本文介绍了无法打开设备上的数据库文件（HTC Desire的）的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我使用了一些code，将复制现有的SQLite数据库从我的资产文件夹到我的/数据/数据/包文件夹。我已经写了code和Android模拟器测试它，它工作正常。如果我试着和我的设备（HTC Desire的）上安装它，我得到'SQLiteException：无法打开数据库文件'
I am using some code that will copy an existing SQLite database from my assets folder into my /data/data/package folder.I have written the code and tested it on the android emulator, and it works fine. If I try and install it on my device (HTC Desire)I get 'SQLiteException:unable to open database file'
我一直停留在这3天现在也弄不清是怎么回事错了。我不知道，如果数据库无法打开，因为它没有创建，或者如果我缺少一些数据库权限清单文件中。这是我的DataBaseHelper code：
I have been stuck on this for 3 days now and cannot figure out what is going wrong.I don't know if the database cannot be opened because it is not created, or if I am lacking some database permissions in the manifest file.This is my DataBaseHelper code:
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;
import android.os.Environment;
import android.util.Log;
public class DataBaseHelper extends SQLiteOpenHelper{
//private static String DB_PATH = "/data/data/com.drager/databases/";
private static String DB_PATH = Environment.getDataDirectory()+"/data/com.drager/databases/";
final static String DB_NAME = "myDBName";
private SQLiteDatabase myDataBase=null;
private final Context myContext;
private DataBaseHelper myDbHelper;
private static String TAG ="MyActivity";
public DataBaseHelper(Context context){
super(context, DB_NAME, null, 1);
this.myContext = context;
}
public DataBaseHelper createDataBase() throws IOException{
boolean dbExist =checkDataBase();
//SQLiteDatabase db_read =null;
Log.i(TAG,"############value of dbExist"+dbExist+"##########");
//if (dbExist){
//db must exist
//}
//else{
//myDbHelper = new DataBaseHelper(myContext);
//myDataBase = myDbHelper.getReadableDatabase();
//myDataBase.close();
//this.getReadableDatabase();
//db_read.close();
// try {
copyDataBase();
// } catch (IOException e) {
// throw new Error("error copying database");
// }
// }
return this;
}
public Cursor executeStatement(){
Log.i(TAG,"in execute statement");
Cursor cursor=null;
cursor=myDataBase.rawQuery("SELECT _ID, title, value "+
"FROM constants ORDER BY title",
null);
return cursor;
}
public String getTextViewItem(){
Cursor cursor=null;
String str="";
//store query results in cursor
cursor=myDataBase.rawQuery("SELECT description FROM product_details" ,
null);
cursor.moveToNext();
//cast cursor content from the index of 'description Column as a string
str =cursor.getString(cursor.getColumnIndex("description"));
return str;
}
public void copyDataBase() throws IOException{
// open db as input stream
InputStream myInput = myContext.getAssets().open(DB_NAME);
//path to newly created db
String outFileName =DB_PATH + DB_NAME;
//open empty db as 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);
}
myOutPut.flush();
myOutPut.close();
myInput.close();
}
private boolean checkDataBase() {
SQLiteDatabase checkDB = null;
String myPath = DB_PATH + DB_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
/*
if (checkDB != null){
checkDB.close();
}*/
return checkDB !=null ? true : false;
}
public void openDataBase()throws SQLException{
//open the database
String myPath = DB_PATH + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}
@Override
public synchronized void close(){
if(myDataBase != null){
myDataBase.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
}
}
这是我的清单文件
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.drager"
android:versionCode="1"
android:versionName="1.0">
<application android:icon="@drawable/icon" android:label="@string/
app_name" android:debuggable="true">
<activity android:name=".Drager"
android:label="Drager">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
这是logcat的
02-09 09:09:15.883: ERROR/AndroidRuntime(8313):
java.lang.RuntimeException: Unable to start activity
ComponentInfo{com.drager/com.drager.Drager}:
android.database.sqlite.SQLiteException: unable to open database file
02-09 09:09:15.883: ERROR/AndroidRuntime(8313): at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:
2787)
02-09 09:09:15.883: ERROR/AndroidRuntime(8313): at
android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:
2803)
02-09 09:09:15.883: ERROR/AndroidRuntime(8313): at
android.app.ActivityThread.access$2300(ActivityThread.java:135)
02-09 09:09:15.883: ERROR/AndroidRuntime(8313): at
android.app.ActivityThread$H.handleMessage(ActivityThread.java:2136)
02-09 09:09:15.883: ERROR/AndroidRuntime(8313): at
android.os.Handler.dispatchMessage(Handler.java:99)
02-09 09:09:15.883: ERROR/AndroidRuntime(8313): at
android.os.Looper.loop(Looper.java:144)
02-09 09:09:15.883: ERROR/AndroidRuntime(8313): at
android.app.ActivityThread.main(ActivityThread.java:4937)
02-09 09:09:15.883: ERROR/AndroidRuntime(8313): at
java.lang.reflect.Method.invokeNative(Native Method)
02-09 09:09:15.883: ERROR/AndroidRuntime(8313): at
java.lang.reflect.Method.invoke(Method.java:521)
02-09 09:09:15.883: ERROR/AndroidRuntime(8313): at
com.android.internal.os.ZygoteInit
$MethodAndArgsCaller.run(ZygoteInit.java:868)
02-09 09:09:15.883: ERROR/AndroidRuntime(8313): at
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
02-09 09:09:15.883: ERROR/AndroidRuntime(8313): at
dalvik.system.NativeStart.main(Native Method)
02-09 09:09:15.883: ERROR/AndroidRuntime(8313): Caused by:
android.database.sqlite.SQLiteException: unable to open database file
02-09 09:09:15.883: ERROR/AndroidRuntime(8313): at
android.database.sqlite.SQLiteDatabase.dbopen(Native Method)
02-09 09:09:15.883: ERROR/AndroidRuntime(8313): at
android.database.sqlite.SQLiteDatabase.<init>(SQLiteDatabase.java:
1902)
02-09 09:09:15.883: ERROR/AndroidRuntime(8313): at
android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:
884)
02-09 09:09:15.883: ERROR/AndroidRuntime(8313): at
com.drager.DataBaseHelper.checkDataBase(DataBaseHelper.java:108)
02-09 09:09:15.883: ERROR/AndroidRuntime(8313): at
com.drager.DataBaseHelper.createDataBase(DataBaseHelper.java:32)
02-09 09:09:15.883: ERROR/AndroidRuntime(8313): at
com.drager.Drager.onCreate(Drager.java:46)
02-09 09:09:15.883: ERROR/AndroidRuntime(8313): at
android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:
1069)
02-09 09:09:15.883: ERROR/AndroidRuntime(8313): at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:
2751)
感谢你在前进
推荐答案
感谢IDX，你的一个非常美丽的男人，还是女人！我想你的建议，带着几分摆弄我得到了它，尝试/渔获量似乎是关键。这是我的修正code，希望这将帮助别人。
Thanks IDX, your a very beautiful man, or woman!I tried what you suggested, with a bit of fiddling I got it, try/catches seem to be the key.Here is my amended code, hopefully it will help someone else.
public class DataBaseHelper extends SQLiteOpenHelper{
//private static String DB_PATH = "/data/data/com.drager/databases/";
private static String DB_PATH = Environment.getDataDirectory()+"/data/com.drager/databases/";
final static String DB_NAME = "myDBName";
private SQLiteDatabase myDataBase=null;
private final Context myContext;
private DataBaseHelper myDbHelper;
private static String TAG ="MyActivity";
public DataBaseHelper(Context context){
super(context, DB_NAME, null, 1);
this.myContext = context;
}
public DataBaseHelper createDataBase() throws IOException{
boolean dbExist =checkDataBase();
//SQLiteDatabase db_read =null;
Log.i(TAG,"############value of dbExist"+dbExist+"##########");
if (dbExist){
//db must exist
}
else{
myDbHelper = new DataBaseHelper(myContext);
myDataBase = myDbHelper.getReadableDatabase();
myDataBase.close();
//this.getReadableDatabase();
//db_read.close();
try {
copyDataBase();
} catch (IOException e) {
throw new Error("error copying database");
}
}
return this;
}
public Cursor executeStatement(){
Log.i(TAG,"in execute statement");
Cursor cursor=null;
cursor=myDataBase.rawQuery("SELECT _ID, title, value "+
"FROM constants ORDER BY title",
null);
return cursor;
}
public String getTextViewItem(){
Cursor cursor=null;
String str="fffff";
//store query results in cursor
cursor=myDataBase.rawQuery("SELECT description FROM product_details" ,
null);
Log.i(TAG,"################in gettextview, value of cursor ="+cursor);
cursor.moveToNext();
//cast cursor content from the index of 'description Column as a string
str =cursor.getString(cursor.getColumnIndex("description"));
return str;
}
public void copyDataBase() throws IOException{
// open db as input stream
InputStream myInput;
//open empty db as output stream
OutputStream myOutPut;
try {
myInput = myContext.getAssets().open(DB_NAME);
//path to newly created db
String outFileName =DB_PATH + DB_NAME;
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);
}
myOutPut.flush();
myOutPut.close();
myInput.close();
}
catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
private boolean checkDataBase() {
SQLiteDatabase checkDB = null;
String myPath = DB_PATH + DB_NAME;
try {
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
} catch (SQLException e) {
e.printStackTrace();
return false;
}
if (checkDB != null){
checkDB.close();
}
return true;
//return checkDB !=null ? true : false;
}
public void openDataBase()throws SQLException{
//open the database
String myPath = DB_PATH + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}
@Override
public synchronized void close(){
if(myDataBase != null){
myDataBase.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
}
}
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