Retrofit使用教程：通過(guò)Retrofit下載大文件并監(jiān)聽(tīng)下載進(jìn)度

前言

在開(kāi)發(fā)項(xiàng)目中不免會(huì)遇到下載文件的需求，如果正好使用的是Retrofit網(wǎng)絡(luò)框架又不想使用其它網(wǎng)絡(luò)框架或者手寫(xiě)的HttpUrlConnection，那只好在Retrofit的基礎(chǔ)上封裝下載。

功能描述

  • 支持下載大文件
  • 支持多個(gè)頁(yè)面監(jiān)聽(tīng)
  • 支持進(jìn)度回調(diào)監(jiān)聽(tīng)

使用說(shuō)明

  • 例一
    通過(guò)AppDownLoadHelper設(shè)置下載地址、存儲(chǔ)位置即可下載文件。
    還可以配置AppProgressListener或者設(shè)置Tag來(lái)滿足更多的需求。
public class MainActivity extends AppCompatActivity {

    private Button mDownButton;

    @Override protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mDownButton = (Button) findViewById(R.id.main_button_down);
        mDownButton.setOnClickListener(mListener);

        findViewById(R.id.main_button_start).setOnClickListener(new View.OnClickListener() {@Override public void onClick(View view) {
                Intent intent = new Intent(MainActivity.this, Main2Activity.class);
                startActivity(intent);
            }
        });
    }

    View.OnClickListener mListener = new View.OnClickListener() {@Override public void onClick(View view) {

            AppDownLoadHelper helper = AppDownLoadManager.getInstance().getHelperByTag("xx");
            if (helper != null) {
                AppDownLoadManager.getInstance().cancelHelperByTag("xx");
                mDownButton.setText("下載");
                return;
            }

            new AppDownLoadHelper.Builder().setPath(SDCardUtil.getLogCacheDir(AppApplication.getContext()) + "/xxx1.apk").setTag("xx").setUrl("http://dl.play.91.com/bigdata/com.ilongyuan.voez.baidu_v1.0.4.apk").setDownLoadListener(new AppProgressListener() {@Override public void onStart() {
                    Log.i("tag", "========開(kāi)始");
                    mDownButton.setText("0%");
                }

                @Override public void update(long bytesRead, long contentLength, boolean done) {
                    int read = (int)(bytesRead * 100f / contentLength);
                    Log.i("tag", "========" + read);
                    mDownButton.setText(read + "%");
                }

                @Override public void onCompleted() {
                    mDownButton.setText("完成");
                    Log.i("tag", "========" + Thread.currentThread().getName());
                }

                @Override public void onError(String err) {
                    mDownButton.setText("失敗");
                    Log.i("tag", "========失敗" + err);
                }
            }).create().execute();
        }
    };

    @Override protected void onDestroy() {
        super.onDestroy();
        AppDownLoadManager.getInstance().unsubscribe();
    }
}
  • 例二
    根據(jù)Tag獲取指定的AppDownLoadHelper，AppDownLoadHelper是下載的總控制器只要獲取到它就可以對(duì)正在下載的文件進(jìn)行取消、進(jìn)度監(jiān)聽(tīng)操作。
public class Main2Activity extends AppCompatActivity {

    private AppDownLoadHelper mHelper;
    private Button mDownButton;

    @Override protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);

        mDownButton = (Button) findViewById(R.id.main2_button_down);

        mHelper = AppDownLoadManager.getInstance().getHelperByTag("xx");
        if (mHelper != null) {
            mHelper.registerListener(mProgressLinstener);
        }
    }

    AppProgressListener mProgressLinstener = new AppProgressListener() {
        @Override public void onStart() {}

        @Override public void update(long bytesRead, long contentLength, boolean done) {
            int read = (int)(bytesRead * 100f / contentLength);
            mDownButton.setText(read + "%");
        }

        @Override public void onCompleted() {
            mDownButton.setText("完成");
        }

        @Override public void onError(String err) {}
    };

    @Override protected void onDestroy() {
        super.onDestroy();
        if (mHelper != null) {
            mHelper.unRegisterListener(mProgressLinstener);
        }
    }
}

源碼解讀

  • 一、定義下載器：負(fù)責(zé)下載功能
public class AppDownLoadHelper {

    省略...

    private AppDownLoadHelper() {
        mDownloadListeners = new HashSet < >();
        mManager = AppDownLoadManager.getInstance();
    }

    public void setCancel(boolean cancel) {
        isCancel = cancel;
    }

    public void setmUrl(String url) {
        if (url != null) {
            int lastIndex = url.lastIndexOf("/");
            if (lastIndex != -1) {
                mApkName = url.substring(lastIndex + 1);
                mBaseUrl = url.substring(0, lastIndex + 1);
            }
        }
    }

    /**
     * 默認(rèn)分配tag
     */
    public void setTag(Object tag) {
        if (tag != null) {
            mTag = tag;
        } else {
            mTag = UUID.randomUUID().toString();
        }
    }

    public void registerListener(AppProgressListener listener) {
        mDownloadListeners.add(listener);
    }

    public void unRegisterListener(AppProgressListener listener) {
        mDownloadListeners.remove(listener);
    }

    private OkHttpClient getDefaultOkHttp() {
        return getBuilder().build();
    }

    private OkHttpClient.Builder getBuilder() {
        AppSigningInterceptor signingInterceptor = new AppSigningInterceptor();
        signingInterceptor.setProgressListener(mListener);
        OkHttpClient.Builder builder = new OkHttpClient.Builder();
        builder.addInterceptor(signingInterceptor);
        builder.connectTimeout(mConnectionTimeout, TimeUnit.SECONDS);
        builder.readTimeout(mReadTimeout, TimeUnit.SECONDS);
        return builder;
    }

    public static class Builder {
        private AppProgressListener mListener;
        private String mUrl;
        private String mPath;
        private int mConnectionTimeout;
        private int mReadTimeout;
        private Object mTag;

        public Builder() {
            this.mConnectionTimeout = CONNECTION_TIMEOUT;
            this.mReadTimeout = READ_DOWN_TIMEOUT;
        }

        /**
         * 設(shè)置任務(wù)標(biāo)記
         */
        public Builder setTag(Object tag) {
            this.mTag = tag;
            return this;
        }

        /**
         * 設(shè)置下載文件的URL
         */
        public Builder setUrl(String url) {
            this.mUrl = url;
            return this;
        }

        /**
         * 設(shè)置HTTP請(qǐng)求連接超時(shí)時(shí)間，默認(rèn)10s
         */
        public Builder setConnectionTimeout(int timeout) {
            this.mConnectionTimeout = timeout;
            return this;
        }

        /**
         * 設(shè)置HTTP請(qǐng)求數(shù)據(jù)讀取超時(shí)時(shí)間，默認(rèn)20s
         */
        public Builder setReadTimeout(int timeout) {
            this.mReadTimeout = timeout;
            return this;
        }

        /**
         * 設(shè)置下載文件保存地址，使用絕對(duì)路徑
         */
        public Builder setPath(String path) {
            this.mPath = path;
            return this;
        }

        /**
         * 設(shè)置下載監(jiān)聽(tīng)
         */
        public Builder setDownLoadListener(AppProgressListener listener) {
            this.mListener = listener;
            return this;
        }

        /**
         * 創(chuàng)建一個(gè)本地任務(wù)
         */
        public AppDownLoadHelper create() {
            final AppDownLoadHelper helper = new AppDownLoadHelper();
            helper.mConnectionTimeout = mConnectionTimeout;
            helper.mReadTimeout = mReadTimeout;
            helper.mPath = mPath;
            helper.setTag(mTag);
            helper.setmUrl(mUrl);
            if (mListener != null) {
                helper.mDownloadListeners.add(mListener);
            }
            return helper;
        }
    }

    public void execute() {
        mManager.addHelper(this);
        mAdapter = new Retrofit.Builder().baseUrl(mBaseUrl).addConverterFactory(GsonConverterFactory.create()).addCallAdapterFactory(RxJavaCallAdapterFactory.create()).client(getDefaultOkHttp()).build();
        mUploadService = mAdapter.create(AppDownloadService.class);

        final long startTime = System.currentTimeMillis();
        mUploadService.download(mApkName).subscribeOn(Schedulers.io()).observeOn(Schedulers.io()).subscribe(new Subscriber < ResponseBody > () {

            @Override public void onCompleted() {
                if (isCancel) {
                    mListener.onError("cancel");
                } else if (mListener != null) {
                    mListener.onCompleted();
                }
            }

            @Override public void onError(Throwable e) {
                if (mListener != null) {
                    mListener.onError(e.getMessage());
                }
            }

            @Override public void onNext(ResponseBody responseBody) {
                Log.i("AppDownLoadHelper", "========next" + responseBody.contentLength());

                省略... 數(shù)據(jù)存儲(chǔ)本地操作
                long endTime = System.currentTimeMillis();
                Log.i("AppDownLoadHelper", "========time" + (endTime - startTime));
            }
        });

        if (mListener != null) {
            mListener.onStart();
        }
    }
}
  • 二、定義下載管理者：通過(guò)Map管理單個(gè)或多個(gè)下載器，并分發(fā)每個(gè)下載器的狀態(tài)。
public class AppDownLoadManager {

    public static final int START = 1;
    public static final int PROGRESSING = 2;
    public static final int COMPLETED = 3;
    public static final int EXCEPTION = 4;

    private static AppDownLoadManager mInstance;
    private ConcurrentHashMap <Object, AppDownLoadHelper> mTagToHelpers;
    private Handler mUIHandler;

    private AppDownLoadManager() {
        mTagToHelpers = new ConcurrentHashMap <Object, AppDownLoadHelper> ();
        mUIHandler = new UIHandler(mTagToHelpers);
    }

    public synchronized static AppDownLoadManager getInstance() {
        if (mInstance == null) {
            mInstance = new AppDownLoadManager();
        }
        return mInstance;
    }

    public void addHelper(final AppDownLoadHelper helper) {
        if (helper == null) return;

        helper.mListener = new AppProgressListener() {@Override public void onStart() {
                Message message = mUIHandler.obtainMessage();
                message.obj = helper.mTag;
                message.what = START;
                message.sendToTarget();
            }

            @Override public void update(long bytesRead, long contentLength, boolean done) {
                Message message = mUIHandler.obtainMessage();
                Bundle bundle = new Bundle();
                bundle.putLong("bytesRead", bytesRead);
                bundle.putLong("contentLength", contentLength);
                bundle.putBoolean("done", done);
                message.setData(bundle);
                message.obj = helper.mTag;
                message.what = PROGRESSING;
                message.sendToTarget();
            }

            @Override public void onCompleted() {
                Message message = mUIHandler.obtainMessage();
                message.obj = helper.mTag;
                message.what = COMPLETED;
                message.sendToTarget();
            }

            @Override public void onError(String err) {
                Message message = mUIHandler.obtainMessage();
                message.obj = helper.mTag;
                message.what = EXCEPTION;
                Bundle bundle = new Bundle();
                bundle.putString("err", err);
                message.setData(bundle);
                message.sendToTarget();
            }
        };
        mTagToHelpers.put(helper.mTag, helper);
    }

    public AppDownLoadHelper getHelperByTag(Object tag) {
        return tag == null ? null: mTagToHelpers.get(tag);
    }

    public void cancelHelperByTag(Object tag) {
        AppDownLoadHelper helper = mTagToHelpers.get(tag);
        if (helper != null) {
            helper.setCancel(true);
            helper.mDownloadListeners.clear();
            mTagToHelpers.remove(tag);
        }
    }

    private static class UIHandler extends Handler {
        private ConcurrentHashMap < Object,
        AppDownLoadHelper > mTagToHelpers;

        public UIHandler(ConcurrentHashMap < Object, AppDownLoadHelper > tagToHelpers) {
            mTagToHelpers = tagToHelpers;
        }

        @Override public void handleMessage(Message msg) {
            super.handleMessage(msg);

            String tagID = (String) msg.obj;
            AppDownLoadHelper helper = mTagToHelpers.get(tagID);
            if (helper == null) return;

            switch (msg.what) {
            case START:
                //任務(wù)開(kāi)始
                for (AppProgressListener listener:
                helper.mDownloadListeners) {
                    listener.onStart();
                }
                break;

            case PROGRESSING:
                //任務(wù)進(jìn)度更新
                Bundle data = msg.getData();
                for (AppProgressListener listener: helper.mDownloadListeners) {
                    listener.update(data.getLong("bytesRead"), data.getLong("contentLength"), data.getBoolean("done"));
                }
                break;

            case COMPLETED:
                //任務(wù)完成
                for (AppProgressListener listener:
                helper.mDownloadListeners) {
                    listener.onCompleted();
                }
                helper.mDownloadListeners.clear();
                mTagToHelpers.remove(tagID);
                break;

            case EXCEPTION:
                //任務(wù)發(fā)生異常
                Bundle e = msg.getData();
                for (AppProgressListener listener: helper.mDownloadListeners) {
                    listener.onError(e.getString("err"));
                }
                helper.mDownloadListeners.clear();
                helper.setCancel(true);
                mTagToHelpers.remove(tagID);
                break;

            default:
                break;
            }
        }
    }

    public void unsubscribe() {
        for (Object key:
        mTagToHelpers.keySet()) {
            AppDownLoadHelper appDownLoadHelper = mTagToHelpers.get(key);
            appDownLoadHelper.setCancel(true);
            appDownLoadHelper.mDownloadListeners.clear();
            mTagToHelpers.remove(key);
        }
    }
}
  • 三、網(wǎng)絡(luò)請(qǐng)求API
public interface AppDownloadService {
    @Streaming
    @GET("{url}") 
    Observable <ResponseBody> download(@Path("url")String apkName);
}
  • 四、下載進(jìn)度回調(diào)接口
public interface AppProgressListener {
    void onStart();
    void update(long bytesRead, long contentLength, boolean done);
    void onCompleted();
    void onError(String err);
}
  • 五、Retrofit使用中的攔截器：用于對(duì)下載進(jìn)度的攔截
public class AppSigningInterceptor implements Interceptor {

    public AppProgressListener mProgressListener;
    public void setProgressListener(AppProgressListener p) {
        mProgressListener = p;
    }

    @Override public Response intercept(Chain chain) throws IOException {

        Request oldRequest = chain.request();
        // 添加新的參數(shù)
        HttpUrl.Builder authorizedUrlBuilder = oldRequest.url().newBuilder().scheme(oldRequest.url().scheme()).host(oldRequest.url().host());

        // 設(shè)置統(tǒng)一請(qǐng)求參數(shù)
        Request.Builder newRequest = oldRequest.newBuilder().method(oldRequest.method(), oldRequest.body())
        .url(authorizedUrlBuilder.build());

        if (mProgressListener != null) {
            Response originalResponse = chain.proceed(newRequest.build());
            return originalResponse.newBuilder().body(new ProgressResponseBody(originalResponse.body(), mProgressListener)).build();
        }
        return chain.proceed(newRequest.build());
    }
}
  • 六、自定義ResponseBody：通過(guò)配置在攔截器里對(duì)下載進(jìn)度監(jiān)聽(tīng)
public class ProgressResponseBody extends ResponseBody {

    private final ResponseBody responseBody;
    private final AppProgressListener progressListener;
    private BufferedSource bufferedSource;

    public ProgressResponseBody(ResponseBody responseBody, AppProgressListener progressListener) {
        this.responseBody = responseBody;
        this.progressListener = progressListener;
    }

    @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 totalBytesRead = 0L;

            @Override public long read(Buffer sink, long byteCount) throws IOException {
                long bytesRead = super.read(sink, byteCount);
                totalBytesRead += bytesRead != -1 ? bytesRead: 0;
                progressListener.update(totalBytesRead, responseBody.contentLength(), bytesRead == -1);
                return bytesRead;
            }
        };
    }
}

github源碼下載

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