我已经制作了一个预制的，并试图从资产文件夹中使用它，但不断出错。
05-02 14:58:44.771: E/Database(573): sqlite3_open_v2("/data/data/com.MC.ChemPal/databases/ChemPaldb.db", &handle, 2, NULL) failed
05-02 14:58:44.792: E/AndroidRuntime(573): FATAL EXCEPTION: main
05-02 14:58:44.792: E/AndroidRuntime(573): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.MC.ChemPal/com.MC.ChemPal.sqlView}: android.database.sqlite.SQLiteException: unable to open database file
05-02 14:58:44.792: E/AndroidRuntime(573): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
05-02 14:58:44.792: E/AndroidRuntime(573): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
05-02 14:58:44.792: E/AndroidRuntime(573): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
05-02 14:58:44.792: E/AndroidRuntime(573): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
05-02 14:58:44.792: E/AndroidRuntime(573): at android.os.Handler.dispatchMessage(Handler.java:99)
05-02 14:58:44.792: E/AndroidRuntime(573): at android.os.Looper.loop(Looper.java:123)
05-02 14:58:44.792: E/AndroidRuntime(573): at android.app.ActivityThread.main(ActivityThread.java:3683)
05-02 14:58:44.792: E/AndroidRuntime(573): at java.lang.reflect.Method.invokeNative(Native Method)
05-02 14:58:44.792: E/AndroidRuntime(573): at java.lang.reflect.Method.invoke(Method.java:507)
05-02 14:58:44.792: E/AndroidRuntime(573): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
05-02 14:58:44.792: E/AndroidRuntime(573): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
05-02 14:58:44.792: E/AndroidRuntime(573): at dalvik.system.NativeStart.main(Native Method)
05-02 14:58:44.792: E/AndroidRuntime(573): Caused by: android.database.sqlite.SQLiteException: unable to open database file
05-02 14:58:44.792: E/AndroidRuntime(573): at android.database.sqlite.SQLiteDatabase.dbopen(Native Method)
05-02 14:58:44.792: E/AndroidRuntime(573): at android.database.sqlite.SQLiteDatabase.<init>(SQLiteDatabase.java:1849)
05-02 14:58:44.792: E/AndroidRuntime(573): at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:820)
05-02 14:58:44.792: E/AndroidRuntime(573): at com.MC.ChemPal.sqlStuff.openDatabase(sqlStuff.java:148)
05-02 14:58:44.792: E/AndroidRuntime(573): at com.MC.ChemPal.sqlView.onCreate(sqlView.java:20)
05-02 14:58:44.792: E/AndroidRuntime(573): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
05-02 14:58:44.792: E/AndroidRuntime(573): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
05-02 14:58:44.792: E/AndroidRuntime(573): ... 11 more
上面的日志猫与下面的代码一起使用我正在尝试使用我在 sqlite 浏览器中创建的数据库我添加了 android 元数据并且数据库中存在整数主键。每当我尝试做任何与我的数据库相关的事情时，它都会导致应用程序崩溃。
package com.MC.ChemPal;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import android.content.ContentValues;
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;
import android.util.Log;
public class sqlStuff extends SQLiteOpenHelper{
public static final String KEY_ROWID= "_id";
public static final String KEY_SYSNAME= "systematic_name";
public static final String KEY_MOLARMASS= "molar_mass";
public static final String KEY_GROUP = "groups";
public static final String KEY_MP ="melting_point";
public static final String KEY_BP ="boiling_point";
public static final String KEY_COMNAME="general_name";
public static final String KEY_CONELEMENTS="elements_included_C_H";
private SQLiteDatabase ChemPal;
private static String DATABASE_NAME = "ChemPaldb.db";
private static int DATABASE_VERSION = 1;
private String DATABASE_PATH = "/data/data/com.MC.ChemPal/databases/";
private static String DATABASE_TABLE = "ChemTable";
private SQLiteDatabase sampleDatabase;
private final Context androidContext;
/**
* Constructor
* Takes and keeps a reference of the passed context in order to access to the application assets and resources.
* @param context
*/
public sqlStuff(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
this.androidContext = context;
}
/**
* Creates a empty database on the system and rewrites it with your own database.
* */
public void createDatabase() throws IOException{
boolean dbExist = checkDatabase();
if(dbExist){
//do nothing - database already exist
}
else {
// Create a skeleton 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 = DATABASE_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;
}
/**
* 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 transfering bytestream.
* */
private void copyDatabase() throws IOException{
//Open your local db as the input stream
InputStream myInput = androidContext.getAssets().open(DATABASE_NAME);
// Path to the just created empty db
String outFileName = DATABASE_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 = DATABASE_PATH + DATABASE_NAME;
sampleDatabase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
}
@Override
public synchronized void close() {
if(sampleDatabase != null)
sampleDatabase.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: Write routines to remove and overwrite the database on an upgrade
db.execSQL("DROP TABLE IF EXISTS" + DATABASE_TABLE);
onCreate(db);
}
/***
* A sample function that returns a Cursor from the database. Should use the Data Provider pattern, but used for brevity
* @return
*/
public Cursor getUserTable() {
SQLiteDatabase db = getReadableDatabase();
Cursor cursor = db.rawQuery("SELECT * FROM User", null);
return cursor;
}
public long createEntry(String SYSNAME, String MOLMASS, String GROUP, String MP, String BP, String COMNAME, String CONELEMENTS){
//TODO Auto-generated method stub
try{
ContentValues cv = new ContentValues();
cv.put(KEY_SYSNAME, SYSNAME);
cv.put(KEY_MOLARMASS, MOLMASS);
cv.put(KEY_GROUP, GROUP);
cv.put(KEY_MP, MP);
cv.put(KEY_BP, BP);
cv.put(KEY_COMNAME, COMNAME);
cv.put(KEY_CONELEMENTS, CONELEMENTS);
return ChemPal.insert(DATABASE_TABLE, null, cv);
} catch (Exception e) {
String TAG = "my tag";
Log.e(TAG, e.toString());
return 0;
}
}
public String getData() {
// TODO Auto-generated method stub
String[] columns = new String[] { KEY_ROWID , KEY_SYSNAME , KEY_MOLARMASS ,KEY_GROUP ,
KEY_MP , KEY_BP , KEY_COMNAME , KEY_CONELEMENTS };
Cursor c = ChemPal.query(DATABASE_TABLE, columns, null, null, null, null, null);
String result = "";
int iRow = c.getColumnIndex(KEY_ROWID);
int iSysName = c.getColumnIndex(KEY_SYSNAME);
int iMolarMass = c.getColumnIndex(KEY_MOLARMASS);
int iGroup = c.getColumnIndex(KEY_GROUP);
int iMp = c.getColumnIndex(KEY_MP);
int iBp = c.getColumnIndex(KEY_BP);
int iCommonName = c.getColumnIndex(KEY_COMNAME);
int iElements = c.getColumnIndex(KEY_CONELEMENTS);
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
result = result + c.getString(iRow) + " " + c.getString(iSysName) + " " + c.getString(iMolarMass) + " " +c.getString(iGroup) +
" " + c.getString(iMp)+ " " + c.getString(iBp) + " "+ c.getString(iCommonName) + " " +c.getString(iElements) + "\n";
}
return result;
}
public String[] getIDSysName()
{
String[] result = new String[0];
try
{
String[] columns = new String[] {KEY_SYSNAME};
Cursor c = ChemPal.query(DATABASE_TABLE, columns, null, null, null, null, null);
Log.d("SqlDStuff", "Cursor count: "+c.getCount());
int iSysName = c.getColumnIndex(KEY_SYSNAME);
int i = 0;
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
i++;
}
result = new String[i];
i = 0;
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
result[i] = c.getString(iSysName);
i++;
}
}
catch(Exception e)
{
}
return result;
}
public String[] getIDGroup()
{
String[] result2 = new String[0];
try
{
String[] columns = new String[] { KEY_GROUP };
Cursor c = ChemPal.query(DATABASE_TABLE, columns, null, null, null, null, null);
int iGroup = c.getColumnIndex(KEY_GROUP);
int i = 0;
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
i++;
}
result2 = new String[i];
i = 0;
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
result2[i] = c.getString(iGroup);
i++;
}
}
catch(Exception e)
{
}
return result2;
}
public String[] getIDMP()
{
String[] result3 = new String[0];
try
{
String[] columns = new String[] { KEY_MP };
Cursor c = ChemPal.query(DATABASE_TABLE, columns, null, null, null, null, null);
int iMp = c.getColumnIndex(KEY_MP);
int i = 0;
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
i++;
}
result3 = new String[i];
i = 0;
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
result3[i] = c.getString(iMp);
i++;
}
}
catch(Exception e)
{
}
return result3;
}
public String[] getIDBP()
{
String[] result3 = new String[0];
try
{
String[] columns = new String[] { KEY_BP };
Cursor c = ChemPal.query(DATABASE_TABLE, columns, null, null, null, null, null);
int iBp = c.getColumnIndex(KEY_BP);
int i = 0;
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
i++;
}
result3 = new String[i];
i = 0;
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
result3[i] = c.getString(iBp);
i++;
}
}
catch(Exception e)
{
}
return result3;
}
public String[] getIDComname()
{
String[] result4 = new String[0];
try
{
String[] columns = new String[] { KEY_COMNAME };
Cursor c = ChemPal.query(DATABASE_TABLE, columns, null, null, null, null, null);
int iCommonName = c.getColumnIndex(KEY_COMNAME);
int i = 0;
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
i++;
}
result4 = new String[i];
i = 0;
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
result4[i] = c.getString(iCommonName);
i++;
}
}
catch(Exception e)
{
}
return result4;
}
public String[] getIDElement()
{
String[] result5 = new String[0];
try
{
String[] columns = new String[] { KEY_CONELEMENTS };
Cursor c = ChemPal.query(DATABASE_TABLE, columns, null, null, null, null, null);
int iElements = c.getColumnIndex(KEY_CONELEMENTS);
int i = 0;
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
i++;
}
result5 = new String[i];
i = 0;
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
result5[i] = c.getString(iElements);
i++;
}
}
catch(Exception e)
{
}
return result5;
}
public String[] getIDMOLARMASS()
{
String[] result6 = new String[0];
try
{
String[] columns = new String[] { KEY_MOLARMASS };
Cursor c = ChemPal.query(DATABASE_TABLE, columns, null, null, null, null, null);
int iElements = c.getColumnIndex(KEY_MOLARMASS);
int i = 0;
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
i++;
}
result6 = new String[i];
i = 0;
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
result6[i] = c.getString(iElements);
i++;
}
}
catch(Exception e)
{
}
return result6;
}
}