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1、首先先建立一個DatabaseHelper類,繼承自SQLiteOpenHelper,用于建立數據庫,并可更新數據庫例如我新建了兩張表
public class DatabaseHelper extends SQLiteOpenHelper {
private static DatabaseHelper _databaseHelper;
private static final String TAG = DatabaseHelper.class.getSimpleName();
public synchronized static DatabaseHelper getInstance(Context context)
{
if(_databaseHelper==null)
{
_databaseHelper = new DatabaseHelper(context,"cgjlb",null,2);
}
return _databaseHelper;
}
public synchronized static void destoryInstance(){
if(_databaseHelper!=null){
_databaseHelper=null;
public DatabaseHelper(@Nullable Context context, @Nullable String name, @Nullable SQLiteDatabase.CursorFactory factory, int version) {
super(context, name, factory, version);
@Override
public void onCreate(SQLiteDatabase sqLiteDatabase) {
//主表記錄
String sql = "create table t_share(_id integer primary key autoincrement,sharenum text,sharename text,shareprice real,sharelastprice real,addtime text,uptime text,bl real)";
sqLiteDatabase.execSQL(sql);
//記錄歷史表
sql = "create table t_sharehis(_id integer primary key autoincrement,shareid integer, shareprice real,uptime text)";
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
Log.d(TAG, "onUpgrade: upddatabase");
sqLiteDatabase.execSQL("drop table t_share");
sqLiteDatabase.execSQL("drop table t_sharehis");
onCreate(sqLiteDatabase);
}
2、編寫數據庫具體操作類、增刪改查我都寫了
public class ShareDbService {
SQLiteDatabase db = null;
DatabaseHelper databaseHelper;
private static final String TAG = ShareDbService.class.getSimpleName();
public ShareDbService(Context context) {
databaseHelper = DatabaseHelper.getInstance(context);
db = databaseHelper.getWritableDatabase();
}
public void addShareInfo(ShareBean shareBean)
{
int Id = getShareId(shareBean.getShareNum());
if(Id==-1) {
ContentValues values = new ContentValues();
values.put("sharenum", shareBean.getShareNum());
values.put("sharename", shareBean.getShareName());
values.put("shareprice", shareBean.getSharePrice());
values.put("sharelastprice", shareBean.getShareLastPrice());
values.put("uptime", shareBean.getUptime());
values.put("addtime",shareBean.getAddtime());
double shareprice = shareBean.getSharePrice();
double sharelastprice = shareBean.getShareLastPrice();
double bl = (sharelastprice-shareprice)/shareprice*100;
values.put("bl", new DecimalFormat("0.00").format(bl));
db = databaseHelper.getWritableDatabase();
db.insert("t_share", null, values);
ShareHisBean shareHisBean = new ShareHisBean();
shareHisBean.setShareId(getShareId(shareBean.getShareNum()));
shareHisBean.setSharePrice(shareBean.getSharePrice());
shareHisBean.setUpTime(shareBean.getUptime());
addShareHis(shareHisBean);
db.close();
}
private void addShareHis(ShareHisBean shareHisBean){
ContentValues values = new ContentValues();
values.put("shareid", shareHisBean.getShareId());
values.put("shareprice", shareHisBean.getSharePrice());
values.put("uptime", shareHisBean.getUptime());
db.insert("t_sharehis", null, values);
db.close();
public void refreshShare(ShareHisBean shareHisBean,double sharePrice){
try {
//更新信息主表
values.put("uptime", shareHisBean.getUptime());
values.put("sharelastprice", shareHisBean.getSharePrice());
String[] args = {String.valueOf(shareHisBean.getShareId())};
double sharelastprice = shareHisBean.getSharePrice();
double bl = (sharelastprice - sharePrice) / sharePrice * 100;
values.put("bl", bl);
db.update("t_share", values, "_Id=?", new String[]{String.valueOf(shareHisBean.getShareId())});
//添加記錄
values = new ContentValues();
values.put("shareid", shareHisBean.getShareId());
values.put("shareprice", shareHisBean.getSharePrice());
db.insert("t_sharehis", null, values);
}catch(Exception ex){
ex.printStackTrace();
finally {
public void delShare(String Id){
db.delete("t_share","_Id=?",new String[]{Id});
db.delete("t_sharehis","shareid=?",new String[]{Id});
private int getShareId(String shareNum) {
db = databaseHelper.getReadableDatabase();
String sql = "select _Id from t_share where sharenum='" + shareNum + "'";
int Id = -1;
Cursor cursor = db.rawQuery(sql, null);
if (cursor != null) {
while (cursor.moveToNext()){
Id = cursor.getInt(0);
}
cursor.close();
return Id;
public List<ShareBean> getShareList(){
List<ShareBean> shareBeans = new ArrayList<>();
String sql = "select _id,sharenum,sharename,shareprice,sharelastprice,uptime,addtime,bl from t_share order by _Id desc";
ShareBean shareBean = new ShareBean();
shareBean.set_Id(cursor.getInt(0));
shareBean.setShareNum(cursor.getString(1));
shareBean.setShareName(cursor.getString(2));
shareBean.setSharePrice(cursor.getDouble(3));
shareBean.setShareLastPrice(cursor.getDouble(4));
shareBean.setUptime(cursor.getString(5));
shareBean.setAddtime(cursor.getString(6));
shareBean.setBl(cursor.getDouble(7));
shareBeans.add(shareBean);
return shareBeans;
public List<ShareHisBean> getShareListHis(int ShareId){
List<ShareHisBean> shareHisBeans = new ArrayList<>();
String sql = "select _id,shareid,shareprice,uptime from t_sharehis where shareid='"+String.valueOf(ShareId)+"' order by _id desc";
ShareHisBean shareHisBean = new ShareHisBean();
shareHisBean.set_Id(cursor.getInt(0));
shareHisBean.setShareId(cursor.getInt(1));
shareHisBean.setSharePrice(cursor.getDouble(2));
shareHisBean.setUpTime(cursor.getString(3));
shareHisBeans.add(shareHisBean);
return shareHisBeans;
public ShareBean getShareInfo(int ShareId) {
ShareBean shareBean = new ShareBean();
//_id integer primary key autoincrement,sharenum text,sharename text,shareprice real,sharelastprice real,addtime text,uptime text,bl real
String sql = "select _id,sharenum,sharename,shareprice,sharelastprice,addtime,uptime,bl from t_share where _Id='"+String.valueOf(ShareId)+"'";
if (cursor.moveToNext()){
shareBean.setAddtime(cursor.getString(5));
shareBean.setUptime(cursor.getString(6));
return shareBean;
}
3、實際中的應用,就舉一個例子吧,數據庫操作不用開新線程,直接在主線程里弄就行
ShareDbService shareDbService = new ShareDbService(getContext());
shareDbService.delShare(String.valueOf(shareBean.get_Id()));
4、需要注意的是SQLite不支持多線程,最好是能批量修改,否則很麻煩,如果一定要多線程 ,比如循環請求網絡更新數據庫時,可以使用CountDownLatch,先將數據弄在一個集合里,等子線程全部執行完成后,再更新數據庫。此方法具體應用如下
先聲明一個變量
CountDownLatch latch;
實際應用代碼
//設置多線程 個數,一共用多少個線程一定要寫清楚,后面是要減的。
latch = new CountDownLatch(count);
for (int i = 0; i < count; i++) {
new Thread(()-> {
try {
//網絡請求等操作
} catch (Exception e) {
e.printStackTrace();
} finally {
//這里會自動減1操作,一定要寫。
latch.countDown();
}
}).start();
};
try {
latch.await();
//最后執行主程序,比如更新數據庫
Toast.makeText(getContext(), "刷新成功", Toast.LENGTH_SHORT).show();
} catch (InterruptedException e) {
e.printStackTrace();
}
原文鏈接:https://www.cnblogs.com/youyuan1980/p/16185784.html
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