Android之离线词典

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="fill_parent"
    android:layout_height="fill_parent">

    <AutoCompleteTextView android:id="@+id/actvWord"
        android:layout_width="fill_parent" android:layout_height="wrap_content"
        android:layout_marginTop="10dp" android:singleLine="true" />
    <Button android:id="@+id/btnSelectWord" android:layout_width="wrap_content"
        android:layout_height="wrap_content" android:text="查单词" />

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/tvWordItem"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:gravity="center_vertical"
    android:paddingLeft="6dip"
    android:textColor="#000"
    android:minHeight="?android:attr/listPreferredItemHeight"/>

import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.View.OnClickListener;
import android.widget.AutoCompleteTextView;
import android.widget.Button;
import android.widget.CursorAdapter;
import android.widget.TextView;

public class Main extends Activity implements OnClickListener, TextWatcher
{
    //dictionary.db的储存目录
    private final String DATABASE_PATH = android.os.Environment
            .getExternalStorageDirectory().getAbsolutePath()
            + "/dictionary";
    private AutoCompleteTextView actvWord;
    private final String DATABASE_FILENAME = "dictionary.db";
    private SQLiteDatabase database;
    private Button btnSelectWord;

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.main);
        //打开Database
        database = openDatabase();
        btnSelectWord = (Button) findViewById(R.id.btnSelectWord);
        actvWord = (AutoCompleteTextView) findViewById(R.id.actvWord);
        //设置按钮监听
        btnSelectWord.setOnClickListener(this);
        //设施字符改变监听
        actvWord.addTextChangedListener(this);
    }

    public class DictionaryAdapter extends CursorAdapter
    {
        private LayoutInflater layoutInflater;
        @Override
        public CharSequence convertToString(Cursor cursor)
        {
            return cursor == null ? "" : cursor.getString(cursor
                    .getColumnIndex("_id"));
        }

        private void setView(View view, Cursor cursor)
        {
            TextView tvWordItem = (TextView) view;
            tvWordItem.setText(cursor.getString(cursor.getColumnIndex("_id")));
        }

        @Override
        public void bindView(View view, Context context, Cursor cursor)
        {
            setView(view, cursor);
        }

        @Override
        public View newView(Context context, Cursor cursor, ViewGroup parent)
        {
            //把布局文件转换为View对象
            View view = layoutInflater.inflate(R.layout.word_list_item, null);
            setView(view, cursor);
            return view;
        }

        public DictionaryAdapter(Context context, Cursor c, boolean autoRequery)
        {
            super(context, c, autoRequery);
            //通过系统服务获得该上下文的LayoutInflater对象
            layoutInflater = (LayoutInflater) context
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        }
    }

    public void afterTextChanged(Editable s)
    {

        //  必须将english字段的别名设为_id
        Cursor cursor = database.rawQuery(
                "select english as _id from t_words where english like ?",
                new String[]
                { s.toString() + "%" });
        DictionaryAdapter dictionaryAdapter = new DictionaryAdapter(this,
                cursor, true);
        actvWord.setAdapter(dictionaryAdapter);

    }

    public void beforeTextChanged(CharSequence s, int start, int count,
            int after)
    {
        // TODO Auto-generated method stub

    }

    public void onTextChanged(CharSequence s, int start, int before, int count)
    {
        // TODO Auto-generated method stub

    }

    public void onClick(View view)
    {
        //从t_words的表中搜索english为输入框中的中文
        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，显示其中文的意思
        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"));
        }
        //  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;
    }

}