如何在Android中写入SD卡上的文件夹？
如何在Android中写入SD卡上的文件夹？
提问于 2010-08-24 05:24:43
我使用以下代码从我的服务器下载一个文件，然后将其写入SD卡的根目录，一切正常：
package com.downloader;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import android.os.Environment;
import android.util.Log;
public class Downloader {
public void DownloadFile(String fileURL, String fileName) {
try {
File root = Environment.getExternalStorageDirectory();
URL u = new URL(fileURL);
HttpURLConnection c = (HttpURLConnection) u.openConnection();
c.setRequestMethod("GET");
c.setDoOutput(true);
c.connect();
FileOutputStream f = new FileOutputStream(new File(root, fileName));
InputStream in = c.getInputStream();
byte[] buffer = new byte[1024];
int len1 = 0;
while ((len1 = in.read(buffer)) > 0) {
f.write(buffer, 0, len1);
}
f.close();
} catch (Exception e) {
Log.d("Downloader", e.getMessage());
}
}
}但是，使用Environment.getExternalStorageDirectory();意味着文件将始终写入根/mnt/sdcard。是否可以指定要将文件写入的某个文件夹？
例如：/mnt/sdcard/myapp/downloads
回答 3
Stack Overflow用户
回答已采纳
发布于 2010-08-24 05:36:24
File sdCard = Environment.getExternalStorageDirectory();
File dir = new File (sdCard.getAbsolutePath() + "/dir1/dir2");
dir.mkdirs();
File file = new File(dir, "filename");
FileOutputStream f = new FileOutputStream(file);
...Stack Overflow用户
发布于 2013-11-21 01:18:42
向Android Manifest添加权限
将this WRITE_EXTERNAL_STORAGE permission添加到应用程序清单中。
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="your.company.package"
android:versionCode="1"
android:versionName="0.1">
<application android:icon="@drawable/icon" android:label="@string/app_name">
<!-- ... -->
</application>
<uses-sdk android:minSdkVersion="7" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
</manifest> 检查外部存储的可用性
您应该始终首先检查可用性。来自the official android documentation on external storage的代码片段。
boolean mExternalStorageAvailable = false;
boolean mExternalStorageWriteable = false;
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state)) {
// We can read and write the media
mExternalStorageAvailable = mExternalStorageWriteable = true;
} else if (Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) {
// We can only read the media
mExternalStorageAvailable = true;
mExternalStorageWriteable = false;
} else {
// Something else is wrong. It may be one of many other states, but all we need
// to know is we can neither read nor write
mExternalStorageAvailable = mExternalStorageWriteable = false;
}使用文件写入器
最后，同样重要的是，忘记FileOutputStream，改用FileWriter。有关该类的更多信息，请参见the FileWriter javadoc。您可能希望在此处添加更多错误处理，以通知用户。
// get external storage file reference
FileWriter writer = new FileWriter(getExternalStorageDirectory());
// Writes the content to the file
writer.write("This\n is\n an\n example\n");
writer.flush();
writer.close();Stack Overflow用户
发布于 2014-01-30 16:05:31
在这里找到了答案- http://mytechead.wordpress.com/2014/01/30/android-create-a-file-and-write-to-external-storage/
上面写着，
/**
* Method to check if user has permissions to write on external storage or not
*/
public static boolean canWriteOnExternalStorage() {
// get the state of your external storage
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state)) {
// if storage is mounted return true
Log.v("sTag", "Yes, can write to external storage.");
return true;
}
return false;
}然后让我们使用这段代码来实际写入外部存储：
// get the path to sdcard
File sdcard = Environment.getExternalStorageDirectory();
// to this path add a new directory path
File dir = new File(sdcard.getAbsolutePath() + "/your-dir-name/");
// create this directory if not already created
dir.mkdir();
// create the file in which we will write the contents
File file = new File(dir, "My-File-Name.txt");
FileOutputStream os = outStream = new FileOutputStream(file);
String data = "This is the content of my file";
os.write(data.getBytes());
os.close();这就是了。如果您现在访问/sdcard/ your -dir-name/文件夹，您将看到一个名为- My- file -Name.txt的文件，其中包含代码中指定的内容。
PS:-您需要以下权限-
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/3551821
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