Android的下载位图回报的空有时 [英] Android Download of bitmap returns null sometimes
本文介绍了Android的下载位图回报的空有时的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我使用下面ASYN任务的code下载一个位图被添加到我的自定义类。但有时它返回空值，没有IOException异常或任何异常。我不是很肯定可以做什么
公共位图downloadFile（字符串fileUrl）{
URL myFileUrl = NULL;
尝试 {
myFileUrl =新的URL（fileUrl）;
}赶上（MalformedURLException异常E）{
// TODO自动生成的catch块
e.printStackTrace（）;
}
尝试 {
HttpURLConnection的康恩=（HttpURLConnection类）myFileUrl.openConnection（）;
conn.setDoInput（真正的）;
//conn.setReadTimeout(500000000）;
conn.connect（）;
InputStream的是= conn.getInputStream（）;
BitmapFactory.Options O =新BitmapFactory.Options（）;
o.inJustDe codeBounds = TRUE;
BitmapFactory.de codeStream（是，空，O）;
is.close（）;
conn.disconnect（）;
int标= 1;
INT IMAGE_MAX_SIZE = 400;
如果（o.outHeight＆GT; IMAGE_MAX_SIZE || o.outWidth＆GT; IMAGE_MAX_SIZE）{
标度=（int）的Math.pow（2，（int）的Math.round（将Math.log（IMAGE_MAX_SIZE /（双）Math.max（o.outHeight，o.outWidth））/将Math.log（0.5）））;
}
//德code与inSampleSize
BitmapFactory.Options O2 =新BitmapFactory.Options（）;
o2.inSampleSize =规模;
康恩=（HttpURLConnection类）myFileUrl.openConnection（）;
conn.setDoInput（真正的）;
//conn.setReadTimeout(500000000）;
conn.connect（）;
是= conn.getInputStream（）;
位图B = BitmapFactory.de codeStream（是，空，O2）;
如果（二== NULL）
Log.e（Config.log_id，下载图像失败）;
返回b;
}
赶上（IOException异常E）{
Log.e（Config.log_id，下载图像失败+ e.getMessage（））;
e.printStackTrace（）;
}
返回null;
}
解决方案
我遇到了这个问题，以及使用非缓冲变量时， 从URL中获取的时候流的读者。
这工作对我来说最简单的解决方案是使用一个BufferedHttpEntity获取图像数据。
进口org.apache.http.Htt presponse;
进口org.apache.http.client.HttpClient;
进口org.apache.http.client.methods.HttpGet;
进口org.apache.http.entity.BufferedHttpEntity;
公共静态位图德codeFromUrl（HttpClient的客户端，网址URL，配置bitmapCOnfig）
{
HTT presponse响应= NULL;
位图B = NULL;
InputStream的河道= NULL;
BitmapFactory.Options德codeOptions =新BitmapFactory.Options（）;
德codeOptions.in preferredConfig = bitmapCOnfig;
尝试
{
HTTPGET请求=新HTTPGET（url.toURI（））;
响应= client.execute（要求）;
如果（response.getStatusLine（）的getStatus code（）！= 200）
{
MyLogger.w（+ url.toString的不良反应（））;
MyLogger.w（HTTP响应：+ response.getStatusLine（）的toString（））;
返回null;
}
BufferedHttpEntity bufHttpEntity =新BufferedHttpEntity（response.getEntity（））;
河道= bufHttpEntity.getContent（）;
返回BitmapFactory.de codeStream（河道内，空，德codeOptions）;
}
赶上（例外前）
{
MyLogger.e（从错误解码位图：+网址，前）;
如果（响应！= NULL）
{
MyLogger.e（HTTP状态：+ response.getStatusLine（）的getStatus code（））;
}
返回null;
}
最后
{
如果（河道！= NULL）
{
尝试 {
instream.close（）;
}赶上（IOException异常E）{
MyLogger.e（错误收盘流，E）;
}
}
}
}
I am using the code below in asyn task to download a bitmap to be added to my custom class. however sometimes it return nulls with no IOException or any exception. i am not very sure what can be done
public Bitmap downloadFile(String fileUrl){
URL myFileUrl =null;
try {
myFileUrl= new URL(fileUrl);
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
HttpURLConnection conn= (HttpURLConnection)myFileUrl.openConnection();
conn.setDoInput(true);
//conn.setReadTimeout(500000000);
conn.connect();
InputStream is = conn.getInputStream();
BitmapFactory.Options o = new BitmapFactory.Options();
o.inJustDecodeBounds = true;
BitmapFactory.decodeStream(is, null, o);
is.close();
conn.disconnect();
int scale = 1;
int IMAGE_MAX_SIZE=400;
if (o.outHeight > IMAGE_MAX_SIZE || o.outWidth > IMAGE_MAX_SIZE) {
scale = (int)Math.pow(2, (int) Math.round(Math.log(IMAGE_MAX_SIZE / (double) Math.max(o.outHeight, o.outWidth)) / Math.log(0.5)));
}
//Decode with inSampleSize
BitmapFactory.Options o2 = new BitmapFactory.Options();
o2.inSampleSize = scale;
conn= (HttpURLConnection)myFileUrl.openConnection();
conn.setDoInput(true);
//conn.setReadTimeout(500000000);
conn.connect();
is = conn.getInputStream();
Bitmap b = BitmapFactory.decodeStream(is, null, o2);
if (b==null)
Log.e(Config.log_id, " Download image failed");
return b;
}
catch (IOException e) {
Log.e(Config.log_id, " Download image failed"+e.getMessage());
e.printStackTrace();
}
return null;
}
解决方案
I have run into this as well when using unbuffered variants of stream readers when getting from urls.
The simple solution that worked for me was to use a BufferedHttpEntity to get the image data.
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.entity.BufferedHttpEntity;
public static Bitmap decodeFromUrl(HttpClient client, URL url, Config bitmapCOnfig)
{
HttpResponse response=null;
Bitmap b=null;
InputStream instream=null;
BitmapFactory.Options decodeOptions = new BitmapFactory.Options();
decodeOptions.inPreferredConfig = bitmapCOnfig;
try
{
HttpGet request = new HttpGet(url.toURI());
response = client.execute(request);
if (response.getStatusLine().getStatusCode() != 200)
{
MyLogger.w("Bad response on " + url.toString());
MyLogger.w ("http response: " + response.getStatusLine().toString());
return null;
}
BufferedHttpEntity bufHttpEntity = new BufferedHttpEntity(response.getEntity());
instream = bufHttpEntity.getContent();
return BitmapFactory.decodeStream(instream, null, decodeOptions);
}
catch (Exception ex)
{
MyLogger.e("error decoding bitmap from:" + url, ex);
if (response != null)
{
MyLogger.e("http status: " + response.getStatusLine().getStatusCode());
}
return null;
}
finally
{
if (instream != null)
{
try {
instream.close();
} catch (IOException e) {
MyLogger.e("error closing stream", e);
}
}
}
}
这篇关于Android的下载位图回报的空有时的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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