Android使用OKHttp3实现下载(断点续传、显示进度)

来源：互联网发布：重庆邮电大学就业知乎编辑：程序博客网时间：2024/06/11 21:14

转载自 http://blog.csdn.net/cfy137000/article/details/54838608 侵权删
在项目的build文件中配置java1.8
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;

//开启Java1.8 能够使用lambda表达式
compileOptions{
sourceCompatibility JavaVersion.VERSION_1_8
targetCompatibility JavaVersion.VERSION_1_8
}

//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'

这是接下来的布局文件

<?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>

创建一个类继承application

public class MyApp extends Application {
public static Context sContext;//全局的Context对象
@Override
public void onCreate() {
super.onCreate();
sContext = this;
}
}

需要在清单文件中进行初始化，并且添加一个网络权限

下载管理器

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;
}
}

观察者

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();
}
}

下载的注册信息

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;
}
}

判断是否为空并且进行关闭

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();
}
}
}
}
}

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;
}
}

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