Android SQLite学习总结
SQLite特点:
1.零配置
2.可移植
3.紧凑
4.简单
5.可靠
SQLite可以解析的sql语句:
查询/排序/分页/插入/更新/删除
使用SQLiteOpenHelper抽象类操作数据库:
SQLiteOpenHelper提供了两个重要方法:
onCreate(SQLiteDatabase db); onUpgrade(SQLiteDatabase db,int oldVersion,int newVersion);
//会以读写方式获得SQLiteDatabase 实例,若数据库未创建则调用onCreate(SQLiteDatabase db)方法创建数据库,
//若版本号变化则会触发onUpgrade(SQLiteDatabase db,int oldVersion,int newVersion)
getWritableDatabase();
//会以只读方式获得SQLiteDatabase 实例,若版本号变化则会触发onUpgrade(SQLiteDatabase db,int oldVersion,int newVersion);
getReadableDatabase();
//版本号只能累加
增删该查有两种实现方式
DatabaseHelper.java 代码如下:
package com.example.service_basic.service;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
public class DatabaseHelper extends SQLiteOpenHelper{
private static final String TAG = DatabaseHelper.class.getSimpleName();
private static final String NAME = "test.db";
private static final int VERSION = 2;
public DatabaseHelper(Context context) {
super(context, NAME, null, VERSION);
Log.i(TAG, "DatabaseHelper()..执行了构造函数");
}
@Override
public void onCreate(SQLiteDatabase db) {
Log.i(TAG, "onCreate()..");
db.execSQL("create table person (personid integer primary key autoincrement,name varchar(20),age integer)");
}
@Override
public void onUpgrade(SQLiteDatabase db, int arg1, int arg2) {
Log.i(TAG, "onUpgrade()..");
}
}
Person.java 代码如下
package com.example.service_basic.domain;
public class Person {
private Integer id;
private String name;
private Integer age;
public Person() {
super();
}
public Person(String name, Integer age) {
super();
this.name = name;
this.age = age;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
@Override
public String toString() {
return "Person [id=" + id + ", name=" + name + ", age=" + age + "]";
}
}
第一种方式实现:
package com.example.service_basic.service;
import java.util.ArrayList;
import java.util.List;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import com.example.service_basic.domain.Person;
public class PersonService {
private DatabaseHelper databaseHelper;
private Context context;
public PersonService(Context context){
this.context = context;
databaseHelper = new DatabaseHelper(this.context);
}
public void save(Person person){
SQLiteDatabase db = databaseHelper.getWritableDatabase();
db.beginTransaction();
db.execSQL("insert into person (name,age) values(?,?) ",new Object[]{person.getName(),person.getAge()});
db.execSQL("insert into person (name,age) values(?,?) ",new Object[]{person.getName(),person.getAge()});
db.setTransactionSuccessful();
db.endTransaction();
}
public void update(Person person){
SQLiteDatabase db = databaseHelper.getWritableDatabase();
db.execSQL("update person set name = ?,age = ? where personid = ? ",new Object[]{person.getName(),person.getAge(),person.getId()});
}
public void delete(Integer id){
SQLiteDatabase db = databaseHelper.getWritableDatabase();
db.execSQL("delete from person where personid=? ",new Object[]{id});
}
public Person query(String name){
SQLiteDatabase db = databaseHelper.getReadableDatabase();
Cursor cursor = db.rawQuery("select * from person where name = ?", new String[]{name});
if(cursor.moveToNext()){
Person person = new Person();
person.setId(cursor.getInt(cursor.getColumnIndex("personid")));
person.setName(cursor.getString(cursor.getColumnIndex("name")));
person.setAge(cursor.getInt(cursor.getColumnIndex("age")));
cursor.close();
return person;
}
cursor.close();
return null;
}
public List<Person> getPageData(int firstResult,int maxResult){
List<Person> persons = new ArrayList<Person>();
SQLiteDatabase db = databaseHelper.getReadableDatabase();
Cursor cursor = db.rawQuery("select personid,name,age from person limit ?,? ",
new String[]{
String.valueOf(firstResult),
String.valueOf(maxResult)
});
while(cursor.moveToNext()){
Person person = new Person();
person.setId(cursor.getInt(cursor.getColumnIndex("personid")));
person.setName(cursor.getString(cursor.getColumnIndex("name")));
person.setAge(cursor.getInt(cursor.getColumnIndex("age")));
persons.add(person);
}
cursor.close();
return persons;
}
public int getCountByPerson(){
SQLiteDatabase db = databaseHelper.getReadableDatabase();
Cursor cursor = db.rawQuery("select count(1) from person ", null);
cursor.moveToFirst();
int count = cursor.getInt(0);
cursor.close();
return count;
}
}
第一种方式单元测试类:
package com.example.service_basic.test;
import java.util.List;
import android.test.AndroidTestCase;
import android.util.Log;
import com.example.service_basic.domain.Person;
import com.example.service_basic.service.PersonService;
public class TestPersonService extends AndroidTestCase{
private static final String TAG = TestPersonService.class.getSimpleName();
public void testSave(){
PersonService service = new PersonService(getContext());
for(int i=0;i<10;i++){
Person person = new Person("Hello"+i,i);
Log.i(TAG, "testSave()"+i+"..begin..");
service.save(person);
Log.i(TAG, "testSave()."+i+".end..");
}
}
public void testUpdate(){
PersonService service = new PersonService(getContext());
Person person = new Person("Charles",32);
person.setId(1);
Log.i(TAG, "testUpdate()..begin..");
service.update(person);
Log.i(TAG, "testUpdate()..end..");
}
public void testDelete(){
PersonService service = new PersonService(getContext());
Log.i(TAG, "testDelete()..begin..");
service.delete(1);
Log.i(TAG, "testDelete()..end..");
}
public void testRawQuery(){
PersonService service = new PersonService(getContext());
Person person = service.query("carl");
Log.i(TAG, "Person..RawQuery()..:"+person);
}
public void testGetPageData(){
PersonService service = new PersonService(getContext());
List<Person> persons = service.getPageData(0, 100);
for(Person p:persons){
Log.i(TAG, "person:"+p);
}
}
public void testGetCountByPerson(){
PersonService service = new PersonService(getContext());
int count = service.getCountByPerson();
Log.i(TAG, "person_count:"+count);
}
}
第二种实现方式:
package com.example.service_basic.service;
import java.util.ArrayList;
import java.util.List;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import com.example.service_basic.domain.Person;
public class OtherPersonService {
private DatabaseHelper databaseHelper;
private Context context;
public OtherPersonService(Context context){
this.context = context;
databaseHelper = new DatabaseHelper(this.context);
}
public void save(Person person){
SQLiteDatabase db = databaseHelper.getWritableDatabase();
ContentValues values = new ContentValues();
values.put("name", person.getName());
values.put("age", person.getAge());
db.insert("person", "name,age", values);
db.close();
}
public void update(Person person){
SQLiteDatabase db = databaseHelper.getWritableDatabase();
ContentValues values = new ContentValues();
values.put("name", person.getName());
values.put("age", person.getAge());
db.update("person", values, "personid = ? ", new String[]{String.valueOf(person.getId())});
db.close();
}
public void delete(Integer id){
SQLiteDatabase db = databaseHelper.getWritableDatabase();
db.delete("person", "personid=?", new String[]{String.valueOf(id)});
db.close();
}
public Person find(Integer id){
SQLiteDatabase db = databaseHelper.getReadableDatabase();
Cursor cursor = db.query("person",
new String[]{"personid","name","age"}, "personid = ? ",
new String[]{String.valueOf(id)}, null, null, null);
if(cursor.moveToNext()){
Person person = new Person();
person.setId(cursor.getInt(0));
person.setName(cursor.getString(1));
person.setAge(cursor.getInt(2));
db.close();
return person;
}
db.close();
return null;
}
public int getCount(){
int count = 0;
SQLiteDatabase db = databaseHelper.getReadableDatabase();
Cursor cursor = db.query("person", new String[]{"count(*)"}, null, null, null, null, null);
cursor.moveToFirst();
count = cursor.getInt(0);
db.close();
return count;
}
public List<Person> getPageData(int startNo,int endNo){
List<Person> list = new ArrayList<Person>();
SQLiteDatabase db = databaseHelper.getReadableDatabase();
Cursor cursor = db.query("person", new String[]{"personid","name","age"}, null, null, null, null, null, startNo+","+endNo);
while(cursor.moveToNext()){
Person person = new Person();
person.setId(cursor.getInt(0));
person.setName(cursor.getString(1));
person.setAge(cursor.getInt(2));
list.add(person);
}
db.close();
return list;
}
}
第二种实现方式单元测试类:
package com.example.service_basic.test;
import java.util.List;
import android.test.AndroidTestCase;
import android.util.Log;
import com.example.service_basic.domain.Person;
import com.example.service_basic.service.OtherPersonService;
public class TestOtherPersonService extends AndroidTestCase{
private static final String TAG = TestOtherPersonService.class.getSimpleName();
public void testOtherSave(){
OtherPersonService service = new OtherPersonService(getContext());
Log.i(TAG, "testOtherSave()..begin..");
Person person = new Person("Jerry_",18);
service.save(person);
Log.i(TAG, "testOtherSave()..end..");
}
public void testOtherUpdate(){
OtherPersonService service = new OtherPersonService(getContext());
Log.i(TAG, "testOtherUpdate()..begin..");
Person person = new Person("Jerry_",18);
person.setId(2);
service.update(person);
Log.i(TAG, "testOtherUpdate()..end..");
}
public void testOtherDelete(){
OtherPersonService service = new OtherPersonService(getContext());
Log.i(TAG, "testOtherDelete()..begin..");
service.delete(2);
Log.i(TAG, "testOtherDelete()..end..");
}
public void testOtherfind(){
OtherPersonService service = new OtherPersonService(getContext());
Log.i(TAG, "testOtherfind()..begin..");
Person person = service.find(2);
Log.i(TAG, "person:"+person);
Log.i(TAG, "testOtherfind()..end..");
}
public void testOtherCount(){
OtherPersonService service = new OtherPersonService(getContext());
Log.i(TAG, "testOtherCount()..begin..");
int count = service.getCount();
Log.i(TAG, "count:"+count);
Log.i(TAG, "testOtherCount()..end..");
}
public void testOtherGetPageData(){
OtherPersonService service = new OtherPersonService(getContext());
Log.i(TAG, "testOtherCount()..begin..");
List<Person> persons = service.getPageData(5, 5);
for(Person p:persons){
Log.i(TAG, "person:"+p);
}
Log.i(TAG, "testOtherCount()..end..");
}
}