我在
Android开发人员上跟进
image cashing tutorial using Volley,我遇到了请求图像请求并缓存它的问题,我想因为我创建的singelton(从教程中复制).
我的Eclipse在getInstance(this)中给出了错误,因为这是上下文而我正在请求一个图像.
ImageRequest request = new ImageRequest(
url,new Response.Listener<Bitmap>() {
@Override
public void onResponse(Bitmap bitmap) {
mNetworkImageView = (NetworkImageView) findViewById(R.id.ImageView);
mImageLoader = MySingleton.getInstance(this).getimageLoader();
mNetworkImageView.setimageUrl(IMAGE_URL,mImageLoader);
// mImageLoader = MySingleton.getInstance(this).getimageLoader();
// mImageLoader.get(IMAGE_URL,ImageLoader.getimageListener(mImageView,// R.drawable.ic_launcher,R.drawable.ic_launcher));
}
},null,new Response.ErrorListener() {
public void onErrorResponse(VolleyError error) {
// mImageView.setimageResource(R.drawable.ic_launcher);
}
});
MySingleton.getInstance(this).addToRequestQueue(request);
这是单身人士：
package com.example.p;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.toolBox.ImageLoader;
import com.android.volley.toolBox.Volley;
import android.content.Context;
import android.graphics.Bitmap;
import android.support.v4.util.LruCache;
public class MySingleton {
private static MySingleton mInstance;
private RequestQueue mRequestQueue;
private ImageLoader mImageLoader;
private static Context mCtx;
private MySingleton(Context context) {
mCtx = context;
mRequestQueue = getRequestQueue();
mImageLoader = new ImageLoader(
mRequestQueue,new ImageLoader.ImageCache() {
private final LruCache<String,Bitmap>
cache = new LruCache<String,Bitmap>(20);
@Override
public Bitmap getBitmap(String url) {
return cache.get(url);
}
@Override
public void putBitmap(String url,Bitmap bitmap) {
cache.put(url,bitmap);
}
});
}
public static synchronized MySingleton getInstance(Context context) {
if (mInstance == null) {
mInstance = new MySingleton(context);
}
return mInstance;
}
public RequestQueue getRequestQueue() {
if (mRequestQueue == null) {
// getApplicationContext() is key,it keeps you from leaking the
// Activity or broadcastReceiver if someone passes one in.
mRequestQueue = Volley.newRequestQueue(mCtx.getApplicationContext());
}
return mRequestQueue;
}
public <T> void addToRequestQueue(Request<T> req) {
getRequestQueue().add(req);
}
public ImageLoader getimageLoader() {
return mImageLoader;
}
}
我能够以这种方式获取图像并显示它,但我需要缓存它,所以我想将它添加到请求中吗？ ..有什么帮助吗？
mNetworkImageView = (NetworkImageView) findViewById(R.id.ImageView); mImageLoader = MySingleton.getInstance(this).getimageLoader(); mNetworkImageView.setimageUrl(IMAGE_URL,mImageLoader);
解决方法
这是我的工作示例代码.希望这个帮助：
MainActivity.java：
import ...
public class MainActivity extends Activity {
final Context mContext = this;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
NetworkImageView mNetworkImageView = (NetworkImageView) findViewById(R.id.networkImageView);
String mUrl = "http://192.168.0.100/api/getimage";
mNetworkImageView.setimageUrl(mUrl,VolleySingleton.getInstance(mContext).getimageLoader());
}
...
}
VolleySingleton.java：
public class VolleySingleton {
private static VolleySingleton mInstance;
private RequestQueue mRequestQueue;
private ImageLoader mImageLoader;
private static Context mContext;
private VolleySingleton(Context context) {
mContext = context;
mRequestQueue = getRequestQueue();
mImageLoader = new ImageLoader(mRequestQueue,new ImageLoader.ImageCache() {
private final LruCache<String,Bitmap>
cache = new LruCache<>(20);
@Override
public Bitmap getBitmap(String url) {
return cache.get(url);
}
@Override
public void putBitmap(String url,Bitmap bitmap) {
cache.put(url,bitmap);
}
});
}
public static synchronized VolleySingleton getInstance(Context context) {
if (mInstance == null) {
mInstance = new VolleySingleton(context);
}
return mInstance;
}
private RequestQueue getRequestQueue() {
if (mRequestQueue == null) {
// getApplicationContext() is key,it keeps you from leaking the
// Activity or broadcastReceiver if someone passes one in.
mRequestQueue = Volley.newRequestQueue(mContext.getApplicationContext(),10 * 1024 * 1024); // this for caching
}
return mRequestQueue;
}
public <T> void addToRequestQueue(Request<T> req) {
getRequestQueue().add(req);
}
public ImageLoader getimageLoader() {
return mImageLoader;
}
}
activity_main.xml中：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
tools:context=".MainActivity">
<com.android.volley.toolBox.NetworkImageView
android:id="@+id/networkImageView"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
AndroidManifest.xml中：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.volleyapp" >
<uses-permission android:name="android.permission.INTERNET" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>