我尝试从准备好的SQLite数据库中获取数据并将其写入TextView但我收到此错误。
这是我的DataBaseHelperClass.java：
package com.ehliyet;
import java.io.File;
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.SQLiteOpenHelper;
public class DataBaseHelperClass extends SQLiteOpenHelper{
//The Android's default system path of your application database.
private static String DB_PATH = "/data/data/com.ehliyet/assets/";
// Data Base Name.
private static final String DATABASE_NAME = "test.db";
// Data Base Version.
private static final int DATABASE_VERSION = 1;
// Table Names of Data Base.
static final String TABLE_Name = "questions";
public Context context;
static SQLiteDatabase sqliteDataBase;
/**
* Constructor
* Takes and keeps a reference of the passed context in order to access to the application assets and resources.
* @param context
* Parameters of super() are 1. Context
* 2. Data Base Name.
* 3. Cursor Factory.
* 4. Data Base Version.
*/
public DataBaseHelperClass(Context context) {
super(context, DATABASE_NAME, null ,DATABASE_VERSION);
this.context = context;
}
/**
* Creates a empty database on the system and rewrites it with your own database.
* 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.
* */
public void createDataBase() throws IOException{
//check if the database exists
boolean databaseExist = checkDataBase();
if(databaseExist){
// Do Nothing.
}else{
this.getWritableDatabase();
copyDataBase();
}// end if else dbExist
} // end createDataBase().
/**
* 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
*/
public boolean checkDataBase(){
File databaseFile = new File(DB_PATH + DATABASE_NAME);
return databaseFile.exists();
}
/**
* Copies your database from your local assets-folder to the just created empty database in the
* system folder, from where it can be accessed and handled.
* This is done by transferring byte stream.
* */
private void copyDataBase() throws IOException{
//Open your local db as the input stream
InputStream myInput = context.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 input file to the output file
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();
}
/**
* This method opens the data base connection.
* First it create the path up till data base of the device.
* Then create connection with data base.
*/
public void openDataBase() throws SQLException{
//Open the database
String myPath = DB_PATH + DATABASE_NAME;
sqliteDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
}
/**
* This Method is used to close the data base connection.
*/
@Override
public synchronized void close() {
if(sqliteDataBase != null)
sqliteDataBase.close();
super.close();
}
/**
* Apply your methods and class to fetch data using raw or queries on data base using
* following demo example code as:
*/
public String getDataDB(){
String query = "select QLect From questions";
Cursor cursor = sqliteDataBase.rawQuery(query, null);
String userName = null;
if(cursor.getCount()>0){
if(cursor.moveToFirst()){
do{
userName = cursor.getString(0);
}while (cursor.moveToNext());
}
}
return userName;
}
@Override
public void onCreate(SQLiteDatabase db) {
// No need to write the create table query.
// As we are using Pre built data base.
// Which is ReadOnly.
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// No need to write the update table query.
// As we are using Pre built data base.
// Which is ReadOnly.
// We should not update it as requirements of application.
}
}
MainActivity.Java：
package com.ehliyet;
import android.app.Activity;
import android.database.Cursor;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btBasla = (Button)findViewById(R.id.button1);
btBasla.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
DataBaseHelperClass myDBHelper = new DataBaseHelperClass(MainActivity.this);
myDBHelper.openDataBase();
String textdt = myDBHelper.getDataDB();
myDBHelper.close();
TextView txtSoru = (TextView)findViewById(R.id.textView1);
txtSoru.setText(textdt);
}
});
}
}
单击按钮时，这是LogCat：
08-09 18:46:38.128: E/SQLiteLog(1172): (14) cannot open file at line 30174 of [00bb9c9ce4]
08-09 18:46:38.128: E/SQLiteLog(1172): (14) os_unix.c:30174: (2) open(/data/data/com.ehliyet/assets/test.db) -
08-09 18:46:38.178: E/SQLiteDatabase(1172): Failed to open database '/data/data/com.ehliyet/assets/test.db'.
08-09 18:46:38.178: E/SQLiteDatabase(1172): android.database.sqlite.SQLiteCantOpenDatabaseException: unknown error (code 14): Could not open database
08-09 18:46:38.178: E/SQLiteDatabase(1172): at android.database.sqlite.SQLiteConnection.nativeOpen(Native Method)
08-09 18:46:38.178: E/SQLiteDatabase(1172): at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:209)
08-09 18:46:38.178: E/SQLiteDatabase(1172): at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:193)
08-09 18:46:38.178: E/SQLiteDatabase(1172): at android.database.sqlite.SQLiteConnectionPool.openConnectionLocked(SQLiteConnectionPool.java:463)
08-09 18:46:38.178: E/SQLiteDatabase(1172): at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:185)
08-09 18:46:38.178: E/SQLiteDatabase(1172): at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:177)
08-09 18:46:38.178: E/SQLiteDatabase(1172): at android.database.sqlite.SQLiteDatabase.openInner(SQLiteDatabase.java:804)
08-09 18:46:38.178: E/SQLiteDatabase(1172): at android.database.sqlite.SQLiteDatabase.open(SQLiteDatabase.java:789)
08-09 18:46:38.178: E/SQLiteDatabase(1172): at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:694)
08-09 18:46:38.178: E/SQLiteDatabase(1172): at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:669)
08-09 18:46:38.178: E/SQLiteDatabase(1172): at com.ehliyet.DataBaseHelperClass.openDataBase(DataBaseHelperClass.java:101)
08-09 18:46:38.178: E/SQLiteDatabase(1172): at com.ehliyet.MainActivity$1.onClick(MainActivity.java:23)
08-09 18:46:38.178: E/SQLiteDatabase(1172): at android.view.View.performClick(View.java:4084)
08-09 18:46:38.178: E/SQLiteDatabase(1172): at android.view.View$PerformClick.run(View.java:16966)
08-09 18:46:38.178: E/SQLiteDatabase(1172): at android.os.Handler.handleCallback(Handler.java:615)
08-09 18:46:38.178: E/SQLiteDatabase(1172): at android.os.Handler.dispatchMessage(Handler.java:92)
08-09 18:46:38.178: E/SQLiteDatabase(1172): at android.os.Looper.loop(Looper.java:137)
08-09 18:46:38.178: E/SQLiteDatabase(1172): at android.app.ActivityThread.main(ActivityThread.java:4745)
08-09 18:46:38.178: E/SQLiteDatabase(1172): at java.lang.reflect.Method.invokeNative(Native Method)
08-09 18:46:38.178: E/SQLiteDatabase(1172): at java.lang.reflect.Method.invoke(Method.java:511)
08-09 18:46:38.178: E/SQLiteDatabase(1172): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
08-09 18:46:38.178: E/SQLiteDatabase(1172): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
08-09 18:46:38.178: E/SQLiteDatabase(1172): at dalvik.system.NativeStart.main(Native Method)
08-09 18:46:38.178: D/AndroidRuntime(1172): Shutting down VM
08-09 18:46:38.188: W/dalvikvm(1172): threadid=1: thread exiting with uncaught exception (group=0x40a13300)
08-09 18:46:38.258: E/AndroidRuntime(1172): FATAL EXCEPTION: main
08-09 18:46:38.258: E/AndroidRuntime(1172): android.database.sqlite.SQLiteCantOpenDatabaseException: unknown error (code 14): Could not open database
08-09 18:46:38.258: E/AndroidRuntime(1172): at android.database.sqlite.SQLiteConnection.nativeOpen(Native Method)
08-09 18:46:38.258: E/AndroidRuntime(1172): at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:209)
08-09 18:46:38.258: E/AndroidRuntime(1172): at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:193)
08-09 18:46:38.258: E/AndroidRuntime(1172): at android.database.sqlite.SQLiteConnectionPool.openConnectionLocked(SQLiteConnectionPool.java:463)
08-09 18:46:38.258: E/AndroidRuntime(1172): at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:185)
08-09 18:46:38.258: E/AndroidRuntime(1172): at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:177)
08-09 18:46:38.258: E/AndroidRuntime(1172): at android.database.sqlite.SQLiteDatabase.openInner(SQLiteDatabase.java:804)
08-09 18:46:38.258: E/AndroidRuntime(1172): at android.database.sqlite.SQLiteDatabase.open(SQLiteDatabase.java:789)
08-09 18:46:38.258: E/AndroidRuntime(1172): at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:694)
08-09 18:46:38.258: E/AndroidRuntime(1172): at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:669)
08-09 18:46:38.258: E/AndroidRuntime(1172): at com.ehliyet.DataBaseHelperClass.openDataBase(DataBaseHelperClass.java:101)
08-09 18:46:38.258: E/AndroidRuntime(1172): at com.ehliyet.MainActivity$1.onClick(MainActivity.java:23)
08-09 18:46:38.258: E/AndroidRuntime(1172): at android.view.View.performClick(View.java:4084)
08-09 18:46:38.258: E/AndroidRuntime(1172): at android.view.View$PerformClick.run(View.java:16966)
08-09 18:46:38.258: E/AndroidRuntime(1172): at android.os.Handler.handleCallback(Handler.java:615)
08-09 18:46:38.258: E/AndroidRuntime(1172): at android.os.Handler.dispatchMessage(Handler.java:92)
08-09 18:46:38.258: E/AndroidRuntime(1172): at android.os.Looper.loop(Looper.java:137)
08-09 18:46:38.258: E/AndroidRuntime(1172): at android.app.ActivityThread.main(ActivityThread.java:4745)
08-09 18:46:38.258: E/AndroidRuntime(1172): at java.lang.reflect.Method.invokeNative(Native Method)
08-09 18:46:38.258: E/AndroidRuntime(1172): at java.lang.reflect.Method.invoke(Method.java:511)
08-09 18:46:38.258: E/AndroidRuntime(1172): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
08-09 18:46:38.258: E/AndroidRuntime(1172): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
08-09 18:46:38.258: E/AndroidRuntime(1172): at dalvik.system.NativeStart.main(Native Method)
08-09 18:46:40.008: I/Process(1172): Sending signal. PID: 1172 SIG: 9
答案 0 :(得分：3)
任何Android设备上都没有名为/data/data/com.ehliyet/assets/test.db的文件，包括您的任何设备。 assets/目录位于开发计算机上，而不是Android中。
请use SQLiteAssetHelper了解一个经过测试的解决方案，用于在您的应用程序中打包数据库。