我希望在URL列表中显示图像时，如果没有来自服务端的图像URL，那么我想显示特定索引的默认图像。为此，我在Volley中使用array adapter进行图像加载。现在我的问题是当我使用默认图像时，图像没有正确显示，有时它与另一个图像重叠。当我没有使用默认图像时，它工作正常。这是我的代码，请告诉我这有什么问题？提前谢谢。
这是我的Adapter类，
public class CustomLocalAlertAdapter extends ArrayAdapter<LocalListItem>
implements AppConstants {
Activity a;
ViewHolder holder;
ImageView mImageview;
private Object mImageLoader;
@SuppressWarnings("static-access")
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
// return super.getView(position, convertView, parent);
LocalListItem LocalList = getItem(position);
if (convertView == null) {
convertView = LayoutInflater.from(getContext()).inflate(
R.layout.activity_add_local_all_alert_details, parent,
false);
holder = new ViewHolder();
holder.missingTitle = (TextView) convertView
.findViewById(R.id.missingTitle);
holder.missingDetails = (TextView) convertView
.findViewById(R.id.missingDetails);
holder.missingImage = (NetworkImageView) convertView
.findViewById(R.id.missingImage);
holder.suspectImage = (NetworkImageView) convertView
.findViewById(R.id.suspectImage);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
String allAlertSuspectDetails = "";
String allAlertVehicleDetails = "";
String allAlertPersonDetails = "";
if (LocalList.title.equalsIgnoreCase("missing_vehicle_report")) {
allAlertPersonDetails = "";
allAlertSuspectDetails = "";
holder.missingTitle.setText("Missing Vehicle");
allAlertVehicleDetails = "\n" + "Year: " + LocalList.Year + "\n"
+ "Make: " + LocalList.Make + "\n" + "Model: "
+ LocalList.Model + "\n" + "Color: " + LocalList.Color
+ "\n" + "LisencePlateNo: " + LocalList.LisencePlateNo
+ "\n" + "Vin: " + LocalList.Vin + "\n" + "Place: "
+ LocalList.Place;
holder.suspectImage.setVisibility(View.GONE);
} else {
holder.suspectImage.setVisibility(View.VISIBLE);
allAlertVehicleDetails = "";
holder.missingTitle.setText("Missing Person");
allAlertPersonDetails = "\n" + "Name: " + LocalList.personName
+ "\n" + "Height: " + LocalList.height + "\n"
+ "Unique Mark: " + LocalList.uniqueMark + "\n"
+ "Last seen: " + LocalList.lastSeen + "\n"
+ "Date Missing: " + LocalList.dateMissing + "\n"
+ "Police department: " + LocalList.policeDept + "\n"
+ "Police dept.phone: " + LocalList.policePhn + "\n" + "\n";
if (LocalList.suspectName.equalsIgnoreCase("")
|| LocalList.suspectName.equalsIgnoreCase("null")
|| LocalList.suspectName.equalsIgnoreCase(" ")) {
allAlertSuspectDetails = "";
holder.suspectImage.setVisibility(View.GONE);
} else {
allAlertSuspectDetails = "Suspect name: "
+ LocalList.suspectName + "\n" + "Vehicle Color: "
+ LocalList.vehicleColor + "\n" + "Vehicle Year: "
+ LocalList.vehicleYear + "\n" + "Vehicle Make: "
+ LocalList.vehicleMake + "\n" + "Vehicle Model: "
+ LocalList.vehicleModel;
}
}
holder.missingDetails.setText(allAlertVehicleDetails
+ allAlertPersonDetails + allAlertSuspectDetails);
if (LocalList.title.equalsIgnoreCase("missing_vehicle_report")) {
if (LocalList.vehicleImg.trim().equalsIgnoreCase(
"")) {
holder.missingImage.setImageResource(R.drawable.no_image_found);
} else {
holder.missingImage.setImageUrl(LocalList.vehicleImg,
VolleySingleton.getInstance(getContext())
.getImageLoader());
}
} else {
if (LocalList.personImage.trim().equalsIgnoreCase(
"")) {
holder.missingImage.setImageResource(R.drawable.no_image_found);
} else {
holder.missingImage.setImageUrl(LocalList.personImage,
VolleySingleton.getInstance(getContext())
.getImageLoader());
}
if (LocalList.suspectImage.trim().equalsIgnoreCase(
"")) {
holder.suspectImage.setImageResource(R.drawable.no_image_found);
} else {
holder.suspectImage.setImageUrl(LocalList.suspectImage,
VolleySingleton.getInstance(getContext())
.getImageLoader());
}
}
return convertView;
}
public static class ViewHolder {
TextView missingTitle;
TextView missingDetails;
NetworkImageView missingImage;
NetworkImageView suspectImage;
}
public CustomLocalAlertAdapter(Context context,
ArrayList<LocalListItem> ListItem, Activity a) {
super(context, 0, ListItem);
// TODO Auto-generated constructor stub
this.a = a;
}
}
这是我的VolleySingleton课程，
public class VolleySingleton {
private static VolleySingleton instance;
private RequestQueue requestQueue;
private static ImageLoader imageLoader;
private VolleySingleton(Context context) {
requestQueue = Volley.newRequestQueue(context);
imageLoader = new ImageLoader(requestQueue,
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 VolleySingleton getInstance(Context context) {
if (instance == null) {
instance = new VolleySingleton(context);
}
return instance;
}
public RequestQueue getRequestQueue() {
return requestQueue;
}
public static ImageLoader getImageLoader() {
return imageLoader;
}
}
答案 0 :(得分：0)
首先按如下方式创建一个文件MultipartRequest：
public class MultipartRequest extends Request<String> {
private MultipartEntityBuilder entity = MultipartEntityBuilder.create();
private final Response.Listener<String> mListener;
private final File file;
private final HashMap<String, String> params;
public MultipartRequest(String url, Response.Listener<String> listener, Response.ErrorListener errorListener, File file, HashMap<String, String> params)
{
super(Method.POST, url, errorListener);
mListener = listener;
this.file = file;
this.params = params;
buildMultipartEntity();
buildMultipartEntity2();
}
private void buildMultipartEntity()
{
entity.addBinaryBody(KEY_IMAGE, file, ContentType.create("image/jpeg"), file.getName());
entity.setMode(HttpMultipartMode.BROWSER_COMPATIBLE);
entity.setLaxMode().setBoundary("xx").setCharset(Charset.forName("UTF-8"));
try
{
for ( String key : params.keySet() ) {
entity.addPart(key, new StringBody(params.get(key)));
}
}
catch (UnsupportedEncodingException e)
{
VolleyLog.e("UnsupportedEncodingException");
}
}
@Override
public String getBodyContentType()
{
return entity.build().getContentType().getValue();
}
@Override
public Map<String, String> getHeaders() throws AuthFailureError {
Map<String, String> headers = super.getHeaders();
if (headers == null
|| headers.equals(Collections.emptyMap())) {
headers = new HashMap<String, String>();
}
headers.put("Accept", "application/json");
return headers;
}
@Override
public byte[] getBody() throws AuthFailureError
{
ByteArrayOutputStream bos = new ByteArrayOutputStream();
try
{
entity.build().writeTo(bos);
}
catch (IOException e)
{
VolleyLog.e("IOException writing to ByteArrayOutputStream");
}
return bos.toByteArray();
}
/**
* copied from Android StringRequest class
*/
@Override
protected Response<String> parseNetworkResponse(NetworkResponse response) {
String parsed;
try {
parsed = new String(response.data, HttpHeaderParser.parseCharset(response.headers));
} catch (UnsupportedEncodingException e) {
parsed = new String(response.data);
}
return Response.success(parsed, HttpHeaderParser.parseCacheHeaders(response));
}
@Override
protected void deliverResponse(String response) {
mListener.onResponse(response);
}}
在您的活动中，只需按照以下方式制作多部分请求：
public void uploadImage()
{
try {
pDialog = new ProgressDialog(getActivity());
pDialog.setMessage("Loading...");
pDialog.show();
HashMap params = new HashMap<String, String>();
params.put(KEY_NAME, name);
MultipartRequest sr = new MultipartRequest( UPLOAD_URL, new Response.Listener<String>() {
@Override
public void onResponse(String response) {
if ((pDialog != null) && pDialog.isShowing()) {
pDialog.dismiss();
}
Log.d("file", f + "");
Log.d("", ".......response====" + response.toString());
////////
try {
JSONObject object = new JSONObject(response);
String serverCode = object.getString("code");
if (serverCode.equalsIgnoreCase("0")) {
}
if (serverCode.equalsIgnoreCase("1")) {
try {
if ("1".equals(serverCode)) {
JSONObject object1 = object.getJSONObject("data");
}
}