[安卓] 数据库的Android仲 – P5备份和导入
今天忙碌的几天对杂乱无章所以新来的一系列写在Android的数据库. 部分 5, 也是最后一部分,我会引导你如何备份和导入数据库的android.
步 1: 允许读取和写入数据,在AndroidManifest.xml中的存储卡
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 | <? xml version = "1.0" encoding = "utf-8" ?> < manifest xmlns:android = "http://schemas.android.com/apk/res/android" package = "cachhoc.net.tut.demodatabase" > <!-- set can read and write on sd card--> < uses-permission android:name = "android.permission.WRITE_EXTERNAL_STORAGE" /> < uses-permission android:name = "android.permission.READ_EXTERNAL_STORAGE" /> < application android:allowBackup = "true" android:icon = "@mipmap/ic_launcher" android:label = "@string/app_name" android:theme = "@style/AppTheme" > < activity android:name = ".MainActivity" android:label = "@string/app_name" > < intent-filter > < action android:name = "android.intent.action.MAIN" /> < category android:name = "android.intent.category.LAUNCHER" /> </ intent-filter > </ activity > < activity android:name = ".NoteActivity" android:label = "@string/title_activity_note" > </ activity > </ application > </ manifest > |
帽山一文件menu_main.xml – 文件菜单CUA MainActivity
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 | < menu xmlns:android = "http://schemas.android.com/apk/res/android" xmlns:app = "http://schemas.android.com/apk/res-auto" xmlns:tools = "http://schemas.android.com/tools" tools:context = ".MainActivity" > < item android:id = "@+id/menu_more" android:icon = "@drawable/ic_more" android:title = "Menu" app:showAsAction = "always" > < menu > < item android:id = "@+id/menu_backup" android:orderInCategory = "100" android:title = "@string/backup_data" app:showAsAction = "never" /> < item android:id = "@+id/menu_import" android:orderInCategory = "100" android:title = "@string/import_data" app:showAsAction = "never" /> </ menu > </ item > </ menu > |
你自己也如上所述 1 项目 – 此产品是一个按钮 3 点 (溢出). 当你点击按钮 3 点会出现 2 菜单备份VA进口 (看视频) 是 2 它里面的物品.
MainActivity.java文件更新赶上事件菜单:
001 002 003 004 005 006 007 008 009 010 011 012 013 014 015 016 017 018 019 020 021 022 023 024 025 026 027 028 029 030 031 032 033 034 035 036 037 038 039 040 041 042 043 044 045 046 047 048 049 050 051 052 053 054 055 056 057 058 059 060 061 062 063 064 065 066 067 068 069 070 071 072 073 074 075 076 077 078 079 080 081 082 083 084 085 086 087 088 089 090 091 092 093 094 095 096 097 098 099 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 | package cachhoc.net.tut.demodatabase; import android.content.Context; import android.content.Intent; import android.os.Bundle; import android.support.v7.app.AppCompatActivity; import android.support.v7.widget.LinearLayoutManager; import android.support.v7.widget.RecyclerView; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.widget.Toast; import java.util.ArrayList; import java.util.List; public class MainActivity extends AppCompatActivity implements View.OnClickListener, BackupData.OnBackupListener { private ItemNoteAdapter adapter; private List<Note> listNote = new ArrayList<>(); private Context context; private DatabaseHelper db; private BackupData backupData; @Override protected void onCreate(Bundle savedInstanceState) { super .onCreate(savedInstanceState); setContentView(R.layout.activity_main); context = this ; db = new DatabaseHelper(context); backupData = new BackupData(context); backupData.setOnBackupListener( this ); connectView(); } /** * connect java with xml view */ private void connectView() { // find Float Action Button findViewById(R.id.fab).setOnClickListener( this ); RecyclerView recyclerView = (RecyclerView) findViewById(R.id.rv_note); // If the size of views will not change as the data changes. recyclerView.setHasFixedSize( true ); // Setting the LayoutManager. RecyclerView.LayoutManager layoutManager = new LinearLayoutManager( this ); recyclerView.setLayoutManager(layoutManager); // Setting the adapter. adapter = new ItemNoteAdapter(context, listNote); recyclerView.setAdapter(adapter); } /** * update list note when resume (open app or finish NoteActivity) */ public void onResume() { super .onResume(); updateListNote(); } /** * select all note from database and set to ls * use for loop to add into listNote. * We must add all item in ls into listNote then adapter can update * we add reverse ls to show new note at top of list */ private void updateListNote() { // clear old list listNote.clear(); // add all notes from database, reverse list ArrayList<Note> ls = db.getListNote( "SELECT * FROM " + DatabaseHelper.TABLE_NOTE); // reverse list for ( int i = ls.size() - 1 ; i >= 0 ; i--) { listNote.add(ls.get(i)); } adapter.notifyDataSetChanged(); } /** * display note have id */ public static void showNote(Context context, long id) { Intent intent = new Intent(context, NoteActivity. class ); // send id to NoteActivity intent.putExtra(NoteActivity.ID, id); context.startActivity(intent); } @Override public void onClick(View v) { switch (v.getId()) { case R.id.fab: showNote(context, NoteActivity.NEW_NOTE); break ; default : break ; } } @Override public boolean onCreateOptionsMenu(Menu menu) { getMenuInflater().inflate(R.menu.menu_main, menu); return true ; } @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case R.id.menu_backup: backupData.exportToSD(); break ; case R.id.menu_import: backupData.importFromSD(); break ; default : break ; } return super .onOptionsItemSelected(item); } @Override public void onFinishExport(String error) { String notify = error; if (error == null ) { notify = "Export success" ; } Toast.makeText(context, notify, Toast.LENGTH_SHORT).show(); } @Override public void onFinishImport(String error) { String notify = error; if (error == null ) { notify = "Import success" ; updateListNote(); } Toast.makeText(context, notify, Toast.LENGTH_SHORT).show(); } } |
你注意到我有 实现接口BackupData.OnBackupListener 在课堂上BackupData (在以后会写) 和覆盖 2 方法 onFinishExport 和 onFinishImport 其, 2 这种方法允许我们处理通知或执行备份和导入完成后,.
当您启动事件中调用菜单 2 方法 backupData.exportToSD 和 backupData.importFromSD 执行.
步 3: 执行写类BackupData
在前面描述她的脚步. 当用户选择backupdata那么我们将数据备份到位于某个文件夹的存储卡, 在此独自它保存在文件夹 MyNote. 该程序会自动创建该文件夹,如果它不存在. 备份文件的名称将是数据库的名称以及日期时间, 小时分秒作为第一视频后.
当用户选择导入数据, 如果你想导入之前备份您的现有数据,我们会问. 如果是这样,备份,然后列出导入先前的备份文件. 否则要导入的文件只只列表.
为了避免数据丢失,并避免在新的结构有些旧数据现有数据的情况下,错误, 我们删除现有的所有数据记录,然后将备份文件复制到一个临时数据库 (临时数据库) 然后复制表中的当前数据的整个记录和临时DATABSE. 例如你当前的数据表注, 此表列LAST_MODIFIED,在老DATABSE没有, 同时,如果直接复制导致了数据库,并没有last_modified列出错的应用.
这里是代码是比较明确的解释. 你可以阅读.
001 002 003 004 005 006 007 008 009 010 011 012 013 014 015 016 017 018 019 020 021 022 023 024 025 026 027 028 029 030 031 032 033 034 035 036 037 038 039 040 041 042 043 044 045 046 047 048 049 050 051 052 053 054 055 056 057 058 059 060 061 062 063 064 065 066 067 068 069 070 071 072 073 074 075 076 077 078 079 080 081 082 083 084 085 086 087 088 089 090 091 092 093 094 095 096 097 098 099 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 | package cachhoc.net.tut.demodatabase; import android.app.ProgressDialog; import android.content.Context; import android.content.DialogInterface; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import android.os.AsyncTask; import android.os.Environment; import android.support.v4.app.FragmentActivity; import android.support.v7.app.AlertDialog; import android.view.LayoutInflater; import android.view.View; import android.widget.AdapterView; import android.widget.AdapterView.OnItemClickListener; import android.widget.ArrayAdapter; import android.widget.ListView; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.nio.channels.FileChannel; import java.text.SimpleDateFormat; import java.util.Date; public class BackupData { // url for database private final String dataPath = "//data//cachhoc.net.tut.demodatabase//databases//" ; // name of main data private final String dataName = DatabaseHelper.DATABASE_NAME; // data main private final String data = dataPath + dataName; // name of temp data private final String dataTempName = DatabaseHelper.DATABASE_NAME + "_temp" ; // temp data for copy data from sd then copy data temp into main data private final String dataTemp = dataPath + dataTempName; // folder on sd to backup data private final String folderSD = Environment.getExternalStorageDirectory() + "/MyNote" ; private Context context; public BackupData(Context context) { this .context = context; } // create folder if it not exist private void createFolder() { File sd = new File(folderSD); if (!sd.exists()) { sd.mkdir(); System.out.println( "create folder" ); } else { System.out.println( "exits" ); } } /** * Copy database to sd card * name of file = database name + time when copy * When finish, we call onFinishExport method to send notify for activity */ public void exportToSD() { String error = null ; try { createFolder(); File sd = new File(folderSD); if (sd.canWrite()) { SimpleDateFormat formatTime = new SimpleDateFormat( "yyyy_MM_dd__HH_mm_ss" ); String backupDBPath = dataName + "_" + formatTime.format( new Date()); File currentDB = new File(Environment.getDataDirectory(), data); File backupDB = new File(sd, backupDBPath); if (currentDB.exists()) { FileChannel src = new FileInputStream(currentDB).getChannel(); FileChannel dst = new FileOutputStream(backupDB).getChannel(); dst.transferFrom(src, 0 , src.size()); src.close(); dst.close(); } else { System.out.println( "db not exist" ); } } } catch (Exception e) { e.printStackTrace(); error = "Error backup" ; } onBackupListener.onFinishExport(error); } /** * import data from file backup on sd card * we must create a temp database for copy file on sd card to it. * Then we copy all row of temp database into main database. * It will keep struct of curren database not change when struct backup database is old * * @param fileNameOnSD name of file database backup on sd card */ public void importData(String fileNameOnSD) { File sd = new File(folderSD); // create temp database SQLiteDatabase dbBackup = context.openOrCreateDatabase(dataTempName, SQLiteDatabase.CREATE_IF_NECESSARY, null ); String error = null ; if (sd.canWrite()) { File currentDB = new File(Environment.getDataDirectory(), dataTemp); File backupDB = new File(sd, fileNameOnSD); if (currentDB.exists()) { FileChannel src; try { src = new FileInputStream(backupDB).getChannel(); FileChannel dst = new FileOutputStream(currentDB) .getChannel(); dst.transferFrom(src, 0 , src.size()); src.close(); dst.close(); } catch (FileNotFoundException e) { e.printStackTrace(); error = "Error load file" ; } catch (IOException e) { error = "Error import" ; } } } /** *when copy old database into temp database success * we copy all row of table into main database */ if (error == null ) { new CopyDataAsyncTask(dbBackup).execute(); } else { onBackupListener.onFinishImport(error); } } /** * show dialog for select backup database before import database * if user select yes, we will export curren database * then show dialog to select old database to import * else we onoly show dialog to select old database to import */ public void importFromSD() { final AlertDialog.Builder builder = new AlertDialog.Builder(context, R.style.AppCompatAlertDialogStyle); builder.setTitle(R.string.backup_data).setIcon(R.mipmap.ic_launcher) .setMessage(R.string.backup_before_import); builder.setPositiveButton(R.string.no, new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { showDialogListFile(folderSD); } }); builder.setNegativeButton(R.string.yes, new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { showDialogListFile(folderSD); exportToSD(); } }); builder.show(); } /** * show dialog list all backup file on sd card * @param forderPath folder conatain backup file */ private void showDialogListFile(String forderPath) { createFolder(); File forder = new File(forderPath); File[] listFile = forder.listFiles(); final String[] listFileName = new String[listFile.length]; for ( int i = 0 , j = listFile.length - 1 ; i < listFile.length; i++, j--) { listFileName[j] = listFile[i].getName(); } if (listFileName.length > 0 ) { // get layout for list LayoutInflater inflater = ((FragmentActivity) context).getLayoutInflater(); View convertView = (View) inflater.inflate(R.layout.list_backup_file, null ); final AlertDialog.Builder builder = new AlertDialog.Builder(context, R.style.AppCompatAlertDialogStyle); // set view for dialog builder.setView(convertView); builder.setTitle(R.string.select_file).setIcon(R.mipmap.ic_launcher); final AlertDialog alert = builder.create(); ListView lv = (ListView) convertView.findViewById(R.id.lv_backup); ArrayAdapter<String> adapter = new ArrayAdapter<String>(context, android.R.layout.simple_list_item_1, listFileName); lv.setAdapter(adapter); lv.setOnItemClickListener( new OnItemClickListener() { @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { alert.dismiss(); importData(listFileName[position]); } }); alert.show(); } else { final AlertDialog.Builder builder = new AlertDialog.Builder(context, R.style.AppCompatAlertDialogStyle); builder.setTitle(R.string.delete).setIcon(R.mipmap.ic_launcher) .setMessage(R.string.backup_empty); builder.show(); } } /** * AsyncTask for copy data */ class CopyDataAsyncTask extends AsyncTask<Void, Void, Void> { ProgressDialog progress = new ProgressDialog(context); SQLiteDatabase db; public CopyDataAsyncTask(SQLiteDatabase dbBackup) { this .db = dbBackup; } /** * will call first */ @Override protected void onPreExecute() { // TODO Auto-generated method stub super .onPreExecute(); progress.setMessage( "Importing..." ); progress.show(); } @Override protected Void doInBackground(Void... params) { copyData(db); return null ; } /** * end process */ @Override protected void onPostExecute(Void error) { // TODO Auto-generated method stub super .onPostExecute(error); if (progress.isShowing()) { progress.dismiss(); } onBackupListener.onFinishImport( null ); } } /** * copy all row of temp database into main database * @param dbBackup */ private void copyData(SQLiteDatabase dbBackup) { DatabaseHelper db = new DatabaseHelper(context); db.deleteNote( null ); /** copy all row of subject table */ Cursor cursor = dbBackup.query( true , DatabaseHelper.TABLE_NOTE, null , null , null , null , null , null , null ); cursor.moveToFirst(); while (!cursor.isAfterLast()) { Note note = db.cursorToNote(cursor); db.insertNote(note); cursor.moveToNext(); } cursor.close(); context.deleteDatabase(dataTempName); } private OnBackupListener onBackupListener; public void setOnBackupListener(OnBackupListener onBackupListener) { this .onBackupListener = onBackupListener; } public interface OnBackupListener { public void onFinishExport(String error); public void onFinishImport(String error); } } |
你需要注意 2 以下:
- 其用于导入数据库AsyncTask的,因为这个过程可能需要很长的时间. 这将有助于展示 1 仿佛没有用户放心的认为具有冷冻应用被处理对话框以指示用户.
-
在副本, 我所说的命令 注意注意= db.cursorToNote(光标); 以前cursorToNote秩序类和私营DatabaseHelper, 你现在要叫 修复公众 NHE.
该界面导入的文件列表
01 02 03 04 05 06 07 08 09 10 11 12 13 | <? xml version = "1.0" encoding = "utf-8" ?> < LinearLayout xmlns:android = "http://schemas.android.com/apk/res/android" android:layout_width = "match_parent" android:layout_height = "match_parent" android:orientation = "vertical" > < ListView android:id = "@+id/lv_backup" android:layout_width = "match_parent" android:layout_height = "match_parent" > </ ListView > </ LinearLayout > |
在文件string.xml一些变化
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 | < resources > < string name = "app_name" >My Note</ string > < string name = "hello_world" >Hello world!</ string > < string name = "action_settings" >Settings</ string > < string name = "add" >Add</ string > < string name = "delete" >Delete</ string > < string name = "save" >Save</ string > < string name = "yes" >Yes</ string > < string name = "no" >No</ string > < string name = "backup_data" >Backup data</ string > < string name = "import_data" >Import data</ string > < string name = "backup_before_import" >Do you want backup curren database before import an old databas?</ string > < string name = "select_file" >Select file</ string > < string name = "backup_empty" >Backup file is empty</ string > <!-- --> < string name = "title_note" >Title note</ string > < string name = "content" >Content</ string > < string name = "title_activity_note" >Create Note</ string > </ resources > |
您可以 在这里下载源代码.
这就是它,然后. 祝你学习好.
在本教程的帖子 数据库的Android仲 由 nguyenvanquan7826
欢迎您,陆军,
首先,我们发现了一系列的Android你的数据库是非常有用的.
我又试了一次,你的指导下,代码共享的东西 5 备份和导入. 但我不备份和导入失败不, 我检查了代码几次也没有找到其中的错误.
他们在Eclipse代码, 这是你的源代码. 我希望你帮她修复错误. 如果导入库项目,然后重新启动该项目再次失败,直到错误信息是构建是.
http://www.mediafire.com/download/jq14bp7dw4poe0a/SQLite_Demo.rar
军事谢谢!
这种新的考验对不起太忙几天来帮助你.
满足你 2 错误:
– 写入字符串表创建错误:
public
static
final
String CREATE_TABLE_NOTE =
"CREATE TABLE "
+ TABLE_NOTE
+
"("
+ KEY_ID_NOTE
+
" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL "
+
","
+ KEY_TITLE_NOTE +
" TEXT NOT NULL"
+
","
+ KEY_CONTENT_NOTE
+
" TEXT NOT NULL"
+
","
+ KEY_LAST_MODIFIED_NOTE
+
" TEXT DEFAULT \'\'"
+
")"
;
当您添加KEY_LAST_MODIFIED_NOTE你没有在文本默认的空间,以便在新的安装将不再作记录.
– 错误备份,因为你错了行:
Cursor cursor = dbBackup.query(
true
, DatabaseHelper.DATABASE_NAME,
null
,
null
,
null
,
null
,
null
,
null
,
null
);
您必须复制从表中TABLE_NOTE不会从数据库中拷贝.
修复:
Cursor cursor = dbBackup.query(
true
, DatabaseHelper.TABLE_NOTE,
null
,
null
,
null
,
null
,
null
,
null
,
null
);
有错误我backupdata.java
在这条线
SQLiteDatabase DBBACKUP = context.openOrCreateDatabase(dataTempName,
SQLiteDatabase.CREATE_IF_NECESSARY, 空值);
什么是错误? 你可以在这里发布错误或拍照?
你好,
请您可以更新到的gradle Android版本 3. 我有在新版本上运行旧的程序太多的问题. 我是一个初学者,所以我不知道该怎么办的变化. 我在网上什么都试过了, 没有任何帮助.
感谢报告. 该项目在我的教程使用旧版本与您. 你能告诉我你的问题?
你可以做一个例子备份和使用客房持久库恢复? 我有难以适应这一功能使用客房持久库
私人无效了CopyData(SQLiteDatabase DBBACKUP) {
DatabaseHelper DB =新DatabaseHelper(背景);
db.deleteNote(空值);
/** 复制主题表的所有行 */
光标光标= dbBackup.query(真正, DatabaseHelper.TABLE_NOTE, 空值, 空值, 空值, 空值, 空值, 空值, 空值);
cursor.moveToFirst();
而 (!cursor.isAfterLast()) {
注意注意= db.cursorToNote(光标);
db.insertNote(注意);
cursor.moveToNext();
}
cursor.close();
context.deleteDatabase(dataTempName);
}
你好, 对不起它, 我不使用这个库, 所以我不知道,使它.
你好,
我正在使用您的代码创建备份. 从getExternalStorageDirectory开始() 已不推荐使用. 下面怎么写 .
私有的最终String文件夹SD = Environment.getExternalStorageDirectory() + “/MyNote”;
谢谢,
你好, 你可以在这里看到: https://stackoverflow.com/questions/57116335/environment-getexternalstoragedirectory-deprecated-in-api-level-29-java