在Android 7中，ContentResolver的method-openAssetFileDescriptor(vCardUri，"r")返回声明为Length为-1的AssetFileDescriptor [英] In Android 7, ContentResolver's method-openAssetFileDescriptor(vCardUri, "r") returns AssetFileDescriptor having declaredLength as -1

问题描述

在Android 7中，getContentResolver().openAssetFileDescriptor(vCardUri, "r")返回将AssetFileDescriptor声明为getDeclaredLength()返回的-1的AssetFileDescriptor.

In Android 7, getContentResolver().openAssetFileDescriptor(vCardUri, "r") returns AssetFileDescriptor having declaredLength as -1 returned by getDeclaredLength().

尝试将联系人作为vcard导出到vcf文件.我尝试过的代码如下

Trying to export the contacts as vcards into vcf file. The code I have tried is as follows

Uri uri = Uri.withAppendedPath(ContactsContract.Contacts.CONTENT_VCARD_URI, lookupKey);
AssetFileDescriptor fd = resolver.openAssetFileDescriptor(uri, "r");
FileInputStream fis = fd.createInputStream();
byte[] b = new byte[(int)fd.getDeclaredLength()];
fis.read(b);

上面的代码在Android 6或更低版本的Android 6上可以完美运行.但是，当使用Android 7运行时，创建byte []的行将导致NegativeByteArraySizeException，因为clarifiedLength为-1. 当我调试下载Android 7的源代码时，发现了这个问题. 任何一种健康都是非常可观的.

The above code works perfectly in Android 6 or below.But when ran using Android 7, The line creating byte[] results in NegativeByteArraySizeException as the declaredLength is -1. When I debugged downloading the sources of Android 7, I observed the problem. Any kind of health would be really appreciable.

推荐答案

在@pskink的帮助下，我发现以下解决了我的问题的方法.

With the help of @pskink, I found the following solve my problem.

String lookupKey = cursor.getString(cursor.getColumnIndex(ContactsContract.Contacts.LOOKUP_KEY));
        Uri vCardUri = Uri.withAppendedPath(ContactsContract.Contacts.CONTENT_VCARD_URI, lookupKey);
        AssetFileDescriptor assetFileDescriptor;
        FileInputStream inputStream;
        try {
            assetFileDescriptor = getActivity().getContentResolver().openAssetFileDescriptor(vCardUri, "r");
            if (assetFileDescriptor != null) {
                inputStream = assetFileDescriptor.createInputStream();
                return readAsByteArray(inputStream);
            }
        } catch (FileNotFoundException e) {
            Log.e(TAG, "Vcard for the contact " + lookupKey + " not found", e);
        } catch (IOException e) {
            Log.e(TAG, "Problem creating stream from the assetFileDescriptor.", e);
        }

其中的readAsByteArray()是使用 Mihai代码段中的代码编写的.

where the readAsByteArray() is written using the code from Mihai Snippet.

谢谢@pskink

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