终于找到了一篇一看就懂的 OKHttp 原理解析

今天药忘吃喽~ 2022-09-30 10:55 198阅读 0赞

### 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

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'

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][]

--------------------

### 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
2.      OkHttpClientManager.getAsyn("https://github.com/hongyangAndroid", new OkHttpClientManager.StringCallback()
                {
                    @Override
                    public void onFailure(Request request, IOException e)
                    {
                        e.printStackTrace();
                    }
         
                    @Override
                    public void onResponse(String bytes)
                    {
                        mTv.setText(bytes);//注意这里是UI线程回调，可以直接操作控件
                    }
                });

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。

1.  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.StringCallback()
        {
            @Override
            public void onFailure(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

对应的是name后面的值，即mFile.

1.  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.StringCallback()
        {
            @Override
            public void onFailure(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
            }
    });

1.  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");

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。

--------------------

#### （二）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.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.net.FileNameMap;
    import java.net.URLConnection;
    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 static final String TAG = "OkHttpClientManager";
     
        private OkHttpClientManager()
        {
            mOkHttpClient = new OkHttpClient();
            mDelivery = new Handler(Looper.getMainLooper());
        }
     
        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 StringCallback 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 StringCallback 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 StringCallback 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, StringCallback 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, StringCallback 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, StringCallback 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 StringCallback 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
                        sendSuccessStringCallback(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, StringCallback 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 StringCallback callback, Param... params)
        {
            getInstance()._postAsyn(url, callback, params);
        }
     
     
        public static void postAsyn(String url, final StringCallback 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, StringCallback callback, File[] files, String[] fileKeys, Param... params) throws IOException
        {
            getInstance()._postAsyn(url, callback, files, fileKeys, params);
        }
     
     
        public static void postAsyn(String url, StringCallback callback, File file, String fileKey) throws IOException
        {
            getInstance()._postAsyn(url, callback, file, fileKey);
        }
     
     
        public static void postAsyn(String url, StringCallback 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, StringCallback 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 void deliveryResult(final StringCallback 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();
                        sendSuccessStringCallback(string, callback);
                    } catch (IOException e)
                    {
                        sendFailedStringCallback(response.request(), e, callback);
                    }
     
                }
            });
        }
     
        private void sendFailedStringCallback(final Request request, final IOException e, final StringCallback callback)
        {
            mDelivery.post(new Runnable()
            {
                @Override
                public void run()
                {
                    if (callback != null)
                        callback.onFailure(request, e);
                }
            });
        }
     
        private void sendSuccessStringCallback(final String string, final StringCallback callback)
        {
            mDelivery.post(new Runnable()
            {
                @Override
                public void run()
                {
                    if (callback != null)
                        callback.onResponse(string);
                }
            });
        }
     
        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 interface StringCallback
        {
            void onFailure(Request request, IOException e);
     
            void onResponse(String 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。

ok ，最后一段代码好长，建议下载源码查看~~

[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