我想从数据库中检索数据。 那么我的代码应该改变什么呢？ 我的班级是
public class Assessment extends Activity
{
private static String DB_PATH = "/data/data/+com.comply.assessment()+/Database/";
private static final String DATABASE_NAME = "LMS_MST";
SQLiteDatabase db;
TextView mod_code,qst_code,question_id,question,qst_opt1,qst_opt2,qst_opt3,qst_opt4,correct_ans,user_ans;
Cursor cursor;
private Button start_test;
@SuppressWarnings("unused")
ListView li;
ArrayList<String> it_info;
ArrayAdapter<String> aa;
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
db= openOrCreateDatabase(AppConstants.DATABASE_NAME, Context.MODE_PRIVATE, null);
db.close();
initControls();
}
protected void initControls() {
// TODO Auto-generated method stub
start_test=(Button)findViewById(R.id.start_test);
start_test.setOnClickListener(new OnClickListener()
{
public void onClick(View v)
{
Intent intent1= new Intent(Assessment.this,Get_Assessment.class);
startActivity(intent1);
}
});
}
protected void DoWork()
{
SQLiteDatabase db= null;
String TableName = "lms_mst";
try {
db = this.openOrCreateDatabase("LMS_MST", MODE_PRIVATE,
null);
db.execSQL("DROP TABLE IF EXISTS lms_mst" );
db.execSQL("create table IF NOT EXISTS "
+AppConstants.TABLE_NAME
+"(id INTEGER primary key AUTOINCREMENT,qst_mod_code TEXT,qst_prg_code TEXT,qst_question TEXT,qst_code TEXT,qst_opt1 TEXT,qst_opt2 TEXT,qst_opt3 TEXT,qst_opt4 TEXT,qst_opt01 TEXT,qst_opt02 TEXT,qst_opt03 TEXT,qst_opt04 TEXT,qst_corctopt TEXT,user_code TEXT,qst_company_code TEXT,qst_Marks TEXT);");
}
catch(Exception e) {
Log.e("Error", "Error", e);
} finally {
if (db != null)
db.close();
}
}
}
我的dbhelper类是
public class MyOpenHelper extends SQLiteOpenHelper
{
private static String DB_PATH = "/data/data/+com.comply.assessment()+/databases/";
private static final String DATABASE_NAME = "LMS_MST";
private static final int DATABASE_VERSION = 1;
private SQLiteDatabase db;
private final Context myContext;
public static final String TABLE_NAME = "LMS_MST";
private static final String COLUMN_ID = "_id";
private static final String QST_CODE="QST_CODE";
private static final String QST_PRG_CODE="QST_PRG_CODE";
private static final String QST_MOD_CODE="QST_MOD_CODE";
private static final String QST_QUESTION="QST_QUESTION";
private static final String QST_OPT1="QST_OPT1";
private static final String QST_OPT2="QST_OPT2";
private static final String QST_OPT3="QST_OPT3";
private static final String QST_OPT4="QST_OPT4";
private static final String QST_OPT01="QST_OPT01";
private static final String QST_OPT02="QST_OPT02";
private static final String QST_OPT03="QST_OPT03";
private static final String QST_OPT04="QST_OPT04";
private static final String QST_CORCTOPT="QST_CORCTOPT";
private static final String USER_CODE="USER_CODE";
public MyOpenHelper(Context context)
{
super(context,DATABASE_NAME,null,1);
this.myContext = context;
}
/* @Override
public void onCreate(SQLiteDatabase db)
{
db.execSQL("CREATE TABLE " + TABLE_NAME
+ "(_id INTEGER PRIMARY KEY AUTOINCREMENT, "
+ QST_CODE+ " TEXT, "
+ QST_PRG_CODE+ " TEXT" + QST_MOD_CODE+ " TEXT" + QST_QUESTION+ " TEXT" +
QST_OPT1+ " TEXT" + QST_OPT2+ " TEXT" + QST_OPT3+ " TEXT" + QST_OPT4+ " TEXT" +
QST_OPT01+ " TEXT" + QST_OPT02+ " TEXT" + QST_OPT03+ " TEXT" + QST_OPT04+ " TEXT" + QST_CORCTOPT+ " TEXT" + USER_CODE+ " TEXT" + ");");
}*/
public void createDataBase() throws IOException{
boolean dbExist = checkDataBase();
if(dbExist){
//do nothing - database already exist
}else{
//By calling this method and empty database will be created into the default system path
//of your application so we are gonna be able to overwrite that database with our database.
this.getReadableDatabase();
try {
copyDataBase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
/**
* Check if the database already exist to avoid re-copying the file each time you open the application.
* @return true if it exists, false if it doesn't
*/
private boolean checkDataBase(){
SQLiteDatabase checkDB = null;
try{
String myPath = DB_PATH + DATABASE_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}catch(SQLiteException e){
//database does't exist yet.
}
if(checkDB != null){
checkDB.close();
}
return checkDB != null ? true : false;
}
private void copyDataBase() throws IOException
{
//Open your local db as the input stream
InputStream myInput = myContext.getAssets().open(DATABASE_NAME);
// Path to the just created empty db
String outFileName = DB_PATH + DATABASE_NAME;
//Open the empty db as the output stream
OutputStream myOutput = new FileOutputStream(outFileName);
//transfer bytes from the inputfile to the outputfile
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer))>0)
{
myOutput.write(buffer, 0, length);
}
//Close the streams
myOutput.flush();
myOutput.close();
myInput.close();
}
public void openDataBase() throws SQLException
{
//Open the database
String myPath = DB_PATH + DATABASE_NAME;
db = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}
@Override
public synchronized void close()
{
if(db != null)
db.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db)
{
// TODO Auto-generated method stub
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{
String sql = myContext.getString(R.string.app_name);
db.beginTransaction();
try
{
db.execSQL(sql);
db.setTransactionSuccessful();
}catch(SQLException e)
{
System.out.println("Error Upgrading tables...");
}
finally
{
db.endTransaction();
}
onCreate(db);
}
public Cursor getData()
{ int qst_code=1;
//Creates the query String. Query is static in DataCursor inner class
String sql = "SELECT * FROM lms_mst_questionbank ";
//Create an array of String to specify values for ?'s in the sql Query
String sqlArgs[] = new String[]{Integer.toString(qst_code) };
//Creates a cursor using the SQLiteDatabase object's rawQuery method
Cursor c = db.rawQuery(sql,sqlArgs);
//The cursor is returned
return c;
/*Cursor cursor = getReadableDatabase().
rawQuery("select * from lms_mst_questionbank where _id = ?", new String[] { COLUMN_ID });
return cursor;*/
}
}
任何类型的链接都会很明显。
答案 0 :(得分：0)
当我向应用程序添加数据库支持时，我总是引用this post。希望它也能帮到你！
答案 1 :(得分：0)
公共类ListActivity扩展了Activity {
List<Question> quesList;
DataBaseHandler db = new DataBaseHandler(this);
ArrayAdapter<String>adapter;
ArrayList<HashMap<String,String>>alist;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list);
ListView lv = (ListView)findViewById(R.id.secondlist);
alist = new ArrayList<HashMap<String,String>>();
quesList = db.getAllQuestions();
for(int i=0;i<db.rowcount();i++){
HashMap<String,String>hm = new HashMap<String,String>();
hm.put("question", quesList.get(i).getQuestion());
hm.put("rightans", quesList.get(i).getCorrectoption());
alist.add(hm);
}
String[]from = {"question","rightans"};
int[]to = {R.id.listtext,R.id.listtextans};
SimpleAdapter adapter = new SimpleAdapter(getApplicationContext(), alist, R.layout.listitemoflist, from, to);
lv.setAdapter(adapter);
/*List<String> listTitle = new ArrayList<String>();
for (int i = 0; i < quesList.size(); i++) {
listTitle.add(i, quesList.get(i).getQuestion());
listTitle.add(quesList.get(i).getCorrectoption());
}
adapter = new ArrayAdapter<String>(this, R.layout.listitemoflist,R.id.listtext, listTitle);
lv.setAdapter(adapter);*/
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.list, menu);
return true;
}
}
答案 2 :(得分：0)
看到这个GIST的数据库。我认为对你有益:) https://gist.github.com/pookie13/952086a7b78989246c01
答案 3 :(得分：0)
String uname = username.getText().toString();
String pword = password.getText().toString();
String cpword = cpassword.getText().toString();
if(uname.equals("") && pword.equals("") && cpword.equals("") ){
Toast.makeText(getApplicationContext(), "failed updation", Toast.LENGTH_SHORT).show();
}
if(!pword.equals(cpword)){
Toast.makeText(getApplicationContext(), "Password does not match"
, Toast.LENGTH_SHORT).show();
}
else{
loginDataBaseAdapter.updateEntry(uname, pword);
Toast.makeText(getApplicationContext(), "Account Successfully Updated"
, Toast.LENGTH_SHORT).show();
Intent i = new Intent(UpdatePassword.this,
LoginActivity.class);
startActivity(i);
finish();
}