问题
I am working on an android game. I want to copy a text file to external SD card when the user installs the game for the first time. The text file is important for properly running the game.
How can I do that? Where should i place the text file in eclipse source project so that when i build the apk file, my text file also gets bundled in it and when a use installs application from that apk file the text file gets copied to "SDcard\data" folder.?
What code should i write and where, so that it gets executed only once at installation time.
Thanks in advance
回答1:
This is the methods I use to copy a file to the sd card when the app is first installed:
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, MainActivity.class);
startActivity(home);
} else { // Otherwise start the application here:
Intent home = new Intent(StartUp.this, MainActivity.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/txt/");
// 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);
}
}
回答2:
For this target the best way is make SharedPreferences or your file must be added in "assets" directory in android project.
回答3:
as per link
There is the ACTION_PACKAGE_ADDED Broadcast Intent, but the application being installed doesn't receive this.
So it looks using SharedPreferences is the easiest way...
SharedPreferences p = PreferenceManager.getDefaultSharedPreferences(this);
boolean firstRun = p.getBoolean(PREFERENCE_FIRST_RUN, true);
p.edit().putBoolean(PREFERENCE_FIRST_RUN, false).commit();
回答4:
Put the file in the assets folder. Then, using whatever logic you come up with, when your app launches determine if it is the first run of the app.
If it is you can use getAssets() from an Activity to access the asset file and just copy it to wherever necessary.
回答5:
Since the file on the sdcard is something that could be accidentally deleted by the user, you should probably check directly for its presence (and possibly verify contents) rather than trying to use something independent such as a shared preference to tell if this is the first run of the activity.
For purposes of potential app upgrades, you should probably put a version number in the file, and check that.
If the file is something you want to let power users manually edit (to change expert options) then you may have a little bit of a challenging situation to handle on upgrade.
来源：https://stackoverflow.com/questions/11121795/copy-a-text-file-on-sd-card-at-the-time-of-application-installation