android中实现OkHttp下载文件并带进度条

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：

github源码地址：

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"/>

 

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。