Android 从资产中读取 sqlite 数据库并将其填充到 listview答案

【问题标题】：Android reading sqlite database from assets and populating it to listviewAndroid 从资产中读取 sqlite 数据库并将其填充到 listview
【发布时间】：2016-12-24 14:54:19
【问题描述】：

我一直在尝试从资产中读取我的 sqlite 数据库并将其填充到列表视图中，每次我得到“找不到这样的表”时，这是我的数据库适配器

DatabaseHelper.Java

public class DatabaseHelper extends SQLiteOpenHelper {

private static String DB_Path="/data/data/com.example.pc.myapp/databases/";
private static String DB_Name= "myDatabase.sqlite";
private final Context mycontext;
private SQLiteDatabase myDatabse;

public DatabaseHelper(Context context) {
    super(context, DB_Name,null,1);
    this.mycontext=context;
}

@Override
public void onCreate(SQLiteDatabase db) {

}

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

}

private boolean chechDatabase(){
    SQLiteDatabase checkDB=null;

    try {
        String myPath=DB_Path+DB_Name;
        checkDB=SQLiteDatabase.openDatabase(myPath,null,SQLiteDatabase.OPEN_READONLY);
    } catch (SQLException e){

    }
    if (checkDB !=null) checkDB.close();
    return checkDB != null ? true : false;
}
private void copyDatabase () throws IOException {
    InputStream myInput=mycontext.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();
    myInput.close();
    myOutput.close();
}
public void openDatabse() throws SQLException{
    String myPath=DB_Path+DB_Name;
    myDatabse=SQLiteDatabase.openDatabase(myPath,null,SQLiteDatabase.OPEN_READONLY);
}
public void ExeSQLData(String sql) throws SQLException{
    myDatabse.execSQL(sql);
}
public Cursor queryData(String query) throws SQLException{
    return myDatabse.rawQuery(query,null);
}

@Override
public synchronized void close() {
    if (myDatabse != null)
        myDatabse.close();
    super.close();
}
public void checkAndCopyDatabase(){
    boolean dbExist=chechDatabase();
    if (dbExist){
        Log.d("TAG","DataBase Already Exists");
    }else {
        this.getReadableDatabase();
        try {
            copyDatabase();
        }catch (IOException e){
            Log.d("Tag","Error Copying Database");
        }
    }
}

这是我的主要活动

Mainactivity.java

公共类 MainActivity 扩展 AppCompatActivity {

ListView listView;
public String TABLE_NAME="dic";
private DatabaseHelper dbHelper;
ArrayList<Word> arrayList=new ArrayList<Word>();
CustomAdapter customAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    //Load Database
    dbHelper=new DatabaseHelper(this);
    try {
        dbHelper.checkAndCopyDatabase();
        dbHelper.openDatabse();
    } catch (SQLException e){
    }
    try {
        Cursor cursor = dbHelper.queryData("Select * from "+TABLE_NAME);
        if (cursor !=null){
            if (cursor.moveToFirst()){
                do {
                    Word word = new Word();
                    word.setmWord(cursor.getString(1));
                    word.setmDescription(cursor.getString(2));
                    arrayList.add(word);

                }while (cursor.moveToNext());
            }
        }
    }catch (SQLException e){ }
    customAdapter = new CustomAdapter(this,R.layout.custom_list_view,arrayList);
    listView = (ListView) findViewById(R.id.listView);
    listView.setAdapter(customAdapter);
    customAdapter.notifyDataSetChanged();
    }
}

日志猫

LOGcat

08-17 22:27:20.757 19145-19145/com.example.pc.myapp E/SQLiteLog: (28) failed to open "/data/data/com.example.pc.myapp/databases/myDatabase.sqlite" with flag (131072) and mode_t (0) due to error (2)
08-17 22:27:20.757 19145-19145/com.example.pc.myapp E/SQLiteLog: (14) cannot open file at line 32546 of [9491ba7d73]
08-17 22:27:20.757 19145-19145/com.example.pc.myapp E/SQLiteLog: (14) os_unix.c:32546: (2) open(/data/data/com.example.pc.myapp/databases/myDatabase.sqlite) - 
08-17 22:27:20.787 19145-19145/com.example.pc.myapp E/SQLiteDatabase: Failed to open database '/data/data/com.example.pc.myapp/databases/myDatabase.sqlite'.
                                                                      android.database.sqlite.SQLiteCantOpenDatabaseException: unknown error (code 1294): Could not open database
                                                                      #################################################################
                                                                      Error Code : 1294 (SQLITE_CANTOPEN_ENOENT)
                                                                      Caused By : Specified directory or database file does not exist.
                                                                        (unknown error (code 1294): Could not open database)
                                                                      #################################################################
                                                                          at android.database.sqlite.SQLiteConnection.nativeOpen(Native Method)
                                                                          at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:318)
                                                                          at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:228)
                                                                          at android.database.sqlite.SQLiteConnectionPool.openConnectionLocked(SQLiteConnectionPool.java:512)
                                                                          at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:206)
                                                                          at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:178)
                                                                          at android.database.sqlite.SQLiteDatabase.openInner(SQLiteDatabase.java:908)
                                                                          at android.database.sqlite.SQLiteDatabase.open(SQLiteDatabase.java:878)
                                                                          at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:699)
                                                                          at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:674)
                                                                          at com.example.pc.myapp.DatabaseHelper.chechDatabase(DatabaseHelper.java:45)
                                                                          at com.example.pc.myapp.DatabaseHelper.checkAndCopyDatabase(DatabaseHelper.java:84)
                                                                          at com.example.pc.myapp.MainActivity.onCreate(MainActivity.java:25)
                                                                          at android.app.Activity.performCreate(Activity.java:6178)
                                                                          at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
                                                                          at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2648)
                                                                          at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2769)
                                                                          at android.app.ActivityThread.access$900(ActivityThread.java:177)
                                                                          at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1430)
                                                                          at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                          at android.os.Looper.loop(Looper.java:135)
                                                                          at android.app.ActivityThread.main(ActivityThread.java:5910)
                                                                          at java.lang.reflect.Method.invoke(Native Method)
                                                                          at java.lang.reflect.Method.invoke(Method.java:372)
                                                                          at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1405)
                                                                          at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1200)
08-17 22:27:21.158 19145-19145/com.example.pc.myapp D/Tag: Error Copying Database
08-17 22:27:21.158 19145-19145/com.example.pc.myapp E/SQLiteLog: (1) no such table: dic
08-17 22:27:21.258 19145-19563/com.example.pc.myapp D/OpenGLRenderer: Use EGL_SWAP_BEHAVIOR_PRESERVED: false
08-17 22:27:21.268 19145-19145/com.example.pc.myapp D/PhoneWindow: *FMB* isFloatingMenuEnabled mFloatingMenuBtn : null
08-17 22:27:21.268 19145-19145/com.example.pc.myapp D/PhoneWindow: *FMB* isFloatingMenuEnabled return false
08-17 22:27:21.488 19145-19563/com.example.pc.myapp I/OpenGLRenderer: Initialized EGL, version 1.4
08-17 22:27:21.498 19145-19563/com.example.pc.myapp D/OpenGLRenderer: Enabling debug mode 0
08-17 22:27:21.808 19145-19145/com.example.pc.myapp I/Timeline: Timeline: Activity_idle id: android.os.BinderProxy@3f408cb9 time:154747142
08-17 22:27:29.086 19145-19145/com.example.pc.myapp I/Timeline: Timeline: Activity_idle id: android.os.BinderProxy@3f408cb9 time:154754420
08-17 22:28:58.363 19145-19145/com.example.pc.myapp D/ViewRootImpl: ViewPostImeInputStage ACTION_DOWN

【问题讨论】：

我建议在您尝试访问数据库的代码中设置一个断点。然后您可以使用adb 和sqlite3 来验证您的数据库是否已正确初始化。
Logcat 消息消息“原因：指定的目录或数据库文件不存在。”表示您的数据库路径不正确。
@Zero_LL 你解决了这个问题吗？

标签： android sqlite listview

【解决方案1】：

你访问数据库的方法不适合我用下面的代码

private void importDatabaseFromAssets() {
        try {
            InputStream myInput = getAssets().open(DatabaseManager.DATABASE_NAME);
            String DB_PATH = "/data/data/" + getPackageName() + "/databases/";
            String outFileName = DB_PATH + DatabaseManager.DATABASE_NAME;
            OutputStream myOutput = new FileOutputStream(outFileName);
            byte[] buffer = new byte[1024];
            int length;
            while ((length = myInput.read(buffer)) > 0) {
                myOutput.write(buffer, 0, length);
            }
            // Close the streams
            myOutput.flush();
            myOutput.close();
            myInput.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

您可以通过以下方式检查数据库是否存在：

private boolean isDataBaseExist() {
    String DB_PATH = "/data/data/" + getPackageName() + "/databases/";
    File dbFile = new File(DB_PATH + DatabaseManager.DATABASE_NAME);
    return dbFile.exists();
}

【讨论】：