Android 如何检查数据库是否存在

Question

我想检查数据库是否存在，并且我从互联网上找到了一些代码。

     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;
    }

但我收到错误..无法打开文件 为什么它不能工作？

: sqlite returned: error code = 14, msg = cannot open file at line 27703 of [8609a15dfa], db=/data/data/com.testing.abcde/databases/scj
: sqlite returned: error code = 14, msg = os_unix.c: open() at line 27703 - "" errno=2 path=/data/data/com.testing.abcde/databases/scj, db=/data/data/com.testing.abcde/databases/scj
: sqlite3_open_v2("/data/data/com.testing.abcde/databases/scj", &handle, 1, NULL) failed
: Failed to open the database. closing it.
: 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:962)
:   at com.lkland.softkeyboard.easytype.SQLite.checkDataBase(SQLite.java:80)
:   at com.lkland.softkeyboard.easytype.SQLite.createDataBase(SQLite.java:55)

Answer 1

我使用这个代码，看起来效果很好:

// Where DB_PATH is /data/data/com.testing.abcde/databases/scj
// and DB_NAME is name.db
public boolean checkDBExists() {
     File dbFile = new File(DB_PATH + DB_NAME);
     return dbFile.exists();
}

您将需要import java.io.File;或提供对File类的完整引用。