内容简介

英语词典小程序,是通过打开数据库来查询单词,通过openDatabase()方法来实现,另外也可以使用openDatabase()方法来实现实现从res\raw目录复制数据库文件到/sdcard/dictionary目录中,复制数据实际上先读取，再写入数据的过程。把数据库复制到手机内存中，更方便数据的读取。

效果图

下载地址

http://download.csdn.net/detail/gxseveryday/8804655

代码

分析：

activity_main.xml中主要定义了一个按钮，作用是查询单词事件处理，定义了一个TextView显示查询的结果，定义了一个AutoCompleteTextView组件，起到显示多个单词的效果。

UI界面

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/mainbg"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <AutoCompleteTextView
        android:id="@+id/etWord"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginTop="31dp"
        android:background="@android:drawable/edit_text"
        android:ems="10"
        android:hint="@string/searchHint"
        android:singleLine="true"
        android:textColor="#552006"
        android:textColorHint="#782f10" >

    </AutoCompleteTextView>

    <Button
        android:id="@+id/btnSearch"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/etWord"
        android:layout_alignBottom="@+id/etWord"
        android:layout_marginLeft="16dp"
        android:layout_toRightOf="@+id/etWord"
        android:background="@drawable/ibsearchword"
        android:onClick="searchWord"
        android:text="@string/serachWord" />

    <TextView
        android:id="@+id/tvSearchResult"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignLeft="@+id/etWord"
        android:layout_below="@+id/etWord"
        android:layout_marginTop="22dp"
        android:textSize="25sp"
        android:background="@drawable/bg_roundcorner"
        android:textAppearance="?android:attr/textAppearanceMedium" />

</RelativeLayout>

分析：

word_list_item.xml中只是定义了一TextView组件，用来显示查询出来的多个单词

word_list_item.xml

<?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:gravity="center_vertical"
    android:minHeight="?android:attr/listPreferredItemHeight"
    android:paddingLeft="6dip"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:textColor="@color/gray" />

类和方法

分析：

Dictionary.java调用activity_main.xml布局，进行事件处理，调用适配器，查询所要查询的单词。

Dictionary.java

package com.bzu.gxs;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import com.bzu.gxs.dao.DictionaryAdapter;
import com.bzu.gxs.db.DBHelper;
import com.bzu.gxs.R;
import android.app.Activity;
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.util.Log;
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 Dictionary extends Activity implements OnClickListener,TextWatcher {
    private DBHelper dbHelper; // 用户输入文本框
    private AutoCompleteTextView word; // 定义数据库的名字
    private SQLiteDatabase database;
    private Button searchWord; // 搜索按钮
    private TextView showResult; // 用户显示查询结果

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        dbHelper = new DBHelper(getBaseContext());// 打开数据库
        database = dbHelper.openDatabase();

        init();

        searchWord.setOnClickListener(this); // 绑定监听器
        word.addTextChangedListener(this); // 绑定文字改变监听器

    }

        public void init() {
        searchWord = (Button) findViewById(R.id.btnSearch);
        word = (AutoCompleteTextView) findViewById(R.id.etWord);
        showResult= (TextView) findViewById(R.id.tvSearchResult);

    }

    public void afterTextChanged(Editable s) {
        Cursor cursor = database.rawQuery("select english as _id
                from t_words where english like ?",
                new String[] { s.toString() + "%" });

        // 新建新的Adapter
        DictionaryAdapter dictionaryAdapter = new DictionaryAdapter(this,cursor, true);

        // 绑定适配器
        word.setAdapter(dictionaryAdapter);

    }

    public void beforeTextChanged(CharSequence s, int start, int count,int after) {

    }

    public void onTextChanged(CharSequence s, int start, int before, int count) {

    }

    public void onClick(View view) {
        // 查询指定的单词
        String sql = "select chinese from t_words where english=?";

        Cursor cursor = database.rawQuery(sql, new String[] { word.getText()
                .toString() });

        String result = "查无该词"; // 如果查找单词，显示其中文的意思

        if (cursor.getCount() > 0) { 

            cursor.moveToFirst(); // 须使用moveToFirst方法将记录指针移动到第1条记录的位置
            result = cursor.getString(cursor.getColumnIndex("chinese")).replace("&", "&");
        }

showResult.setText(word.getText() + "\n" + result.toString());// 将结果显示到TextView中
    }

}

分析：

DictionaryAdapter.java是自定义的适配器，调用word_list_item.xml布局， 将单词信息显示到列表中，绑定选项到列表中，生成新的选项。

DictionaryAdapter.java

package com.bzu.gxs.dao;
import android.content.Context;
import android.database.Cursor;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.CursorAdapter;
import android.widget.TextView;
import com.bzu.gxs.R;

public class DictionaryAdapter extends CursorAdapter {
    private LayoutInflater layoutInflater;

    @Override
    public CharSequence convertToString(Cursor cursor) {
        return cursor == null ? "" : cursor.getString(cursor
                .getColumnIndex("_id"));
    }

    // 将单词信息显示到列表中
    private void setView(View view, Cursor cursor) {
        TextView tvWordItem = (TextView) view;
        tvWordItem.setText(cursor.getString(cursor.getColumnIndex("_id")));
    }

    // 绑定选项到列表中
    @Override
    public void bindView(View view, Context context, Cursor cursor) {
        setView(view, cursor);
    }

    // 生成新的选项
    @Override
    public View newView(Context context, Cursor cursor, ViewGroup parent) {
        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);
        layoutInflater = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }
}

分析：

DBHelper.java数据库操作类，调用数据库，打开数据库，读取数据库中的数据，关闭数据库。通过InputStream输入流，获得封装dictionary.db文件的InputStream对象。

DBHelper.java

package com.bzu.gxs.db;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import com.bzu.gxs.R;

public class DBHelper {
    // 定义数据库的存放路径
    private final String DATABASE_PATH = android.os.Environment
            .getExternalStorageDirectory().getAbsolutePath() + "/dictionary";
    private final String DATABASE_FILENAME = "dictionary.db";
    private Context context;

    public DBHelper(Context context) {
        this.context = context;
    }

    public 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();

            if (!(new File(databaseFilename)).exists()) {

                // 获得封装dictionary.db文件的InputStream对象
                InputStream is = context.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);
                }
                // 关闭文件流
                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) {

        }
        // 如果打开出错，则返回null
        return null;
    }

}