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);}@Overridepublic void onCreate(SQLiteDatabase db) {// TODO Auto-generated method stubdb.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();}@Overridepublic 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。