Android數(shù)據(jù)庫(kù)中事務(wù)操作方法之銀行轉(zhuǎn)賬示例

package com.itheima.transtation;
import com.itheima.transtation.db.BankOpenHelper;
import android.os.Bundle;
import android.app.Activity;
import android.database.sqlite.SQLiteDatabase;
import android.view.Menu;
import android.view.View;
public class MainActivity extends Activity {
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
 }
 //點(diǎn)擊按鈕執(zhí)行該方法
 public void transtation(View v){
  //1.創(chuàng)建一個(gè)幫助類的對(duì)象
  BankOpenHelper bankOpenHelper = new BankOpenHelper(this);
  //2.調(diào)用數(shù)據(jù)庫(kù)幫助類對(duì)象的getReadableDatabase創(chuàng)建數(shù)據(jù)庫(kù)，初始化表數(shù)據(jù)，獲取一個(gè)SqliteDatabase對(duì)象去做轉(zhuǎn)賬（sql語(yǔ)句）
  SQLiteDatabase db = bankOpenHelper.getReadableDatabase();
  //3.轉(zhuǎn)賬,將李四的錢減200，張三加200
  db.beginTransaction();//開啟一個(gè)數(shù)據(jù)庫(kù)事務(wù)
  try {
   db.execSQL("update account set money= money-200 where name=?",new String[]{"李四"});
   int i = 100/0;//模擬一個(gè)異常
   db.execSQL("update account set money= money+200 where name=?",new String[]{"張三"});
   db.setTransactionSuccessful();//標(biāo)記事務(wù)中的sql語(yǔ)句全部成功執(zhí)行
  } finally {
   db.endTransaction();//判斷事務(wù)的標(biāo)記是否成功，如果不成功，回滾錯(cuò)誤之前執(zhí)行的sql語(yǔ)句
  }
 }
}

package com.itheima.transtation.db;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
public class BankOpenHelper extends SQLiteOpenHelper {
 public BankOpenHelper(Context context) {
  super(context, "bank.db", null, 1);
  // TODO Auto-generated constructor stub
 }
 @Override
 public void onCreate(SQLiteDatabase db) {
  db.execSQL("create table account (_id integer primary key autoincrement,name varchar(20),money varchar(20))");
  db.execSQL("insert into account ('name','money') values ('張三','2000')");
  db.execSQL("insert into account ('name','money') values ('李四','5000')");
 }
 @Override
 public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
  // TODO Auto-generated method stub
 }
}

<?xml version="1.0"?>
-<RelativeLayout tools:context=".MainActivity" android:paddingTop="@dimen/activity_vertical_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingBottom="@dimen/activity_vertical_margin" android:layout_height="match_parent" android:layout_width="match_parent" xmlns:tools="http://schemas.android.com/tools" xmlns:android="http://schemas.android.com/apk/res/android">
<Button android:layout_height="wrap_content" android:layout_width="fill_parent" android:text="@string/transtation" android:onClick="transtation" android:layout_centerInParent="true"/>
</RelativeLayout>

//點(diǎn)擊按鈕執(zhí)行該方法
public void transtation(View v){
 //1.創(chuàng)建一個(gè)幫助類的對(duì)象
 BankOpenHelper bankOpenHelper = new BankOpenHelper(this);
 //2.調(diào)用數(shù)據(jù)庫(kù)幫助類對(duì)象的getReadableDatabase創(chuàng)建數(shù)據(jù)庫(kù)，初始化表數(shù)據(jù)，獲取一個(gè)SqliteDatabase對(duì)象去做轉(zhuǎn)賬（sql語(yǔ)句）
 SQLiteDatabase db = bankOpenHelper.getReadableDatabase();
 //3.轉(zhuǎn)賬,將李四的錢減200，張三加200
 db.beginTransaction();//開啟一個(gè)數(shù)據(jù)庫(kù)事務(wù)
 try {
  db.execSQL("update account set money= money-200 where name=?",new String[]{"李四"});
  int i = 100/0;//模擬一個(gè)異常
  db.execSQL("update account set money= money+200 where name=?",new String[]{"張三"});
  db.setTransactionSuccessful();//標(biāo)記事務(wù)中的sql語(yǔ)句全部成功執(zhí)行
 } finally {
  db.endTransaction();//判斷事務(wù)的標(biāo)記是否成功，如果不成功，回滾錯(cuò)誤之前執(zhí)行的sql語(yǔ)句
 }
}