Android实现简单的电子词典

使用AutoCompleteTextView，词典数据保存在小型数据库sqlite中，在res的raw文件夹下，运行改程序会自动复制到手机内置SD卡下。

本地电子词典保存在数据库中，源文件代码在http://download.csdn.net/detail/bq1073100909/8079045

添加对SD卡的读写权限：

<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

MainActivity.java

package org.dyb.activity;

import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;

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

public class MainActivity extends Activity implements OnClickListener,
TextWatcher {
// 定义数据库的存放路径
private final String DATABASE_PATH = android.os.Environment
.getExternalStorageDirectory().getAbsolutePath() + "/dictionary";
// 用户输入文本框
private AutoCompleteTextView word;
// 定义数据库的名字
private final String DATABASE_FILENAME = "dictionary.db";
private SQLiteDatabase database;
private Button searchWord;
// 用户显示查询结果
private TextView showResult;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// 打开数据库
database = openDatabase();
searchWord = (Button) findViewById(R.id.searchWord);
word = (AutoCompleteTextView) findViewById(R.id.word);
// 绑定监听器
searchWord.setOnClickListener(this);
word.addTextChangedListener(this);
showResult = (TextView) findViewById(R.id.result);
}

public class DictionaryAdapter extends CursorAdapter {
private LayoutInflater layoutInflater;

public DictionaryAdapter(Context context, Cursor c, boolean flags) {
super(context, c, flags);
layoutInflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}

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

// 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;
}

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

// 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")));
}

}

// 打开数据库
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);
// 如果目录不存在，则创建这个目录
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);
}
// 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) {
e.printStackTrace();
}
return null;
}

@Override
public void onClick(View v) {
// 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 = "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"))
.replace("&", "&");
}
// 将结果显示到TextView中
showResult.setText(word.getText() + "\n" + result.toString());
}

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

}

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

}

@Override
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() + "%" });
// 新建新的Adapter
DictionaryAdapter dictionaryAdapter = new DictionaryAdapter(this,
cursor, true);
// 绑定适配器
word.setAdapter(dictionaryAdapter);
}

}

布局文件：

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
>
<!-- 使用RelativeLayout布局用于在一行中显示两个元素 -->
<RelativeLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:id="@+id/search"
>
<AutoCompleteTextView
android:id="@+id/word"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_toLeftOf="@+id/searchWord"
android:ems="20"
android:singleLine="true" >
<requestFocus />
</AutoCompleteTextView>
<!-- 搜索按钮，供用户点击查询单词 -->
<Button
android:id="@+id/searchWord"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:text="@string/searchWord" />

</RelativeLayout>
<TextView
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:text="@string/searchLable"
/>
<TextView
android:id="@+id/result"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="0.68"
android:background="@color/white"
android:textColor="@color/blue" />
/>

</LinearLayout>

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" />

strings.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="app_name">字典</string>
<string name="action_settings">Settings</string>
<string name="hello_world">Hello world!</string>
<string name="searchWord">搜索</string>
<string name="searchLable">查询结果</string>
</resources>