android获取网络图片的用法

关于android获取网络图片主要是把网络图片的数据流读入到内存中然后用
1.Bitmap bitMap = BitmapFactory.decodeByteArray(data, 0, length);
方法来将图片流传化为bitmap类型这样才能用到
1.imageView.setImageBitmap(bitMap);
来进行转化
在获取bitmap时候出现null
错误代码：
byte[] data = GetImageForNet.getImage(path);
int length = data.length;
Bitmap bitMap = BitmapFactory.decodeByteArray(data, 0, length);
imageView.setImageBitmap(bitMap);
下面是 GetImageForNet.getImage()方法的代码清单
public static byte[] getImage(String path) throws Exception {
        URL url = new URL(path);
        HttpURLConnection httpURLconnection = (HttpURLConnection)url.openConnection();
        httpURLconnection.setRequestMethod("GET");
        httpURLconnection.setReadTimeout(6*1000);
        InputStream in = null;
       byte[] b = new byte[1024];
        int len = -1;
        if (httpURLconnection.getResponseCode() == 200) {
             in = httpURLconnection.getInputStream();
             in.read(b);
             in.close();
             return b;
        }
       return null;
    }
看起来没有问题获取网络图片输入流，填充二进制数组，返回二进制数组，然后使用 Bitmap bitMap = BitmapFactory.decodeByteArray(data, 0, length); data就是返回的二进制数组
获取bitMap 看起来没有问题，可是bitMap就是为null！
BitmapFactory.decodeByteArray方法中所需要的data不一定是传统意义上的字节数组，查看android api，最后发现BitmapFactory.decodeByteArray所需要的data字节数组并不是想象中的数组！而是把输入流传化为字节内存输出流的字节数组格式
正确代码：
try {
            byte[] data = GetImageForNet.getImage(path);
            String d = new String(data);
           // File file = new File("1.jpg");
            //OutputStream out = new FileOutputStream(file);
            //out.write(data);
            //out.close();
            int length = data.length;
            Bitmap bitMap = BitmapFactory.decodeByteArray(data, 0, length);
            imageView.setImageBitmap(bitMap);
            //imageView.seti
        } catch (Exception e) {
            Log.i(TAG, e.toString());
            Toast.makeText(DataActivity.this, "获取图片失败", 1).show();
        }
下面是改进后的 GetImageForNet.getImage()方法的代码清单
public static byte[] getImage(String path) throws Exception {
        URL url = new URL(path);
        HttpURLConnection httpURLconnection = (HttpURLConnection)url.openConnection();
        httpURLconnection.setRequestMethod("GET");
        httpURLconnection.setReadTimeout(6*1000);
        InputStream in = null;
        byte[] b = new byte[1024];
        int len = -1;
        if (httpURLconnection.getResponseCode() == 200) {
             in = httpURLconnection.getInputStream();
             byte[] result = readStream(in);
             in.close();
             return result;

        }
        return null;
    }

    public static byte[] readStream(InputStream in) throws Exception{
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int len = -1;
        while((len = in.read(buffer)) != -1) {
            outputStream.write(buffer, 0, len);
        }
        outputStream.close();
        in.close();
        return outputStream.toByteArray();
    }

摘自 qingli518

补充：移动开发 , Android ,