一、判斷SD卡使用情況
if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED))
{
Toast.makeText(MainActivity.this,"SD卡準備就緒!",Toast.LENGTH_SHORT).show();
}
else
{
Toast.makeText(MainActivity.this,"SD卡不存在或者未掛載!",Toast.LENGTH_SHORT).show();
}
二、獲取SD卡的儲存情況
File ext=Environment.getExternalStorageDirectory();
long usableSpace=ext.getUsableSpace();
long totalSpace=ext.getTotalSpace();
String usableSize= Formatter.formatFileSize(MainActivity.this,usableSpace);
String totalSize=Formatter.formatFileSize(MainActivity.this,totalSpace);
Toast.makeText(MainActivity.this,"usableSize:"+usableSize+"--"+totalSize,Toast.LENGTH_SHORT).show();
三、權限問題
//在AndroidManifest中添加SD卡讀寫的權限
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
//從Android6.0開始需要動態授權
Manifest.permission.READ_EXTERNAL_STORAGE
Manifest.permission.WRITE_EXTERNAL_STORAGE
四、權限申請
//動態申請權限方法
private static final int REQUEST_EXTERNAL_STORAGE = 1;
private static String[] PERMISSIONS_STORAGE = {
"android.permission.READ_EXTERNAL_STORAGE",
"android.permission.WRITE_EXTERNAL_STORAGE" };
public static void verifyStoragePermissions(Activity activity) {
try {
//檢測是否有寫的權限
int permission = ActivityCompat.checkSelfPermission(activity,
"android.permission.WRITE_EXTERNAL_STORAGE");
if (permission != PackageManager.PERMISSION_GRANTED) {
// 沒有寫的權限,去申請寫的權限,會彈出對話框
ActivityCompat.requestPermissions(activity, PERMISSIONS_STORAGE,REQUEST_EXTERNAL_STORAGE);
}
} catch (Exception e) {
e.printStackTrace();
}
}
五、寫入數據
File f2=new File(ext,"test.data");
try {
verifyStoragePermissions(MainActivity.this);
OutputStream out=new FileOutputStream(f2);
out.write("test".getBytes());
out.close();
} catch (Exception e) {
e.printStackTrace();
}
六、讀取數據
try {
InputStream in=new FileInputStream(f2);
byte[] buffer=new byte[64];
int len=in.read(buffer);
String str=new String(buffer,0,len);
} catch (Exception e) {
e.printStackTrace();
}