本文主要是介绍OkHttp学习（2）--异步下载图片、文件（拦截器重写Response方法实现下载进度获取），希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
OkHttp学习（1）–>>同步和异步(get、post键值对、post带map、请求头体封装json)
Volley学习链接—想了解Volley的可以看我这5篇
今天来了解下okHttp如何进行图片、文件下载的
首先在OkHttpManger弄一个单利模式，初始化一个OkHttpClient，然后放进去一个handler，线程更新ui使用
private Handler okHttpHandler;private OkHttpClient mOkHttpClient;private OkHttpManger(){this.mOkHttpClient = new OkHttpClient.Builder().connectTimeout(30, TimeUnit.SECONDS)//连接超时限制.writeTimeout(30, TimeUnit.SECONDS)//写入超时.readTimeout(30, TimeUnit.SECONDS)//读取超时.build();this.okHttpHandler = new Handler(Looper.getMainLooper());}public static final OkHttpManger getInstance(){return SingleFactory.manger;}private static final class SingleFactory{private static final OkHttpManger manger = new OkHttpManger();}
然后直接执行下载方法
public void downloadAsync(final String url, final String destFileDir,final OKHttpUICallback.ProgressCallback downListener) throws IOException {File file = new File(destFileDir,getFileName(url));if(!file.exists()){file.createNewFile();}downloadAsync(url, file, downListener);}参数1为图片的url，我们这里用了http://img.mukewang.com/55249cf30001ae8a06000338.jpg来测试，
参数2destFileDir这个是下载完毕保存到手机的目录地址，我们传入的参数如下：
Config.getDirFile("download").getAbsolutePath()这里做了一些目录的设置
public static File getDirFile(String subFileName){if(isSDMounted()){return mkdirsFolder(getSDirAbsolutePath() + "/Seeker/" + subFileName);}return null;}public static boolean isSDMounted(){return Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED);}public static File mkdirsFolder(String path){File file = new File(path);if(!file.exists()){return file.mkdirs()?file:null;}return file;}public static String getSDirAbsolutePath(){return Environment.getExternalStorageDirectory().getAbsolutePath();}就是在sd卡根目录下创建Seeker/download文件夹，下载的图片就存在download文件夹下
目录有了，下载完毕图片，我们需要起一个名字把：
File file = new File(destFileDir,getFileName(url));if(!file.exists()){file.createNewFile();} private String getFileName(String url){int lastSeparaorIndex = url.lastIndexOf("/");return (lastSeparaorIndex < 0) ? url : url.substring(lastSeparaorIndex + 1, url.length());}然后正式进入下载的代码
public void downloadAsync(final String url, final File downFile,final OKHttpUICallback.ProgressCallback downListener) throws IOException {OkHttpClient downLoadClient = mOkHttpClient.newBuilder().addInterceptor(new Interceptor() {@Overridepublic Response intercept(Chain chain) throws IOException {//拦截Response origin = chain.proceed(chain.request());//包装响应体return origin.newBuilder().body(new ProgressBody.ProgressResponseBody(origin.body(), downListener, okHttpHandler)).build();}}).build();final Request request = new Request.Builder().url(url).build();downLoadClient.newCall(request).enqueue(new OKHttpThreadCallback(okHttpHandler,downListener,true).setFile(downFile));}我们来看下代码里面做了什么操作?我们首先想到的是弄一个接口把
OKHttpUICallback.ProgressCallback downListener接口有3个接口方法，意思很明显。
public interface ProgressCallback{void onSuccess(Call call, Response response, String path);void onProgress(long byteReadOrWrite, long contentLength, boolean done);void onError(Call call, IOException e);}okhttp实现了拦截器Interceptor，这个是什么意思呢？
Interceptors area powerful mechanism that can monitor, rewrite, and retry calls.
拦截器可以用来转换，重试，重写请求的机制。这是官方的定义。
一句话就是对请求、相应加上自己的代码，重写方法
OkHttpClient downLoadClient = mOkHttpClient.newBuilder().addInterceptor(new Interceptor() {@Overridepublic Response intercept(Chain chain) throws IOException {//拦截Response origin = chain.proceed(chain.request());//包装响应体return origin.newBuilder().body(new ProgressBody.ProgressResponseBody(origin.body(), downListener, okHttpHandler)).build();}}).build();这里就是用到了拦截器，大概意思就是，对请求响应体，进行二次包装，比如请求图片、文件的进度问题
我们看下我们做了什么操作呢？
new ProgressBody.ProgressResponseBody(origin.body(), downListener, okHttpHandler) @Overridepublic BufferedSource source() {if(bufferedSource == null){bufferedSource = Okio.buffer(source(responseBody.source()));}return bufferedSource;}/*** 读取，回调进度接口* @return*/private Source source(Source source){return new ForwardingSource(source) {//读取当前获取的字节数long totalBytesRead = 0L;@Overridepublic long read(Buffer sink, long byteCount) throws IOException {final long byteRead = super.read(sink, byteCount);if(mHandler != null && mListener != null){//增加当前读取的字节数，如果读取完成则返回-1totalBytesRead += byteRead != -1?byteRead:0;//回调，若是contentLength()不知道长度，则返回-1mHandler.post(new Runnable() {@Overridepublic void run() {mListener.onProgress(totalBytesRead, contentLength(), byteRead == -1);}});}return byteRead;}};}mListener.onProgress(totalBytesRead, contentLength(), byteRead == -1);就是对请求进度的一个对外通讯，告诉ui界面可以做一些操作，比如进度条之类的
然后继续看那个下载的入口方法里面的
downLoadClient.newCall(request).enqueue(new OKHttpThreadCallback(okHttpHandler,downListener,true).setFile(downFile));这里面做了什么操作呢？
@Overridepublic void onFailure(final Call call, final IOException e) {if(UICallback != null && UIHandler != null){UIHandler.post(new Runnable() {@Overridepublic void run() {UICallback.onError(call,e);}});}}@Overridepublic void onResponse(Call call, Response response) throws IOException {if(isDownload){download(call,response);}else{postSuccess(call,response);}}
就是在请求相应里面，进行sd写入
private void download(Call call, Response response) throws IOException {if(downFile == null){throw new NullPointerException("downFile == null");}byte[] buffer = new byte[2048];InputStream is = response.body().byteStream();int len;FileOutputStream fos = new FileOutputStream(downFile);while ((len = is.read(buffer)) != -1){fos.write(buffer,0,len);}fos.flush();if(is != null){is.close();}if (fos != null){fos.close();}postSuccess(call,null);}
然后在主界面进行接口方法实现，去实现其他需要处理的
UICallback.onSuccess(call, response,downFile == null?null:downFile.getAbsolutePath());如下是下载过程的log
09-01 18:05:55.398 22636-22636/com.example.administrator.myapplication I/MainActivity: downloadAsync
09-01 18:05:55.826 22636-22636/com.example.administrator.myapplication I/MainActivity: byteReadOrWrite:798,contentLength:471776,done:false
................
...............
09-01 18:06:04.795 22636-22636/com.example.administrator.myapplication I/MainActivity: byteReadOrWrite:471776,contentLength:471776,done:true
09-01 18:06:04.797 22636-22636/com.example.administrator.myapplication I/MainActivity: path:/storage/emulated/0/Seeker/download/55249cf30001ae8a06000338.jpg
另外附下载截图一张：
//以下是代码堆积区//
MainActivity
package com.example.administrator.myapplication;import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;import java.io.IOException;import okhttp3.Call;
import okhttp3.Response;public class MainActivity extends AppCompatActivity implements View.OnClickListener {Button downloadAsync;ImageView imageView;String url = "http://img.mukewang.com/55249cf30001ae8a06000338.jpg";@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);imageView = (ImageView) findViewById(R.id.imageView);downloadAsync = (Button) findViewById(R.id.downloadAsync);downloadAsync.setOnClickListener(this);}@Overridepublic void onClick(View v) {switch (v.getId()){case R.id.downloadAsync:Log.i("MainActivity","downloadAsync");//下载图片try {OkHttpManger.getInstance().downloadAsync(url, Config.getDirFile("download").getAbsolutePath(), new OKHttpUICallback.ProgressCallback() {@Overridepublic void onSuccess(Call call, Response response, String path) {Log.i("MainActivity","path:"+path);}@Overridepublic void onProgress(long byteReadOrWrite, long contentLength, boolean done) {Log.i("MainActivity","byteReadOrWrite:"+byteReadOrWrite+",contentLength:"+contentLength+",done:"+done);}@Overridepublic void onError(Call call, IOException e) {Log.i("MainActivity","onError");}});} catch (IOException e) {e.printStackTrace();}break;}}
}OkHttpManger
package com.example.administrator.myapplication;import android.os.Handler;
import android.os.Looper;
import android.util.Log;import com.alibaba.fastjson.JSON;import java.io.File;
import java.io.IOException;
import java.net.FileNameMap;
import java.net.URLConnection;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.TimeUnit;
import okhttp3.Call;
import okhttp3.Callback;
import okhttp3.FormBody;
import okhttp3.Headers;
import okhttp3.Interceptor;
import okhttp3.MediaType;
import okhttp3.MultipartBody;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;/*** OkHttp 工具类，* get的同步异步请求* post的json字符串同步异步上传* post的键值对同步异步上传* post文件异步上传，回调结果以及进度* 异步下载文件，回调结果以及进度** Created by Seeker on 2016/6/24.*/
public final class OkHttpManger {private static final String TAG = "OkHttpManger";private static final MediaType JSON_TYPE = MediaType.parse("application/json; charset=utf-8");private Handler okHttpHandler;private OkHttpClient mOkHttpClient;private OkHttpManger(){this.mOkHttpClient = new OkHttpClient.Builder().connectTimeout(30, TimeUnit.SECONDS)//连接超时限制.writeTimeout(30, TimeUnit.SECONDS)//写入超时.readTimeout(30, TimeUnit.SECONDS)//读取超时.build();this.okHttpHandler = new Handler(Looper.getMainLooper());}public static final OkHttpManger getInstance(){return SingleFactory.manger;}private static final class SingleFactory{private static final OkHttpManger manger = new OkHttpManger();}/*** 异步下载文件,实现了下载进度的提示** @param url* @param destFileDir 文件存储根路径* @param downListener*/public void downloadAsync(final String url, final String destFileDir,final OKHttpUICallback.ProgressCallback downListener) throws IOException {File file = new File(destFileDir,getFileName(url));if(!file.exists()){file.createNewFile();}downloadAsync(url, file, downListener);}/*** 获取文件名** @param path*/private String getFileName(String url){int lastSeparaorIndex = url.lastIndexOf("/");return (lastSeparaorIndex < 0) ? url : url.substring(lastSeparaorIndex + 1, url.length());}/*** 异步下载文件,实现了下载进度的提示* @param url* @param downFile:存储文件(文件存储绝对路径文件)* @param downListener* @throws IOException*/public void downloadAsync(final String url, final File downFile,final OKHttpUICallback.ProgressCallback downListener) throws IOException {OkHttpClient downLoadClient = mOkHttpClient.newBuilder().addInterceptor(new Interceptor() {@Overridepublic Response intercept(Chain chain) throws IOException {//拦截Response origin = chain.proceed(chain.request());//包装响应体return origin.newBuilder().body(new ProgressBody.ProgressResponseBody(origin.body(), downListener, okHttpHandler)).build();}}).build();final Request request = new Request.Builder().url(url).build();downLoadClient.newCall(request).enqueue(new OKHttpThreadCallback(okHttpHandler,downListener,true).setFile(downFile));}}
ProgressBody
package com.example.administrator.myapplication;import android.os.Handler;
import java.io.IOException;
import okhttp3.MediaType;
import okhttp3.RequestBody;
import okhttp3.ResponseBody;
import okio.Buffer;
import okio.BufferedSink;
import okio.BufferedSource;
import okio.ForwardingSink;
import okio.ForwardingSource;
import okio.Okio;
import okio.Sink;
import okio.Source;/*** Created by Safly on 2016/9/1.*/
public final class ProgressBody {/*** 包装响应体，用于处理提示下载进度** Created by Seeker on 2016/6/29.*/public static final class ProgressResponseBody extends ResponseBody {//实际待包装的响应体private final ResponseBody responseBody;//进度回调接口private OKHttpUICallback.ProgressCallback mListener;//包装完成的BufferedSourceprivate BufferedSource bufferedSource;//传递下载进度到主线程private Handler mHandler;public ProgressResponseBody(ResponseBody responseBody, OKHttpUICallback.ProgressCallback listener, Handler handler){this.responseBody = responseBody;this.mListener = listener;this.mHandler = handler;}@Overridepublic MediaType contentType() {return responseBody.contentType();}@Overridepublic long contentLength() {return responseBody.contentLength();}@Overridepublic BufferedSource source() {if(bufferedSource == null){bufferedSource = Okio.buffer(source(responseBody.source()));}return bufferedSource;}/*** 读取，回调进度接口* @return*/private Source source(Source source){return new ForwardingSource(source) {//读取当前获取的字节数long totalBytesRead = 0L;@Overridepublic long read(Buffer sink, long byteCount) throws IOException {final long byteRead = super.read(sink, byteCount);if(mHandler != null && mListener != null){//增加当前读取的字节数，如果读取完成则返回-1totalBytesRead += byteRead != -1?byteRead:0;//回调，若是contentLength()不知道长度，则返回-1mHandler.post(new Runnable() {@Overridepublic void run() {mListener.onProgress(totalBytesRead, contentLength(), byteRead == -1);}});}return byteRead;}};}}}
OKHttpThreadCallback
package com.example.administrator.myapplication;import android.os.Handler;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import okhttp3.Call;
import okhttp3.Callback;
import okhttp3.Response;public final class OKHttpThreadCallback implements Callback {private Handler UIHandler;private OKHttpUICallback.ProgressCallback UICallback;private boolean isDownload;private File downFile;public OKHttpThreadCallback(Handler handler, OKHttpUICallback.ProgressCallback callback, boolean isDownload){this.UIHandler = handler;this.UICallback = callback;this.isDownload = isDownload;}@Overridepublic void onFailure(final Call call, final IOException e) {if(UICallback != null && UIHandler != null){UIHandler.post(new Runnable() {@Overridepublic void run() {UICallback.onError(call,e);}});}}@Overridepublic void onResponse(Call call, Response response) throws IOException {if(isDownload){download(call,response);}else{postSuccess(call,response);}}/*** 设置保存file* @param file*/public OKHttpThreadCallback setFile(File file){this.downFile = file;return this;}/*** 获取下载数据并写入文件* @param response*/private void download(Call call, Response response) throws IOException {if(downFile == null){throw new NullPointerException("downFile == null");}byte[] buffer = new byte[2048];InputStream is = response.body().byteStream();int len;FileOutputStream fos = new FileOutputStream(downFile);while ((len = is.read(buffer)) != -1){fos.write(buffer,0,len);}fos.flush();if(is != null){is.close();}if (fos != null){fos.close();}postSuccess(call,null);}/*** 回调成功信息* @param call* @param response*/private void postSuccess(final Call call, final Response response){if(UICallback != null && UIHandler != null){UIHandler.post(new Runnable() {@Overridepublic void run() {UICallback.onSuccess(call, response,downFile == null?null:downFile.getAbsolutePath());}});}}
}
Config
package com.example.administrator.myapplication;import android.os.Environment;import java.io.File;public class Config {public static File getDirFile(String subFileName){if(isSDMounted()){return mkdirsFolder(getSDirAbsolutePath() + "/Seeker/" + subFileName);}return null;}public static boolean isSDMounted(){return Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED);}public static File mkdirsFolder(String path){File file = new File(path);if(!file.exists()){return file.mkdirs()?file:null;}return file;}public static String getSDirAbsolutePath(){return Environment.getExternalStorageDirectory().getAbsolutePath();}}
最后看一个接口
package com.example.administrator.myapplication;import java.io.IOException;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;import okhttp3.Call;
import okhttp3.Response;/*** Created by safly on 2016/9/1.* 回调主线程的接口*/
public class OKHttpUICallback {/*** 带有进度的上传、下载回调接口*/public interface ProgressCallback{void onSuccess(Call call, Response response, String path);void onProgress(long byteReadOrWrite, long contentLength, boolean done);void onError(Call call, IOException e);}
}
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