2

我已经经历了其他类似的问题，但我没有得到答案。

在我的 android 应用程序中，我正在打开一个预先构建的数据库。它位于 assets 文件夹中并使用SQLiteOpenHelper复制（如果尚未存在）。这堂课：

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import android.content.Context;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class ExternalDbOpenHelper extends SQLiteOpenHelper {

public static String DB_PATH;
public static String DB_NAME;
public SQLiteDatabase database;
public final Context context;

public SQLiteDatabase getDb() {
    return database;
}

public ExternalDbOpenHelper(Context context, String databaseName) {
    super(context, databaseName, null, 1);
    this.context = context;

    String packageName = context.getPackageName();
    DB_PATH = String.format("//data//data//%s//databases//", packageName);
    DB_NAME = databaseName;
    openDataBase();
}

public void createDataBase() {
    boolean dbExist = checkDataBase();
    if (!dbExist) {
        this.getReadableDatabase();
        try {
            copyDataBase();
        } catch (IOException e) {
            // Log.e(this.getClass().toString(), "Copying error");
            //throw new Error("Error copying database!");
        }
    } else {
        // Log.i(this.getClass().toString(), "Database already exists");
    }
}

private boolean checkDataBase() {
    SQLiteDatabase checkDb = null;
    try {
        String path = DB_PATH + DB_NAME;
        checkDb = SQLiteDatabase.openDatabase(path, null,
                SQLiteDatabase.OPEN_READONLY); 
    } catch (SQLException e) {
        // Log.e(this.getClass().toString(), "Error while checking db");
    }

    if (checkDb != null) {
        checkDb.close();
    }
    return checkDb != null;
}

private void copyDataBase() throws IOException {

    InputStream externalDbStream = context.getAssets().open(DB_NAME);

    String outFileName = DB_PATH + DB_NAME;

    OutputStream localDbStream = new FileOutputStream(outFileName);

    byte[] buffer = new byte[1024];
    int bytesRead;
    while ((bytesRead = externalDbStream.read(buffer)) > 0) {
        localDbStream.write(buffer, 0, bytesRead);
    }

    localDbStream.close();
    externalDbStream.close();

}

public SQLiteDatabase openDataBase() throws SQLException {
    String path = DB_PATH + DB_NAME;
    if (database == null) {
        createDataBase();
        database = SQLiteDatabase.openDatabase(path, null,
                SQLiteDatabase.OPEN_READWRITE); //caused by this line
    }
    return database;
}

@Override
public synchronized void close() {
    if (database != null) {
        database.close();
    }
    super.close();
}

@Override
public void onCreate(SQLiteDatabase db) {
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}

这是在我的活动中：

private static final String DB_NAME = "myDB.sqlite";
private SQLiteDatabase database;
private ExternalDbOpenHelper dbOpenHelper;

//in onCreate()
dbOpenHelper = new ExternalDbOpenHelper(this,DB_NAME);
database = dbOpenHelper.openDataBase();

在我的应用程序中，我使用游标和rawQuery反复查询数据库。我打开数据库 OPEN_READONLY 因为我从不修改它。所以之前没有关闭它。现在添加了这个：

@Override
protected void onDestroy()
{
    dbOpenHelper.close();
    super.onDestroy();

}

这是问题吗？我之前从未遇到过 SQLite 磁盘 IO 异常和无法打开数据库异常（没有dbOpenHelper.close();. 在崩溃报告中每次都报告一次）。两次应用程序在启动时崩溃并且是由线路引起的

database = SQLiteDatabase.openDatabase(path, null, SQLiteDatabase.OPEN_READWRITE);

在ExternalDbOpenHelper 类的openDataBase() 中。

我无法重现错误。报告它的两个设备的设备名称为“其他”且为空白。

android.database.sqlite.SQLiteCantOpenDatabaseException
in android.database.sqlite.SQLiteDatabase.dbopen:

java.lang.RuntimeException: Unable to start activity        ComponentInfo{com.technicosa.unjumble/com.technicosa.unjumble.MainActivity}: android.database.sqlite.SQLiteCantOpenDatabaseException: unable to open database file
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
at android.app.ActivityThread.access$600(ActivityThread.java:123)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4424)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
at dalvik.system.NativeStart.main(Native Method)
Caused by: android.database.sqlite.SQLiteCantOpenDatabaseException: unable to open database file
at android.database.sqlite.SQLiteDatabase.dbopen(Native Method)
at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:1013)
at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:986)
at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:1024)
at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:986)
at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:962)
at com.technicosa.unjumble.dbhelper.ExternalDbOpenHelper.openDataBase(ExternalDbOpenHelper.java:90)
at com.technicosa.unjumble.dbhelper.ExternalDbOpenHelper.<init>(ExternalDbOpenHelper.java:33)
at com.technicosa.unjumble.MainActivity.onCreate(MainActivity.java:131)
at android.app.Activity.performCreate(Activity.java:4465)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
... 11 more
4

2 回答 2

0

看看这这就像一个魅力

public class SmartOpenHelper extends SQLiteOpenHelper {

    private Context context;
    private SQLiteDatabase myDataBase;
    private String DB_SQL;
    private SmartVersionHandler smartVersionHandler;

    SmartOpenHelper(Context context, String dbname, int dbversion, String dbSqlName, SmartVersionHandler smartVersionHandler) throws IOException {
        super(context, dbname, null, dbversion);
        this.context = context;
        this.DB_SQL = dbSqlName;
        this.smartVersionHandler = smartVersionHandler;
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        try {
            BufferedInputStream inStream = new BufferedInputStream(context.getAssets().open(DB_SQL));
            String sql = "";
            int character = -2;
            do {
                character = inStream.read();
                if ((character != -1) && (character != -2))
                    sql += (char) character;
                else
                    break;
            } while (true);
            System.out.println("onCreate DB SQL = " + sql.split("\n"));
            String[] arrSQL = sql.split("\n");

            for (int i = 0; i < arrSQL.length; i++) {
                db.execSQL(arrSQL[i]);
            }

        } catch (IOException e) {
            e.printStackTrace();
        }
        if (this.smartVersionHandler != null) {
            this.smartVersionHandler.onInstalling(SmartApplication.REF_SMART_APPLICATION);
        }
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

        try {
            BufferedInputStream inStream = new BufferedInputStream(context.getAssets().open(DB_SQL));
            String sql = "";
            int character = -2;
            do {
                character = inStream.read();
                if ((character != -1) && (character != -2))
                    sql += (char) character;
                else
                    break;
            } while (true);

            System.out.println("onUpgrade DB SQL = " + sql.split("\n"));
            String[] arrSQL = sql.split("\n");
            for (int i = 0; i < arrSQL.length; i++) {
                db.execSQL(arrSQL[i]);
            }

        } catch (IOException e) {
            e.printStackTrace();
        }
        if (this.smartVersionHandler != null) {
            this.smartVersionHandler.onUpgrading(oldVersion, newVersion, SmartApplication.REF_SMART_APPLICATION);
        }
    }

    public SQLiteDatabase getOpenDatabase() {
        return myDataBase;
    }

    public synchronized void close() {
        if (myDataBase != null) {
            myDataBase.close();
        }
        super.close();
    }

}
于 2013-08-24T04:56:05.253 回答
0

我真的不认为这是解决问题的好方法。SQLiteOpenHelper 它不应该像那样使用。您应该将数据库复制到帮助程序类之外，然后初始化应该只为您服务的帮助程序以获取 SQLiteDatabase（通过 getReadableDatabase 和/或 getWritableDatabase）。

但是，阅读代码我不明白为什么在 createDataBase 函数中的 copyDataBase 之前调用 getReadableDatabase 。您还应该按照 hotveryspicy 的建议检查数据库路径。

您能否发布异常的堆栈跟踪？

试试这个编辑：

public class ExternalDbOpenHelper extends SQLiteOpenHelper {

public static String DB_PATH;
public static String DB_NAME;
public SQLiteDatabase database;
public final Context context;

public SQLiteDatabase getDb() {
    return database;
}

public ExternalDbOpenHelper(Context context, String databaseName) {
    super(context, databaseName, null, 1);
    this.context = context;

    String packageName = context.getPackageName();
    DB_PATH = String.format("%s//data//%s//databases//", Environment.getDataDirectory(), packageName); // as per hotveryspicy comment
    DB_NAME = databaseName;
    openDataBase();
}

public void createDataBase() {
    boolean dbExist = checkDataBase();
    if (!dbExist) {
        //this.getReadableDatabase(); why do you call getReadableDatabase() here?
        try {
            copyDataBase();
        } catch (IOException e) {
            // Log.e(this.getClass().toString(), "Copying error");
            //throw new Error("Error copying database!");
        }
    } else {
        // Log.i(this.getClass().toString(), "Database already exists");
    }
}

private boolean checkDataBase() {
    SQLiteDatabase checkDb = null;
    try {
        String path = DB_PATH + DB_NAME;
        checkDb = SQLiteDatabase.openDatabase(path, null,
                SQLiteDatabase.OPEN_READONLY); 
    } catch (SQLException e) {
        // Log.e(this.getClass().toString(), "Error while checking db");
    }

    if (checkDb != null) {
        checkDb.close();
    }
    return checkDb != null;
}

private void copyDataBase() throws IOException {

    InputStream externalDbStream = context.getAssets().open(DB_NAME);

    String outFileName = DB_PATH + DB_NAME;

    OutputStream localDbStream = new FileOutputStream(outFileName);

    byte[] buffer = new byte[1024];
    int bytesRead;
    while ((bytesRead = externalDbStream.read(buffer)) > 0) {
        localDbStream.write(buffer, 0, bytesRead);
    }

    localDbStream.close();
    externalDbStream.close();

}

public SQLiteDatabase openDataBase() throws SQLException {
    String path = DB_PATH + DB_NAME;
    if (database == null) {
        createDataBase();
        //database = SQLiteDatabase.openDatabase(path, null,
                //SQLiteDatabase.OPEN_READWRITE);

        database = getWritableDatabase(); // <- try with this        
    }
    return database;
}

@Override
public synchronized void close() {
    if (database != null) {
        database.close();
    }
    super.close();
}

@Override
public void onCreate(SQLiteDatabase db) {
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
于 2013-08-27T07:42:17.100 回答