温故知新----5种数据存储方式之SQLiteOpenHelper

SQLiteOpenHelper常用方法:DBHelper.Java<span style="font-family:Microsoft YaHei;font-size:18px;">import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;/*** Created by tangjiarao on 16/9/7.*/public class DbHelper extends SQLiteOpenHelper{private static final String DATABASE_NAME = "person.db"; //数据库名称private static final int DATABASE_VERSION = 1;//数据库版本public DbHelper(Context context){super(context,DATABASE_NAME,null,DATABASE_VERSION);}public void onCreate(SQLiteDatabase db) {db.execSQL("CREATE TABLE person " +"(_id integer primary key autoincrement, " +"name varchar(20), " +"age varchar(10))");}@Overridepublic void onUpgrade(SQLiteDatabase db, int i, int i1) {db.execSQL("DROP TABLE IF EXISTS person");onCreate(db);}}</span>PersonService.Java<span style="font-family:Microsoft YaHei;font-size:18px;">import android.content.Context;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import java.util.ArrayList;import java.util.List;import tplusr.storagetest.db.DbHelper;public class PersonService {private DbHelper dbHelper;private SQLiteDatabase db;public PersonService(Context context) {dbHelper=new DbHelper(context);db=dbHelper.getReadableDatabase();}/*** 插入方法* @param person*/public void insert(Person person){SQLiteDatabase db=dbHelper.getWritableDatabase();db.execSQL("insert into person(name,age) values(?,?)",new Object[]{person.getName(),person.getAge()});}/*** 删除方法* @param _id*/public void delete(Integer _id){SQLiteDatabase db=dbHelper.getWritableDatabase();db.execSQL("delete from person where _id=?",new Object[]{_id});}/*** 查找某行数据方法* @param _id* @return*/public Person find(Integer _id){SQLiteDatabase db=dbHelper.getWritableDatabase();Cursor cursor=db.rawQuery("select * from person where _id=?", new String[]{_id.toString()});if(cursor.moveToFirst()){int id = cursor.getInt(cursor.getColumnIndex("_id"));String name = cursor.getString(cursor.getColumnIndex("name"));String age = cursor.getString(cursor.getColumnIndex("age"));Person person = new Person();person.set_id(id);person.setName(name);person.setAge(age);return person;}return null;}/*** 查找所有数据方法* @return*/public List<Person> findAll(){SQLiteDatabase db=dbHelper.getReadableDatabase();List<Person> persons = new ArrayList<Person>();Cursor cursor=db.rawQuery("select * from person", null);while(cursor.moveToNext()){Person person=new Person();int id=cursor.getInt(cursor.getColumnIndex("_id"));String name=cursor.getString(cursor.getColumnIndex("name"));String age=cursor.getString(cursor.getColumnIndex("age"));person.set_id(id);person.setName(name);person.setAge(age);persons.add(person);}return persons;}}</span>Person.Java<span style="font-family:Microsoft YaHei;font-size:18px;">public class Person {private int _id;private String name;private String age;public int get_id() {return _id;}public void set_id(int _id) {this._id = _id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getAge() {return age;}public void setAge(String age) {this.age = age;}}</span>

DBActivity.Java

<span style="font-family:Microsoft YaHei;font-size:18px;">import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;

import java.util.List;

import tplusr.storagetest.R;

public class DBActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_db);

PersonService service =new PersonService(this);
Person person =new Person();
person.setName("ahdad");
person.setAge("39");
service.insert(person);

List<Person> p =service.findAll();
for (int i =0;i<p.size();i++){
Log.d("db",p.get(i).toString());
}
}
}
</span>

结果：