java - Android sqlite 日志报告和 db.close()

Question

日志报告数据库或游标未关闭。我基本上有一个带有自定义表面 View 的 Activity ，并使用处理程序向该 Activity 报告。当我收到消息时，我会显示一个警报对话框并更新数据库。

private Handler handler = new Handler() {
    public void handleMessage(Message msg) {
        switch(msg.what) {
        case 1:
            dh.open();
            dh.updateEvent("id", "name", "someone");
            dh.close();
            successAlert.show();
            break;
        case 2:
            failAlert.show();
            break;
        }
    }
};

以前我没有“dh.close()”，那是当日志报告数据库/游标未关闭时。但是自从我把它加进去之后，真的需要很长时间才能完成。收到消息后，系统似乎挂起。我做错了什么还是通常需要这么长时间。我还尝试使用带有 finally 的 try block 来关闭数据库。

编辑:

public class DatabaseHelper {

private Database dbHelper;
private SQLiteDatabase db;
private Context context;

public DatabaseHelper(Context context) {
    this.context = context;
    //database = new Database(context);
}

public void open() {
    dbHelper = new Database(context);
    db = dbHelper.getWritableDatabase();
}

public void close() {
    dbHelper.close();
}

public void updateEvent(int id, String name, int other) {
    ContentValues cv = new ContentValues();
    cv.put("id", id);
    cv.put("name", name);
    cv.put("other", other);
    db.update("stateTable", cv, "id=" + id, null);
}

public boolean checkState(int id) {
    db = dbHelper.getReadableDatabase();
    Cursor cursor = db.query("stateTable", null, null, null, null, null, null);
    cursor.moveToPosition(id - 1);
    int i = cursor.getInt(2);
    android.util.Log.d("semajhan", ": " + i);
    if (i == 1) {
        return true;
    } else {
        return false;
    }
}

扩展的 SQLiteOpenHelper:

public class Database extends SQLiteOpenHelper {

private static final String DATABASE_NAME = "events.db";
private static final int DATABASE_VERSION = 1;
private static final String TABLE_NAME = "stateTable";
private static final String ID = "id";
private static final String NAME = "name";
private static final String OTHER = "other";
private static final String DATABASE_CREATE = "CREATE TABLE stateTable (id INT, name TEXT, other INT)";
private static final String DATABASE_UPGRADE = "DROP TABLE IF EXISTS table";

public Database(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
    // TODO Auto-generated constructor stub
}

@Override
public void onCreate(SQLiteDatabase db) {
    // TODO Auto-generated method stub
    db.execSQL(DATABASE_CREATE);
    // added initial values
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // TODO Auto-generated method stub
    db.execSQL(DATABASE_UPGRADE);
    onCreate(db);
}

01-11 13:57:41.239: ERROR/ActivityManager(61): ANR in com.semajhan.soodles  (com.semajhan.soodles/.Level1)
01-11 13:57:41.239: ERROR/ActivityManager(61): Reason: keyDispatchingTimedOut
01-11 13:57:41.239: ERROR/ActivityManager(61): Load: 1.64 / 0.56 / 0.26
01-11 13:57:41.239: ERROR/ActivityManager(61): CPU usage from 35716ms to -1ms ago:
01-11 13:57:41.239: ERROR/ActivityManager(61):   44% 862/com.semajhan.soodles: 37% user + 7.2% kernel / faults: 853 minor
01-11 13:57:41.239: ERROR/ActivityManager(61):   29% 61/system_server: 27% user + 1.9% kernel / faults: 142 minor
01-11 13:57:41.239: ERROR/ActivityManager(61):   0.2% 731/com.android.quicksearchbox: 0% user + 0.2% kernel / faults: 30 minor
01-11 13:57:41.239: ERROR/ActivityManager(61):   0.2% 707/com.android.launcher: 0.2% user + 0% kernel / faults: 30 minor
01-11 13:57:41.239: ERROR/ActivityManager(61):   0.2% 801/com.svox.pico: 0.1% user + 0.1% kernel / faults: 363 minor
01-11 13:57:41.239: ERROR/ActivityManager(61):   0% 117/com.android.systemui: 0% user + 0% kernel
01-11 13:57:41.239: ERROR/ActivityManager(61):   0% 41/adbd: 0% user + 0% kernel
01-11 13:57:41.239: ERROR/ActivityManager(61): 99% TOTAL: 86% user + 13% kernel + 0% irq
01-11 13:57:41.239: ERROR/ActivityManager(61): CPU usage from 1969ms to 2620ms later:
01-11 13:57:41.239: ERROR/ActivityManager(61):   54% 61/system_server: 48% user + 6% kernel
01-11 13:57:41.239: ERROR/ActivityManager(61):     40% 69/SurfaceFlinger: 40% user + 0% kernel
01-11 13:57:41.239: ERROR/ActivityManager(61):     10% 92/InputDispatcher: 7.5% user + 3% kernel
01-11 13:57:41.239: ERROR/ActivityManager(61):     1.5% 62/HeapWorker: 1.5% user + 0% kernel
01-11 13:57:41.239: ERROR/ActivityManager(61):   44% 862/com.semajhan.soodles: 32% user + 12% kernel / faults: 2 minor
01-11 13:57:41.239: ERROR/ActivityManager(61):     24% 874/Thread-13: 24% user + 0% kernel
01-11 13:57:41.239: ERROR/ActivityManager(61):     23% 862/studios.soodles: 4.6% user + 18% kernel
01-11 13:57:41.239: ERROR/ActivityManager(61):     1.5% 867/Compiler: 0% user + 1.5% kernel
01-11 13:57:41.239: ERROR/ActivityManager(61):   0.8% 731/com.android.quicksearchbox: 0% user + 0.8% kernel
01-11 13:57:41.239: ERROR/ActivityManager(61):     0.8% 732/HeapWorker: 0% user + 0.8% kernel
01-11 13:57:41.239: ERROR/ActivityManager(61): 100% TOTAL: 76% user + 23% kernel

Answer 1

第一次调用 SQLiteOpenHelper 实例的 getReadableDatabase 或 getWritableDatabase 需要很长时间才能完成。您不应该在每次需要查询数据库时都创建一个新的 Database 对象(您的 SQLiteOpenHelper 实例)。尝试在 DatabaseHelper 中使用相同的 Database 实例。

当使用 SQLiteOpenHelper 时，您不想关闭 SQLiteOpenHelper 的 SQLiteDatabase 对象，因为它是共享的；即 getWritableDatabase 总是返回相同的 SQLiteDatabase 对象。

请注意您的 checkState 方法泄漏了一个游标。为了帮助防止游标泄漏，我总是在获取游标后使用 try-finally。例如:

    db = dbHelper.getReadableDatabase();
    Cursor cursor = db.query("stateTable", null, null, null, null, null, null);
    try {
        cursor.moveToPosition(id - 1);
        int i = cursor.getInt(2);
        android.util.Log.d("semajhan", ": " + i);
        if (i == 1) {
                return true;
        } else {
                return false;
        }
    } finally {
        cursor.close();
    }