OKHttp3是如今非常流行的Android网络请求框架,那么如何利用Android实现断点续传呢,今天写了个Demo尝试了一下,感觉还是有点意思
准备阶段
我们会用到OKHttp3来做网络请求,使用RxJava来实现线程的切换,并且开启Java8来启用Lambda表达式,毕竟RxJava实现线程切换非常方便,而且数据流的形式也非常舒服,同时Lambda和RxJava配合食用味道更佳
打开我们的app Module下的build.gradle,代码如下
- apply plugin: 'com.android.application'
- android {
- compileSdkVersion 24
- buildToolsVersion "24.0.3"
- defaultConfig {
- applicationId "com.lanou3g.downdemo"
- minSdkVersion 15
- targetSdkVersion 24
- versionCode 1
- versionName "1.0"
- testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
- //为了开启Java8
- jackOptions{
- enabled true;
- }
- }
- buildTypes {
- release {
- minifyEnabled false
- proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
- }
- }
- //开启Java1.8 能够使用lambda表达式
- compileOptions{
- sourceCompatibility JavaVersion.VERSION_1_8
- targetCompatibility JavaVersion.VERSION_1_8
- }
- }
- dependencies {
- compile fileTree(dir: 'libs', include: ['*.jar'])
- androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
- exclude group: 'com.android.support', module: 'support-annotations'
- })
- compile 'com.android.support:appcompat-v7:24.1.1'
- testCompile 'junit:junit:4.12'
- //OKHttp
- compile 'com.squareup.okhttp3:okhttp:3.6.0'
- //RxJava和RxAndroid 用来做线程切换的
- compile 'io.reactivex.rxjava2:rxandroid:2.0.1'
- compile 'io.reactivex.rxjava2:rxjava:2.0.1'
- }
布局文件
接着开始书写布局文件- <?xml version="1.0" encoding="utf-8"?>
- <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
- xmlns:tools="http://schemas.android.com/tools"
- android:id="@+id/activity_main"
- android:layout_width="match_parent"
- android:layout_height="match_parent"
- android:paddingBottom="@dimen/activity_vertical_margin"
- android:paddingLeft="@dimen/activity_horizontal_margin"
- android:paddingRight="@dimen/activity_horizontal_margin"
- android:paddingTop="@dimen/activity_vertical_margin"
- android:orientation="vertical"
- tools:context="com.lanou3g.downdemo.MainActivity">
- <LinearLayout
- android:layout_width="match_parent"
- android:layout_height="wrap_content"
- android:orientation="horizontal">
- <ProgressBar
- android:id="@+id/main_progress1"
- android:layout_width="0dp"
- android:layout_weight="1"
- android:layout_height="match_parent"
- style="@style/Widget.AppCompat.ProgressBar.Horizontal" />
- <Button
- android:id="@+id/main_btn_down1"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:text="下载1"/>
- <Button
- android:id="@+id/main_btn_cancel1"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:text="取消1"/>
- </LinearLayout>
- <LinearLayout
- android:layout_width="match_parent"
- android:layout_height="wrap_content"
- android:orientation="horizontal">
- <ProgressBar
- android:id="@+id/main_progress2"
- android:layout_width="0dp"
- android:layout_weight="1"
- android:layout_height="match_parent"
- style="@style/Widget.AppCompat.ProgressBar.Horizontal" />
- <Button
- android:id="@+id/main_btn_down2"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:text="下载2"/>
- <Button
- android:id="@+id/main_btn_cancel2"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:text="取消2"/>
- </LinearLayout>
- <LinearLayout
- android:layout_width="match_parent"
- android:layout_height="wrap_content"
- android:orientation="horizontal">
- <ProgressBar
- android:id="@+id/main_progress3"
- android:layout_width="0dp"
- android:layout_weight="1"
- android:layout_height="match_parent"
- style="@style/Widget.AppCompat.ProgressBar.Horizontal" />
- <Button
- android:id="@+id/main_btn_down3"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:text="下载3"/>
- <Button
- android:id="@+id/main_btn_cancel3"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:text="取消3"/>
- </LinearLayout>
- </LinearLayout>
3个ProgressBar就是为了显示进度的,每个ProgressBar对应2个Button,一个是开始下载,一个是暂停(取消)下载,这里需要说明的是,对下载来说暂停和取消没有什么区别,除非当取消的时候,会顺带把临时文件都删除了,在本例里是不区分他俩的.
Application
- package com.lanou3g.downdemo;
- import android.app.Application;
- import android.content.Context;
- /**
- * Created by 陈丰尧 on 2017/2/2.
- */
- public class MyApp extends Application {
- public static Context sContext;//全局的Context对象
- @Override
- public void onCreate() {
- super.onCreate();
- sContext = this;
- }
- }
- <?xml version="1.0" encoding="utf-8"?>
- <manifest xmlns:android="http://schemas.android.com/apk/res/android"
- package="com.lanou3g.downdemo">
- <!--网络权限-->
- <uses-permission android:name="android.permission.INTERNET"/>
- <application
- android:allowBackup="true"
- android:icon="@mipmap/ic_launcher"
- android:label="@string/app_name"
- android:supportsRtl="true"
- android:name=".MyApp"
- android:theme="@style/AppTheme">
- <activity android:name=".MainActivity">
- <intent-filter>
- <action android:name="android.intent.action.MAIN" />
- <category android:name="android.intent.category.LAUNCHER" />
- </intent-filter>
- </activity>
- </application>
- </manifest>
DownloadManager
- package com.lanou3g.downdemo;
- import java.io.File;
- import java.io.FileOutputStream;
- import java.io.IOException;
- import java.io.InputStream;
- import java.util.HashMap;
- import java.util.concurrent.atomic.AtomicReference;
- import io.reactivex.Observable;
- import io.reactivex.ObservableEmitter;
- import io.reactivex.ObservableOnSubscribe;
- import io.reactivex.android.schedulers.AndroidSchedulers;
- import io.reactivex.schedulers.Schedulers;
- import okhttp3.Call;
- import okhttp3.OkHttpClient;
- import okhttp3.Request;
- import okhttp3.Response;
- /**
- * Created by 陈丰尧 on 2017/2/2.
- */
- public class DownloadManager {
- private static final AtomicReference<DownloadManager> INSTANCE = new AtomicReference<>();
- private HashMap<String, Call> downCalls;//用来存放各个下载的请求
- private OkHttpClient mClient;//OKHttpClient;
- //获得一个单例类
- public static DownloadManager getInstance() {
- for (; ; ) {
- DownloadManager current = INSTANCE.get();
- if (current != null) {
- return current;
- }
- current = new DownloadManager();
- if (INSTANCE.compareAndSet(null, current)) {
- return current;
- }
- }
- }
- private DownloadManager() {
- downCalls = new HashMap<>();
- mClient = new OkHttpClient.Builder().build();
- }
- /**
- * 开始下载
- *
- * @param url 下载请求的网址
- * @param downLoadObserver 用来回调的接口
- */
- public void download(String url, DownLoadObserver downLoadObserver) {
- Observable.just(url)
- .filter(s -> !downCalls.containsKey(s))//call的map已经有了,就证明正在下载,则这次不下载
- .flatMap(s -> Observable.just(createDownInfo(s)))
- .map(this::getRealFileName)//检测本地文件夹,生成新的文件名
- .flatMap(downloadInfo -> Observable.create(new DownloadSubscribe(downloadInfo)))//下载
- .observeOn(AndroidSchedulers.mainThread())//在主线程回调
- .subscribeOn(Schedulers.io())//在子线程执行
- .subscribe(downLoadObserver);//添加观察者
- }
- public void cancel(String url) {
- Call call = downCalls.get(url);
- if (call != null) {
- call.cancel();//取消
- }
- downCalls.remove(url);
- }
- /**
- * 创建DownInfo
- *
- * @param url 请求网址
- * @return DownInfo
- */
- private DownloadInfo createDownInfo(String url) {
- DownloadInfo downloadInfo = new DownloadInfo(url);
- long contentLength = getContentLength(url);//获得文件大小
- downloadInfo.setTotal(contentLength);
- String fileName = url.substring(url.lastIndexOf("/"));
- downloadInfo.setFileName(fileName);
- return downloadInfo;
- }
- private DownloadInfo getRealFileName(DownloadInfo downloadInfo) {
- String fileName = downloadInfo.getFileName();
- long downloadLength = 0, contentLength = downloadInfo.getTotal();
- File file = new File(MyApp.sContext.getFilesDir(), fileName);
- if (file.exists()) {
- //找到了文件,代表已经下载过,则获取其长度
- downloadLength = file.length();
- }
- //之前下载过,需要重新来一个文件
- int i = 1;
- while (downloadLength >= contentLength) {
- int dotIndex = fileName.lastIndexOf(".");
- String fileNameOther;
- if (dotIndex == -1) {
- fileNameOther = fileName + "(" + i + ")";
- } else {
- fileNameOther = fileName.substring(0, dotIndex)
- + "(" + i + ")" + fileName.substring(dotIndex);
- }
- File newFile = new File(MyApp.sContext.getFilesDir(), fileNameOther);
- file = newFile;
- downloadLength = newFile.length();
- i++;
- }
- //设置改变过的文件名/大小
- downloadInfo.setProgress(downloadLength);
- downloadInfo.setFileName(file.getName());
- return downloadInfo;
- }
- private class DownloadSubscribe implements ObservableOnSubscribe<DownloadInfo> {
- private DownloadInfo downloadInfo;
- public DownloadSubscribe(DownloadInfo downloadInfo) {
- this.downloadInfo = downloadInfo;
- }
- @Override
- public void subscribe(ObservableEmitter<DownloadInfo> e) throws Exception {
- String url = downloadInfo.getUrl();
- long downloadLength = downloadInfo.getProgress();//已经下载好的长度
- long contentLength = downloadInfo.getTotal();//文件的总长度
- //初始进度信息
- e.onNext(downloadInfo);
- Request request = new Request.Builder()
- //确定下载的范围,添加此头,则服务器就可以跳过已经下载好的部分
- .addHeader("RANGE", "bytes=" + downloadLength + "-" + contentLength)
- .url(url)
- .build();
- Call call = mClient.newCall(request);
- downCalls.put(url, call);//把这个添加到call里,方便取消
- Response response = call.execute();
- File file = new File(MyApp.sContext.getFilesDir(), downloadInfo.getFileName());
- InputStream is = null;
- FileOutputStream fileOutputStream = null;
- try {
- is = response.body().byteStream();
- fileOutputStream = new FileOutputStream(file, true);
- byte[] buffer = new byte[2048];//缓冲数组2kB
- int len;
- while ((len = is.read(buffer)) != -1) {
- fileOutputStream.write(buffer, 0, len);
- downloadLength += len;
- downloadInfo.setProgress(downloadLength);
- e.onNext(downloadInfo);
- }
- fileOutputStream.flush();
- downCalls.remove(url);
- } finally {
- //关闭IO流
- IOUtil.closeAll(is, fileOutputStream);
- }
- e.onComplete();//完成
- }
- }
- /**
- * 获取下载长度
- *
- * @param downloadUrl
- * @return
- */
- private long getContentLength(String downloadUrl) {
- Request request = new Request.Builder()
- .url(downloadUrl)
- .build();
- try {
- Response response = mClient.newCall(request).execute();
- if (response != null && response.isSuccessful()) {
- long contentLength = response.body().contentLength();
- response.close();
- return contentLength == 0 ? DownloadInfo.TOTAL_ERROR : contentLength;
- }
- } catch (IOException e) {
- e.printStackTrace();
- }
- return DownloadInfo.TOTAL_ERROR;
- }
- }
- package com.lanou3g.downdemo;
- import io.reactivex.Observer;
- import io.reactivex.disposables.Disposable;
- /**
- * Created by 陈丰尧 on 2017/2/2.
- */
- public abstract class DownLoadObserver implements Observer<DownloadInfo> {
- protected Disposable d;//可以用于取消注册的监听者
- protected DownloadInfo downloadInfo;
- @Override
- public void onSubscribe(Disposable d) {
- this.d = d;
- }
- @Override
- public void onNext(DownloadInfo downloadInfo) {
- this.downloadInfo = downloadInfo;
- }
- @Override
- public void onError(Throwable e) {
- e.printStackTrace();
- }
- }
- package com.lanou3g.downdemo;
- /**
- * Created by 陈丰尧 on 2017/2/2.
- * 下载信息
- */
- public class DownloadInfo {
- public static final long TOTAL_ERROR = -1;//获取进度失败
- private String url;
- private long total;
- private long progress;
- private String fileName;
- public DownloadInfo(String url) {
- this.url = url;
- }
- public String getUrl() {
- return url;
- }
- public String getFileName() {
- return fileName;
- }
- public void setFileName(String fileName) {
- this.fileName = fileName;
- }
- public long getTotal() {
- return total;
- }
- public void setTotal(long total) {
- this.total = total;
- }
- public long getProgress() {
- return progress;
- }
- public void setProgress(long progress) {
- this.progress = progress;
- }
- }
- /**
- * 获取下载长度
- *
- * @param downloadUrl
- * @return
- */
- private long getContentLength(String downloadUrl) {
- Request request = new Request.Builder()
- .url(downloadUrl)
- .build();
- try {
- Response response = mClient.newCall(request).execute();
- if (response != null && response.isSuccessful()) {
- long contentLength = response.body().contentLength();
- response.close();
- return contentLength == 0 ? DownloadInfo.TOTAL_ERROR : contentLength;
- }
- } catch (IOException e) {
- e.printStackTrace();
- }
- return DownloadInfo.TOTAL_ERROR;
- }
获取完文件大小后,就可以去硬盘里找文件了,这里调用了getRealFileName方法
- private DownloadInfo getRealFileName(DownloadInfo downloadInfo) {
- String fileName = downloadInfo.getFileName();
- long downloadLength = 0, contentLength = downloadInfo.getTotal();
- File file = new File(MyApp.sContext.getFilesDir(), fileName);
- if (file.exists()) {
- //找到了文件,代表已经下载过,则获取其长度
- downloadLength = file.length();
- }
- //之前下载过,需要重新来一个文件
- int i = 1;
- while (downloadLength >= contentLength) {
- int dotIndex = fileName.lastIndexOf(".");
- String fileNameOther;
- if (dotIndex == -1) {
- fileNameOther = fileName + "(" + i + ")";
- } else {
- fileNameOther = fileName.substring(0, dotIndex)
- + "(" + i + ")" + fileName.substring(dotIndex);
- }
- File newFile = new File(MyApp.sContext.getFilesDir(), fileNameOther);
- file = newFile;
- downloadLength = newFile.length();
- i++;
- }
- //设置改变过的文件名/大小
- downloadInfo.setProgress(downloadLength);
- downloadInfo.setFileName(file.getName());
- return downloadInfo;
- }
之后就开始真正的网络请求了,这里写了一个内部类来实现ObservableOnSubscribe接口,这个接口也是RxJava2的,东西和之前一样,好像只改了名字,看一下代码
- private class DownloadSubscribe implements ObservableOnSubscribe<DownloadInfo> {
- private DownloadInfo downloadInfo;
- public DownloadSubscribe(DownloadInfo downloadInfo) {
- this.downloadInfo = downloadInfo;
- }
- @Override
- public void subscribe(ObservableEmitter<DownloadInfo> e) throws Exception {
- String url = downloadInfo.getUrl();
- long downloadLength = downloadInfo.getProgress();//已经下载好的长度
- long contentLength = downloadInfo.getTotal();//文件的总长度
- //初始进度信息
- e.onNext(downloadInfo);
- Request request = new Request.Builder()
- //确定下载的范围,添加此头,则服务器就可以跳过已经下载好的部分
- .addHeader("RANGE", "bytes=" + downloadLength + "-" + contentLength)
- .url(url)
- .build();
- Call call = mClient.newCall(request);
- downCalls.put(url, call);//把这个添加到call里,方便取消
- Response response = call.execute();
- File file = new File(MyApp.sContext.getFilesDir(), downloadInfo.getFileName());
- InputStream is = null;
- FileOutputStream fileOutputStream = null;
- try {
- is = response.body().byteStream();
- fileOutputStream = new FileOutputStream(file, true);
- byte[] buffer = new byte[2048];//缓冲数组2kB
- int len;
- while ((len = is.read(buffer)) != -1) {
- fileOutputStream.write(buffer, 0, len);
- downloadLength += len;
- downloadInfo.setProgress(downloadLength);
- e.onNext(downloadInfo);
- }
- fileOutputStream.flush();
- downCalls.remove(url);
- } finally {
- //关闭IO流
- IOUtil.closeAll(is, fileOutputStream);
- }
- e.onComplete();//完成
- }
- }
首先拿到url,当前进度信息和文件的总大小,然后开始网络请求,注意这次网络请求的时候需要添加一条头信息
- .addHeader("RANGE", "bytes=" + downloadLength + "-" + contentLength)
接下来就是正常的网络请求,向本地写文件了,而写文件到本地这,网上大多用的是RandomAccessFile这个类,但是如果不涉及到多个部分拼接的话是没必要的,直接使用输出流就好了,在输出流的构造方法上添加一个true的参数,代表是在原文件的后面添加数据即可,而在循环里,不断的调用onNext方法发送进度信息,当写完了之后别忘了关流,同时把call对象从hashMap中移除了.这里写了一个IOUtil来关流
- package com.lanou3g.downdemo;
- import java.io.Closeable;
- import java.io.IOException;
- /**
- * Created by 陈丰尧 on 2017/2/2.
- */
- public class IOUtil {
- public static void closeAll(Closeable... closeables){
- if(closeables == null){
- return;
- }
- for (Closeable closeable : closeables) {
- if(closeable!=null){
- try {
- closeable.close();
- } catch (IOException e) {
- e.printStackTrace();
- }
- }
- }
- }
- }
这样download方法就完成了,剩下的就是切换线程,注册观察者了
MainActivity
- package com.lanou3g.downdemo;
- import android.net.Uri;
- import android.support.annotation.IdRes;
- import android.support.v7.app.AppCompatActivity;
- import android.os.Bundle;
- import android.view.View;
- import android.widget.Button;
- import android.widget.ProgressBar;
- import android.widget.Toast;
- public class MainActivity extends AppCompatActivity implements View.OnClickListener {
- private Button downloadBtn1, downloadBtn2, downloadBtn3;
- private Button cancelBtn1, cancelBtn2, cancelBtn3;
- private ProgressBar progress1, progress2, progress3;
- private String url1 = "http://192.168.31.169:8080/out/dream.flac";
- private String url2 = "http://192.168.31.169:8080/out/music.mp3";
- private String url3 = "http://192.168.31.169:8080/out/code.zip";
- @Override
- protected void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- setContentView(R.layout.activity_main);
- downloadBtn1 = bindView(R.id.main_btn_down1);
- downloadBtn2 = bindView(R.id.main_btn_down2);
- downloadBtn3 = bindView(R.id.main_btn_down3);
- cancelBtn1 = bindView(R.id.main_btn_cancel1);
- cancelBtn2 = bindView(R.id.main_btn_cancel2);
- cancelBtn3 = bindView(R.id.main_btn_cancel3);
- progress1 = bindView(R.id.main_progress1);
- progress2 = bindView(R.id.main_progress2);
- progress3 = bindView(R.id.main_progress3);
- downloadBtn1.setOnClickListener(this);
- downloadBtn2.setOnClickListener(this);
- downloadBtn3.setOnClickListener(this);
- cancelBtn1.setOnClickListener(this);
- cancelBtn2.setOnClickListener(this);
- cancelBtn3.setOnClickListener(this);
- }
- @Override
- public void onClick(View v) {
- switch (v.getId()) {
- case R.id.main_btn_down1:
- DownloadManager.getInstance().download(url1, new DownLoadObserver() {
- @Override
- public void onNext(DownloadInfo value) {
- super.onNext(value);
- progress1.setMax((int) value.getTotal());
- progress1.setProgress((int) value.getProgress());
- }
- @Override
- public void onComplete() {
- if(downloadInfo != null){
- Toast.makeText(MainActivity.this,
- downloadInfo.getFileName() + "-DownloadComplete",
- Toast.LENGTH_SHORT).show();
- }
- }
- });
- break;
- case R.id.main_btn_down2:
- DownloadManager.getInstance().download(url2, new DownLoadObserver() {
- @Override
- public void onNext(DownloadInfo value) {
- super.onNext(value);
- progress2.setMax((int) value.getTotal());
- progress2.setProgress((int) value.getProgress());
- }
- @Override
- public void onComplete() {
- if(downloadInfo != null){
- Toast.makeText(MainActivity.this,
- downloadInfo.getFileName() + Uri.encode("下载完成"),
- Toast.LENGTH_SHORT).show();
- }
- }
- });
- break;
- case R.id.main_btn_down3:
- DownloadManager.getInstance().download(url3, new DownLoadObserver() {
- @Override
- public void onNext(DownloadInfo value) {
- super.onNext(value);
- progress3.setMax((int) value.getTotal());
- progress3.setProgress((int) value.getProgress());
- }
- @Override
- public void onComplete() {
- if(downloadInfo != null){
- Toast.makeText(MainActivity.this,
- downloadInfo.getFileName() + "下载完成",
- Toast.LENGTH_SHORT).show();
- }
- }
- });
- break;
- case R.id.main_btn_cancel1:
- DownloadManager.getInstance().cancel(url1);
- break;
- case R.id.main_btn_cancel2:
- DownloadManager.getInstance().cancel(url2);
- break;
- case R.id.main_btn_cancel3:
- DownloadManager.getInstance().cancel(url3);
- break;
- }
- }
- private <T extends View> T bindView(@IdRes int id){
- View viewById = findViewById(id);
- return (T) viewById;
- }
- }
可以看到 多个下载,断点续传什么的都已经成功了,最后我的文件网址是我自己的局域网,大家写的时候别忘了换了..