android直接读取数据库文件

public class Dictionary extends Activity  implements OnClickListener, TextWatcher{
    private final String DATABASE_PATH = android.os.Environment
            .getExternalStorageDirectory().getAbsolutePath()
            + "/dictionary";
    private final String DATABASE_FILENAME = "dictionary.db3";
    SQLiteDatabase database;
    Button btnSelectWord;
    AutoCompleteTextView actvWord;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        // 打开数据库，database是在Main类中定义的一个SQLiteDatabase类型的变量
        database = openDatabase();
        // 下面的代码装载了相关组件，并设置了相应的事件
        btnSelectWord = (Button) findViewById(R.id.btnSelectWord);
        actvWord = (AutoCompleteTextView) findViewById(R.id.actvWord);
        btnSelectWord.setOnClickListener(this);
        actvWord.addTextChangedListener(this);
    }
    public void onClick(View view)
    {
        //  查找单词的SQL语句
        String sql = "select chinese from t_words where english=?";  
        Cursor cursor = database.rawQuery(sql, new String[]
        { actvWord.getText().toString() });
        String result = "未找到该单词.";
        //  如果查找单词，显示其中文信息
        if (cursor.getCount() > 0)
        {
            //  必须使用moveToFirst方法将记录指针移动到第1条记录的位置
            cursor.moveToFirst();
            result = cursor.getString(cursor.getColumnIndex("chinese"));
            Log.i("tran", "success"+result);
        }
        //  显示查询结果对话框
        new AlertDialog.Builder(this).setTitle("查询结果").setMessage(result)
                .setPositiveButton("关闭", null).show();

    }

    private SQLiteDatabase openDatabase() {
        try {
            // 获得dictionary.db文件的绝对路径
            String databaseFilename = DATABASE_PATH + "/" + DATABASE_FILENAME;
            File dir = new File(DATABASE_PATH);
            // 如果/sdcard/dictionary目录中存在，创建这个目录
            if (!dir.exists())
                dir.mkdir();
            // 如果在/sdcard/dictionary目录中不存在
            // dictionary.db文件，则从res\raw目录中复制这个文件到
            // SD卡的目录（/sdcard/dictionary）
            if (!(new File(databaseFilename)).exists()) {
                // 获得封装dictionary.db文件的InputStream对象
                InputStream is = getResources().openRawResource(
                        R.raw.dictionary);
                FileOutputStream fos = new FileOutputStream(databaseFilename);
                byte[] buffer = new byte[8192];
                int count = 0;
                // 开始复制dictionary.db文件
                while ((count = is.read(buffer)) > 0) {
                    fos.write(buffer, 0, count);
                }

                fos.close();
                is.close();
            }
            // 打开/sdcard/dictionary目录中的dictionary.db文件
            SQLiteDatabase database = SQLiteDatabase.openOrCreateDatabase(
                    databaseFilename, null);
            return database;
        } catch (Exception e) {
        }
        return null;
    }
    @Override
    public void afterTextChanged(Editable s) {
    }
    @Override
    public void beforeTextChanged(CharSequence s, int start, int count,
            int after) {
    }
    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {
    }

}