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我正在使用的“资产/数据库”文件夹中我自己的数据的基础上，我已经给出的.java数据库文件的路径，如何从Android上的SQLite数据库检索数据？
我想执行的启动按钮的活动和代码是：
GreTest.java
package andro.Alkonsys.example;
import android.app.Activity;
import android.database.Cursor;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.RadioButton;
import android.widget.TextView;
import andro.Alkonsys.example.DataBaseHelper;
public class GreTest extends Activity {
public Button start_test1;
public Button next;
public TextView Question;
public RadioButton Option_first;
public RadioButton Option_second;
public RadioButton Option_third;
public RadioButton Option_forth;
private DataBaseHelper db;
@Override
public void onCreate(Bundle SaveInstanceState)
{
super.onCreate(SaveInstanceState);
setContentView(R.layout.gretest);
start_test1=(Button)findViewById(R.id.btnstart_test);
next=(Button)findViewById(R.id.btnnextquastion);
Question=(TextView)findViewById(R.id.testquestion);
Option_first=(RadioButton)findViewById(R.id.radio_first);
Option_second=(RadioButton)findViewById(R.id.radio_second);
Option_third=(RadioButton)findViewById(R.id.radio_third);
Option_forth=(RadioButton)findViewById(R.id.radio_forth);
start_test1.setOnClickListener(new OnClickListener()
{
//int Qno;
//Cursor c;
public void onClick(View v){
// TODO Auto-generated method stub
Cursor c = db.getData();
//if(c.moveToFirst())
//{
Question.setText(c.getString(2));
//Option_first.setText(c.getString(3));
//}
//Qno += 1;
}
});
}
}
/* private OnClickListener radio_listener = new OnClickListener() {
public void onClick(View v) {
// Perform action on clicks
RadioButton rb = (RadioButton) v;
Toast.makeText(GreTest.this, rb.getText(), Toast.LENGTH_SHORT).show();
}}; */
和我的数据库文件是有所有的查询和声明：
DataBaseHelper.java
package andro.Alkonsys.example;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
public class DataBaseHelper extends SQLiteOpenHelper
{
//The Android's default system path of your application database.
private static String DB_PATH = "/data/data/+andro.Alkonsys.example()+/Database/";
private static final String DATABASE_NAME ="GreSatDbase";
//The version of the database that this class understands
private static final int DATABASE_VERSION = 1;
//private SQLiteDatabase myDataBase;
private final Context myContext;
private SQLiteDatabase db;
/**
* Constructor
* Takes and keeps a reference of the passed context in order to access to the application assets and resources.
* @param context
*/
public DataBaseHelper(Context context)
{
super(context, DATABASE_NAME, null, DATABASE_VERSION);
myContext = context;
}
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");
}
}
}
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)
{
// TODO Auto-generated method stub
String sql = myContext.getString(R.string.satgreDbase_onUpgrade);
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 Qno=1;
// TODO Auto-generated method stub
//Creates the query String. Query is static in DataCursor inner class
String sql = "SELECT Question FROM PracTestAlgebra WHERE Qno = ?";
//Create an array of String to specify values for ?'s in the sql Query
String sqlArgs[] = new String[]{Integer.toString(Qno)};
//Creates a cursor using the SQLiteDatabase object's rawQuery method
Cursor c = db.rawQuery(sql,sqlArgs);
//The cursor is returned
return c;
}
}
我想从我的数据库中检索数据，所以请帮助我。
感谢