我是 Android 工作室的新手。在这里,我尝试从存储在在线服务器中的 mysql 数据库中获取图像并在 listvew 上显示图像。但我的自定义文件中出现错误。请帮帮我。 this is the error i'm getting in log when i try to run my application
这是我的自定义Java代码: 包 com.example.manarpatel.book_app;
import android.app.Activity;
import android.graphics.Bitmap;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;
public class CustomList extends ArrayAdapter<String> {
private String[] urls;
private Bitmap[] bitmaps;
private Activity context;
public CustomList(Activity context, String[] urls, Bitmap[] bitmaps) {
super(context, R.layout.image_list_view, urls);
this.context = context;
this.urls= urls;
this.bitmaps= bitmaps;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = context.getLayoutInflater();
View listViewItem = inflater.inflate(R.layout.image_list_view,parent, true);
TextView textViewURL = (TextView) listViewItem.findViewById(R.id.textViewURL);
ImageView image = (ImageView) listViewItem.findViewById(R.id.imageDownloaded);
textViewURL.setText(urls[position]);
Bitmap smaller = Bitmap.createScaledBitmap(bitmaps[position], 100, 50, false);
image.setImageBitmap(smaller);
// image.setImageBitmap(Bitmap.createScaledBitmap(bitmaps[position], 100, 50, false));
return listViewItem;
}
}
这里是我的 imageList 查看器 java 代码:
package com.example.manarpatel.book_app;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
import org.json.JSONException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
public class ImageListView extends AppCompatActivity implements AdapterView.OnItemClickListener {
private ListView listView;
public static final String GET_IMAGE_URL="http://usedbookapp.esy.es/getAllImages.php";
public GetAlImages getAlImages;
public static final String BITMAP_ID = "BITMAP_ID";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_image_list_view);
listView = (ListView) findViewById(R.id.listView);
listView.setOnItemClickListener(this);
getURLs();
}
private void getImages(){
class GetImages extends AsyncTask<Void,Void,Void>{
ProgressDialog loading;
@Override
protected void onPreExecute() {
super.onPreExecute();
loading = ProgressDialog.show(ImageListView.this,"Downloading images...","Please wait...",false,false);
}
@Override
protected void onPostExecute(Void v) {
super.onPostExecute(v);
loading.dismiss();
//Toast.makeText(ImageListView.this,"Success",Toast.LENGTH_LONG).show();
CustomList customList = new CustomList(ImageListView.this,GetAlImages.imageURLs,GetAlImages.bitmaps);
listView.setAdapter(customList);
}
@Override
protected Void doInBackground(Void... voids) {
try {
getAlImages.getAllImages();
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
}
GetImages getImages = new GetImages();
getImages.execute();
}
private void getURLs() {
class GetURLs extends AsyncTask<String,Void,String>{
ProgressDialog loading;
@Override
protected void onPreExecute() {
super.onPreExecute();
loading = ProgressDialog.show(ImageListView.this,"Loading...","Please Wait...",true,true);
}
@Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
loading.dismiss();
getAlImages = new GetAlImages(s);
getImages();
}
@Override
protected String doInBackground(String... strings) {
BufferedReader bufferedReader = null;
try {
URL url = new URL(strings[0]);
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;
}
}
}
GetURLs gu = new GetURLs();
gu.execute(GET_IMAGE_URL);
}
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
Intent intent = new Intent(this, ViewFullImage.class);
intent.putExtra(BITMAP_ID,i);
startActivity(intent);
}
}
获取所有图像的java代码:
package com.example.manarpatel.book_app;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
public class GetAlImages {
public static String[] imageURLs;
public static Bitmap[] bitmaps;
public static final String JSON_ARRAY="result";
public static final String IMAGE_URL = "url";
private String json;
private JSONArray urls;
public GetAlImages(String json){
this.json = json;
try {
JSONObject jsonObject = new JSONObject(json);
urls = jsonObject.getJSONArray(JSON_ARRAY);
} catch (JSONException e) {
e.printStackTrace();
}
}
private Bitmap getImage(JSONObject jo){
URL url = null;
Bitmap image = null;
try {
url = new URL(jo.getString(IMAGE_URL));
image = BitmapFactory.decodeStream(url.openConnection().getInputStream());
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
return image;
}
public void getAllImages() throws JSONException {
bitmaps = new Bitmap[urls.length()];
imageURLs = new String[urls.length()];
for(int i=0;i<urls.length();i++){
imageURLs[i] = urls.getJSONObject(i).getString(IMAGE_URL);
JSONObject jsonObject = urls.getJSONObject(i);
bitmaps[i]=getImage(jsonObject);
}
}
}
这里是图片 ListView 的xml代码
<LinearLayoutandroid:orientation="horizontal"android:layout_width="fill_parent" android:layout_height="wrap_content">
<ImageView android:id="@+id/imageDownloaded" android:layout_width="wrap_content" android:layout_height="wrap_content" android:src="@drawable/abc_ic_menu_copy_mtrl_am_alpha"/>
<TextView android:id="@+id/textViewURL" android:layout_width="wrap_content" android:layout_height="wrap_content"/>
</LinearLayout>
最佳答案
尝试使用Glide从数据库中检索图像
public class NetworkImageView extends ImageView {
private String imageURL;
/**
* Resource ID of the image to be used as a placeholder until the network image is loaded.
*/
private int mDefaultImageId;
/**
* Resource ID of the image to be used if the network response fails.
*/
private int mErrorImageId;
private Bitmap bitmap;
public NetworkImageView(Context context) {
super(context);
}
public NetworkImageView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public NetworkImageView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public String getImageURL() {
return imageURL;
}
public void setImageUrl(String imageURL) {
this.imageURL = imageURL;
Glide.with(getContext())
.load(imageURL)
.override(200, 200)
.diskCacheStrategy(DiskCacheStrategy.ALL)
.into(this);
}
/**
* Sets the default image resource ID to be used for this view until the attempt to load it
* completes.
*/
public void setDefaultImageResId(int defaultImage) {
mDefaultImageId = defaultImage;
}
/**
* Sets the error image resource ID to be used for this view in the event that the image
* requested fails to load.
*/
public void setErrorImageResId(int errorImage) {
mErrorImageId = errorImage;
}
public void setLocalImageBitmap(Bitmap bitmap) {
this.bitmap = bitmap;
}
}
xml 布局:
<com.vynd.solution.utiles.NetworkImageView
android:id="@+id/backdrop"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/gradient"
android:scaleType="centerCrop"
android:src="@null" />
并使用这个
photo = (NetworkImageView) itemView.findViewById(R.id.photoItem);
photo.setImageUrl(url);
我希望这个例子有用 更多信息Link
关于java - 从android studio中的mysql数据库检索图像,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/36269091/