【Android】- OkHttp實現斷點續傳
阿新 • • 發佈：2019-02-09
1.匯入依賴包
//retrofit, 基於Okhttp，考慮到專案中經常會用到retrofit，就匯入這個了。 compile 'com.squareup.retrofit2:retrofit:2.1.0' //ButterKnife compile 'com.jakewharton:butterknife:7.0.1' //rxjava 本例中執行緒切換要用到，代替handler compile 'io.reactivex:rxjava:1.1.6' compile 'io.reactivex:rxandroid:1.2.1'
2.繼承ResponseBody，生成帶進度監聽的ProgressResponseBody
package com.example.hxl.breakpointresumeokhttp; import java.io.IOException; import okhttp3.MediaType; import okhttp3.ResponseBody; import okio.Buffer; import okio.BufferedSource; import okio.ForwardingSource; import okio.Okio; import okio.Source; /** * Created by hxl on 2017/2/24 at haiChou. * 進度響應體*/ public class ProgressResponseBody extends ResponseBody{ //設定對外訪問的進度監聽 public interface ProgressListener { void onPreExecute(long contentLength); void update(long totalBytes, boolean done); } private final ResponseBody responseBody; private final ProgressListener progressListener; private BufferedSource bufferedSource; public ProgressResponseBody(ResponseBody responseBody, ProgressListener progressListener) { this.responseBody = responseBody; this.progressListener = progressListener; if(progressListener!=null){ progressListener.onPreExecute(contentLength()); } } @Override public MediaType contentType() { return responseBody.contentType(); } @Override public long contentLength() { return responseBody.contentLength(); } @Override public BufferedSource source() { if (bufferedSource == null) { bufferedSource = Okio.buffer(source(responseBody.source())); } return bufferedSource; } private Source source(Source source) { return new ForwardingSource(source) { long totalBytes = 0L; @Override public long read(Buffer sink, long byteCount) throws IOException { long bytesRead = super.read(sink, byteCount); // read() returns the number of bytes read, or -1 if this source is exhausted. totalBytes += bytesRead != -1 ? bytesRead : 0; if (null != progressListener) { progressListener.update(totalBytes, bytesRead == -1); } return bytesRead; } }; } }
3.建立ProgressDownloader
package com.example.hxl.breakpointresumeokhttp;
import java.io.File; import java.io.IOException; import java.io.InputStream; import java.io.RandomAccessFile; import java.nio.MappedByteBuffer; import java.nio.channels.FileChannel; import okhttp3.Call; import okhttp3.Callback; import okhttp3.Interceptor; import okhttp3.OkHttpClient; import okhttp3.Request; import okhttp3.Response; import okhttp3.ResponseBody; /** * Created by hxl on 2017/2/24 at haiChou. * 建立ProgressDownloader帶進度監聽功能的輔助類 */ public class ProgressDownloader { public static final String TAG = "ProgressDownloader"; private ProgressResponseBody.ProgressListener progressListener; private String url; private OkHttpClient client; private File destination; private Call call; public ProgressDownloader(String url, File destination, ProgressResponseBody.ProgressListener progressListener) { this.url = url; this.destination = destination; this.progressListener = progressListener; //在下載、暫停後的繼續下載中可複用同一個client物件 client = getProgressClient(); } //每次下載需要新建新的Call物件 private Call newCall(long startPoints) { Request request = new Request.Builder() .url(url) .header("RANGE", "bytes=" + startPoints + "-")//斷點續傳要用到的，指示下載的區間 .build(); return client.newCall(request); } public OkHttpClient getProgressClient() { // 攔截器，用上ProgressResponseBody Interceptor interceptor = new Interceptor() { @Override public Response intercept(Chain chain) throws IOException { Response originalResponse = chain.proceed(chain.request()); return originalResponse.newBuilder() .body(new ProgressResponseBody(originalResponse.body(), progressListener)) .build(); } }; return new OkHttpClient.Builder() .addNetworkInterceptor(interceptor) .build(); } // startsPoint指定開始下載的點 public void download(final long startsPoint) { call = newCall(startsPoint); call.enqueue(new Callback() { @Override public void onFailure(Call call, IOException e) { } @Override public void onResponse(Call call, Response response) throws IOException { save(response, startsPoint); } }); } public void pause() { if(call!=null){ call.cancel(); } } private void save(Response response, long startsPoint) { ResponseBody body = response.body(); InputStream in = body.byteStream(); FileChannel channelOut = null; // 隨機訪問檔案，可以指定斷點續傳的起始位置 RandomAccessFile randomAccessFile = null; try { randomAccessFile = new RandomAccessFile(destination, "rwd"); //Chanel NIO中的用法，由於RandomAccessFile沒有使用快取策略，直接使用會使得下載速度變慢，親測快取下載3.3秒的檔案，用普通的RandomAccessFile需要20多秒。 channelOut = randomAccessFile.getChannel(); // 記憶體對映，直接使用RandomAccessFile，是用其seek方法指定下載的起始位置，使用快取下載，在這裡指定下載位置。 MappedByteBuffer mappedBuffer = channelOut.map(FileChannel.MapMode.READ_WRITE, startsPoint, body.contentLength()); byte[] buffer = new byte[1024]; int len; while ((len = in.read(buffer)) != -1) { mappedBuffer.put(buffer, 0, len); } } catch (IOException e) { e.printStackTrace(); }finally { try { in.close(); if (channelOut != null) { channelOut.close(); } if (randomAccessFile != null) { randomAccessFile.close(); } } catch (IOException e) { e.printStackTrace(); } } } }4.清單檔案中新增網路許可權和檔案訪問許可權
<uses-permission android:name="android.permission.INTERNET"/> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
5.測試
package com.example.hxl.breakpointresumeokhttp; import android.os.Environment; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.ProgressBar; import android.widget.Toast; import java.io.File; import butterknife.Bind; import butterknife.ButterKnife; import butterknife.OnClick; import rx.Observable; import rx.android.schedulers.AndroidSchedulers; import rx.functions.Action0; /** * 1.新增依賴 * 2.生成帶進度監聽的ProgressResponseBody * 3.建立ProgressDownloader * 4.清單檔案中新增網路許可權和檔案訪問許可權 */ public class MainActivity extends AppCompatActivity implements ProgressResponseBody.ProgressListener{ public static final String TAG = "MainActivity"; public static final String PACKAGE_URL = "http://gdown.baidu.com/data/wisegame/df65a597122796a4/weixin_821.apk"; @Bind(R.id.progressBar) ProgressBar progressBar; private long breakPoints; private ProgressDownloader downloader; private File file; private long totalBytes; private long contentLength; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); ButterKnife.bind(this); } @OnClick({R.id.downloadButton, R.id.cancel_button, R.id.continue_button}) public void onClick(View view) { switch (view.getId()) { case R.id.downloadButton: // 新下載前清空斷點資訊 breakPoints = 0L; file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS), "sample.apk"); downloader = new ProgressDownloader(PACKAGE_URL, file, this); downloader.download(0L); break; case R.id.cancel_button: downloader.pause(); Toast.makeText(this, "下載暫停", Toast.LENGTH_SHORT).show(); // 儲存此時的totalBytes，即斷點位置。 breakPoints = totalBytes; break; case R.id.continue_button: downloader.download(breakPoints); break; } } @Override public void onPreExecute(long contentLength) { // 檔案總長只需記錄一次，要注意斷點續傳後的contentLength只是剩餘部分的長度 if (this.contentLength == 0L) { this.contentLength = contentLength; progressBar.setMax((int) (contentLength / 1024)); } } @Override public void update(long totalBytes, boolean done) { // 注意加上斷點的長度 this.totalBytes = totalBytes + breakPoints; progressBar.setProgress((int) (totalBytes + breakPoints) / 1024); if (done) { // 切換到主執行緒 Observable .empty() .observeOn(AndroidSchedulers.mainThread()) .doOnCompleted(new Action0() { @Override public void call() { Toast.makeText(MainActivity.this, "下載完成", Toast.LENGTH_SHORT).show(); } }) .subscribe(); } } }6.xml佈局檔案
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" tools:context="com.example.hxl.breakpointresumeokhttp.MainActivity"> <ProgressBar android:id="@+id/progressBar" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginLeft="10dp" android:layout_marginRight="10dp" android:max="100" style="?android:attr/progressBarStyleHorizontal" /> <Button android:id="@+id/downloadButton" android:layout_marginTop="10dp" android:layout_marginLeft="10dp" android:layout_marginRight="10dp" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="下載"/> <Button android:id="@+id/cancel_button" android:layout_marginTop="10dp" android:layout_marginLeft="10dp" android:layout_marginRight="10dp" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="暫停"/> <Button android:id="@+id/continue_button" android:layout_marginTop="10dp" android:layout_marginLeft="10dp" android:layout_marginRight="10dp" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="繼續"/> </LinearLayout>7.效果圖
