详解Android OkHttp完全解析

2019-12-12 04:31:12

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来源：转载

供稿：网友

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：http://xiazai.VeVB.COm/201611/yuanma/okhttputils-master_jb51.zip

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jarokhttp 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Requestfinal Request request = new Request.Builder()    .url("https://github.com/hongyangAndroid")    .build();//new callCall 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：

1、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：

@Overridepublic void onResponse(final Response response) throws IOException{  final String res = response.body().string();  runOnUiThread(new Runnable()  {   @Override   public void run()   {   mTv.setText(res);   }  });}

2、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。

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(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。

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（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。

接下来我们主要看如何封装上述的代码。

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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。

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.

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  }});

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。

四、整合Json

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json，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。

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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：demo下载http://xiazai.VeVB.COm/201611/yuanma/okhttputils-master_jb51.zip
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