Android OkHttp详细介绍

一 前言

之前的项目中一直使用volley,特别的方便，但是我们服务端为了数据的安全性能突然加了一个是SSL证书，使用Https请求数据。然而volley只支持Http服务器，so不得不换成另外一种网络通信的框架OKHttp,研究了三天的OKHttp这篇文章就大概的讲一下OKHttp的使用方法。

二 Android OkHttp

2.1 使用OKHttp首先在项目中导入三方框架的库

  compile 'com.squareup.okhttp:okhttp:2.4.0'  compile 'com.squareup.okio:okio:1.5.0'

注意：:okhttp内部依赖okio，别忘了同时导入okio：

2.2 使用详细说明（文章后面有封装包）
思路：

1. 首先创建一个request对象，通过request设置请求url,通过这个类还可以设置更多的请求信息。

2. 然后通过Request去构造一个Call对象。

3. 调用enqueue执行异步请求，有一个参数设置回调。请求成功或者失败会调用Callback接口的onResponse跟onFailure方法，因为这是异步请求，在回调方法中是不能直接更新UI，所以我们需要通过Handler去更新UI。
   handler的代码很简单，就是把请求的结果显示在TextView上

2.2.1 get请求

首先需要创建一个全局的OkHttpClient对象,所有的Http请求都共用这个对象就行。

private OkHttpClient client = new OkHttpClient();一般从服务器获取信息的接口都是get请求，这里我们调用获取用户信息接口。private void getUserInfo(){    //创建一个Request    Request.Builder builder = new Request.Builder().url("http://139.196.35.30:8080/OkHttpTest/getUserInfo.do");    execute(builder);}//执行请求private void execute(Request.Builder builder){    Call call = client.newCall(builder.build());    call.enqueue(callback);//加入调度队列}//请求回调private Callback callback=new Callback(){        @Override        public void onFailure(Call call, IOException e) {            Log.i("MainActivity","onFailure");            e.printStackTrace();        }        @Override        public void onResponse(Call call, Response response) throws IOException {            //从response从获取服务器返回的数据，转成字符串处理            String str = new String(response.body().bytes(),"utf-8");            Log.i("MainActivity","onResponse:"+str);            //通过handler更新UI            Message message=handler.obtainMessage();            message.obj=str;            message.sendToTarget();        }};private Handler handler=new Handler(){    @Override    public void handleMessage(Message msg) {        String result= (String) msg.obj;        tvResult.setText(result);    }};

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()

2.2.2 Post请求

通过调用登录接口发送一个post请求。跟get不一样的地方就是传参数不一样，post请求需要把参数封装到RequestBody对象，调用Request对象的post方法把RequestBody传入进去。最后调用execute方法执行请求，这个方法前面get请求的时候讲过。

private void login(){    //把请求参数封装到RequestBody里面    FormBody.Builder formBuilder = new FormBody.Builder();    formBuilder.add("username","ansen");//请求参数一    formBuilder.add("password","123");//请求参数二    RequestBody requestBody = formBuilder.build();    Request.Builder builder = new  Request.Builder().url("http://139.196.35.30:8080/OkHttpTest/login.do").post(requestBody);    execute(builder);}

2.2.3 文件上传

上传文件需要用到MultipartBody对象，通过调用addFormDataPart方法添加表单参数，通过setType方法设置内容类型，这边设置form表单类型，调用自己的getUploadFileBytes方法获取文件byte数组，通过addFormDataPart方法添加文件，后面的流程跟之前的post请求一样。

private void uploadFile(){    MultipartBody.Builder builder = new MultipartBody.Builder();    builder.addFormDataPart("username", "ansen");//表单参数    builder.addFormDataPart("password", "123456");//表单参数    builder.setType(MultipartBody.FORM);    MediaType mediaType = MediaType.parse("application/octet-stream");    byte[] bytes=getUploadFileBytes();//获取文件内容存入byte数组    //上传文件 参数1:name 参数2:文件名称 参数3:文件byte数组    builder.addFormDataPart("upload_file", "ansen.txt",RequestBody.create(mediaType,bytes));    RequestBody requestBody = builder.build();    Request.Builder requestBuider = new Request.Builder();    requestBuider.url("http://139.196.35.30:8080/OkHttpTest/uploadFile.do");    requestBuider.post(requestBody);    execute(requestBuider);}

通过http协议请求服务器数据，常用的就这几种请求，如果有特殊需求自己扩展。例如:下载文件，从服务器下载图片等。。。。

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。

2.3封装代码

2.3.1 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。

2.3.2 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.

2.3.3 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        }});

2.3.4 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。

2.3.5 、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 ，ok ， 如果发现bug或者有任何意见欢迎留言。

2.3.6 封装的工具类

/** * Created by liangguliang on 17/8/23. */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;    }}

大家认真看肯定会学到很多东西
源码地址okhttp-utils，可以自己下载查看。

转自：http://blog.csdn.net/lmj623565791/article/details/47911083