面试题 -- 下载并安装APK

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面试题 – 下载并安装APK

任务：

下载一个apk文件，并显示下载的速度、进度百分比、下载用时时间，并且下载完毕后，自动安装apk

布局文件：一个进度条，一个文本，一个按钮

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:padding="15dp">    <ProgressBar        android:id="@+id/progressBar"        style="?android:attr/progressBarStyleHorizontal"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignParentEnd="true"        android:layout_alignParentStart="true"        android:layout_alignParentTop="true"        android:layout_marginTop="50dp" />    <TextView        android:id="@+id/textView"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignParentEnd="true"        android:layout_below="@id/progressBar"        android:text="Medium Text" />    <Button        android:id="@+id/button"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_below="@id/textView"        android:layout_centerHorizontal="true"        android:onClick="startDownLoad"        android:text="Start DownLoad" /></RelativeLayout>

DownLoadActivity:负责下载的控制与显示

public class DownLoadActivity extends AppCompatActivity {    private static final String QQMusicUri = "http://dldir1.qq.com/music/clntupate/QQMusic.apk";    private ProgressBar progressBar;    private TextView downloadingInfo;    private Button downloadButton;    final String fileName = "QQMusic.apk";    public static final String rootDirectory = Environment.getExternalStorageDirectory().getPath() + "/Download";    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        initViews();    }    private Handler mHandler = new Handler() {        @Override        public void handleMessage(Message msg) {            int speed = (int) msg.obj;            int percent = msg.arg1;            int userTime = msg.arg2;            downloadingInfo.setText(speed + "KB/S  " + percent + "% "                    + formatTime(userTime));            downloadButton.setClickable(false);            if (percent == 100) {                Toast.makeText(MainActivity.this, "Download Finished", Toast.LENGTH_SHORT).show();                downloadButton.setClickable(true);            }        }    };    /**     * 格式化时间     */    public static String formatTime(int time) {        if (time < 60) {            return time + "s";        } else {            return time / 60 + "min" + time % 60 + "s";        }    }    /**     * 初始化控件     */    private void initViews() {        progressBar = (ProgressBar) findViewById(R.id.progressBar);        downloadingInfo = (TextView) findViewById(R.id.textView);        downloadButton = (Button) findViewById(R.id.button);    }    /**     * 开始下载     */    public void startDownLoad(View view) {        downloadButton.setText("Stop DownLoad");        Toast.makeText(this, rootDirectory, Toast.LENGTH_SHORT).show();        new Thread(new Runnable() {            @Override            public void run() {                installApk(downloadFile());            }        }).start();    }    /**     * 安装APK     *     * @param file     */    public void installApk(File file) {        Intent intent = new Intent();        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);        intent.setAction(Intent.ACTION_VIEW);        intent.setDataAndType(Uri.fromFile(file),                "application/vnd.android.package-archive");        startActivity(intent);    }     /**      * 下载文件      */    public File downloadFile() {        File tempFile = new File(rootDirectory);        if (!tempFile.exists()) {            tempFile.mkdir();        }        File file = new File(tempFile + "/" + fileName);        return HttpRequestUtils.downLoad(file, QQMusicUri, mHandler,progressBar);    }}

下载工具类：

public class HttpRequestUtils {    /**     * 下载     *     * @param file     * @param urlStr 下载地址     * @return     */    public static File downLoad(File file, String urlStr, Handler handler,ProgressBar progressBar) {        HttpURLConnection connection = null;        FileOutputStream fos = null;        InputStream is = null;        try {            URL url = new URL(urlStr);            //创建HttpURLConnection对象            connection = (HttpURLConnection) url.openConnection();            //配置参数            //允许输入，默认为false            connection.setDoOutput(true);            //允许输出，默认为true            connection.setDoInput(true);            //设为POST请求，默认为GET            connection.setRequestMethod("POST");            //设置连接超时            connection.setConnectTimeout(20 * 1000);            //设置读取数据超时            connection.setReadTimeout(20 * 1000);            //连接            connection.connect();            if (connection.getResponseCode() == 200) {                is = connection.getInputStream();                fos = new FileOutputStream(file);                byte[] buffer = new byte[1024];                int totalSize = connection.getContentLength();//获取文件的总大小                progressBar.setMax(totalSize);//设置总进度                int len = 0;                Long startTime = System.currentTimeMillis();//开始时间                while ((len = is.read(buffer)) != -1) {                    fos.write(buffer, 0, len);                    progressBar.setProgress((int) file.length());//设置完成进度                    Long stopTime = System.currentTimeMillis();//结束时间                    Long time = (stopTime - startTime) / 1000;//读取用时时间                    if (time != 0) {                        //下载百分比                        int percent = (int) (file.length() * 100 / totalSize);                        //下载速度                        int speed = (int) (file.length() / 1024 / time);                        //下载时间                        int useTime = (int) (stopTime - startTime) / 1000;                        Message msg = new Message();                        msg.obj = speed;                        msg.arg1 = percent;                        msg.arg2 = useTime;                        handler.sendMessage(msg);                    }                }            }        } catch (MalformedURLException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        } finally {            try {                if (fos != null) {                    fos.close();                }                if (is != null) {                    is.close();                }                if (connection != null) {                    connection.disconnect();                }            } catch (IOException e) {                e.printStackTrace();            }        }        return file;    }}

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