我在 stackoverflow 上看了很多关于这个错误的帖子，看起来解决方法是重写 onDestroy() 方法并关闭数据库。但这对我来说似乎不起作用。当 Eclipse 最初在我的手机上运行该应用程序时，我实际上没有收到任何错误，但是当我关闭该应用程序并在我的手机上重新启动它时 - 那是 close() 从未在数据库上显式调用出现在 LogCat 中。我正在调用 Assets 文件夹中的外部数据库，不确定这是否与它有任何关系。

数据库适配器:

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.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;

public class DBAdapter extends SQLiteOpenHelper {

public static final String KEY_ROWID = "_id";
public static final String KEY_HDATE = "date";
public static final String KEY_MONTHDAY = "monthday";
public static final String KEY_YEAR = "year";
public static final String KEY_HD = "happened";

// The Android's default system path of your application database.
private static String DB_PATH = "/data/data/com.vdm.whtt/databases/";
private static String DB_NAME = "wht.db";
private static final String DB_TABLE = "historydaytable";

private SQLiteDatabase db;

private final Context ourContext;

public DBAdapter(Context context) {
    super(context, DB_NAME, null, 1);
    this.ourContext = context;
}

public void createDataBase() throws IOException {

    boolean dbExist = checkDataBase();

    if (dbExist) {
        // do nothing - database already exist
    } else {

        // 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.
        this.getReadableDatabase();

        try {

            copyDataBase();

        } catch (IOException e) {

            throw new Error("Error copying database");

        }
    }

}

private boolean checkDataBase() {
    SQLiteDatabase checkDB = null;

    try {
        String myPath = DB_PATH + DB_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;
}

private void copyDataBase() throws IOException {
    InputStream myInput = ourContext.getAssets().open(DB_NAME);
    String outFileName = DB_PATH + DB_NAME;
    OutputStream myOutput = new FileOutputStream(outFileName);

    byte[] buffer = new byte[1024];
    int length;
    while ((length = myInput.read(buffer)) > 0) {
        myOutput.write(buffer, 0, length);
    }

    myOutput.flush();
    myOutput.close();
    myInput.close();
}

public void open() throws SQLException {
    String myPath = DB_PATH + DB_NAME;
    db = SQLiteDatabase.openDatabase(myPath, null,
            SQLiteDatabase.OPEN_READONLY);
}

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

@Override
public void onCreate(SQLiteDatabase db) {
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    db.execSQL("DROP TABLE IF EXISTS " + DB_TABLE);
    onCreate(db);
}

public String[] getTH(long aLong) { 
    String[] columns = new String[] { KEY_YEAR, KEY_MONTHDAY, KEY_HD };
    Cursor cursor = db.query(DB_TABLE, columns, KEY_HDATE + "=" + aLong,
            null, null, null, null);

    if (cursor != null) {
        cursor.moveToFirst();
        String hpToday[] = new String[3];
        hapToday[0] = cursor.getString(0);
        hapToday[1] = cursor.getString(1);
        hapToday[2] = cursor.getString(2);
        cursor.close();
        this.db.close();
        return hpToday;
    }
    return null;
}

public String[] getFirstRandomAnswer(int randomNum1) {
    String[] columns = new String[] { KEY_YEAR, KEY_MONTHDAY, KEY_HD };
    Cursor cursor = db.query(DB_TABLE, columns, null,
            null, null, null, null);
    if (cursor != null) {
        cursor.moveToPosition(randomNum1);
        String r1Str[] = new String[3];
        r1Str[0] = cursor.getString(0);
        r1Str[1] = cursor.getString(1);
        r1Str[2] = cursor.getString(2);
        cursor.close();
        this.db.close();
        return r1Str;
    }
    return null;
}

public String[] getSecondRandomAnswer(int randomNum2) {
    String[] columns = new String[] { KEY_YEAR, KEY_MONTHDAY, KEY_HD };
    Cursor cursor = db.query(DB_TABLE, columns, null,
            null, null, null, null);
    if (cursor != null) {
        cursor.moveToPosition(randomNum2);
        String r2Str[] = new String[3];
        r2Str[0] = cursor.getString(0);
        r2Str[1] = cursor.getString(1);
        r2Str[2] = cursor.getString(2);
        cursor.close();
        this.db.close();
        return r2Str;
    }
    return null;
}
}

主要 Activity :

    import java.io.IOException;
import java.util.Locale;
import java.util.Date;
import java.text.ParseException;
import java.text.SimpleDateFormat;

import android.os.Bundle;
import android.text.Html;
import android.widget.TextView;
import android.app.Activity;
import android.database.SQLException;

public class MainActivity extends Activity {
private DBAdapter dba;
TextView hiddenDBdatetv, todayIstv, optionAtv;
String MMdStr;
String[] todayArray;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    hiddenDBdatetv = (TextView) findViewById(R.id.hiddenDBdate_TV);
    todayIstv = (TextView) findViewById(R.id.todayIs_TV);
    optionAtv = (TextView) findViewById(R.id.optionA_TV);

    dba = new DBAdapter(this);

    try {
        dba.createDataBase();
    } catch (IOException ioe) {
        throw new Error("Unable to create database");
    }
    try {
        dba.open();
    } catch (SQLException sqle) {
        throw sqle;
    }

    getMMdDate();
    getTH();
}

private void getMMdDate() {
    Date anotherCurDate = new Date();
    SimpleDateFormat formatter = new SimpleDateFormat("MMd", Locale.US);
    MMdStr = formatter.format(anotherCurDate);
    SimpleDateFormat dateFormat = new SimpleDateFormat("MMd");
    Date myDate = null;
    try {
        myDate = dateFormat.parse(MMdStr);
    } catch (ParseException e) {
        e.printStackTrace();
    }
    SimpleDateFormat timeFormat = new SimpleDateFormat("MMMMMMMMMM d");
    String finalDate = timeFormat.format(myDate);
}

private void getTH() {
    long aLong = Long.parseLong(MMdStr);
    dba.open();
    todayArray = dba.getTH(aLong);
    dba.close();
    optionAtv.setText(todayArray[2]);
}

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

}

最佳答案

您将在 createDatabase() 中打开一个数据库(当 dbExist == false 时)，并且您将在 onCreate( )，然后再次在 getTH()...

避免此错误的技巧是跟踪您的数据库何时打开，并确保在您使用完后关闭它。考虑检查 isOpen()如果您发现自己多次打开数据库，请在尝试打开数据库之前。

关于android - close() 从未在 Android 和 SQlite 中显式调用，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/13615348/