在模拟器上，应用运行良好。在设备上，当我试图通过应用程序的数据库复制我的数据库并执行查询时，应用程序强制关闭。知道为什么会发生这种情况吗？我是否必须请求任何类型的权限或清单中的某些内容才能运行？
Database.Java
public class Database extends SQLiteOpenHelper{
//The Android's default system path of your application database.
private static String DB_PATH = "/data/data/gr.BHC.www/databases/";
//Name of the Database to be created.
private static String DB_NAME = "BHCLibrary3.sqlite";
private SQLiteDatabase myDataBase;
private final Context myContext;
* Constructor
* Takes and keeps a reference of the passed context in order to access to the application assets and resources.
* @param context
*/
public Database(Context context) {
super(context, DB_NAME, null, 1);
this.myContext = context;
}
/**
* Creates a empty database on the system and rewrites it with your own database.
* */
public void createDataBase() throws IOException{
//First we check if the database already exists, Method declared later
boolean dbExist = checkDataBase();
if(dbExist){
//do nothing - database already exists
}else{
//By calling this method an empty database will be created into the default system path
//of your application so we are going to be able to overwrite that database with our database.
this.getReadableDatabase();
try {
copyDataBase(); //Method declared later
} 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;
boolean checkdb = false;
try{
String myPath = DB_PATH + DB_NAME;
File dbfile = new File(myPath);
//checkdb = SQLiteDatabase.openDatabase(myPath,null,SQLiteDatabase.OPEN_READWRITE);
checkdb = dbfile.exists();
}
catch(SQLiteException e){
System.out.println("Database doesn't exist");
}
return checkdb;
}
/**
* 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 = myContext.getAssets().open(DB_NAME);
// Path to the just created empty db
String outFileName = DB_PATH + DB_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();
}
//Opening the Database
public void openDataBase() throws SQLException{
//Open the database
String myPath = DB_PATH + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
}
//Finally overriding a few methods as required
@Override
public synchronized void close() {
if(myDataBase != null)
myDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
//First we check if the database already exists, Method declared later
boolean dbExist = checkDataBase();
if(dbExist){
//do nothing - database already exists
}else{
//By calling this method an empty database will be created into the default system path
//of your application so we are going to be able to overwrite that database with our database.
this.getReadableDatabase();
try {
copyDataBase(); //Method declared later
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
Results.java （我运行查询的活动）
public class SearchResults extends ListActivity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.searchresults);
Database myDbHelper = new Database(null);
myDbHelper = new Database(this);
}
// Get the intent, verify the action and get the query
Intent intent = getIntent();
String query = intent.getStringExtra(SearchManager.QUERY);
SQLiteDatabase myDb = myDbHelper.getReadableDatabase();
//Executing our query against the server using rawQuery and getting the cursor
String select="SELECT DISTINCT b._ISBN as _id, b.BookTitle, b.Edition, b.Year, b.Pages, b.Rating, c.Category, p.Publisher, w.LastName" +
" FROM" +
" Books b" +
" JOIN Categories_Books cb ON cb._Books_ISBN = _id" +
" JOIN Categories c ON c._CategoryID = cb._Categories_CategoryID" +
" JOIN Publishers p ON p._PublisherID = b.PublisherID" +
" JOIN Writers_Books wb ON wb._Books_ISBN = _id" +
" JOIN Writers w ON w._WriterID = wb._Writers_WriterID" +
" WHERE b.BookTitle LIKE '%" + query +"%'" +
" OR c.Category LIKE '%" + query +"%'" +
" OR p.Publisher LIKE '%" + query +"%'" +
" OR w.LastName LIKE '%" + query +"%'" +
" OR _id LIKE '%" + query +"%'" +
" GROUP BY b.BookTitle";
Cursor c = myDb.rawQuery(select, null);
startManagingCursor(c);
// the desired columns to be bound
String[] columns = new String[] { "Books.BookTitle", "Publishers.Publisher" };
// the XML defined views which the data will be bound to
int[] to = new int[] { R.id.ISBN_entry, R.id.Title_entry };
//Getting results into our listview
try
{
SimpleCursorAdapter mAdapter = new SimpleCursorAdapter(this, R.layout.listlayout, c, columns, to);
this.setListAdapter(mAdapter);
}
catch( Exception e)
{
}
}
}
帮助将不胜感激。
编辑：我得到的错误是：java.lang.runtimeexception：无法启动活动Componentinfo（gr.BHC.www / gr.BHC.www.SearchResults}，然后表示不存在表书等的各种异常。
EDIT2：我看到异常通常与内容提供商有关，但我仍然无法弄清楚为什么我会这样做。
答案 0 :(得分：1)
我想我解决了这个问题。我对您的代码进行了一些更改，现在它正在运行。以下是代码：
public class SearchResults extends ListActivity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// setContentView(R.layout.searchresults);
DbManager myDbHelper = new DbManager(null);
myDbHelper = new DbManager(this);
// Get the intent, verify the action and get the query
myDbHelper.createNewDatabase();
try {
myDbHelper.open();
Log.d("Search Results", "database opened");
} catch (SQLException sqle) {
throw sqle;
}
Intent intent = getIntent();
String query = intent.getStringExtra(SearchManager.QUERY);
// Executing our query against the server using rawQuery and getting the
// cursor
String select = "SELECT DISTINCT b._ISBN as _id, b.BookTitle, b.Edition, b.Year, b.Pages, b.Rating, c.Category, p.Publisher, w.LastName"
+ " FROM"
+ " Books b"
+ " JOIN Categories_Books cb ON cb._Books_ISBN = _id"
+ " JOIN Categories c ON c._CategoryID = cb._Categories_CategoryID"
+ " JOIN Publishers p ON p._PublisherID = b.PublisherID"
+ " JOIN Writers_Books wb ON wb._Books_ISBN = _id"
+ " JOIN Writers w ON w._WriterID = wb._Writers_WriterID"
+ " WHERE b.BookTitle LIKE '%"
+ query
+ "%'"
+ " OR c.Category LIKE '%"
+ query
+ "%'"
+ " OR p.Publisher LIKE '%"
+ query
+ "%'"
+ " OR w.LastName LIKE '%"
+ query
+ "%'"
+ " OR _id LIKE '%"
+ query
+ "%'"
+ " GROUP BY b.BookTitle";
Cursor c = myDbHelper.rawQ(select);
startManagingCursor(c);
// the desired columns to be bound
String[] columns = new String[] { "Books.BookTitle",
"Publishers.Publisher" };
// the XML defined views which the data will be bound to
int[] to = new int[] { R.id.ISBN_entry, R.id.Title_entry };
// Getting results into our listview
try {
SimpleCursorAdapter mAdapter = new SimpleCursorAdapter(this,
R.layout.listlayout, c, columns, to);
this.setListAdapter(mAdapter);
} catch (Exception e) {
}
}
}
你的新数据库助手DbManager：
public class DbManager extends SQLiteOpenHelper {
private static final String DB_NAME = "BHCLibrary3.sqlite";
private static final String DB_PATH = "/data/data/gr.BHC.www/databases/";
private static final Integer DB_VERSION = 1;
private static final String TAG = "DbManager";
private final Context context;
private SQLiteDatabase db;
private DbManager dbManager;
public DbManager(Context context) {
super(context, DB_NAME, null, DB_VERSION);
this.context = context;
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE 'notes' (_id integer primary key autoincrement, title text not null);");
}
@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
}
public DbManager open() {
dbManager = new DbManager(context);
db = dbManager.getWritableDatabase();
return this;
}
public void createNewDatabase() {
InputStream assetsDB = null;
try {
assetsDB = context.getAssets().open(DB_NAME);
OutputStream dbOut = new FileOutputStream(DB_PATH + DB_NAME);
byte[] buffer = new byte[1024];
int length;
while ((length = assetsDB.read(buffer)) > 0) {
dbOut.write(buffer, 0, length);
}
dbOut.flush();
dbOut.close();
assetsDB.close();
Log.i(TAG, "New database created...");
} catch (IOException e) {
Log.e(TAG, "Could not create new database...");
e.printStackTrace();
}
}
public Cursor rawQ(String select) {
return db.rawQuery(select, null);
}
}
答案 1 :(得分：0)
看起来您的数据库大小超过一MB。在这种情况下，您需要将其作为.jpg存储在assets文件夹中，然后将其复制。这是因为Android对文本资产的大小设置了限制。