Android开发之用SQLite实现增上改查操作和事务操作
一）开发前准备工作，下载SQLite Expert工具（SQLite的可视化工具），大家可以去搜一下二）工具准备好了，咱们开始开发吧
先贴一下项目的目录结构：
1.写一个获得创建修改数据库的工具类，这个类继承自SQLiteOpenHelper
package com.xiaobo.service;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DbOpenHelper extends SQLiteOpenHelper{
public DbOpenHelper(Context context) {// 初始化时把数据库名和版本带上
super(context, "itxiaobo.db", null, 3);
}
@Override
public void onCreate(SQLiteDatabase db) {// 数据库第一次被创建的时候调用的
db.execSQL("CREATE TABLE person (personid integer primary key autoincrement, name varchar(20))");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {// 数据库版本更改后执行这个方法
db.execSQL("ALTER TABLE person ADD amount INTEGER NULL ");
}
}
2.然后再下一个测试类PersonServiceTest，测试一下是否成功创建的数据库和表
package com.xiaobo.juit;
import java.util.List;
import android.test.AndroidTestCase;
import android.util.Log;
import com.xiaobo.domain.Person;
import com.xiaobo.service.DbOpenHelper;
import com.xiaobo.service.PersonService;
public class PersonServiceTest extends AndroidTestCase{
// 本测试类的专有TAG标签，利于LogCat调试
private final static String TAG = "PersonServiceTest";
/**
* 测试创建或更改数据库
* @throws Throwable
*/
public void testCreateDb() throws Throwable{
DbOpenHelper dbOpenHelper = new DbOpenHelper(getContext());
dbOpenHelper.getWritableDatabase();
}
}
备注：写单元测试时得在AndroidManifest.xml配置一下，看下图
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.xiaobo.db"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="3"
android:targetSdkVersion="17" />
<instrumentation android:name="android.test.InstrumentationTestRunner"
android:targetPackage="com.xiaobo.db"
android:label="JUnit Test"/>
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<!-- 单元测试的library -->
<uses-library android:name="android.test.runner" />
<activity
android:name="com.xiaobo.db.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>
</application>
</manifest>
3.写业务逻辑类PersonService，其中包含了增上改查，看代码吧
package com.xiaobo.service;
import java.util.ArrayList;
import java.util.List;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import com.xiaobo.domain.Person;
public class PersonService {
private DbOpenHelper dbOpenHelper;
public PersonService(Context context) {
this.dbOpenHelper = new DbOpenHelper(context);
}
/**
* 添加记录
* @param person
*/
public void save(Person person){
SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
db.execSQL("insert into person(name, phone, amount) values(?,?)", new Object[]{person.getName(), person.getPhone(), person.getAmount()});
}
/**
* 根据id删除记录
* @param id
*/
public void delete(Integer id){
SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
db.execSQL("delete from person where personid=?", new Object[]{id});
}
/**
* 更新记录
* @param person
*/
public void update(Person person){
SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
db.execSQL("update person set name=?, phone=?, amount=? where personid=?", new Object[]{person.getName(), person.getPhone(),person.getAmount(), person.getId()});
}
/**
* 根据id查找一条记录
* @param id
* @return
*/
public Person find(Integer id){
SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
Cursor cursor = db.rawQuery("select * from person where personid=?", new String[]{id.toString()});
if(cursor.moveToFirst()){
int personid = cursor.getInt(cursor.getColumnIndex("personid"));
String name = cursor.getString(cursor.getColumnIndex("name"));
String phone = cursor.getString(cursor.getColumnIndex("phone"));
int amount = cursor.getInt(cursor.getColumnIndex("amount"));
return new Person(personid, name, phone, amount);
}
return null;
}
/**
* 查询翻页记录
* @param offset
* @param maxResult
* @return
*/
public List<Person> getScrollData(int offset, int maxResult){
List<Person> persons = new ArrayList<Person>();
SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
Cursor cursor = db.rawQuery("select * from person order by personid asc limit ?,?", new String[]{String.valueOf(offset), String.valueOf(maxResult)});
while(cursor.moveToNext()){
int personid = cursor.getInt(cursor.getColumnIndex("personid"));
String name = cursor.getString(cursor.getColumnIndex("name"));
String phone = cursor.getString(cursor.getColumnIndex("phone"));
int amount = cursor.getInt(cursor.getColumnIndex("amount"));
persons.add(new Person(personid, name, phone, amount));
}
cursor.close();
return persons;
}
/**
* 获取记录总数
* @return
*/
public long getCount(){
SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
Cursor cursor = db.rawQuery("select count(*) from person", null);
cursor.moveToFirst();
long count = cursor.getLong(0);
return count;
}
/**
* 转账汇款事务
* @param fromId 汇款账户
* @param toId 接收账户
*/
public void payment(Integer fromId, Integer toId){
SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
db.beginTransaction();// 开启事务
try{
db.execSQL("update person set amount=amount-500 where personid=?", new Object[]{fromId});
db.execSQL("update person set amount=amount+500 where personid=?", new Object[]{toId});
// 结束事务有两种情况，要么commit,要么rollback,是根据事务的标志决定的，默认为False，如果为True,就会提交
db.setTransactionSuccessful();
}finally{
db.endTransaction();// 结束事务
}
}
}
4.在先前创建的PersonServiceTest类里面写其他的测试方法，上代码
package com.xiaobo.juit;
import java.util.List;
import android.test.AndroidTestCase;
import android.util.Log;
import com.xiaobo.domain.Person;
import com.xiaobo.service.DbOpenHelper;
import com.xiaobo.service.PersonService;
public class PersonServiceTest extends AndroidTestCase{
// 本测试类的专有TAG标签，利于LogCat调试
private final static String TAG = "PersonServiceTest";
/**
* 测试创建或更改数据库
* @throws Throwable
*/
public void testCreateDb() throws Throwable{
DbOpenHelper dbOpenHelper = new DbOpenHelper(getContext());
dbOpenHelper.getWritableDatabase();
}
/**
* 测试保存
* @throws Throwable
*/
public void testSave() throws Throwable{
PersonService personService = new PersonService(getContext());
personService.save(new Person(1, "yellow", "18706487378", 2000));
personService.save(new Person(2, "yuan", "18706697820", 3000));
personService.save(new Person(3, "zhen", "13658662813", 4000));
}
/**
* 测试根据id查找一条记录
* @throws Throwable
*/
public void testFind() throws Throwable{
PersonService personService = new PersonService(getContext());
Person person = personService.find(1);
Log.i(TAG, person.toString());
}
/**
* 测试更新记录
* @throws Throwable
*/
public void testUpdate() throws Throwable{
PersonService personService = new PersonService(getContext());
personService.update(new Person(2, "yellow", "18706487378", 5000));
personService.update(new Person(3, "yuan", "18706697820", 5000));
}
/**
* 测试删除记录
* @throws Throwable
*/
public void testDelete() throws Throwable{
PersonService personService = new PersonService(getContext());
personService.delete(1);
}
/**
* 测试获得记录总条数
* @throws Throwable
*/
public void testGetCount() throws Throwable{
PersonService personService = new PersonService(getContext());
Log.i(TAG, String.valueOf(personService.getCount()));
}
/**
* 测试分页记录
* @throws Throwable
*/
public void testGetScrollData() throws Throwable{
PersonService personService = new PersonService(getContext());
List<Person> persons = personService.getScrollData(0, 5);
for(Person person :persons){
Log.i(TAG, person.toString());
}
}
/**
* 测试转账汇款
* @throws Throwable
*/
public void testUpdateAmount() throws Throwable{
PersonService personService = new PersonService(getContext());
Person p01 = personService.find(2);
Person p02 = personService.find(3);
System.out.println(p01.toString());
System.out.println(p02.toString());
p01.setAmount(500);
p02.setAmount(600);
personService.update(p01);
personService.update(p02);
Log.i(TAG, p01.getAmount().toString());
Log.i(TAG, p02.getAmount().toString());
}
/**
* 测试转账汇款2
* @throws Throwable
*/
public void testPayment() throws Throwable{
PersonService personService = new PersonService(getContext());
Person p01 = personService.find(2);
Person p02 = personService.find(3);
// 打印转账之前账户信息
Log.i(TAG, p01.toString());
Log.i(TAG, p02.toString());
personService.payment(2, 3);
// 再次打印转账之后账户信息
Log.i(TAG, p01.toString());
Log.i(TAG, p02.toString());
}
}
5.大家可以下源代码看一下，不是很会写原理，呵呵，希望大家共同进步
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