android学习杂记.10

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本地数据库sqlite的简单用法

先创建一个类继承 SQLiteOpenHelper

public class SqlLiteOpHelper extends SQLiteOpenHelper {    //数据库名字    private static final String DATABASE_NAME="swJAB";    //数据库版本    private static final int DATABASE_VERSION=1;    private static SqlLiteOpHelper sSqlLiteOpHelper;    public SqlLiteOpHelper(Context context) {        super(context,DATABASE_NAME,null,DATABASE_VERSION);    }    public synchronized static SqlLiteOpHelper getInstance(Context context)    {        if(null==sSqlLiteOpHelper)        {            sSqlLiteOpHelper=new SqlLiteOpHelper(context);        }        return  sSqlLiteOpHelper;    }    public synchronized static void destoryInstance() {        if (null != sSqlLiteOpHelper) {            sSqlLiteOpHelper.close();        }    }    public static final String WALK_COUNT="WALK_COUNT";    public static final String YESTDAY_DATE="YESTDAY_DATE";    public static final String BEI_WANG_LU="BEI_WANG_LU";    @Override    public void onCreate(SQLiteDatabase sqLiteDatabase) {           sqLiteDatabase.execSQL("create table "+WALK_COUNT+" ( _ID integer primary key autoincrement,"           +"allcount integer not null,lastdate bigint not null )"           );           sqLiteDatabase.execSQL("create table "+YESTDAY_DATE+" ( _ID integer primary key autoincrement,"           +"yesterday bigint not null )"           );           sqLiteDatabase.execSQL("create table "+BEI_WANG_LU+" ( _ID integer primary key autoincrement,"           +"title text not null, "+             "content text not null,"+                   "date text not null"+                   ")"           );    }    @Override    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {    }}

app在安装的时候在oncreate里面执行语句创建了3张表

再创建一个sqlite工具类在里面写增删改查方法

/** *   向表里面写数据 */public boolean addBeiWangLu(BeiWangLu beiWangLu){    ContentValues contentValues=new ContentValues();    contentValues.put("title",beiWangLu.getTitle());    contentValues.put("content",beiWangLu.getContent());    contentValues.put("date",beiWangLu.getDate());    long rows= MyApplication.getWriteableInstance().insert(SqlLiteOpHelper.BEI_WANG_LU,null,contentValues);    if (rows > 0) {        return true;    }    return false;}

/** *    从表里面拿所有数据，按id降序 排序 */public List<BeiWangLu> getBeiWangLus(){    List<BeiWangLu> lists=new ArrayList<BeiWangLu>();    Cursor cursor= MyApplication.getReadableInstance().query(SqlLiteOpHelper.BEI_WANG_LU,null,null,null,null,null,"_ID desc");    for (cursor.moveToFirst(); !cursor.isAfterLast(); cursor.moveToNext()) {        BeiWangLu beiWangLu=new BeiWangLu();        beiWangLu.setId(cursor.getInt(cursor.getColumnIndexOrThrow("_ID")));        beiWangLu.setTitle(cursor.getString(cursor.getColumnIndexOrThrow("title")));        beiWangLu.setContent(cursor.getString(cursor.getColumnIndexOrThrow("content")));        beiWangLu.setDate(cursor.getString(cursor.getColumnIndexOrThrow("date")));        lists.add(beiWangLu);    }    return  lists;}

/** *    从表里面拿一条数据 根据id */public BeiWangLu getOneBeiWangLus(int id){    Cursor cursor= MyApplication.getReadableInstance().query(SqlLiteOpHelper.BEI_WANG_LU,null,"_ID="+id,null,null,null,null);    cursor.moveToFirst();        BeiWangLu beiWangLu=new BeiWangLu();        beiWangLu.setId(cursor.getInt(cursor.getColumnIndexOrThrow("_ID")));        beiWangLu.setTitle(cursor.getString(cursor.getColumnIndexOrThrow("title")));        beiWangLu.setContent(cursor.getString(cursor.getColumnIndexOrThrow("content")));        beiWangLu.setDate(cursor.getString(cursor.getColumnIndexOrThrow("date")));    return  beiWangLu;}

/** * 删除表里一条数据 根据id */public boolean deleteOneBeiWangLu(int id){  int  rows=  MyApplication.getWriteableInstance().delete(SqlLiteOpHelper.BEI_WANG_LU,"_ID="+id,null);    if(rows>0)    {        return true;    }    return  false;}

/** * 删除表里所有数据 */public  synchronized boolean  deleteJiBuAndAdd(JiBu jiBu){    int  rows=  MyApplication.getWriteableInstance().delete(SqlLiteOpHelper.WALK_COUNT,null,null);        if(rows>0)        return true;    return  false;}

/** * 修改表里面的数据 根据id */public boolean upDateJiBu(JiBu jiBu){    ContentValues contentValues=new ContentValues();    contentValues.put("allcount",jiBu.getCount());    contentValues.put("lastdate",jiBu.getLastDate());    int  rows=  MyApplication.getWriteableInstance().update(SqlLiteOpHelper.WALK_COUNT,contentValues,"_ID=1",null);    if (rows > 0) {        return true;    }    return false;}

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