图像下载代码适用于所有图像格式，PNG 格式呈现问题

Image download code works for all image format, issues with PNG format rendering(图像下载代码适用于所有图像格式，PNG 格式呈现问题)

问题描述

我正在使用下面的代码从服务器下载图像并将其显示到我的 ImageView

I am using the code below to download and show image from server to my ImageView

import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;

public class HTTPTest extends Activity {


     ImageView imView;
     String imageUrl="http://11.0.6.23/";
     Random r= new Random();
    /** Called when the activity is first created. */ 
    @Override
    public void onCreate(Bundle icicle) {
        super.onCreate(icicle);
        setContentView(R.layout.main);

        Button bt3= (Button)findViewById(R.id.get_imagebt);
        bt3.setOnClickListener(getImgListener);
        imView = (ImageView)findViewById(R.id.imview);
    }    

    View.OnClickListener getImgListener = new View.OnClickListener()
    {

          @Override
          public void onClick(View view) {
               // TODO Auto-generated method stub

               //i tried to randomize the file download, in my server i put 4 files with name like
                        //png0.png, png1.png, png2.png so different file is downloaded in button press
               int i =r.nextInt(4);
               downloadFile(imageUrl+"png"+i+".png");
               Log.i("im url",imageUrl+"png"+i+".png");
          }

    };


    Bitmap bmImg;
    void 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.connect();
               int length = conn.getContentLength();
               InputStream is = conn.getInputStream();

               bmImg = BitmapFactory.decodeStream(is);
               imView.setImageBitmap(bmImg);
          } catch (IOException e) {
               // TODO Auto-generated catch block
               e.printStackTrace();
          }
     }
}

此代码适用于所有格式的图像文件，但当涉及到 PNG 时，它不会让图像在下载并显示在 ImageView 后透明.

This code works file for all format of images but when it comes to PNG it wont let the image transparent after download and displaying on ImageView.

有什么想法吗?

推荐答案

我不知道它是否适合你

但你可以使用 Drawable 代替 Bitmap

But you can use a Drawable instead of Bitmap

这里是代码

void downloadFile(String fileUrl) {
try{
      InputStream is = (InputStream) new URL(fileUrl).getContent();
      Drawable d = Drawable.createFromStream(is, "src name");
      imgView.setImageDrawable(d);            
        } catch (IOException e) {
            e.printStackTrace();                
        }

}

这将正确显示 png

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