当 UrlEncodedFormEntity 带有图像时内存不足

Question

我正在尝试将数据发送到服务器。也就是一些字符串字段和一张图片，编码为base64，作为String传递，像这样：

ByteArrayOutputStream stream = new ByteArrayOutputStream();
        mBitmap.compress(Bitmap.CompressFormat.JPEG, 100, stream);
        byte[] byteArray = stream.toByteArray();
        //Cleaning memory
        try {
            stream.close();
            stream = null;
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        //Eecode base64
        nameValuePairs.add(new BasicNameValuePair(DatosDB.KEY_IMG, Base64.encodeToString(byteArray, Base64.DEFAULT)));
        byteArray = null;

然后，在准备 HTTP PUT 请求时：

 try{
        HttpClient httpclient = new DefaultHttpClient();
        //PUT
        HttpPut httpput = new HttpPut(KEY_121 + ruta);
        //The exception is thrown when executing next instruction
        httpput.setEntity(new UrlEncodedFormEntity(nameValuePairs));
        HttpResponse response = httpclient.execute(httpput);

        HttpEntity entity = response.getEntity();
        is = entity.getContent();

        }catch(Exception e){
        Log.e(TAG, "Error in http connection "+e.toString());
        }   

错误如下所示：

12-20 00:24:11.622: ERROR/AndroidRuntime(7499): FATAL EXCEPTION: main
12-20 00:24:11.622: ERROR/AndroidRuntime(7499): java.lang.OutOfMemoryError
12-20 00:24:11.622: ERROR/AndroidRuntime(7499):     at java.lang.AbstractStringBuilder.enlargeBuffer(AbstractStringBuilder.java:95)
12-20 00:24:11.622: ERROR/AndroidRuntime(7499):     at java.lang.AbstractStringBuilder.append0(AbstractStringBuilder.java:140)
12-20 00:24:11.622: ERROR/AndroidRuntime(7499):     at java.lang.StringBuilder.append(StringBuilder.java:125)
12-20 00:24:11.622: ERROR/AndroidRuntime(7499):     at java.net.URLEncoder.encode(URLEncoder.java:109)
12-20 00:24:11.622: ERROR/AndroidRuntime(7499):     at org.apache.http.client.utils.URLEncodedUtils.encode(URLEncodedUtils.java:184)
12-20 00:24:11.622: ERROR/AndroidRuntime(7499):     at org.apache.http.client.utils.URLEncodedUtils.format(URLEncodedUtils.java:163)
12-20 00:24:11.622: ERROR/AndroidRuntime(7499):     at org.apache.http.client.entity.UrlEncodedFormEntity.<init>(UrlEncodedFormEntity.java:71)
12-20 00:24:11.622: ERROR/AndroidRuntime(7499):     at com.android.upvar.Http_Request.put(Http_Request.java:171)
12-20 00:24:11.622: ERROR/AndroidRuntime(7499):     at com.android.upvar.Http_Request.poi(Http_Request.java:108)
12-20 00:24:11.622: ERROR/AndroidRuntime(7499):     at com.android.upvar.NewPOI.putPOI(NewPOI.java:360)
12-20 00:24:11.622: ERROR/AndroidRuntime(7499):     at com.android.upvar.NewPOI.access$6(NewPOI.java:325)
12-20 00:24:11.622: ERROR/AndroidRuntime(7499):     at com.android.upvar.NewPOI$5.onClick(NewPOI.java:157)
12-20 00:24:11.622: ERROR/AndroidRuntime(7499):     at android.view.View.performClick(View.java:2538)
12-20 00:24:11.622: ERROR/AndroidRuntime(7499):     at android.view.View$PerformClick.run(View.java:9152)
12-20 00:24:11.622: ERROR/AndroidRuntime(7499):     at android.os.Handler.handleCallback(Handler.java:587)
12-20 00:24:11.622: ERROR/AndroidRuntime(7499):     at android.os.Handler.dispatchMessage(Handler.java:92)
12-20 00:24:11.622: ERROR/AndroidRuntime(7499):     at android.os.Looper.loop(Looper.java:130)
12-20 00:24:11.622: ERROR/AndroidRuntime(7499):     at android.app.ActivityThread.main(ActivityThread.java:3687)
12-20 00:24:11.622: ERROR/AndroidRuntime(7499):     at java.lang.reflect.Method.invokeNative(Native Method)
12-20 00:24:11.622: ERROR/AndroidRuntime(7499):     at java.lang.reflect.Method.invoke(Method.java:507)
12-20 00:24:11.622: ERROR/AndroidRuntime(7499):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:842)
12-20 00:24:11.622: ERROR/AndroidRuntime(7499):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
12-20 00:24:11.622: ERROR/AndroidRuntime(7499):     at dalvik.system.NativeStart.main(Native Method)
12-20 00:24:11.632: WARN/ActivityManager(3923):   Force finishing activity com.android.upvar/.NewPOI
12-20 00:24:11.636: ERROR/(3923): Dumpstate > /data/log/dumpstate_app_error

我不明白为什么会出现此异常。我只是发送从三星 Galaxay 相机拍摄的常规图像（肯定小于 16MB）。有什么想法吗？

编辑：我必须补充一点，第一块代码和第二块代码在不同的类上，所以第一块代码上的数据被传递给另一个类的对象，后者将它传递给另一个类的另一个对象具有 HTTP 请求的类。

Answer 1

为您的实体使用流式传输，以便它仅消耗流所要求的较小缓冲区大小。 ByteArrayOutputStream 将所有数据保存在内存中。

HTTPClient - Performance Guide

尝试如下实现，它不会在内存对象中创建不必要的。以下可能不是完整的实现。玩得开心编码！

class BitMapRequestEntity extends AbstractHttpEntity {

    private Bitmap bitmap;

    public BitMapRequestEntity(Bitmap mBitmap) {
        super();
        this.bitmap = mBitmap;
    }

    @Override
    public InputStream getContent() throws IOException,
            IllegalStateException {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public long getContentLength() {
        // TODO Auto-generated method stub
        return 0;
    }

    @Override
    public boolean isRepeatable() {
        // TODO Auto-generated method stub
        return false;
    }

    @Override
    public boolean isStreaming() {
        return true;
    }

    @Override
    public void writeTo(OutputStream outstream) throws IOException {
        bitmap.compress(Bitmap.CompressFormat.JPEG, 100, outstream);
    }

}
try {
    org.apache.http.client.HttpClient httpclient = new DefaultHttpClient();
    // PUT
    HttpPut httpput = new HttpPut(KEY_121 + ruta);
    // The exception is thrown when executing next instruction
    httpput.setEntity(new BitMapRequestEntity(mBitmap));
    HttpResponse response = httpclient.execute(httpput);

    HttpEntity entity = response.getEntity();
    is = entity.getContent();

} catch (Exception e) {
    Log.e(TAG, "Error in http connection " + e.toString());
}

Answer 2

最后，解决办法是把图片压缩到50%，如下：

mBitmap.compress(Bitmap.CompressFormat.JPEG, 100, stream);

它减小了图像大小并使其足够小以将其作为字符串发送。

Answer 3

做完之后

mBitmap.compress(Bitmap.CompressFormat.JPEG, 100, stream);
byte[] byteArray = stream.toByteArray();

您在内存中有两个版本的图像，一个是位图，一个是字节数组。通过Bitmap.recycle() 清理前者可能会有所帮助。

不请自来的建议：用于传输图像的“多部分表单数据”是否不符合您的目的？这非常节省内存。