1. 程式人生 > >終於找到了一篇一看就懂的 OKHttp 原理解析

終於找到了一篇一看就懂的 OKHttp 原理解析

一、概述

最近在群裡聽到各種討論okhttp的話題,可見okhttp的口碑相當好了。再加上Google貌似在6.0版本里面刪除了HttpClient相關API,對於這個行為不做評價。為了更好的在應對網路訪問,學習下okhttp還是蠻必要的,本篇部落格首先介紹okhttp的簡單使用,主要包含:

  • 一般的get請求

  • 一般的post請求

  • 基於Http的檔案上傳

  • 檔案下載

  • 載入圖片

使用前,對於Android Studio的使用者,可以選擇新增

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


或者Eclipse的使用者,可以下載最新的jar 

okhttp he latest JAR ,新增依賴就可以用了。

注意:okhttp內部依賴okio,別忘了同時匯入okio:

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

二、使用教程

(一)Http Get

對了網路載入庫,那麼最常見的肯定就是http get請求了,比如獲取一個網頁的內容。

//建立okHttpClient物件
OkHttpClient mOkHttpClient = new OkHttpClient();
//建立一個Request
final Request request = new Request.Builder()
                .url("https://github.com/hongyangAndroid")
                .build();
//new call
Call call = mOkHttpClient.newCall(request); 
//請求加入排程
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. 以上就是傳送一個get請求的步驟,首先構造一個Request物件,引數最起碼有個url,當然你可以通過Request.Builder設定更多的引數比如:header、method等。

  2. 然後通過request的物件去構造得到一個Call物件,類似於將你的請求封裝成了任務,既然是任務,就會有execute()和cancel()等方法。

  3. 最後,我們希望以非同步的方式去執行請求,所以我們呼叫的是call.enqueue,將call加入排程佇列,然後等待任務執行完成,我們在Callback中即可得到結果。

看到這,你會發現,整體的寫法還是比較長的,所以封裝肯定是要做的,不然每個請求這麼寫,得累死。

ok,需要注意幾點:

  • onResponse回撥的引數是response,一般情況下,比如我們希望獲得返回的字串,可以通過response.body().string()獲取;如果希望獲得返回的二進位制位元組陣列,則呼叫response.body().bytes();如果你想拿到返回的inputStream,則呼叫response.body().byteStream()

    看到這,你可能會奇怪,竟然還能拿到返回的inputStream,看到這個最起碼能意識到一點,這裡支援大檔案下載,有inputStream我們就可以通過IO的方式寫檔案。不過也說明一個問題,這個onResponse執行的執行緒並不是UI執行緒。的確是的,如果你希望操作控制元件,還是需要使用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);
              }
     
          });
    }


  • 我們這裡是非同步的方式去執行,當然也支援阻塞的方式,上面我們也說了Call有一個execute()方法,你也可以直接呼叫call.execute()通過返回一個Response。

(二) Http Post 攜帶引數

看來上面的簡單的get請求,基本上整個的用法也就掌握了,比如post攜帶引數,也僅僅是Request的構造的不同。

Request request = buildMultipartFormRequest(
        url, new File[]{file}, new String[]{fileKey}, null);
FormEncodingBuilder builder = new FormEncodingBuilder();   
builder.add("username","張鴻洋");
 
Request request = new Request.Builder()
                   .url(url)
                .post(builder.build())
                .build();
 mOkHttpClient.newCall(request).enqueue(new Callback(){});


大家都清楚,post的時候,引數是包含在請求體中的;所以我們通過FormEncodingBuilder。新增多個String鍵值對,然後去構造RequestBody,最後完成我們Request的構造。

後面的就和上面一樣了。

(三)基於Http的檔案上傳

接下來我們在介紹一個可以構造RequestBody的Builder,叫做MultipartBuilder。當我們需要做類似於表單上傳的時候,就可以使用它來構造我們的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, "張鴻洋"))
     .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()
{
    //...
});


上述程式碼向伺服器傳遞了一個鍵值對username:張鴻洋和一個檔案。我們通過MultipartBuilder的addPart方法可以新增鍵值對或者檔案。

ok,對於我們最開始的目錄還剩下圖片下載,檔案下載;這兩個一個是通過回撥的Response拿到byte[]然後decode成圖片;檔案下載,就是拿到inputStream做寫檔案操作,我們這裡就不贅述了。

接下來我們主要看如何封裝上述的程式碼。

三、封裝

由於按照上述的程式碼,寫多個請求肯定包含大量的重複程式碼,所以我希望封裝後的程式碼呼叫是這樣的:

(一)使用

  1. 一般的get請求

  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);//注意這裡是UI執行緒回撥,可以直接操作控制元件
                }
            });


對於一般的請求,我們希望給個url,然後CallBack裡面直接操作控制元件。

  1. 檔案上傳且攜帶引數

我們希望提供一個方法,傳入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")}
        );


鍵值對沒什麼說的,引數3為file,引數4為file對應的name,這個name不是檔案的名字; 
對應於http中的

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

對應的是name後面的值,即mFile.

  1. 檔案下載

對於檔案下載,提供url,目標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)
        {
            //檔案下載成功,這裡回撥的reponse為檔案的absolutePath
        }
});


  1. 展示圖片

展示圖片,我們希望提供一個url和一個imageview,如果下載成功,直接幫我們設定上即可。

OkHttpClientManager.displayImage(mImageView, "http://images.csdn.net/20150817/1.jpg");


內部會自動根據imageview的大小自動對圖片進行合適的壓縮。雖然,這裡可能不適合一次性載入大量圖片的場景,但是對於app中偶爾有幾個圖片的載入,還是可用的。

(二)原始碼

ok,基本介紹完了,對於封裝的程式碼其實也很簡單,我就直接貼出來了,因為也沒什麼好介紹的,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請求
     *
     * @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請求
     *
     * @param url
     * @return 字串
     */
    private String _getAsString(String url) throws IOException
    {
        Response execute = _getAsyn(url);
        return execute.body().string();
    }
 
 
    /**
     * 非同步的get請求
     *
     * @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請求
     *
     * @param url
     * @param params post的引數
     * @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請求
     *
     * @param url
     * @param params post的引數
     * @return 字串
     */
    private String _postAsString(String url, Param... params) throws IOException
    {
        Response response = _post(url, params);
        return response.body().string();
    }
 
    /**
     * 非同步的post請求
     *
     * @param url
     * @param callback
     * @param params
     */
    private void _postAsyn(String url, final StringCallback callback, Param... params)
    {
        Request request = buildPostRequest(url, params);
        deliveryResult(callback, request);
    }
 
    /**
     * 非同步的post請求
     *
     * @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);
    }
 
    /**
     * 同步基於post的檔案上傳
     *
     * @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();
    }
 
    /**
     * 非同步基於post的檔案上傳
     *
     * @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);
    }
 
    /**
     * 非同步基於post的檔案上傳,單檔案不帶引數上傳
     *
     * @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);
    }
 
    /**
     * 非同步基於post的檔案上傳,單檔案且攜帶其他form引數上傳
     *
     * @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);
    }
 
    /**
     * 非同步下載檔案
     *
     * @param url
     * @param destFileDir 本地檔案儲存的資料夾
     * @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();
                    //如果下載檔案成功,第一個引數為檔案的絕對路徑
                    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());
    }
 
    /**
     * 載入圖片
     *
     * @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);
            }
        });
    }
 
 
    //*************對外公佈的方法************
 
 
    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 根據檔名設定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;
    }
 
 
}


ok ,最後一段程式碼好長,建議下載原始碼檢視~~