android中实现OkHttp下载文件并带进度条

2019-12-12 02:33:12

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OkHttp是比较火的网络框架，它支持同步与异步请求，支持缓存，可以拦截，更方便下载大文件与上传文件的操作。下面我们用OkHttp来下载文件并带进度条！

相关资料：

官网地址：http://square.github.io/okhttp/

github源码地址：https://github.com/square/okhttp

一、服务器端简单搭建

可以参考搭建本地Tomcat服务器及相关配置这篇文章。

新建项目OkHttpServer，在WebContent目录下新建downloadfile目录，将要下载的jpg文件放在项目下。如下图：

启动服务器，文件下载地址为http://localhost:8080/OkHttpServer/download/2.jpg 。这样我们服务器就搭好了。

二、Android端

下面我们进入正题。

1.build.gradle的dependencies配置如下

compile 'com.android.support:appcompat-v7:24.1.1'compile 'com.squareup.okhttp3:okhttp:3.2.0'compile 'com.squareup.okio:okio:1.7.0'

2.activity_main.xml

<?xml version="1.0" encoding="utf-8"?><RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"  android:paddingLeft="@dimen/activity_horizontal_margin"  android:paddingRight="@dimen/activity_horizontal_margin"  android:paddingTop="@dimen/activity_vertical_margin"  tools:context="com.huang.myokhttp.MainActivity">  <Button    android:id="@+id/ok_download"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:text="下载文件" />  <TextView    android:id="@+id/download_text"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:gravity="center"    android:text="0" />  <ProgressBar    android:id="@+id/download_progress"    style="?android:attr/progressBarStyleHorizontal"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:max="100" /></RelativeLayout>

3.编写OkHttpUtil如下：

 private static OkHttpClient okHttpClient = new OkHttpClient.Builder().connectTimeout(10000, TimeUnit.MILLISECONDS)                        .readTimeout(10000,TimeUnit.MILLISECONDS)                        .writeTimeout(10000,TimeUnit.MILLISECONDS).build();  //下载文件方法  public static void downloadFile(String url, final ProgressListener listener, Callback callback){  //增加拦截器    OkHttpClient client = okHttpClient.newBuilder().addNetworkInterceptor(new Interceptor() {      @Override      public Response intercept(Chain chain) throws IOException {        Response response = chain.proceed(chain.request());        return response.newBuilder().body(new ProgressResponseBody(response.body(),listener)).build();      }    }).build();    Request request = new Request.Builder().url(url).build();    client.newCall(request).enqueue(callback);  }

4.上面代码中的ProgressResponseBody是自己编写的类，ProgressListener 是监听的接口：

ProgressListener 接口

public interface ProgressListener {//已完成的 总的文件长度 是否完成  void onProgress(long currentBytes, long contentLength, boolean done);}

ProgressResponseBody继承ResponseBody ，返回监听进度

public class ProgressResponseBody extends ResponseBody {  public static final int UPDATE = 0x01;  public static final String TAG = ProgressResponseBody.class.getName();  private ResponseBody responseBody;  private ProgressListener mListener;  private BufferedSource bufferedSource;  private Handler myHandler;  public ProgressResponseBody(ResponseBody body, ProgressListener listener) {    responseBody = body;    mListener = listener;    if (myHandler==null){      myHandler = new MyHandler();    }  }  /**   * 将进度放到主线程中显示   */  class MyHandler extends Handler {    public MyHandler() {      super(Looper.getMainLooper());    }    @Override    public void handleMessage(Message msg) {      switch (msg.what){        case UPDATE:          ProgressModel progressModel = (ProgressModel) msg.obj;          //接口返回          if (mListener!=null)mListener.onProgress(progressModel.getCurrentBytes(),progressModel.getContentLength(),progressModel.isDone());          break;      }    }  }  @Override  public MediaType contentType() {    return responseBody.contentType();  }  @Override  public long contentLength() {    return responseBody.contentLength();  }  @Override  public BufferedSource source() {    if (bufferedSource==null){      bufferedSource = Okio.buffer(mySource(responseBody.source()));    }    return bufferedSource;  }  private Source mySource(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;        //发送消息到主线程，ProgressModel为自定义实体类        Message msg = Message.obtain();        msg.what = UPDATE;        msg.obj = new ProgressModel(totalBytesRead,contentLength(),totalBytesRead==contentLength());        myHandler.sendMessage(msg);        return bytesRead;      }    };  }}

5.MainActivity的代码：

public class MainActivity extends AppCompatActivity implements View.OnClickListener{  public static final String TAG = MainActivity.class.getName();  private ProgressBar download_progress;  private TextView download_text;  public static String basePath = Environment.getExternalStorageDirectory().getAbsolutePath() + "/okhttp";  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    download_progress = (ProgressBar) findViewById(R.id.download_progress);    download_text = (TextView) findViewById(R.id.download_text);    findViewById(R.id.ok_download).setOnClickListener(this);  }  @Override  public void onClick(View view) {    switch (view.getId()){      case R.id.ok_download:        String url = "http://192.168.0.104:8080/OkHttpServer/download/2.jpg";        final String fileName = url.split("/")[url.split("/").length - 1];        Log.i(TAG, "fileName==" + fileName);        OkHttpUtil.downloadFile(url, new ProgressListener() {          @Override          public void onProgress(long currentBytes, long contentLength, boolean done) {            Log.i(TAG, "currentBytes==" + currentBytes + "==contentLength==" + contentLength + "==done==" + done);            int progress = (int) (currentBytes * 100 / contentLength);            download_progress.setProgress(progress);            download_text.setText(progress + "%");          }        }, new Callback() {          @Override          public void onFailure(Call call, IOException e) {          }          @Override          public void onResponse(Call call, Response response) throws IOException {            if (response != null) {              InputStream is = response.body().byteStream();              FileOutputStream fos = new FileOutputStream(new File(basePath + "/" + fileName));              int len = 0;              byte[] buffer = new byte[2048];              while (-1 != (len = is.read(buffer))) {                fos.write(buffer, 0, len);              }              fos.flush();              fos.close();              is.close();            }          }        });        break;    }  }}

6.最后不要忘了添加权限：

 <uses-permission android:name="android.permission.INTERNET"/><uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/><uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

这里写图片描述