square.github.io_okhttp]: http://square.github.io/okhttp/