十一、SQLite数据库增删改查操作案例
Person实体类
package com.ljq.domain;
public class Person {
private Integer id;
private String name;
private String phone;
public Person() {
super();
}
public Person(String name, String phone) {
super();
this.name = name;
this.phone = phone;
}
public Person(Integer id, String name, String phone) {
super();
this.id = id;
this.name = name;
this.phone = phone;
}
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 String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
}
DBOpenHelper数据库关联类
package com.ljq.db;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DBOpenHelper extends SQLiteOpenHelper {
// 类没有实例化,是不能用作父类构造器的参数,必须声明为静态
private static final String DBNAME = "ljq.db";
private static final int VERSION = 1;
// 第三个参数CursorFactory指定在执行查询时获得一个游标实例的工厂类,
// 设置为null,代表使用系统默认的工厂类
public DBOpenHelper(Context context) {
super(context, DBNAME, null, VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
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) {
// 注：生产环境上不能做删除操作
db.execSQL("DROP TABLE IF EXISTS PERSON");
onCreate(db);
}
}
PersonService业务类
package com.ljq.db;
import java.util.ArrayList;
import java.util.List;
import android.content.Context;
import android.database.Cursor;
import com.ljq.domain.Person;
public class PersonService {
private DBOpenHelper dbOpenHelper = null;
/**
* 构造函数
*
* 调用getWritableDatabase()或getReadableDatabase()方法后，会缓存SQLiteDatabase实例；
* 因为这里是手机应用程序，一般只有一个用户访问数据库，所以建议不关闭数据库，保持连接状态。
* getWritableDatabase()，getReadableDatabase的区别是当数据库写满时，调用前者会报错，调用后者不会，
* 所以如果不是更新数据库的话，最好调用后者来获得数据库连接。
*
* 对于熟悉SQL语句的程序员最好使用exeSQL(),rawQuery(),因为比较直观明了
*
* @param context
*/
public PersonService(Context context){
dbOpenHelper = new DBOpenHelper(context);
}
public void save(Person person){
dbOpenHelper.getWritableDatabase().execSQL("insert into person(name, phone) values (?, ?)",
new Object[]{person.getName(), person.getPhone()});
}
public void update(Person person){
dbOpenHelper.getWritableDatabase().execSQL("update person set name=?, phone=? where id=?",
new Object[]{person.getName(), person.getPhone(), person.getId()});
}
public void delete(Integer... ids){
if(ids.length>0){
StringBuffer sb = new StringBuffer();
for(Integer id : ids){
sb.append("?").append(",");
}
sb.deleteCharAt(sb.length() - 1);
dbOpenHelper.getWritableDatabase().execSQL("delete from person where id in ("+sb+")", (Object[])ids);
}
}
public Person find(Integer id){
Cursor cursor = dbOpenHelper.getReadableDatabase().rawQuery("select id, name, phone from person where id=?",
new String[]{String.valueOf(id)});
if(cursor.moveToNext()){
int personid = cursor.getInt(0);
String name = cursor.getString(1);
String phone = cursor.getString(2);
return new Person(personid, name, phone);
}
return null;
}
public long getCount(){
Cursor cursor = dbOpenHelper.getReadableDatabase().query("person",
new String[]{"count(*)"}, null,null,null,null,null);
if(cursor.moveToNext()){
return cursor.getLong(0);
}
return 0;
}
/**
* 分页
*
* @param startResult 偏移量，默认从0开始
* @param maxResult 每页显示的条数
* @return
*/
public List<Person> getScrollData(int startResult, int maxResult){
List<Person> persons = new ArrayList<Person>();
//Cursor cursor = dbOpenHelper.getReadableDatabase().query("person", new String[]{"id, name, phone"},
// "name like ?", new String[]{"%ljq%"}, null, null, "id desc", "1,2");
Cursor cursor = dbOpenHelper.getReadableDatabase().rawQuery("select * from person limit ?,?",
new String[]{String.valueOf(startResult), String.valueOf(maxResult)});
while(cursor.moveToNext()) {
int personid = cursor.getInt(0);
String name = cursor.getString(1);
String phone = cursor.getString(2);
persons.add(new Person(personid, name, phone));
}
return persons;
}
}
PersonServiceTest测试类
package com.ljq.test;
import java.util.List;
import com.ljq.db.PersonService;
import com.ljq.domain.Person;
import android.test.AndroidTestCase;
import android.util.Log;
public class PersonServiceTest extends AndroidTestCase{
private final String TAG = "PersonServiceTest";
public void testSave() throws Exception{
PersonService personService = new PersonService(this.getContext());
personService.save(new Person("zhangsan1", "059188893343"));
personService.save(new Person("zhangsan2", "059188893343"));
personService.save(new Person("zhangsan3", "059188893343"));
personService.save(new Person("zhangsan4", "059188893343"));
personService.save(new Person("zhangsan5", "059188893343"));
}
public void testUpdate() throws Exception{
PersonService personService = new PersonService(this.getContext());
Person person = personService.find(1);
person.setName("linjiqin");
personService.update(person);
}
public void testFind() throws Exception{
PersonService personService = new PersonService(this.getContext());
Person person = personService.find(1);
Log.i(TAG, person.getName());
}
public void testList() throws Exception{
PersonService personService = new PersonService(this.getContext());
List<Person> persons = personService.getScrollData(0, 10);
for(Person person : persons){
Log.i(TAG, person.getId() + " : " + person.getName());
}
}
public void testCount() throws Exception{
PersonService personService = new PersonService(this.getContext());
Log.i(TAG, String.valueOf(personService.getCount()));
}
public void testDelete() throws Exception{
PersonService personService = new PersonService(this.getContext());
personService.delete(1);
}
public void testDeleteMore() throws Exception{
PersonService personService = new PersonService(this.getContext());
personService.delete(new Integer[]{2, 5, 6});
}
}
运行结果
