我在连接数据库时遇到了一些麻烦。所以我有一个名为HealthySizing的数据库，这也是文件的名称，没有像.sqlite3或.db那样的扩展名，这个表有你需要的元表，还有一个名为Shirts的表， 6列，但它没有任何ID列。此数据库位于我的资源文件夹中。因此，当我运行我的应用程序时，我得到的唯一错误是它无法创建或打开数据库。我在DBHelper.java，MainActivity.java和activity_main.xml下面发布了。如果有人可以帮助我解决这个问题并让数据从数据库中出来，那就太好了。
package com.example.ListViewFromSQLiteDB;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Locale;
public class DBHelper extends SQLiteOpenHelper {
private static final String DATABASE_PATH = "/data/data/com.example.ListViewFromSQLiteDB/databases";
private static final String DATABASE_NAME = "HealthySizing";
private static final int SCHEMA_VERSION = 3;
public SQLiteDatabase dbSqlite;
private final Context myContext;
public static String tableName = "Shirts";
public DBHelper(Context context) {
super(context, DATABASE_NAME, null, SCHEMA_VERSION);
this.myContext = context;
}
public void onCreate(SQLiteDatabase db) {
}
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
public void createDatabase() {
createDB();
}
private void createDB() {
boolean dbExist = DBExists();
if (!dbExist) {
this.getReadableDatabase();
copyDBFromResource();
}
}
private boolean DBExists() {
SQLiteDatabase db = null;
try {
String databasePath = DATABASE_PATH + DATABASE_NAME;
db = SQLiteDatabase.openDatabase(databasePath, null, SQLiteDatabase.OPEN_READWRITE);
db.setLocale(Locale.getDefault());
db.setLockingEnabled(true);
db.setVersion(1);
} catch (SQLiteException e) {
Log.e("SqlHelper", "database not found");
}
if (db != null) {
db.close();
}
return db != null ? true : false;
}
private void copyDBFromResource() {
InputStream inputStream = null;
OutputStream outStream = null;
String dbFilePath = DATABASE_PATH + DATABASE_NAME;
try {
inputStream = myContext.getAssets().open(DATABASE_NAME);
outStream = new FileOutputStream(dbFilePath);
byte[] buffer = new byte[1024];
int length;
while((length = inputStream.read(buffer)) > 0) {
outStream.write(buffer, 0, length);
}
outStream.flush();
outStream.close();
inputStream.close();
} catch (IOException e) {
throw new Error("Problem copying database from resource file");
}
}
@Override
public synchronized void close() {
if (dbSqlite != null) {
dbSqlite.close();
}
super.close();
}
}package com.example.ListViewFromSQLiteDB;
import java.sql.SQLException;
import java.util.ArrayList;
import android.app.ListActivity;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.os.Bundle;
import android.util.Log;
import android.widget.ArrayAdapter;
import android.widget.TextView;
public class MainActivity extends ListActivity {
private ArrayList<String> results = new ArrayList<String>();
private String tableName = DBHelper.tableName;
private SQLiteDatabase newDB;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
DBHelper dbHelper = new DBHelper(this.getApplicationContext());
openAndQueryDatabase();
displayResultList();
}
private void displayResultList() {
TextView tView = new TextView(this);
//tView.setText("This data is retrieved from the database and only 4 " +
// "of the results are displayed");
getListView().addHeaderView(tView);
setListAdapter(new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, results));
getListView().setTextFilterEnabled(true);
}
private void openAndQueryDatabase() {
try {
DBHelper dbHelper = new DBHelper(this.getApplicationContext());
newDB = dbHelper.getWritableDatabase();
Cursor c = newDB.rawQuery("SELECT Name FROM " +
tableName, null);
if (c != null ) {
if (c.moveToFirst()) {
do {
String name = c.getString(c.getColumnIndex("Name"));
results.add(name);
} while (c.moveToNext());
}
//c.close();
}
//String name = c.getString(c.getInt(1));
//results.add(name);
//c.close();
}
catch (SQLiteException se ) {
Log.e(getClass().getSimpleName(), "Could not create or Open the database");
}
finally {
try {
if (newDB != null){
newDB.execSQL("DELETE FROM " + tableName );
newDB.close();
}
} catch (SQLiteException e) {
e.printStackTrace();
}
}
}
}04-11 19:26:00.728 1933-1933/com.example.ListViewFromSQLiteDB I/art﹕ Not late-enabling -Xcheck:jni (already on)
04-11 19:26:00.798 1933-1933/com.example.ListViewFromSQLiteDB E/MainActivity﹕ Could not create or Open the database
04-11 19:26:00.838 1933-1945/com.example.ListViewFromSQLiteDB W/art﹕ Suspending all threads took: 8.691ms
04-11 19:26:00.854 1933-1945/com.example.ListViewFromSQLiteDB I/art﹕ Background sticky concurrent mark sweep GC freed 1680(81KB) AllocSpace objects, 0(0B) LOS objects, 0% free, 689KB/689KB, paused 12.131ms total 28.447ms
04-11 19:26:00.890 1933-1948/com.example.ListViewFromSQLiteDB D/OpenGLRenderer﹕ Render dirty regions requested: true
04-11 19:26:00.894 1933-1933/com.example.ListViewFromSQLiteDB D/﹕ HostConnection::get() New Host Connection established 0xae0f8ee0, tid 1933
04-11 19:26:00.902 1933-1933/com.example.ListViewFromSQLiteDB D/Atlas﹕ Validating map...
04-11 19:26:00.955 1933-1948/com.example.ListViewFromSQLiteDB D/﹕ HostConnection::get() New Host Connection established 0xae0f8f90, tid 1948
04-11 19:26:00.970 1933-1948/com.example.ListViewFromSQLiteDB I/OpenGLRenderer﹕ Initialized EGL, version 1.4
04-11 19:26:00.983 1933-1948/com.example.ListViewFromSQLiteDB D/OpenGLRenderer﹕ Enabling debug mode 0
04-11 19:26:00.998 1933-1948/com.example.ListViewFromSQLiteDB W/EGL_emulation﹕ eglSurfaceAttrib not implemented
04-11 19:26:00.999 1933-1948/com.example.ListViewFromSQLiteDB W/OpenGLRenderer﹕ Failed to set EGL_SWAP_BEHAVIOR on surface 0xa6c83c00, error=EGL_SUCCESS
04-11 19:26:12.961 1933-1933/com.example.ListViewFromSQLiteDB E/MainActivity﹕ Could not create or Open the database
04-11 19:26:13.103 1933-1948/com.example.ListViewFromSQLiteDB W/EGL_emulation﹕ eglSurfaceAttrib not implemented
04-11 19:26:13.103 1933-1948/com.example.ListViewFromSQLiteDB W/OpenGLRenderer﹕ Failed to set EGL_SWAP_BEHAVIOR on surface 0xa6c83c00, error=EGL_SUCCESS
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:weightSum="1">
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
android:layout_weight="0.12" />
</LinearLayout>