Question

我有一个使用SQLite数据库的应用程序。

我在应用程序启动时创建了数据库，调用了RSSDatabase的构造函数，工作正常。单击一个按钮后，我从RSS提要中获取数据并在AsyncTask中插入数据，但是当我调用db.insert("posts", "", values)时会导致错误，这是logcat的错误消息：

02-04 21:43:22.050  19154-19357/com.example.aolreader E/SQLiteLog﹕ (1802) os_unix.c:30026: (2) stat(/data/data/com.example.aolreader/databases/rss_db) -
02-04 21:43:22.050  19154-19357/com.example.aolreader E/SQLiteLog﹕ (1802) statement aborts at 13: [INSERT INTO posts(author,title,date,description,link) VALUES (?,?,?,?,?)]
02-04 21:43:22.050  19154-19357/com.example.aolreader E/SQLiteDatabase﹕ Error inserting author=AP title=UK admits ‘limited’ role in Operation Blue Star  date=Tue, 4 Feb 2014 19:03:27 +0530 description=
    The British government had recently ordered an urgent investigation into possible U.K. involvement in the raid.
    link=http://www.thehindu.com/news/international/world/uk-admits-limited-role-in-operation-blue-star/article5653316.ece
    android.database.sqlite.SQLiteDiskIOException: disk I/O error (code 1802)
            at android.database.sqlite.SQLiteConnection.nativeExecuteForLastInsertedRowId(Native Method)
            at android.database.sqlite.SQLiteConnection.executeForLastInsertedRowId(SQLiteConnection.java:782)
            at android.database.sqlite.SQLiteSession.executeForLastInsertedRowId(SQLiteSession.java:788)
            at android.database.sqlite.SQLiteStatement.executeInsert(SQLiteStatement.java:86)
            at android.database.sqlite.SQLiteDatabase.insertWithOnConflict(SQLiteDatabase.java:1469)
            at android.database.sqlite.SQLiteDatabase.insert(SQLiteDatabase.java:1339)
            at com.example.aolreader.RSSDatabase.insertPost(RSSDatabase.java:44)
            at com.example.aolreader.XMLRSSActivity.parseNews(XMLRSSActivity.java:386)
            at com.example.aolreader.XMLRSSActivity.access$000(XMLRSSActivity.java:33)
            at com.example.aolreader.XMLRSSActivity$ParseTask.doInBackground(XMLRSSActivity.java:171)
            at com.example.aolreader.XMLRSSActivity$ParseTask.doInBackground(XMLRSSActivity.java:134)
            at android.os.AsyncTask$2.call(AsyncTask.java:288)
            at java.util.concurrent.FutureTask.run(FutureTask.java:237)
            at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
            at java.lang.Thread.run(Thread.java:841)

我搜索了这个错误，发现它可能是由同一时间访问数据库的不同线程引起的，但我查看了我的代码，发现没有多线程有竞争条件的条件。

这是我的数据库助手类：

class RSSDatabaseHelper extends SQLiteOpenHelper {

    private static final String createPostTableSql = "create table posts (" +
            "_id integer primary key autoincrement," +
            "title varchar," +
            "author varchar," +
            "link varchar," +
            "description varchar," +
            "date varchar)";

    private Context context;

    public RSSDatabaseHelper(Context c, String name, SQLiteDatabase.CursorFactory factory, int version) {
        super(c, name, factory, version);
        context = c;
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(createPostTableSql);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("drop table if exists posts");
        onCreate(db);
    }
}

我的数据库类：

public class RSSDatabase {
    private static RSSDatabase instance;

    private SQLiteDatabase db;
    private RSSDatabaseHelper dbHelper;

    private RSSDatabase(Context c) {
        dbHelper = new RSSDatabaseHelper(c, "rss_db", null, 1);
        db = dbHelper.getWritableDatabase();
    }

    public static synchronized RSSDatabase getDatabaseInstance(Context c) {
        if (instance == null) {
            instance = new RSSDatabase(c);
        }
        return instance;
    }

    public void insertPost(Post post) {
        ContentValues values = new ContentValues();
        values.put("title", post.title);
        values.put("author", post.author);
        values.put("link", post.link);
        values.put("description", post.description);
        values.put("date", post.date);
        db.insert("posts", "", values);
    }
}

有人能解释一下这个问题吗？

提前致谢！

Answer 1

当应用程序启动时，调用RSSDatabase的构造函数，UI Thread将锁定您的数据库

db = dbHelper.getWritableDatabase(); // In the constructor

现在来自Async任务（不同的线程），您正在尝试在由UI线程锁定的数据库中插入数据。这将引发异常，因为第一次写入对数据库有锁定。

Android SQLite数据库：SQLiteDiskIOException：磁盘I / O错误（代码1802）

1 个答案: