【练习】使用服务下载图片并保存到sdcard

public class StringUtils {
    public static String getStr(String path){
        String[] strs = path.split("/");
        return strs[strs.length-1];
    }
}

public class SdCardUtils {
    public static void saveDataToSdcard(byte[] data,String filename){
        File file = Environment.getExternalStorageDirectory();
        Log.i("Mian",file.getAbsolutePath());
        File file2 = new File(file,filename);
        try {
            FileOutputStream fos = new FileOutputStream(file2);
            fos.write(data);
            fos.flush();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

public class MainActivity extends AppCompatActivity {

    private ImageView imageView;
    private Intent intent ;
    private String path = "http://www.baidu.com/img/bdlogo.gif";
    private String filename;
    private String bitmap_path;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        imageView = (ImageView) findViewById(R.id.image);
        filename = StringUtils.getStr(path);
        bitmap_path = Environment.getExternalStorageDirectory().getAbsolutePath()+"/"+filename;
    }

    public void download(View view){
        intent = new Intent(this,MyService.class);
        intent.putExtra("key",path);
        startService(intent);
    }

    public void see(View view){
        Bitmap bitmap = BitmapFactory.decodeFile(bitmap_path);
        if(bitmap!=null){
            imageView.setImageBitmap(bitmap);
        }
    }
}

public class MyService extends Service {

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onCreate() {
        super.onCreate();
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        final String path = intent.getStringExtra("key");

        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    URL url = new URL(path);
                    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                    int code = conn.getResponseCode();
                    if (code == 200) {
                        InputStream is = conn.getInputStream();
                        ByteArrayOutputStream baos = new ByteArrayOutputStream();
                        byte[] buffer = new byte[1024 * 2];
                        int ret;
                        while ((ret = is.read(buffer)) > 0) {
                            baos.write(buffer, 0, ret);
                        }
                        //保存到内存卡
                        SdCardUtils.saveDataToSdcard(baos.toByteArray(), StringUtils.getStr(path));
                    }

                } catch (MalformedURLException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }).start();
        return super.onStartCommand(intent, flags, startId);
    }

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

* 图片下载完成后增加通知

优化MyService类

public class MyService extends Service {

    private NotificationManager manager;
    private NotificationCompat.Builder builder;
    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        manager = (NotificationManager) getSystemService(Service.NOTIFICATION_SERVICE);
        builder = new NotificationCompat.Builder(getApplicationContext());
        builder.setAutoCancel(true);
        builder.setContentText("下载完成");
        builder.setContentTitle("通知");
        builder.setSmallIcon(R.mipmap.ic_launcher);
        Intent intent = new Intent(this,MainActivity.class);
        intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        PendingIntent pendingIntent = PendingIntent.getActivity(getApplicationContext(),0,intent,PendingIntent.FLAG_ONE_SHOT);
        builder.setContentIntent(pendingIntent);
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        final String path = intent.getStringExtra("key");

        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    URL url = new URL(path);
                    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                    int code = conn.getResponseCode();
                    if (code == 200) {
                        InputStream is = conn.getInputStream();
                        ByteArrayOutputStream baos = new ByteArrayOutputStream();
                        byte[] buffer = new byte[1024 * 2];
                        int ret;
                        while ((ret = is.read(buffer)) > 0) {
                            baos.write(buffer, 0, ret);
                        }
                        //保存到内存卡
                        SdCardUtils.saveDataToSdcard(baos.toByteArray(), StringUtils.getStr(path));
                        manager.notify(1,builder.build());
                    }

                } catch (MalformedURLException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }).start();
        return super.onStartCommand(intent, flags, startId);
    }

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