Question

如何在不点击获取图片按钮的情况下获取第一张图片

此代码工作正常，但点击获取图像按钮但我想要获取图像没有点击获取图像按钮我想删除此按钮

Public class MainActivity extends AppCompatActivity implements 
View.OnClickListener {

    private String imagesJSON;

    private static final String JSON_ARRAY ="result";

    private static final String IMAGE_URL = "url";

    private JSONArray arrayImages= null;

    private int TRACK = 0;

    private static final String IMAGES_URL = "http://www.simplifiedcoding.16mb.com/ImageUpload/getAllImages.php";

    private Button buttonFetchImages;
    private Button buttonMoveNext;
    private Button buttonMovePrevious;
    private ImageView imageView;


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

        imageView = (ImageView) findViewById(R.id.imageView);
        buttonFetchImages = (Button) findViewById(R.id.buttonFetchImages);
        buttonMoveNext = (Button) findViewById(R.id.buttonNext);
        buttonMovePrevious = (Button) findViewById(R.id.buttonPrev);
        buttonFetchImages.setOnClickListener(this);
        buttonMoveNext.setOnClickListener(this);
        buttonMovePrevious.setOnClickListener(this);
    }


    private void extractJSON(){
        try {
            JSONObject jsonObject = new JSONObject(imagesJSON);
            arrayImages = jsonObject.getJSONArray(JSON_ARRAY);
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }

    private void showImage(){
        try {
            JSONObject jsonObject = arrayImages.getJSONObject(TRACK);
            getImage(jsonObject.getString(IMAGE_URL));
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }

    private void moveNext(){
        if(TRACK < arrayImages.length()){
            TRACK++;
            showImage();
        }
    }

    private void movePrevious(){
        if(TRACK>0){
            TRACK--;
            showImage();
        }
    }



    private void getAllImages() {
        class GetAllImages extends AsyncTask<String,Void,String>{
            ProgressDialog loading;
            @Override
            protected void onPreExecute() {
                super.onPreExecute();
                loading = ProgressDialog.show(MainActivity.this, "Fetching Data...","Please Wait...",true,true);
            }

            @Override
            protected void onPostExecute(String s) {
                super.onPostExecute(s);
                loading.dismiss();
                imagesJSON = s;
                extractJSON();
                showImage();
            }

            @Override
            protected String doInBackground(String... params) {
                String uri = params[0];
                BufferedReader bufferedReader = null;
                try {
                    URL url = new URL(uri);
                    HttpURLConnection con = (HttpURLConnection) url.openConnection();
                    StringBuilder sb = new StringBuilder();

                    bufferedReader = new BufferedReader(new InputStreamReader(con.getInputStream()));

                    String json;
                    while((json = bufferedReader.readLine())!= null){
                        sb.append(json+"\n");
                    }

                    return sb.toString().trim();

                }catch(Exception e){
                    return null;
                }
            }
        }
        GetAllImages gai = new GetAllImages();
        gai.execute(IMAGES_URL);
    }

    private void getImage(String urlToImage){
        class GetImage extends AsyncTask<String,Void,Bitmap>{
            ProgressDialog loading;
            @Override
            protected Bitmap doInBackground(String... params) {
                URL url = null;
                Bitmap image = null;

                String urlToImage = params[0];
                try {
                    url = new URL(urlToImage);
                    image = BitmapFactory.decodeStream(url.openConnection().getInputStream());
                } catch (MalformedURLException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                return image;
            }

            @Override
            protected void onPreExecute() {
                super.onPreExecute();
                loading = ProgressDialog.show(MainActivity.this,"Downloading Image...","Please wait...",true,true);
            }

            @Override
            protected void onPostExecute(Bitmap bitmap) {
                super.onPostExecute(bitmap);
                loading.dismiss();
                imageView.setImageBitmap(bitmap);
            }
        }
        GetImage gi = new GetImage();
        gi.execute(urlToImage);
    }

    @Override
    public void onClick(View v) {
        if(v == buttonFetchImages) {
            getAllImages();
        }
        if(v == buttonMoveNext){
            moveNext();
        }
        if(v== buttonMovePrevious){
            movePrevious();
        }
    }
}

Answer 1

你可以在onCreate（）中触发它，但你不能在UI线程上运行它，因为它可能是一个耗时的操作。阅读Specifying the Code to Run on a Thread来帮忙，您可以在onCreate（）方法中添加以下块：

new Runnable() {
        @Override
        public void run() {
            getAllImages();
        }
    }.run();

如何在没有按钮点击的情况下获取数据

1 个答案: