Android使用OKHttp3实现下载(断点续传、显示运行进度)
OKHttp3是现在很流行的Android网络请求框架,那么怎样利用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实现线程切换很方便,并且数据流的形式也很舒服,同一时候Lambda和RxJava配合食用味道更佳
打开我们的app Module下的build.gradle,代码例如以下
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 可以使用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'
}
OKHttp和RxJava,RxAndroid使用的都是最新的版本号,而且配置开启了Java8
布局文件
接着開始书写布局文件<?xml version="1.0" encoding="utf-8"?大概是这个样子的> <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就是为了显示运行进度的,每一个ProgressBar相应2个Button,一个是開始下载,一个是暂停(取消)下载,这里须要说明的是,对下载来说暂停和取消没有什么差别,除非当取消的时候,会顺带把暂时文件都删除了,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;
}
}能够看到,我们就是要获得一个全局的Context对象的<?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>我们仅仅须要一个网络权限,在application标签下,加入name属性,来指向我们的ApplicationDownloadManager
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();
}
/**
* 開始下载
*
* @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)//检測本地目录,生成新的文件名称
.flatMap(downloadInfo -> Observable.create(new DownloadSubscribe(downloadInfo)))//下载
.observeOn(AndroidSchedulers.mainThread())//在主线程回调
.subscribeOn(Schedulers.io())//在子线程运行
.subscribe(downLoadObserver);//加入观察者
}
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,须要又一次来一个文件
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称/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,加入此头,则服务器就能够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);//把这个加入到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();//完毕
}
}
/**
* 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;//能够用于取消注冊的监听者
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();
}
}在RxJava2中 这个Observer有点变化,当注冊观察者的时候,会调用onSubscribe方法,而该方法參数就是用来取消注冊的,这种修改能够更灵活的有监听者来取消监听了,我们的进度信息会一直的传送的onNext方法里,这里将下载所须要的内容封了一个类叫DownloadInfopackage 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;
}
}
这个类就是一些基本信息,total就是须要下载的文件的总大小,而progress就是当前下载的进度了,这样就能够计算出下载的进度信息了 /**
* 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;
}能够看到,事实上就是在通过OK进行了一次网络请求,而且从返回的头信息里拿到文件的大小信息,一般这个信息都是能够拿到的,除非下载网址不是直接指向资源文件的,而是自己手写的Servlet,那就得跟后台人员沟通好了.注意,这次网络请求并没有真正的去下载文件,而是请求个大小就结束了,详细原因会在后面真正请求数据的时候解释获取完文件大小后,就能够去硬盘里找文件了,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,须要又一次来一个文件
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称/大小
downloadInfo.setProgress(downloadLength);
downloadInfo.setFileName(file.getName());
return downloadInfo;
}这种方法就是看本地是否有已经下载过的文件,假设有,再推断一次本地文件的大小和server上数据的大小,假设是一样的,证明之前下载全了,就再成一个带(1)这种文件,而假设本地文件大小比server上的小的话,那么证明之前下载了一半断掉了,那么就把进度信息保存上,并把文件名称也存上,看完了再回到download方法
之后就開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,好像仅仅改了名字,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,加入此头,则server就能够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);//把这个加入到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();//完毕
}
}主要看subscribe方法
首先拿到url,当前进度信息和文件的总大小,然后開始网络请求,注意这次网络请求的时候须要加入一条头信息
.addHeader("RANGE", "bytes=" + downloadLength + "-" + contentLength)这条头信息的意思是下载的范围是多少,downloadLength是从哪開始下载,contentLength是下载到哪,当要断点续传的话必须加入这个头,让输入流跳过多少字节的形式是不行的,所以我们要想能成功的加入这条信息那么就必须对这个url请求2次,一次拿到总长度,来方便推断本地是否有下载一半的数据,第二次才開始真正的读流进行网络请求,我还想了一种思路,当文件没有下载完毕的时候加入一个自己定义的后缀,当下载完毕再把这个后缀取消了,应该就不须要请求两次了.
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,可是假设不涉及到多个部分拼接的话是不是必需的,直接使用输出流就好了,在输出流的构造方法上加入一个true的參数,代表是在原文件的后面加入数据就可以,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,同一时候把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();
}
}
}
}
}事实上就是挨一个推断是否为空,并关闭罢了
这样download方法就完毕了,剩下的就是切换线程,注冊观察者了
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("下载完毕"),
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() + "下载完毕",
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;
}
}
Activity里没什么了,就是注冊监听,開始下载,取消下载这些了,以下我们来看看效果吧执行效果
能够看到 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..
posted on 2017-08-17 12:43 yjbjingcha 阅读(786) 评论(0) 编辑 收藏 举报
