sqllite事务和MySQL事务_Android学习---SQLite数据库的增删改查和事务(transaction)调用...
上一篇文章中介紹了手工拼寫sql語句進行數據庫的CRUD操作,本文將介紹調用sqlite內置的方法實現CRUD操作,其實質也是通過拼寫sql語句.
首先,創建一個新的android項目:
其次,查看代碼實現增刪查改:
1.創建DB工具類
MyDBHelper.java(創建數據庫的操作)
packagecom.amos.android_db;importandroid.content.Context;importandroid.database.sqlite.SQLiteDatabase;importandroid.database.sqlite.SQLiteOpenHelper;/*** Created by amosli on 14-6-12.*/
public class MyDBHelper extendsSQLiteOpenHelper{/***
*@paramcontext*/
publicMyDBHelper(Context context) {super(context, "sqlitedb", null, 1);
}/*** 數據庫第一次創建的時候調用此方法
*@paramdb*/@Overridepublic voidonCreate(SQLiteDatabase db) {
db.execSQL("create table if not exists person (personid integer primary key autoincrement ,name varchar(30) ,age integer(3) )");
}
@Overridepublic void onUpgrade(SQLiteDatabase db, int oldVersion, intnewVersion) {
}
}
2.配置測試環境
AndroidManifest.xml
3.PersonDao.java(實現增刪查改的方法)
packagecom.amos.android_db.dao;importandroid.content.ContentValues;importandroid.content.Context;importandroid.database.Cursor;importandroid.database.sqlite.SQLiteDatabase;importandroid.util.Log;importcom.amos.android_db.MyDBHelper;importjava.util.ArrayList;importjava.util.List;/*** Created by amosli on 14-6-12.*/
public classPersonDao {privateContext context;
MyDBHelper dbHelper;publicPersonDao(Context context) {this.context =context;
dbHelper= newMyDBHelper(context);
}/*** 添加一條記錄*/
public void add(String name, intage) {
SQLiteDatabase db=dbHelper.getWritableDatabase();if(db.isOpen()) {
ContentValues values= newContentValues();
values.put("age", age);
values.put("name", name);//不允許插入一個空值,如果contentvalue,一般第二個參
db.insert("person", null, values);//通過組拼完成的添加的操作
}
db.close();
}
}
１)測試add方法:
packagecom.amos.android_db.test;importandroid.test.AndroidTestCase;importcom.amos.android_db.dao.PersonDao;/*** Created by amosli on 14-6-13.*/
public class TestPersonDao extendsAndroidTestCase{public void testAdd() throwsException{
PersonDao personDao= new PersonDao(this.getContext());
personDao.add("amosli",10);
personDao.add("amosli",10);for(int i=0;i<10;i++){
personDao.add("amos"+i,10+i);
}
}
}
查看結果:
打開新創建的數據庫sqlitedb
./adb shell
#cd/data/data/com.amos.android_db/databases
#lssqlitedb
# sqlite3 sqlitedb
SQLite version3.6.22Enter".help" forinstructions
Enter SQL statements terminated with a";"sqlite>.databaseseq name file
--- --------------- ----------------------------------------------------------
0 main /data/data/com.amos.android_db/databases/sqlitedb
sqlite>.table
android_metadata person
查看寫入的值:
sqlite> select *from person;1|amosli|10
2|amosli|10
3|amos0|10
4|amos1|11
5|amos2|12
6|amos3|13
7|amos4|14
8|amos5|15
9|amos6|16
10|amos7|17
11|amos8|18
12|amos9|19
２)刪除數據
delete方法,主要是調用了SQLiteDatabase的delete方法.其實質上也是在拼sql語句.
public voiddelete(String name) {
SQLiteDatabase db=dbHelper.getWritableDatabase();if(db.isOpen()) {
db.delete("person", "name=?", newString[]{name});
db.close();
}
}
測試delete方法:
public void testDelete() throwsException{
PersonDao personDao= new PersonDao(this.getContext());
personDao.delete("amosli");
}
查看結果:
sqlite> select *from person;3|amos0|10
4|amos1|11
5|amos2|12
6|amos3|13
7|amos4|14
8|amos5|15
9|amos6|16
10|amos7|17
11|amos8|18
12|amos9|19
3)更新數據
public void update(String name, String newname, intnewage) {
SQLiteDatabase db=dbHelper.getWritableDatabase();if(db.isOpen()) {
ContentValues contentValues= newContentValues();
contentValues.put("name", newname);
contentValues.put("age", newage);
db.update("person", contentValues, "name=?", newString[]{name});
db.close();
}
}
測試方法:
public void testUpdate() throwsException{
PersonDao personDao= new PersonDao(this.getContext());
personDao.update("amos0","0amos",35);
}
查看結果:
sqlite> select *from person;3|0amos|35
4|amos1|11
5|amos2|12
6|amos3|13
7|amos4|14
8|amos5|15
9|amos6|16
10|amos7|17
11|amos8|18
12|amos9|19
4)查找數據
public booleanfind(String name) {boolean status_result = false;
SQLiteDatabase db=dbHelper.getReadableDatabase();//public android.database.Cursor query(//String table,//String[] columns,//String selection,//String[] selectionArgs,//String groupBy,//String having,//String orderBy)
if(db.isOpen()) {
Cursor cursor= db.query("person", null, "name=?", new String[]{name}, null, null, null);if(cursor.moveToFirst()) {
status_result= true;
}
cursor.close();
db.close();
}returnstatus_result;
}
測試方法:
public void testFind() throwsException{
PersonDao personDao= new PersonDao(this.getContext());
assertEquals(true,personDao.find("amos1"));
}
5)查找所有數據
public ListfindAll(){
List persons = null;
SQLiteDatabase db=dbHelper.getReadableDatabase();if(db.isOpen()){
persons= new ArrayList();
Cursor cursor= db.query("person", null, null, null, null, null, null);while(cursor.moveToNext()){
Person person= newPerson();
person.setName(cursor.getString(cursor.getColumnIndex("name")));
person.setAge(cursor.getInt(cursor.getColumnIndex("age")));
persons.add(person);
}
cursor.close();
db.close();
}returnpersons;
}
測試方法:
public void testFindAll() throwsException{
PersonDao personDao= newPersonDao(getContext());
List personList =personDao.findAll();for(Person person:personList){
Log.d("person:",person.toString());
}
}
輸出結果:
4.擴展--SQLite中的事務
這里以amos1向amos2轉錢200元為例:
1),amos1賬戶初始1000元,amos2賬戶初始0元.
2),從amos1中減去200元,amos2中加上200元,這兩個步驟要么同時成功,要么同時失敗,不能一方成功,另一主失敗,這就是事務.
代碼實現:
packagecom.amos.android_db;importandroid.content.Context;importandroid.database.sqlite.SQLiteDatabase;importandroid.database.sqlite.SQLiteOpenHelper;/*** Created by amosli on 14-6-12.*/
public class MyDBHelper extendsSQLiteOpenHelper{
publicMyDBHelper(Context context) {super(context, "sqlitedb", null, 2);
}/*** 數據庫第一次創建的時候調用此方法
*@paramdb*/@Overridepublic voidonCreate(SQLiteDatabase db) {
db.execSQL("create table if not exists person (personid integer primary key autoincrement ,name varchar(30) ,age integer(3) )");
}
@Overridepublic void onUpgrade(SQLiteDatabase db, int oldVersion, intnewVersion) {
db.execSQL("alter table person add account integer null");
}
}
在初始化時更新表的結構,添加account一列,用來表示賬戶余額.
在PersonDao中添加如下方法:
public voidtransferMoney() {
SQLiteDatabase db=dbHelper.getWritableDatabase();if(db.isOpen()){try{
db.beginTransaction();//給amos1賬戶里設置1000元,amost account=0;
db.execSQL("update person set account=? where name = ?",new Object[]{1000,"amos1"});
db.execSQL("update person set account=? where name = ?",new Object[]{0,"amos2"});//從amos1賬戶里扣除200元
db.execSQL("update person set account=account-? where name = ?",new Object[]{200,"amos1"});//把amos1的錢轉給amos2
db.execSQL("update person set account=account+? where name=?",new Object[]{200,"amos2"});
}catch(Exception e){
e.printStackTrace();
}finally{//顯示的設置數據事務是否成功
db.setTransactionSuccessful();
db.endTransaction();
db.close();
}
}
}
和hibernate里的事務調用很類似,這里先beginTransaction,然后要注意的是setTransactionSuccessful和endTransaction.
測試方法:
public void testTransaction() throwsException{
PersonDao personDao= newPersonDao(getContext());
personDao.transferMoney();
}
測試結果:
sqlite> select *from person;3|0amos|35|
4|amos1|11|800
5|amos2|12|200
6|amos3|13|
7|amos4|14|
8|amos5|15|
9|amos6|16|
10|amos7|17|
11|amos8|18|
12|amos9|19|
創作挑戰賽新人創作獎勵來咯，堅持創作打卡瓜分現金大獎總結
以上是生活随笔為你收集整理的sqllite事务和MySQL事务_Android学习---SQLite数据库的增删改查和事务(transaction)调用...的全部內容，希望文章能夠幫你解決所遇到的問題。
- 上一篇： flask 部署_只需10分钟！就能用F
- 下一篇： linux cmake编译源码,linu