如何将文件(SQLlite、Text 等)从 Assets 文件夹加载到 SD 卡上，并且仅在应用程序首次运行时加载？
最佳答案
这是我使用的方法。将其作为您应用程序的主要 Activity ，并使用它来启动您真正的应用程序 Activity 。
public class StartUp extends Activity {
/**
* -- Called when the activity is first created.
* ==============================================================
**/
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
FirstRun();
}
private void FirstRun() {
SharedPreferences settings = this.getSharedPreferences("YourAppName", 0);
boolean firstrun = settings.getBoolean("firstrun", true);
if (firstrun) { // Checks to see if we've ran the application b4
SharedPreferences.Editor e = settings.edit();
e.putBoolean("firstrun", false);
e.commit();
// If not, run these methods:
SetDirectory();
Intent home = new Intent(StartUp.this, YourMainActivity.class);
startActivity(home);
} else { // Otherwise start the application here:
Intent home = new Intent(StartUp.this, YourMainActivity.class);
startActivity(home);
}
}
/**
* -- Check to see if the sdCard is mounted and create a directory w/in it
* ========================================================================
**/
private void SetDirectory() {
if (android.os.Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED)) {
extStorageDirectory = Environment.getExternalStorageDirectory().toString();
File txtDirectory = new File(extStorageDirectory + "/yourAppName/txtDirectory/");//Example name for txt files
// Create
// a
// File
// object
// for
// the
// parent
// directory
txtDirectory.mkdirs();// Have the object build the directory
// structure, if needed.
CopyAssets(); // Then run the method to copy the file.
} else if (android.os.Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED_READ_ONLY)) {
AlertsAndDialogs.sdCardMissing(this);//Or use your own method ie: Toast
}
}
/**
* -- Copy the file from the assets folder to the sdCard
* ===========================================================
**/
private void CopyAssets() {
AssetManager assetManager = getAssets();
String[] files = null;
try {
files = assetManager.list("");
} catch (IOException e) {
Log.e("tag", e.getMessage());
}
for (int i = 0; i < files.length; i++) {
InputStream in = null;
OutputStream out = null;
try {
in = assetManager.open(files[i]);
out = new FileOutputStream(extStorageDirectory + "/yourAppName/txt/" + files[i]);
copyFile(in, out);
in.close();
in = null;
out.flush();
out.close();
out = null;
} catch (Exception e) {
Log.e("tag", e.getMessage());
}
}
}
private void copyFile(InputStream in, OutputStream out) throws IOException {
byte[] buffer = new byte[1024];
int read;
while ((read = in.read(buffer)) != -1) {
out.write(buffer, 0, read);
}
}
关于Android:如何在首次运行时将文件从 Assets 加载到 SD？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/11128260/