Android 下载apk更新应用

更新适配Android 7.0 文件访问
/-------------------------------------------/
看到一篇介绍DownloadManger的文章 ，记得以前自己也写过，中午找出来，整理了一下

/**
 * 创建下载对象，传入界面的context与下载的url，文件默认保存在/download目录下
 */
new Download(context).execute(url);

package cn.ljt.download;

import android.app.NotificationManager;
import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Environment;
import android.support.v7.app.NotificationCompat;
import android.util.Log;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.util.List;
import java.util.Map;
import java.util.Set;

/**
 * Created by jiangtao on 2017/3/13 13:04
 * E-mail：[email protected]
 */

public final class Download extends AsyncTask {
    private File file;
    private Context context;
    private String fileName;
    private NotificationCompat.Builder builder;
    private NotificationManager notificationManager;

    public Download(Context context) {
        this.context = context;
        notificationManager = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
        builder = new NotificationCompat.Builder(context);
        builder.setTicker("下载开始了...")
                .setContentTitle("Download")
                .setSmallIcon(R.mipmap.ic_launcher);
    }

    @Override
    protected String doInBackground(String... params) {
        URL url;
        HttpURLConnection conn;
        BufferedInputStream bis = null;
        FileOutputStream fos = null;

        try {
            url = new URL(params[0]);
            Log.i("TAG", url.toString());
            conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod("GET");
            conn.setConnectTimeout(5000);

            int fileLength = conn.getContentLength();
            bis = new BufferedInputStream(conn.getInputStream());

            fileName = getFileName(params[0]);
            builder.setContentTitle(fileName);
            String fileDir = Environment.getExternalStorageDirectory().getPath() + "/Download/" + fileName;
            file = new File(fileDir);
            if (!file.exists()) {
                if (!file.getParentFile().exists()) {
                    if (file.getParentFile().mkdirs()) {
                        file.createNewFile();
                    }
                }
            } else {
                return "文件已存在";//可以删除或者忽略，自己处理
            }
            fos = new FileOutputStream(file);
            byte data[] = new byte[4 * 1024];
            long total = 0;
            int count;
            while ((count = bis.read(data)) != -1) {
                total += count;
                Log.i("TAG", "total:" + total);
                publishProgress((int) (total * 100 / fileLength));
                fos.write(data, 0, count);
                fos.flush();
            }
            fos.flush();
            return "下载成功";
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (fos != null) {
                    fos.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if (bis != null) {
                    bis.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        return "网络错误";
    }

    @Override
    protected void onProgressUpdate(Integer... progress) {
        super.onProgressUpdate(progress);
        if (progress[0] == 100) {
            builder.setTicker("下载完成！");
        }
        builder.setProgress(100, progress[0], false);
        builder.setContentText("正在下载..." + progress[0] + "%");
        notificationManager.notify(1, builder.build());
    }

    @Override
    protected void onPostExecute(String s) {
        super.onPostExecute(s);
        builder.setContentText(s);
        builder.setProgress(0, 0, false);
        notificationManager.notify(1, builder.build());
        if (fileName.endsWith(".apk")) {
            openFile(file);
        }
    }

    public static String getFileName(String url) {
        String filename = "";
        boolean isOk = false;
        // 从UrlConnection中获取文件名称
        try {
            URL myURL = new URL(url);
            URLConnection conn = myURL.openConnection();
            if (conn == null) {
                return null;
            }
            Map> hf = conn.getHeaderFields();
            if (hf == null) {
                return null;
            }
            Set key = hf.keySet();
            if (key == null) {
                return null;
            }
            for (String stringKey : key) {
                List values = hf.get(stringKey);
                for (String value : values) {
                    String result;
                    try {
                        result = new String(value.getBytes("ISO-8859-1"), "GBK");
                        int location = result.indexOf("filename");
                        if (location >= 0) {
                            result = result.substring(location + "filename".length());
                            filename = result.substring(result.indexOf("=") + 1);
                            isOk = true;
                        }
                    } catch (UnsupportedEncodingException e) {
                        e.printStackTrace();
                    }// ISO-8859-1 UTF-8 gb2312
                }
                if (isOk) {
                    break;
                }
            }
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        // 从路径中获取
        if (filename == null || "".equals(filename)) {
            filename = url.substring(url.lastIndexOf("/") + 1);
        }
        return filename;
    }

    private void openFile(File file) {
         if (file != null) {
                Intent intent = new Intent();
                intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                intent.setAction(Intent.ACTION_VIEW);
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) { //判读版本是否在7.0以上
                    Uri apkUri = FileProvider.getUriForFile(context, "com.ljt.download.fileprovider", file);
                    intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
                    intent.setDataAndType(apkUri, "application/vnd.android.package-archive");
                } else {
                    intent.setDataAndType(Uri.fromFile(file), "application/vnd.android.package-archive");
                }
                context.startActivity(intent);
            }
    }
}

定义自己的fileprovider：
首先在AndroidManifest.xml文件中注册一个provider

创建filepaths.xml

放在xml文件夹下，如果res目录下没有就自己创建一个