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Android利用Volley异步加载数据(JSON和图片)完整示例

 3 years ago
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Android利用Volley异步加载数据(JSON和图片)完整示例 – Android开发中文站

MainActivity如下:

package androidchina.net.testvolley;
import org.json.JSONObject;
import android.app.Activity;
import android.app.ProgressDialog;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.support.v4.util.LruCache;
import android.widget.ImageView;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.ImageLoader;
import com.android.volley.toolbox.ImageLoader.ImageCache;
import com.android.volley.toolbox.ImageLoader.ImageListener;
import com.android.volley.toolbox.JsonObjectRequest;
import com.android.volley.toolbox.NetworkImageView;
import com.android.volley.toolbox.Volley;
/**
* Demo描述:
* 1 利用Volley获取JSON数据
* 2 利用Volley异步加载图片
* 1 利用NetworkImageView加载网路图片
*
* 参考资料:
* Thank you very much
*/
public class MainActivity extends Activity {
private ImageView mImageView;
private NetworkImageView mNetworkImageView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
init();
}
private void init(){
mImageView=(ImageView) findViewById(R.id.imageView);
mNetworkImageView=(NetworkImageView)findViewById(R.id.networkImageView);
getJSONByVolley();
loadImageByVolley();
showImageByNetworkImageView();
}
/**
* 利用Volley获取JSON数据
*/
private void getJSONByVolley() {
RequestQueue requestQueue = Volley.newRequestQueue(this);
final ProgressDialog progressDialog = ProgressDialog.show(this, "This is title", "...Loading...");
JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Request.Method.GET, JSONDataUrl, null,
new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
System.out.println("response="+response);
if (progressDialog.isShowing()&&progressDialog!=null) {
progressDialog.dismiss();
}
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError arg0) {
System.out.println("sorry,Error");
}
});
requestQueue.add(jsonObjectRequest);
}
/**
* 利用Volley异步加载图片
*
* 注意方法参数:
* getImageListener(ImageView view, int defaultImageResId, int errorImageResId)
* 第一个参数:显示图片的ImageView
* 第二个参数:默认显示的图片资源
* 第三个参数:加载错误时显示的图片资源
*/
private void loadImageByVolley(){
RequestQueue requestQueue = Volley.newRequestQueue(this);
final LruCache<String, Bitmap> lruCache = new LruCache<String, Bitmap>(20);
ImageCache imageCache = new ImageCache() {
@Override
public void putBitmap(String key, Bitmap value) {
lruCache.put(key, value);
}
@Override
public Bitmap getBitmap(String key) {
return lruCache.get(key);
}
};
ImageLoader imageLoader = new ImageLoader(requestQueue, imageCache);
ImageListener listener = ImageLoader.getImageListener(mImageView, R.drawable.ic_launcher,R.drawable.ic_launcher);
imageLoader.get(imageUrl, listener);
}
/**
* 利用NetworkImageView显示网络图片
*/
private void showImageByNetworkImageView(){
RequestQueue requestQueue = Volley.newRequestQueue(this);
final LruCache<String, Bitmap> lruCache = new LruCache<String, Bitmap>(20);
ImageCache imageCache = new ImageCache() {
@Override
public void putBitmap(String key, Bitmap value) {
lruCache.put(key, value);
}
@Override
public Bitmap getBitmap(String key) {
return lruCache.get(key);
}
};
ImageLoader imageLoader = new ImageLoader(requestQueue, imageCache);
mNetworkImageView.setTag("url");
mNetworkImageView.setImageUrl(imageUrl,imageLoader);
}
}

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