[英]How can I backup SharedPreferences to SD card?
I saw in a lot of places that it's a problem to copy the SharedPreferences file to the sd card because every manufacturer place it somewhere else. 我在很多地方看到将SharedPreferences文件复制到SD卡是一个问题,因为每个制造商都将它放在其他地方。
I want to backup on the sd card no matter where is the file located. 无论文件位于何处,我都想在SD卡上备份。 Is there any way to do this?
有没有办法做到这一点?
The SharedPreferences
interface contains a method called getAll()
which returns a map with the key-value pairs. SharedPreferences
接口包含一个名为getAll()
的方法,该方法返回带有键值对的映射。 So instead of copying the file itself, I just serialize the map that being returned from this method and then retrieve it back afterwards. 因此,我只是序列化从此方法返回的映射,而不是复制文件本身,然后将其检索回来。
Some code: 一些代码:
private boolean saveSharedPreferencesToFile(File dst) {
boolean res = false;
ObjectOutputStream output = null;
try {
output = new ObjectOutputStream(new FileOutputStream(dst));
SharedPreferences pref =
getSharedPreferences(prefName, MODE_PRIVATE);
output.writeObject(pref.getAll());
res = true;
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}finally {
try {
if (output != null) {
output.flush();
output.close();
}
} catch (IOException ex) {
ex.printStackTrace();
}
}
return res;
}
@SuppressWarnings({ "unchecked" })
private boolean loadSharedPreferencesFromFile(File src) {
boolean res = false;
ObjectInputStream input = null;
try {
input = new ObjectInputStream(new FileInputStream(src));
Editor prefEdit = getSharedPreferences(prefName, MODE_PRIVATE).edit();
prefEdit.clear();
Map<String, ?> entries = (Map<String, ?>) input.readObject();
for (Entry<String, ?> entry : entries.entrySet()) {
Object v = entry.getValue();
String key = entry.getKey();
if (v instanceof Boolean)
prefEdit.putBoolean(key, ((Boolean) v).booleanValue());
else if (v instanceof Float)
prefEdit.putFloat(key, ((Float) v).floatValue());
else if (v instanceof Integer)
prefEdit.putInt(key, ((Integer) v).intValue());
else if (v instanceof Long)
prefEdit.putLong(key, ((Long) v).longValue());
else if (v instanceof String)
prefEdit.putString(key, ((String) v));
}
prefEdit.commit();
res = true;
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}finally {
try {
if (input != null) {
input.close();
}
} catch (IOException ex) {
ex.printStackTrace();
}
}
return res;
}
I hope that I helped someone, and if something here is wrong please tell me. 我希望我能帮助别人,如果有什么不对的地方请告诉我。
Elad 埃拉德
File ff = new File("/data/data/"
+ MainActivity.this.getPackageName()
+ "/shared_prefs/pref file name.xml");
Log.i("ddddddddddddd", ff.getPath() + "");
copyFile(ff.getPath().toString(), sdcard path/save file name.xml");
private void copyFile(String filepath, String storefilepath) {
try {
File f1 = new File(filepath);
File f2 = new File(storefilepath);
InputStream in = new FileInputStream(f1);
OutputStream out = new FileOutputStream(f2);
byte[] buf = new byte[1024];
int len;
while ((len = in.read(buf)) > 0) {
out.write(buf, 0, len);
}
in.close();
out.close();
System.out.println("File copied.");
} catch (FileNotFoundException ex) {
System.out.println(ex.getMessage());
} catch (IOException e) {
System.out.println(e.getMessage());
}
}
An alternative to using ObjectOutputStream/ObjectInputStream is to add the XmlUtils.java and FastXmlSerializer.java files from the Android source to your project, and then use XmlUtils.writeMapXml() and XmlUtils.readMapXml(): 使用ObjectOutputStream / ObjectInputStream的另一种方法是将Android源中的XmlUtils.java和FastXmlSerializer.java文件添加到项目中,然后使用XmlUtils.writeMapXml()和XmlUtils.readMapXml():
boolean res = false;
FileOutputStream output = null;
try {
output = new FileOutputStream(dst);
SharedPreferences pref =
getSharedPreferences(prefName, MODE_PRIVATE);
XmlUtils.writeMapXml(pref.getAll(), output);
res = true;
}
..... .....
FileInputStream input = null;
try {
input = new FileInputStream(src);
Editor prefEdit = getSharedPreferences(prefName, MODE_PRIVATE).edit();
prefEdit.clear();
Map<String, ?> entries = XmlUtils.readMapXml(input);
for (Entry<String, ?> entry : entries.entrySet()) {
putObject(prefEdit, entry.getKey(), entry.getValue());
}
}
..... .....
static SharedPreferences.Editor putObject(final SharedPreferences.Editor edit,
final String key, final Object val) {
if (val instanceof Boolean)
return edit.putBoolean(key, ((Boolean)val).booleanValue());
else if (val instanceof Float)
return edit.putFloat(key, ((Float)val).floatValue());
else if (val instanceof Integer)
return edit.putInt(key, ((Integer)val).intValue());
else if (val instanceof Long)
return edit.putLong(key, ((Long)val).longValue());
else if (val instanceof String)
return edit.putString(key, ((String)val));
return edit;
}
The storage format will then be the same XML as is used to store the SharedPreferences. 然后,存储格式将与用于存储SharedPreferences的XML相同。
try {
input = new FileInputStream(src1);
SharedPreferences.Editor prefEdit = getSharedPreferences("prueba100", MODE_PRIVATE).edit();
prefEdit.clear();
Map<String, ?> entries = XmlUtils.readMapXml(input);
for (Map.Entry<String, ?> entry : entries.entrySet()) {
putObject(prefEdit, entry.getKey(), entry.getValue());
}
prefEdit.apply();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (XmlPullParserException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
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