在Android應用中使用SQLite資料庫
應用生成的資料庫檔案儲存為/data/data/應用包名/databases/name.db，生成的檔案可用SQLite Expert打開
（name是自定義的，例如，我的應用是儲存在：/data/data/com.sinaapp.sql/databases/ssun.db中）
SQLiteActivity.java源碼：
package .sinaapp.sql;
import .sinaapp.sql.R;
import android.app.Activity;
import android.os.Bundle;
public class SQLiteActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
} Pseron.java源碼：
package .sinaapp.domain;
public class Person {
private String name;
private Integer id;
private String phone;
private Integer amount;
public Person() {}
@Override
public String toString() {
return "Person [name=" + name + ", id=" + id + ", phone=" + phone
+ ", amount=" + amount + "]";
}
public Person(String name, Integer id, String phone, Integer amount) {
this.name = name;
this.id = id;
this.phone = phone;
this.amount = amount;
}
public Person(String name, String phone, Integer amount) {
this.name = name;
this.phone = phone;
this.amount = amount;
}
public Integer getAmount() {
return amount;
}
public void setAmount(Integer amount) {
this.amount = amount;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
}
DBOpenHelper.java源碼：
package .sinaapp.service;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DBOpenHelper extends SQLiteOpenHelper {
public DBOpenHelper(Context context) {
super(context, "ssun.db", null, 3);//資料庫版本号改變，将會執行onUpgrade方法
}
@Override
public void onCreate(SQLiteDatabase db) {//第一次使用時執行的方法
// TODO Auto-generated method stub
db.execSQL("create table person(id integer primary key autoincrement,name varchar(20),phone varchar(20))");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
db.execSQL("alter table person add amount int(10)");
}
}
PersonService.java源碼：
package .sinaapp.service;
import java.util.ArrayList;
import java.util.List;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import .sinaapp.domain.Person;
public class PersonService {
private DBOpenHelper helper;
public PersonService(Context context){
this.helper = new DBOpenHelper(context);
}
public void payment(){
SQLiteDatabase db = helper.getWritableDatabase();
try{
db.beginTransaction();
db.execSQL("update person set amount = amount - 10 where id = 3");
db.execSQL("update person set amount = amount + 10 where id = 4");
db.setTransactionSuccessful();
}finally{
db.endTransaction();
}
}
/**
* 添加記錄
* @param person
*/
public void add(Person person){
SQLiteDatabase db = helper.getWritableDatabase();
db.execSQL("insert into person(name,phone,amount) values(?,?,?) ",
new Object[]{person.getName(),person.getPhone(),person.getAmount()});
}
/**
* 删除記錄
* @param integer 将要删除的記錄的ID号
*/
public void delete(Integer integer){
SQLiteDatabase db = helper.getWritableDatabase();
db.execSQL("delete from person where id = ?",new Object[]{integer});
}
/**
* 更新記錄
* @param person 更新的記錄
*/
public void update(Person person){
SQLiteDatabase db = helper.getWritableDatabase();
db.execSQL("update person set name=?, phone=?, amount=? where id = ?",
new Object[]{person.getName(),person.getPhone(),person.getAmount(),person.getId()});
}
/**
* 查找記錄
* @param integer
* @return
*/
public Person find(Integer integer){
Person person = null;
SQLiteDatabase db = helper.getWritableDatabase();
Cursor cursor = db.rawQuery("select * from person where id = ?",
new String[]{integer.toString()});
if(cursor.moveToFirst()){
int id = cursor.getInt(cursor.getColumnIndex("id"));
String name = cursor.getString(cursor.getColumnIndex("name"));
String phone = cursor.getString(cursor.getColumnIndex("phone"));
int amount = cursor.getInt(cursor.getColumnIndex("amount"));
person = new Person(name,id,phone,amount);
}
return person;
}
/**
* 分頁顯示記錄
* @param start 開始記錄号
* @param length 記錄長度
* @return
*/
public List<Person> getPersons(Integer start, Integer length){
List<Person> persons = new ArrayList<Person>();
Person person = null;
SQLiteDatabase db = helper.getWritableDatabase();
Cursor cursor = db.rawQuery("select * from person order by id limit ?, ?",
new String[]{start.toString(),length.toString()});
while(cursor.moveToNext()){
int id = cursor.getInt(cursor.getColumnIndex("id"));
String name = cursor.getString(cursor.getColumnIndex("name"));
String phone = cursor.getString(cursor.getColumnIndex("phone"));
int amount = cursor.getInt(cursor.getColumnIndex("amount"));
person = new Person(name,id,phone,amount);
persons.add(person);
person = null;
}
cursor.close();
return persons;
}
/**
* 得到記錄數
* @return
*/
public Integer getCounts(){
SQLiteDatabase db = helper.getWritableDatabase();
Cursor cursor = db.rawQuery("select count(*) from person",null);
cursor.moveToFirst();
Integer counts = cursor.getInt(0);
return counts;
}
}
單元測試TestService.java源碼：
package .sinaapp.test;
import java.util.List;
import android.test.AndroidTestCase;
import android.util.Log;
import .sinaapp.domain.Person;
import .sinaapp.service.DBOpenHelper;
import .sinaapp.service.PersonService;
public class TestService extends AndroidTestCase {
public void testCreateDB() {
DBOpenHelper helper = new DBOpenHelper(this.getContext());
helper.getWritableDatabase();
}
public void testAdd(){
PersonService service = new PersonService(this.getContext());
service.add(new Person("luolin","12345",100));
}
public void testUpdate(){
PersonService service = new PersonService(this.getContext());
service.update(new Person("zhang",4,"2222222",200));
}
public void testFind(){
PersonService service = new PersonService(this.getContext());
Person person = service.find(1);
Log.i("TestService", person.toString());
}
public void testDel(){
PersonService service = new PersonService(this.getContext());
service.delete(2);
}
public void testGetCounts(){
PersonService service = new PersonService(this.getContext());
Integer i = service.getCounts();
Log.i("TestService", i.toString());
}
public void testGetPersons(){
PersonService service = new PersonService(this.getContext());
List<Person> persons = service.getPersons(0, 4);
for(Person p : persons){
Log.i("TestService", p.toString());
}
}
public void testPayment(){
PersonService service = new PersonService(this.getContext());
service.payment();
}
}
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="://schemas.android./apk/res/android"
package=".sinaapp.sql"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk android:minSdkVersion="8" />
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name" >
<activity
android:name=".SQLiteActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<uses-library android:name="android.test.runner"/>
</application>
<instrumentation android:name="android.test.InstrumentationTestRunner"
android:targetPackage=".sinaapp.sql" />
</manifest> ![SQL優化SQL語句優化的目的[圖]](data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACwAAAAAAQABAAACAkQBADs=)