Android 版本更新

//首先自行判断版本号是否需要升级，这里就不做判断了

private void downFile(final String url) {
    new Thread(){
        @Override
        public void run() {
            super.run();
            DownloadUtil.get().download(url, "acct", new DownloadUtil.OnDownloadListener() {
                //                   版本需要更新，正常下载
                @Override
                public void onDownloadSuccess() {//下载完成
                    handler.sendEmptyMessage(3);
                }
                //                  下载中，显示下载进度
                @Override
                public void onDownloading(int progress) {//下载中
                    Message message = Message.obtain();
                    Bundle bundle = new Bundle();
                    message.what = 4;
                    bundle.putInt("progress",progress);
                    message.setData(bundle);
                    handler.sendMessage(message);
                }
                @Override
                public void onDownloadFailed() {//下载失败
                    handler.sendEmptyMessage(5);
                }
            },MainActivity.this);
        }
    }.start();
}

//工具类

public class DownloadUtil {
    private static DownloadUtil downloadUtil;
    private final OkHttpClient okHttpClient;

    public static DownloadUtil get() {
        if (downloadUtil == null) {
            downloadUtil = new DownloadUtil();
        }
        return downloadUtil;
    }

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

    /**
     * @param url 下载连接
     * @param saveDir 储存下载文件的SDCard目录
     * @param listener 下载监听
     */
    public void download(final String url, final String saveDir, final OnDownloadListener listener, final Activity activity) {
        Request request = new Request.Builder().url(url).build();
        okHttpClient.newCall(request).enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
                // 下载失败
                listener.onDownloadFailed();
            }
            @Override
            public void onResponse(Call call, Response response) throws IOException {
                InputStream is = null;
                byte[] buf = new byte[2048];
                int len = 0;
                FileOutputStream fos = null;
                // 储存下载文件的目录
                String savePath = isExistDir(saveDir);
                try {
                    is = response.body().byteStream();
                    long total = response.body().contentLength();
                    File outputImage = new File(activity.getExternalCacheDir(), getNameFromUrl(url));
                    try {
                        if (outputImage.exists()){
                            outputImage.delete();
                        }
                        outputImage.createNewFile();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                    Uri imageUri;
                    if (Build.VERSION.SDK_INT >= 24){
                        imageUri = FileProvider.getUriForFile(activity,"xxx.xxx.xxx.provider",outputImage);
                    }else {
                        imageUri = Uri.fromFile(outputImage);
                    }

//                    File file = new File(savePath, getNameFromUrl(url));
                    fos = new FileOutputStream(outputImage);
                    long sum = 0;
                    while ((len = is.read(buf)) != -1) {
                        fos.write(buf, 0, len);
                        sum += len;
                        int progress = (int) (sum * 1.0f / total * 100);
                        // 下载中
                        listener.onDownloading(progress);
                    }

                    fos.flush();
                    // 下载完成
                    listener.onDownloadSuccess();
                } catch (Exception e) {
                    listener.onDownloadFailed();
                } finally {
                    try {
                        if (is != null)
                            is.close();
                    } catch (IOException e) {
                    }
                    try {
                        if (fos != null)
                            fos.close();
                    } catch (IOException e) {
                    }
                }
            }

        });
    }

    /**
     * @param saveDir
     * @return
     * @throws IOException
     * 判断下载目录是否存在
     */
    public String isExistDir(String saveDir) throws IOException {
        // 下载位置
        File downloadFile = new File(Environment.getExternalStorageDirectory(), saveDir);
        if (!downloadFile.mkdirs()) {
            downloadFile.createNewFile();
        }
        String savePath = downloadFile.getAbsolutePath();
        return savePath;
    }

    /**
     * @param url
     * @return
     * 从下载连接中解析出文件名
     */
    @NonNull
    public String getNameFromUrl(String url) {
        return url.substring(url.lastIndexOf("/") + 1);
    }

    public interface OnDownloadListener {
        /**
         * 下载成功
         */
        void onDownloadSuccess();

        /**
         * @param progress
         * 下载进度
         */
        void onDownloading(int progress);

        /**
         * 下载失败
         */
        void onDownloadFailed();
    }
}

//记得添加

<provider
    android:name="android.support.v4.content.FileProvider"
    android:authorities="xxx.xxx.xxx.provider"    //xxx为项目包名
    android:exported="false"
    android:grantUriPermissions="true">
    <meta-data
        android:name="android.support.FILE_PROVIDER_PATHS"
        android:resource="@xml/provider_paths" />    //xml文件下创建provider_paths
</provider>

//最后别忘在res文件夹下建xml文件夹

<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
    <!--"."表示所有路径-->
    <external-path name="external_files" path="."/>
</paths>

  private Handler handler=new Handler(){
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            if(msg.what==3){
                Intent intent = new Intent(Intent.ACTION_VIEW);
                File db = null;
                Uri data;
//              检测版本号是否大于等于24
                if (Build.VERSION.SDK_INT >= 24){
                    db = new File(MainActivity.this.getExternalCacheDir(),url.substring(url.lastIndexOf("/") + 1));
                    data = FileProvider.getUriForFile(MainActivity.this, "xxx.xxx.xxx.provider", db);
//              给目标应用一个临时授权
                    intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
                    intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                    intent.setDataAndType(data, "application/vnd.android.package-archive");
                }else {
                    db = new File(MainActivity.this.getExternalCacheDir(),url.substring(url.lastIndexOf("/") + 1));
                    intent.setDataAndType(Uri.fromFile(db), "application/vnd.android.package-archive");
                }

                startActivity(intent);
                Toast.makeText(MainActivity.this,"下载完成",Toast.LENGTH_SHORT).show();
            }
            if(msg.what==4){
                int progress = msg.getData().getInt("progress");
                pd.setMessage("已经下载"+String.valueOf(progress)+"%");
                pd.setProgressStyle(ProgressDialog.STYLE_SPINNER);
                pd.show();
            }
            if(msg.what==5){
                Toast.makeText(MainActivity.this,"下载失败",Toast.LENGTH_SHORT).show();
            }
        }
    };