使用手机本地sqlite数据库存一些类

最近工作需要，把用户检测的一些数据存到本地，因为检测完用户可能不想上传，或者上传失败，网络断了。这时候我们可以提供一个历史数据上传的功能，方便用户选择合适的数据上传，避免浪费开销，话不多说直接贴代码。

package cp.sample.com.fetalheartmonitor_demo.db;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

import cp.sample.com.fetalheartmonitor_demo.AppContext;

public class DBServices extends SQLiteOpenHelper{

public final static int version = 1;
public final static String dbName = "MonitorData"+ AppContext.getInstance().getProperty("UsrName");//不同数据库名，登陆后显示不同列表

public DBServices(Context context){
super(context,dbName,null,version);
}

@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
db.beginTransaction();
//创建邮件表
String create_mail_sql = "CREATE TABLE if not exists [MonitorData]"+
"(_id integer primary key autoincrement,object object)";
db.execSQL(create_mail_sql);

db.setTransactionSuccessful();
db.endTransaction();
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub

}
//增
public void insert(String table, String nullColumnHack, ContentValues values){
SQLiteDatabase db = this.getWritableDatabase();
db.beginTransaction();
db.insert(table, nullColumnHack, values);
db.setTransactionSuccessful();
db.endTransaction();
}
//删
public void delete(String table , String whereClause , String[] whereArgs){
SQLiteDatabase db = this.getWritableDatabase();
db.beginTransaction();
db.delete(table, whereClause, whereArgs);
db.setTransactionSuccessful();
db.endTransaction();
}
//改
public void update(String table, ContentValues values,
String whereClause, String[] whereArgs){
SQLiteDatabase db = this.getWritableDatabase();
db.beginTransaction();
db.update(table, values, whereClause, whereArgs);
db.setTransactionSuccessful();
db.endTransaction();
}
//查
public Cursor read(String sql ,String[] args){
SQLiteDatabase db = this.getReadableDatabase();
db.beginTransaction();
Cursor cursor = db.rawQuery(sql, args);
db.setTransactionSuccessful();
db.endTransaction();
return cursor;
}

}

然后在需要使用的activity或者fragment里：

DBServices db = new DBServices(this.getContext());

db = new DBServices(this.getContext());

/**
* 保存数据
*/
public void saveData(MonitorDataObject object) {
ByteArrayOutputStream arrayOutputStream = new ByteArrayOutputStream();
try {
ObjectOutputStream objectOutputStream = new ObjectOutputStream(arrayOutputStream);
objectOutputStream.writeObject(object);
objectOutputStream.flush();
byte data[] = arrayOutputStream.toByteArray();
objectOutputStream.close();
arrayOutputStream.close();
SQLiteDatabase database = db.getWritableDatabase();
database.execSQL("insert into MonitorData (object) values(?)", new Object[] { data });
database.close();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

这就直接存了类到数据表了。

怎么拿去类呢，下面是拿去这个类的相关代码：

DBServices db = new DBServices(this);//定义变量
db = new DBServices(this);//初始化
//拿到主键_id的列表方便查询，通过object是查不到的
public ArrayList<Integer> getAllInt() {
ArrayList<Integer> persons = new ArrayList<Integer>();
SQLiteDatabase database = db.getReadableDatabase();
Cursor cursor = database.rawQuery("select * from MonitorData", null);
if (cursor != null) {
while (cursor.moveToNext()) {
//如果你代码中有用它从数据库中取一个整型值，需要注意：如果数据库中的这一个数据恰好是null，而null又不是int，此时并不会抛出NumberFormatException 异常，而是直接返回0！
int person =cursor.getInt(0);
persons.add(person);
}
}
Log.d("Persons-Count",Integer.toString(persons.size()));
return persons;
}

//拿去数据
public ArrayList<MonitorDataObject> getAllObject() {
ArrayList<MonitorDataObject> persons = new ArrayList<MonitorDataObject>
();
SQLiteDatabase database = db.getReadableDatabase();
Cursor cursor = database.rawQuery("select * from MonitorData", null);
if (cursor != null) {
while (cursor.moveToNext()) {
Log.d("data-id",cursor.getString(0));
byte data[] = cursor.getBlob(cursor.getColumnIndex("object"));
ByteArrayInputStream arrayInputStream = new
ByteArrayInputStream(data);
try {
ObjectInputStream inputStream = new ObjectInputStream
(arrayInputStream);
MonitorDataObject person = (MonitorDataObject)
inputStream.readObject();
persons.add(person);
inputStream.close();
arrayInputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
Log.d("Persons-Count",Integer.toString(persons.size()));
return persons;
}下面举一个删除的例子：
DBServices db = new DBServices(this);
db = new DBServices(this);
//index需要删除的_id,上面代码有拿到id的列表
String[] args = {String.valueOf(index)};
db.delete("MonitorData","_id=?",args);

记录一下，方便以后查询。