Android Multi-threaded Operation SQLite (SQLite solves database locked problem)

Reference http://blog.csdn.net/sdsxleon/article/details/18259973 very good

https://github.com/2point0/Android-Database-Locking-Collisions-Example Example

http://www.eoeandroid.com/forum.php?mod=viewthread&tid=333473

Http://bbs.51cto.com/thread-990260-1.html

With transactions, the speed will be very

Scenario 1:

SQLiteis essentially writing the data to a file, typically found under the app's package namexxx.dbthe file that hasRootpermission of the phone, which can be passedadb Shell, seedata/data/PackageName/databases/xxx.dbsuch a file.

we can learnSQLiteis a file-level lock: Multiple threads can read at the same time, but only one thread is written at a time. Androidprovides aSqliteopenhelperclass, addingJavalock mechanism in order to invoke.

if multithreading is read and written at the same time (this refers to different threads using differentHelperinstance), you will encounter the followingAndroid.database.sqlite.SQLiteException:database is lockedsuch an exception.
for such a problem, the solution isKeep single SQLite connection,Keep a singleSqliteopenhelperinstance, while adding a method to all database operationssynchronizedkey word.

Perfect solution to SQLite database locked or error 5:database locked problem

/** * @FileName: Databasehelper.java * @ProjectName: Sqlitepractice * @PakageName: Com.sqlitepractice.database * @Autho R:brant * @CreateDate: 2012-12-16 */package com.sqlitepractice.database;import Android.content.contentvalues;import Android.content.context;import Android.database.cursor;import Android.database.sqlite.sqlitedatabase;import Android.database.sqlite.sqliteopenhelper;import Android.provider.basecolumns;import android.util.Log;/** * @Module : Name of the Membership module * @Comments: Description * @Author: Brant * @CreateDate: 2012-12-16 * @ModifiedBy: Brant * @ModifiedDate: 2012-12-16 * @Modified: * 2012-12-16: Implement basic functions */public class Databasehelper extends Sqliteopenhelper {public static final String TAG = " Databasehelper ";p rivate static final String db_name =" Practice.db ";p rivate final static string Db_table_app =" APP ";p Riva Te static final int db_version = 1;private static final String Db_create_table_app = "CREATE TABLE" + Db_table_app + "(" + app_columns._id + "INTEGER PRIMARY KEY AutoinCrement, "+ app_columns. Package_name+ "NTEXT not NULL," + app_columns. App_name + "NTEXT not NULL," + app_columns. App_name_pinyin + "NTEXT," + app_columns. Class_name + "NTEXT not NULL);"; private static Databasehelper minstance;protected Databasehelper (context context) {Super (context, db_name, NULL, db_ VERSION);} Public synchronized static Databasehelper getinstance (context context) {if (minstance = = null) {minstance = new Databasehe Lper (context);} return minstance;} Public synchronized static void Destoryinstance () {if (minstance! = null) {Minstance.close ();}} @Overridepublic void OnCreate (Sqlitedatabase db) {db.execsql (Db_create_table_app);} @Overridepublic void Onupgrade (sqlitedatabase db, int oldversion, int newversion) {//TODO auto-generated method Stub}publ IC synchronized int getcount () {LOG.D (TAG, "GetCount"); int count =-1; Cursor C = getreadabledatabase (). query (Db_table_app, NULL, NULL, NULL, NULL, NULL, NULL), if (C.movetofirst ()) {count = C.G Etcount ();} C.close (); c = Null;return COunt;} Public synchronized void Insert (String packagename, String applabel, string pinyin, String className) {log.d (TAG, "Insert" ); Contentvalues values = new Contentvalues (4); Values.put (App_columns. Package_name, PackageName); Values.put (App_columns. App_name, Applabel); Values.put (App_columns. App_name_pinyin, PINYIN); Values.put (App_columns. Class_name, ClassName); Getwritabledatabase (). Insert (Db_table_app, NULL, values);} public static class App_columns implements Basecolumns {public static final String package_name = "Package_name";p Ublic St  Atic final String app_name = "App_name";p ublic static final String app_name_pinyin = "App_name_pinyin";p ublic static final String class_name = "class_name";p ublic static final int id_index = 0;public static final int package_name_index = 1;publ IC static final int app_name_index = 2;public static final int app_name_pinyin_index = 3;public static final int Class_nam E_index = 4;}}

　　

Package Com.sqlitepractice;import Java.util.arraylist;import Java.util.list;import android.app.activity;import Android.os.bundle;import Android.util.log;import Android.view.menu;import Com.sqlitepractice.database.databasehelper;public class Mainactivity extends Activity {private static final String TAG = "Mainactivity";p rivate static int sthreadcounter = 0; @Overridepublic void onCreate (Bundle savedinstancestate) { Super.oncreate (savedinstancestate); Setcontentview (r.layout.activity_main); final int threadcount = 8;final List< thread> allthreads = new Arraylist<thread> (threadcount);D atabasehelper helper = databasehelper.getinstance ( This): for (int i = 0; i < ThreadCount; i++) {Allthreads.add (New Dbinsertthread (Helper, sthreadcounter++));} for (int i = 0; i < ThreadCount; i++) {Allthreads.add (New Fastselectthread (helper, sthreadcounter++, 50));} for (Thread thread:allthreads) {Thread.Start ();} Wait for all threads to complete before runningfor (Thread Thread:allthreaDS) {try {thread.join (); LOG.I (Thread.getname (), "collected");} catch (Interruptedexception e) {log.e (TAG, "interrupted", e);}} LOG.I (TAG, "All Threads finished!");} @Overridepublic boolean Oncreateoptionsmenu (Menu menu) {getmenuinflater (). Inflate (R.menu.activity_main, menu); return true;} Class Dbinsertthread extends Thread {private final String TAG = DbInsertThread.class.getSimpleName ();p rivate final Databa Sehelper mdbhelper;private int Mruncount;dbinsertthread (databasehelper helper, int runcount, int id) {SetName ( String.Format ("%1$s-%2$d", TAG, id)); mdbhelper = Helper;mruncount = Runcount; LOG.I (GetName (), helper.tostring ());} @Overridepublic void Run () {for (int i = 0; i < Mruncount; i++) {try {Mdbhelper.insert ("com.xx.xxxx", "Test", "Ceshi", "M Ainactivity ");} catch (Exception e) {log.e (GetName (), "Insert failed!!!, stopping writes", e); break;}} LOG.I (GetName (), "finished!");}} Class Fastselectthread extends Thread {private final String TAG = FastSelectThread.class.getSimpleName ();p rivateFinal databasehelper mhelper;private final int mCount; Fastselectthread (databasehelper helper, int id, int selectcount) {setName (String.Format ("%1$s-%2$d", TAG, id)); mhelper = Helper;mcount = selectcount > 0? selectcount:50; LOG.I (GetName (), helper.tostring ());} @Overridepublic void Run () {int count = 0;while (Count < MCount) {mhelper.getcount (); LOG.I (GetName (), "Start Wait"), try {thread.sleep ($);} catch (Interruptedexception e) {e.printstacktrace ();} LOG.I (GetName (), "End Wait"); count++;} LOG.I (GetName (), "finished!");}}}

　　

Android Multi-threaded Operation SQLite (SQLite solves database locked problem)