Question

我试图将文件从服务器下载到外部SD卡。这是我的代码：

try {
            URL url = new URL(address);

            HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.setRequestMethod("GET");
            urlConnection.setDoOutput(true);
            urlConnection.connect();

            File SDCardRoot = Environment.getExternalStorageDirectory();
            File file = new File(SDCardRoot,"myfile.txt");

            FileOutputStream fileOutput = new FileOutputStream(file);

            InputStream inputStream = urlConnection.getInputStream();

            //this is the total size of the file
            int totalSize = urlConnection.getContentLength();
            int downloadedSize = 0;

            byte[] buffer = new byte[1024];
            int bufferLength = 0; //used to store a temporary size of the buffer

            while ( (bufferLength = inputStream.read(buffer)) > 0 )
                fileOutput.write(buffer, 0, bufferLength);
                downloadedSize += bufferLength;
                publishProgress(downloadedSize, totalSize);

            }

            fileOutput.close();

问题是，该应用程序似乎无法找到外部SD卡位置：

03-20 13:03:29.615 16992-17244/com.example.myapp W/System.err: java.io.FileNotFoundException: /storage/emulated/0/myfile.txt: open failed: EACCES (Permission denied)

我需要添加一些新的权限吗？我添加了读写外部存储权限。有什么东西我不见了吗？非常感谢任何输入！

这是我的AndroidManifest.xml：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.myapp" >

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name=".MainActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

Android应用无法将文件保存到SD卡？

0 个答案: