Android开发中利用DownloadManager实现下载功能（视频，音频等）

DownloadManager是Android自带的下载器。（自带断点续传功能）

1、MyDownLoadAsyncTask.java的代码如下：

package com.deepreality.mydownloadfiledemo;

import android.app.DownloadManager;
import android.content.Context;
import android.database.Cursor;
import android.net.Uri;
import android.os.AsyncTask;
import android.util.Log;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;
import java.io.File;
import java.io.PrintWriter;
import java.io.StringWriter;
import static android.content.Context.DOWNLOAD_SERVICE;



public class MyDownLoadAsyncTask extends AsyncTask,Integer,String> {

    private TextView tvTitle;
    private ProgressBar pbarDownLoad;
    private Context mContext;

    private static String HOST_PC_IP = "cdn.llscdn.com";
    private long currentDownloadID;
    private boolean idDownloading = true;
    private String urlPath;

    public MyDownLoadAsyncTask(Context mContext, TextView tvTitle, ProgressBar pbarDownLoad, String urlPath) {
        this.mContext = mContext;
        this.tvTitle = tvTitle;
        this.pbarDownLoad = pbarDownLoad;
        this.urlPath = urlPath;
    }

    @Override
    protected String doInBackground(Integer... integers) {
        downloadByDownloadManager(mContext, urlPath);
        return String.valueOf(integers[0].intValue());
    }

    @Override
    protected void onPreExecute() {
        Toast.makeText(mContext, "开始下载", Toast.LENGTH_SHORT).show();
        super.onPreExecute();
    }

    @Override
    protected void onProgressUpdate(Integer... values) {
        int value = values[0];
        if (value <= 100) {
            pbarDownLoad.setProgress(value);
            if (value == 100) {
                Toast.makeText(mContext, "下载完成", Toast.LENGTH_SHORT).show();
            }
        }
    }

    //"https://cdn.llscdn.com/yy/files/xs8qmxn8-lls-LLS-5.8-800-20171207-111607.apk"
    // 4下载器下载
    public void downloadByDownloadManager(Context context, String downloadUrlStr) {
        StringBuffer httpDownloadUrl = new StringBuffer("https://")
                .append(HOST_PC_IP)
                .append(downloadUrlStr);

        DownloadManager.Request downloadRequest = new DownloadManager.Request(Uri.parse(httpDownloadUrl.toString()));
        // 通过setAllowedNetworkTypes方法可以设置允许在何种网络下下载
        downloadRequest.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_WIFI);
        downloadRequest.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
        // 文件后缀
        String fileFormat = PublicMethodUtils.regGetFileFormat(downloadUrlStr);
        // 获取文件名
        String resourceName = PublicMethodUtils.regFormatInFile(downloadUrlStr, fileFormat);
        // 本地保存地址
        String resourcePath = PublicMethodUtils.getResourcePath();
        // 下载标题
        downloadRequest.setTitle("下载" + resourceName);
        File saveFile = new File(resourcePath, resourceName);
        downloadRequest.setDestinationUri(Uri.fromFile(saveFile));

        DownloadManager manager = (DownloadManager) context.getSystemService(DOWNLOAD_SERVICE);
        currentDownloadID = manager.enqueue(downloadRequest);
        Log.e("e", "DownloadManager start downloading ---------");
        // 获取下载进度
        getDownloadProgress(manager, currentDownloadID, resourceName);

    }

    // 5下载进度并返回完成
    public void getDownloadProgress(final DownloadManager manager,final long downloadID, final String resourceName) {
        while (idDownloading) {
            DownloadManager.Query query = new DownloadManager.Query();
            query.setFilterById(downloadID);
            Cursor cursor = manager.query(query);

            if (cursor.moveToFirst()) {
                long bytesDownloaded = cursor.getInt(cursor.getColumnIndex(DownloadManager.COLUMN_BYTES_DOWNLOADED_SO_FAR));
                long bytesTotal = cursor.getInt(cursor.getColumnIndex(DownloadManager.COLUMN_TOTAL_SIZE_BYTES));
                final int downloadProgress = (int) (bytesDownloaded * 100 / bytesTotal);

                publishProgress(downloadProgress);

                Log.e("e",resourceName + ":下载进度: " + downloadProgress + "%");
                if (downloadProgress == 100) {
                    currentDownloadID = -1;
                    break;
                } else {
                    try {
                        Thread.sleep(500);
                    } catch (InterruptedException e) {
                        StringWriter stringWriter = new StringWriter();
                        e.printStackTrace(new PrintWriter(stringWriter, true));
                    }
                }

                /*int status = cursor.getInt(cursor.getColumnIndexOrThrow(DownloadManager.COLUMN_STATUS));
                if (status == DownloadManager.STATUS_PENDING) {
                    Log.e("status", "pengding");
                } else if (status ==DownloadManager.STATUS_PAUSED) {
                    Log.e("status", "paused");
                } else if (status == DownloadManager.STATUS_RUNNING) {
                    Log.e("status", "runing");
                } else if (status == DownloadManager.STATUS_SUCCESSFUL) {
                    Log.e("status", "successful");
                    break;
                } else if (status == DownloadManager.STATUS_FAILED) {
                    Log.e("status", "failed");
                    break;
                }*/
                cursor.close();
            }
        }
    }

    public void remove(Context context){
        DownloadManager downloadManager = (DownloadManager) context.getSystemService(DOWNLOAD_SERVICE);
        if (currentDownloadID >= 0){
            downloadManager.remove(currentDownloadID);
        }
        idDownloading = false;
    }
}

2、MainActivity.java的主要代码如下：

package com.deepreality.mydownloadfiledemo;

import android.Manifest;
import android.app.DownloadManager;
import android.content.Context;
import android.content.pm.PackageManager;
import android.database.Cursor;
import android.net.Uri;
import android.os.Build;
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;

import java.io.File;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private Context mContext;
    private Button btnStartDownLoad, btnStopDownLoad;
    private TextView tvDownLoadFileName;
    private ProgressBar pBar;
    private String urlPath = "/yy/files/xs8qmxn8-lls-LLS-5.8-800-20171207-111607.apk";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // 判断android版本号，弹出申请权限
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            showConfirmAppPermissions();
        }

        bindViews();

        // 获取文件名
        String resourceName = PublicMethodUtils.regGetFileNameWithoutFileFormat(urlPath, "apk") + ".apk";
        tvDownLoadFileName.setText(resourceName);

    }

    private void bindViews() {
        mContext = MainActivity.this;
        btnStartDownLoad = findViewById(R.id.main_btnStartDownLoad);
        btnStopDownLoad = findViewById(R.id.main_btnStopDownLoad);
        tvDownLoadFileName = findViewById(R.id.main_tvDownLoadFileName);
        pBar = findViewById(R.id.main_pBarProgress);
        pBar.setMax(100);

        btnStartDownLoad.setOnClickListener(this);
        btnStopDownLoad.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        MyDownLoadAsyncTask myDownLoadAsyncTask = new MyDownLoadAsyncTask(mContext, tvDownLoadFileName, pBar, urlPath);
        switch (v.getId()) {
            case R.id.main_btnStartDownLoad:{
               //执行下载任务
                myDownLoadAsyncTask.execute(500);
                //Toast.makeText(mContext, "开始下载", Toast.LENGTH_SHORT).show();
                break;
            }
            case R.id.main_btnStopDownLoad:{
                pBar.setProgress(0);
                //取消下载任务
                myDownLoadAsyncTask.remove(mContext);
                break;
            }
            default:break;
        }
    }



    @Override
    protected void onDestroy() {
        super.onDestroy();
    }

    // 7.0动态申请权限
    public void showConfirmAppPermissions() {
        if (ContextCompat.checkSelfPermission(this,
                Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
            if (ActivityCompat.shouldShowRequestPermissionRationale(this,
                    Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
            } else {
                ActivityCompat.requestPermissions(this,
                        new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE,
                                Manifest.permission.READ_EXTERNAL_STORAGE}, 1);
            }
        }
    }
}