Android基於Okhttp3的文件下載工具類

需求中有需要簡易的下載文件的，例如圖片，音頻，視頻等。首先這個下載工具類沒有斷點下載，也就是說沒有暫停，緩存。不過解決日常工作中的小文件下載是綽綽有餘的。下面可以看一看

一、添加okhttp3的遠程依賴

 

compile 'com.squareup.okhttp3:okhttp:3.4.1'
compile 'com.squareup.okhttp3:okhttp-urlconnection:3.4.1'

二、添加網絡和文件讀寫權限

 

 

 

 

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

三、全部代碼

 

 

package com.qiumilianmeng.qmlm.utils;

import android.os.Handler;
import android.os.Message;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;

import okhttp3.Call;
import okhttp3.Callback;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

/**
 * Created by yufs on 2017/8/16.
 */

public class DownloadUtil {
    public static final int DOWNLOAD_FAIL=0;
    public static final int DOWNLOAD_PROGRESS=1;
    public static final int DOWNLOAD_SUCCESS=2;
    private static DownloadUtil downloadUtil;
    private final OkHttpClient okHttpClient;
    public static DownloadUtil getInstance() {
        if (downloadUtil == null) {
            downloadUtil = new DownloadUtil();
        }
        return downloadUtil;
    }

    private DownloadUtil() {
        okHttpClient = new OkHttpClient();
    }

    /**
     *
     */
    public void download(final String url,final String saveDir,final OnDownloadListener listener){
        this.listener=listener;
        Request request=new Request.Builder().url(url).build();
        okHttpClient.newCall(request).enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
                Message message=Message.obtain();
                message.what=DOWNLOAD_FAIL;
                mHandler.sendMessage(message);
            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {
                InputStream is=null;
                byte[] buf=new byte[2048];
                int len=0;
                FileOutputStream fos=null;
                //儲存下載文件的目錄
                String savePath=isExistDir(saveDir);
                try{
                    is=response.body().byteStream();
                    long total=response.body().contentLength();
                    File file=new File(savePath,getNameFromUrl(url));
                    fos=new FileOutputStream(file);
                    long sum=0;
                    while((len = is.read(buf))!=-1){
                        fos.write(buf,0,len);
                        sum+=len;
                        int progress=(int)(sum*1.0f/total*100);
                        //下載中
                        Message message=Message.obtain();
                        message.what=DOWNLOAD_PROGRESS;
                        message.obj=progress;
                        mHandler.sendMessage(message);

                    }
                    fos.flush();
                    //下載完成
                    Message message=Message.obtain();
                    message.what=DOWNLOAD_SUCCESS;
                    message.obj=file.getAbsolutePath();
                    mHandler.sendMessage(message);
                }catch (Exception e){
                    Message message=Message.obtain();
                    message.what=DOWNLOAD_FAIL;
                    mHandler.sendMessage(message);
                }finally{
                    try{
                        if(is!=null)
                            is.close();
                    }catch (IOException e){

                    }
                    try {
                        if(fos!=null){
                            fos.close();
                        }
                    }catch (IOException e){

                    }
                }
            }
        });
    }

    private String getNameFromUrl(String url) {
        return url.substring(url.lastIndexOf("/")+1);
    }


    private String isExistDir(String saveDir) throws IOException {
        File downloadFile=new File(saveDir);
        if(!downloadFile.mkdirs()){
            downloadFile.createNewFile();
        }
        String savePath=downloadFile.getAbsolutePath();
        return savePath;
    }




    private Handler mHandler=new Handler(){
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            switch (msg.what){
                case DOWNLOAD_PROGRESS:
                    listener.onDownloading((Integer) msg.obj);
                    break;
                case DOWNLOAD_FAIL:
                    listener.onDownloadFailed();
                    break;
                case DOWNLOAD_SUCCESS:
                    listener.onDownloadSuccess((String) msg.obj);
                    break;
            }
        }
    };


    OnDownloadListener listener;
    public interface OnDownloadListener{
        /**
         * 下載成功
         */
        void onDownloadSuccess(String path);
        /**
         * 下載進度
         * @param progress
         */
        void onDownloading(int progress);
        /**
         * 下載失敗
         */
        void onDownloadFailed();
    }
}

 

部分代碼參考網絡上okhttp3的使用，其中需要注意的是okhttp3中的Callback回調是發生在工作線程，也就是說此回調方法不能直接返回進度更新ui，需要使用handler切換回主線程。

 

四、使用方法

 

 

DownloadUtil.getInstance().download(videoUrl, MyApplication.PATH_DOWNLOAD_VIDEO, new DownloadUtil.OnDownloadListener() {
                    @Override
                    public void onDownloadSuccess(String path) {
                        btn_download.setClickable(true);
                        dialog.hide();
                        ToastMgr.showLong(NetVideoPlayerActivity.this,"視頻已保存："+path);
                    }

                    @Override
                    public void onDownloading(int progress) {
                        dialog.setMessage("已下載"+progress+"%");
                    }

                    @Override
                    public void onDownloadFailed() {
                        dialog.hide();
                        btn_download.setClickable(true);
                    }
                });

videoUrl是你需要下載的文件地址，一般爲網絡文件地址，MyApplication.PATH_DOWNLOAD_VIDEO是我項目中SD卡上的一個文件目錄，此目錄也就是保存下載文件的地址，而文件名稱是已網絡文件名稱命名的，也可自行修改，ok到此完了。