我从日志中的json webservice获得了图像路径。我使用hashmap在listview中使用json显示图像。但无法在列表视图中显示任何图像。以下是我的源代码。
public class New_PDF_List extends Activity {
ListView mListView;
// Default url
private static String strUrl = "http://thetilesofindia.com/webservice.php";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Remove Titlebar
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
// Remove Notificationbar
this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_HIDDEN);
setContentView(R.layout.pdf_list);
// Creating a new non-ui thread task to download json data
DownloadTask downloadTask = new DownloadTask();
// Starting the download process
downloadTask.execute(strUrl);
// Getting a reference to ListView of activity_main
mListView = (ListView) findViewById(R.id.listView1);
}
/** A method to download json data from url */
private String downloadUrl(String strUrl) throws IOException{
String data = "";
InputStream iStream = null;
try{
URL url = new URL(strUrl);
// Creating an http connection to communicate with url
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
// Connecting to url
urlConnection.connect();
// Reading data from url
iStream = urlConnection.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(iStream));
StringBuffer sb = new StringBuffer();
String line = "";
while( ( line = br.readLine()) != null){
sb.append(line);
}
data = sb.toString();
br.close();
}catch(Exception e){
Log.d("Exception while downloading url", e.toString());
}finally{
iStream.close();
}
return data;
}
/** AsyncTask to download json data */
private class DownloadTask extends AsyncTask<String, Integer, String>{
String data = null;
@Override
protected String doInBackground(String... url) {
try{
data = downloadUrl(url[0]);
}catch(Exception e){
Log.d("Background Task",e.toString());
}
return data;
}
@Override
protected void onPostExecute(String result) {
// The parsing of the xml data is done in a non-ui thread
ListViewLoaderTask listViewLoaderTask = new ListViewLoaderTask();
// Start parsing xml data
listViewLoaderTask.execute(result);
}
}
/** AsyncTask to parse json data and load ListView */
private class ListViewLoaderTask extends AsyncTask<String, Void, SimpleAdapter>{
JSONObject jObject;
// Doing the parsing of xml data in a non-ui thread
@Override
protected SimpleAdapter doInBackground(String... strJson) {
try{
jObject = new JSONObject(strJson[0]);
TileJSONParser tilesjsonparser = new TileJSONParser();
tilesjsonparser.parse(jObject);
}catch(Exception e){
Log.d("JSON Exception1",e.toString());
}
// Instantiating json parser class
TileJSONParser tilesjsonparser = new TileJSONParser();
// A list object to store the parsed countries list
List<HashMap<String, Object>> countries = null;
try{
// Getting the parsed data as a List construct
countries = tilesjsonparser.parse(jObject);
}catch(Exception e){
Log.d("Exception",e.toString());
}
// Keys used in Hashmap
String[] from = { "name","imagepath"};
// Ids of views in listview_layout
int[] to = { R.id.mtextview_title,R.id.mImageview_pdf};
// Instantiating an adapter to store each items
// R.layout.listview_layout defines the layout of each item
SimpleAdapter adapter = new SimpleAdapter(getBaseContext(), countries, R.layout.list_item, from, to);
return adapter;
}
private void loadNetworkThumNail(final Context context,
ImageView imageview, String Url) {
// TODO Auto-generated method stub
Picasso.with(context).load(Url.trim()).resize(98, 98).placeholder(R.drawable.ic_launcher).into(imageview);
}
/** Invoked by the Android on "doInBackground" is executed */
@Override
protected void onPostExecute(SimpleAdapter adapter) {
// Setting adapter for the listview
mListView.setAdapter(adapter);
for(int i=0;i<adapter.getCount();i++){
HashMap<String, Object> hm = (HashMap<String, Object>) adapter.getItem(i);
String imgUrl = (String) hm.get("image_flag_path");
ImageLoaderTask imageLoaderTask = new ImageLoaderTask();
HashMap<String, Object> hmDownload = new HashMap<String, Object>();
hm.put("image_flag_path",imgUrl);
hm.put("position", i);
// Starting ImageLoaderTask to download and populate image in the listview
imageLoaderTask.execute(hm);
}
}
}
/** AsyncTask to download and load an image in ListView */
private class ImageLoaderTask extends AsyncTask<HashMap<String, Object>, Void, HashMap<String, Object>>{
@Override
protected HashMap<String, Object> doInBackground(HashMap<String, Object>... hm) {
InputStream iStream;
String imgUrl = (String) hm[0].get("image_flag_path");
int position = (Integer) hm[0].get("position");
URL url;
try {
url = new URL(imgUrl);
// Creating an http connection to communicate with url
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
// Connecting to url
urlConnection.connect();
// Reading data from url
iStream = urlConnection.getInputStream();
// Getting Caching directory
File cacheDirectory = getBaseContext().getCacheDir();
// Temporary file to store the downloaded image
File tmpFile = new File(cacheDirectory.getPath() + "/the_tiles_of_india_"+position+".png");
// The FileOutputStream to the temporary file
FileOutputStream fOutStream = new FileOutputStream(tmpFile);
/* // Creating a bitmap from the downloaded inputstream
Bitmap b = BitmapFactory.decodeStream(iStream);
// Writing the bitmap to the temporary file as png file
b.compress(Bitmap.CompressFormat.PNG,100, fOutStream); */
// Flush the FileOutputStream
fOutStream.flush();
//Close the FileOutputStream
fOutStream.close();
// Create a hashmap object to store image path and its position in the listview
HashMap<String, Object> hmBitmap = new HashMap<String, Object>();
// Storing the path to the temporary image file
hmBitmap.put("imagepath",tmpFile.getPath());
// Storing the position of the image in the listview
hmBitmap.put("position",position);
// Returning the HashMap object containing the image path and position
return hmBitmap;
}catch (Exception e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(HashMap<String, Object> result) {
// Getting the path to the downloaded image
String path = (String) result.get("imagepath");
// Getting the position of the downloaded image
int position = (Integer) result.get("position");
// Getting adapter of the listview
SimpleAdapter adapter = (SimpleAdapter ) mListView.getAdapter();
// Getting the hashmap object at the specified position of the listview
@SuppressWarnings("unchecked")
HashMap<String, Object> hm = (HashMap<String, Object>) adapter.getItem(position);
// Overwriting the existing path in the adapter
hm.put("imagepath",path);
// Noticing listview about the dataset changes
adapter.notifyDataSetChanged();
}
}
}
下面是具有Listview
的布局文件<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:background="#ffffff" >
<ImageView
android:id="@+id/imageView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:src="@drawable/tiles_logo" />
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/imageView1"
android:layout_marginBottom="16dp"
android:layout_marginLeft="87dp"
android:layout_toRightOf="@+id/imageView1"
android:background="@drawable/info_btn" />
<Button
android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/button1"
android:layout_marginLeft="21dp"
android:layout_toRightOf="@+id/button1"
android:background="@drawable/delete_btn" />
<Button
android:id="@+id/button3"
android:layout_width="55dp"
android:layout_height="43dp"
android:layout_alignBaseline="@+id/button2"
android:layout_alignBottom="@+id/button2"
android:layout_alignParentRight="true"
android:background="@drawable/refresh_btn" />
<Button
android:id="@+id/mPdf_list_btn_more"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignRight="@+id/imageView1"
android:layout_below="@+id/button3"
android:background="@drawable/more_button" />
<ListView
android:id="@+id/listView1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_below="@+id/mPdf_list_btn_more" >
</ListView>
</RelativeLayout>
下面是另一个在simpleAdapter中使用的布局文件
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<ImageView
android:id="@+id/mImageview_pdf"
android:layout_width="50dp"
android:layout_height="50dp"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:src="@drawable/ic_launcher" />
<TextView
android:id="@+id/mtextview_title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/mImageview_pdf"
android:layout_marginBottom="14dp"
android:layout_marginLeft="57dp"
android:layout_toRightOf="@+id/mImageview_pdf"
android:textColor="#ea0b1e"
android:text="TextView" />
<TextView
android:id="@+id/mtextview_type"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/mtextview_title"
android:layout_below="@+id/mtextview_title"
android:text="Free" />
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/mtextview_type"
android:layout_below="@+id/mtextview_type"
android:layout_marginTop="21dp"
android:background="@drawable/btn_download" />
</RelativeLayout>
答案 0 :(得分：0)
在做了很多R＆amp; D后，我得到了我的问题的答案。
public static final int DIALOG_DOWNLOAD_JSON_PROGRESS = 0;
private ProgressDialog mProgressDialog;
Button mButtonHelp,mButtonDelete,mButtonRefresh;
ArrayList<HashMap<String, Object>> MyArrList;
public static final String TAG_DOCUMENT = "docs";
public static final String TAG_TITLE = "name";
public static final String TAG_PDF_PATH = "path";
public static final String TAG_IMAGEPATH = "imagepath";
JSONArray document = null;
ListView lstView1;
// Default url
private static String url = "your url";
Button mPdf_list_btn_more;
ProgressDialog pDialog;
// flag for Internet connection status
Boolean isInternetPresent = false;
ConnectionDetector cd;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Remove Titlebar
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
// Remove Notificationbar
this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_HIDDEN);
setContentView(R.layout.pdf_list);
// Permission StrictMode
if (android.os.Build.VERSION.SDK_INT > 9) {
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
}
lstView1 = (ListView)findViewById(R.id.listView1);
mPdf_list_btn_more = (Button)findViewById(R.id.mPdf_list_btn_more);
mPdf_list_btn_more.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent i = new Intent(PDF_List_New.this,Info_Screen.class);
startActivity(i);
}
});
mButtonHelp = (Button)findViewById(R.id.mButtonHelp);
mButtonHelp.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Toast.makeText(getApplicationContext(), "Help", 2).show();
}
});
mButtonDelete = (Button)findViewById(R.id.mButtonDelete);
mButtonDelete.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Toast.makeText(getApplicationContext(), "Delete", 2).show();
}
});
mButtonRefresh = (Button)findViewById(R.id.mButtonRefresh);
mButtonRefresh.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
new DownloadJSONFileAsync().execute();
}
});
// Download JSON File
new DownloadJSONFileAsync().execute();
}
@Override
protected Dialog onCreateDialog(int id) {
switch (id) {
case DIALOG_DOWNLOAD_JSON_PROGRESS:
mProgressDialog = new ProgressDialog(this);
mProgressDialog.setMessage("Please Wait.....");
mProgressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
mProgressDialog.setCancelable(true);
mProgressDialog.show();
return mProgressDialog;
default:
return null;
}
}
// Show All Content
public void ShowAllContent()
{
// listView1
lstView1 = (ListView)findViewById(R.id.listView1);
lstView1.setAdapter(new ImageAdapter(PDF_List_New.this, MyArrList));
}
// Download JSON in Background
public class DownloadJSONFileAsync extends AsyncTask<String, Void, Void> {
protected void onPreExecute() {
super.onPreExecute();
showDialog(DIALOG_DOWNLOAD_JSON_PROGRESS);
ImageAdapter imgadapter=new ImageAdapter(PDF_List_New.this, MyArrList);
imgadapter.notifyDataSetChanged();
lstView1.invalidate();
}
@Override
protected Void doInBackground(String... params) {
// TODO Auto-generated method stub
ServiceHandler sh = new ServiceHandler();
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url, ServiceHandler.GET);
Log.d("Response: ", "> " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
MyArrList = new ArrayList<HashMap<String, Object>>();
HashMap<String, Object> map;
// Getting JSON Array node
document = jsonObj.getJSONArray(TAG_DOCUMENT);
// looping through All Contacts
for (int i = 0; i < document.length(); i++) {
JSONObject c = document.getJSONObject(i);
String name = c.getString(TAG_TITLE);
String image_path = c.getString(TAG_IMAGEPATH);
String pdf_path = c.getString(TAG_PDF_PATH);
Log.i("Name:--->", name);
Log.i("Image_Path--->",image_path);
Log.i("PDF Download Path", pdf_path);
// tmp hashmap for single contact
map = new HashMap<String, Object>();
map.put("name", (String)c.getString("name"));
map.put("imagepath", (Bitmap)loadBitmap(c.getString("imagepath")));
MyArrList.add(map);
}
}
catch(JSONException e){
}
}
else {
Log.e("ServiceHandler", "Couldn't get any data from the url");
}
return null;
}
protected void onPostExecute(Void unused) {
ShowAllContent(); // When Finish Show Content
dismissDialog(DIALOG_DOWNLOAD_JSON_PROGRESS);
removeDialog(DIALOG_DOWNLOAD_JSON_PROGRESS);
}
}
/*** Get JSON Code from URL ***/
public String getJSONUrl(String url) {
StringBuilder str = new StringBuilder();
HttpClient client = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(url);
try {
HttpResponse response = client.execute(httpGet);
StatusLine statusLine = response.getStatusLine();
int statusCode = statusLine.getStatusCode();
if (statusCode == 200) { // Download OK
HttpEntity entity = response.getEntity();
InputStream content = entity.getContent();
BufferedReader reader = new BufferedReader(new InputStreamReader(content));
String line;
while ((line = reader.readLine()) != null) {
str.append(line);
}
} else {
Log.e("Log", "Failed to download file..");
}
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return str.toString();
}
/***** Get Image Resource from URL (Start) *****/
private static final String TAG = "Image";
private static final int IO_BUFFER_SIZE = 4 * 1024;
public static Bitmap loadBitmap(String url) {
Bitmap bitmap = null;
InputStream in = null;
BufferedOutputStream out = null;
try {
in = new BufferedInputStream(new URL(url).openStream(), IO_BUFFER_SIZE);
final ByteArrayOutputStream dataStream = new ByteArrayOutputStream();
out = new BufferedOutputStream(dataStream, IO_BUFFER_SIZE);
copy(in, out);
out.flush();
final byte[] data = dataStream.toByteArray();
BitmapFactory.Options options = new BitmapFactory.Options();
//options.inSampleSize = 1;
bitmap = BitmapFactory.decodeByteArray(data, 0, data.length,options);
} catch (IOException e) {
Log.e(TAG, "Could not load Bitmap from: " + url);
} finally {
closeStream(in);
closeStream(out);
}
return bitmap;
}
private static void closeStream(Closeable stream) {
if (stream != null) {
try {
stream.close();
} catch (IOException e) {
android.util.Log.e(TAG, "Could not close stream", e);
}
}
}
private static void copy(InputStream in, OutputStream out) throws IOException {
byte[] b = new byte[IO_BUFFER_SIZE];
int read;
while ((read = in.read(b)) != -1) {
out.write(b, 0, read);
}
}
public class ImageAdapter extends BaseAdapter {
private Context context;
TextView txtPicName;
private ArrayList<HashMap<String, Object>> MyArr = new ArrayList<HashMap<String, Object>>();
public ImageAdapter(Context c, ArrayList<HashMap<String, Object>> myArrList)
{
// TODO Auto-generated method stub
context = c;
MyArr = myArrList;
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return MyArr.size();
}
@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return position;
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
LayoutInflater inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
if (convertView == null) {
convertView = inflater.inflate(R.layout.list_item, null);
}
// ColImage
ImageView imageView = (ImageView) convertView.findViewById(R.id.mImageview_pdf);
try
{
imageView.setImageBitmap((Bitmap)MyArr.get(position).get("imagepath"));
} catch (Exception e) {
// When Error
imageView.setImageResource(android.R.drawable.ic_menu_report_image);
}
// ColImgName
txtPicName = (TextView) convertView.findViewById(R.id.mtextview_title);
txtPicName.setText(MyArr.get(position).get("name").toString());
Button button1 = (Button) convertView.findViewById(R.id.button1);
button1.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Toast.makeText(context, "Clicked", 2).show();
// downloadPdfContent("http://thetilesofindia.com/magazines/SPECIAL INTERNATIONAL ISSUE - APR-MAY 2013.pdf");
}
});
return convertView;
}
public void downloadPdfContent(String urlToDownload){
try {
String fileName="xyz";
String fileExtension=".pdf";
// download pdf file.
URL url = new URL(urlToDownload);
HttpURLConnection c = (HttpURLConnection) url.openConnection();
c.setRequestMethod("GET");
c.setDoOutput(true);
c.connect();
String PATH = Environment.getExternalStorageDirectory() + "/mydownload/";
File file = new File(PATH);
file.mkdirs();
File outputFile = new File(file, fileName+fileExtension);
FileOutputStream fos = new FileOutputStream(outputFile);
InputStream is = c.getInputStream();
byte[] buffer = new byte[1024];
int len1 = 0;
while ((len1 = is.read(buffer)) != -1) {
fos.write(buffer, 0, len1);
}
fos.close();
is.close();
System.out.println("--pdf downloaded--ok--"+urlToDownload);
} catch (Exception e) {
e.printStackTrace();
}
}
}