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我的Android案例—电子词典
2015年的Android案例之旅
案例七：电子词典
知识点：
1.自动完成文本框(AutoCompleteTextView)
AutoCompleteTextView是从EditText派生出来的，当用户输入一定字符之后，AutoCompleteTextView会显示一个下拉菜单，供用户选择，当用户选择某个菜单之后，内容会被填充到该文本中。
使用AutoCompleteTextView需要设置一个Adapter，该Adapter封装了预设的提示文本
2.SQLiteDataBase数据库
3.Adapter适配器
涉及文件：
res->layout->activity_main.xml 布局文件
res->layout->word_list_item.xml 布局文件
res->raw-> dictionary.db 词典数据库
res->values->strings 资源文件之字符串资源
res->values->color 资源文件之颜色资源
res->AndroidManifest.xml 系统清单文件主要添加SD卡相关权限
src->package->MainActivity.java java文件
activity_main.xml
<!-- 线性布局 -->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:background="#ff808080">
<!-- 相对布局
用于设置搜索框和搜索按钮 -->
<RelativeLayout android:layout_width="match_parent"
android:layout_height="wrap_content">
<!-- 定义自动完成文本框，供用户输入单词 -->
<AutoCompleteTextView
android:id="@+id/word"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:ems="20"
android:layout_toLeftOf="@+id/searchWord"/>
<!-- 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_alignParentTop="true"
android:layout_alignParentRight="true"
android:text="@string/search"/>
</RelativeLayout>
<!-- 查询结果 -->
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/result"/>
<!-- 用户显示查询的结果 -->
<TextView
android:id="@+id/show"
android:layout_width="match_parent"
android:layout_height="match_parent"
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" />MainActivity.java
package com.example.mydicitonary;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import android.app.Activity;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.support.v4.widget.CursorAdapter;
import android.text.Editable;
import android.text.TextWatcher;
import android.util.Log;
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.TextView;
public class MainActivity extends Activity {
//定义Log标签
private static final String TAG = "DICITONARY";
//声明控件对象
private Button search;
private TextView show;
private AutoCompleteTextView actv;
//用到SQLiteDateBase
//定义数据库的存放路径
private static final String DATEBASE_PATH = android.os.Environment
.getExternalStorageDirectory().getAbsolutePath()
+ "/dictionary";
//定义数据库的名字
private static final String DATEBASE_NAME = "dictionary.db";
private SQLiteDatabase database;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.i(TAG, "DICITONARY is onCreate");
//获取布局中的控件
init();
//打开数据库
database = openDateBase();
//监听事件处理
listener();
}
/**
* @oaram 初始化控件
*/
private void init(){
search = (Button)this.findViewById(R.id.searchWord);
show = (TextView)this.findViewById(R.id.show);
actv = (AutoCompleteTextView)this.findViewById(R.id.word);
}
/**
* @param 处理监听事件
*/
private void listener(){
//按钮点击事件
search.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View arg0) {
String result = "未查到该单词信息";
//查询指定的单词
String sql = "select chinese from t_words where english=?";
Cursor cursor = database.rawQuery(sql, new String[]{
actv.getText().toString()
});
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
show.setText(actv.getText().toString() +"\n"+result);
}
});
//文本变动事件
actv.addTextChangedListener(new TextWatcher() {
@Override
public void onTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {
// TODO Auto-generated method stub
}
@Override
public void beforeTextChanged(CharSequence arg0, int arg1, int arg2,
int arg3) {
// TODO Auto-generated method stub
}
@Override
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(MainActivity.this,
cursor, true);
//绑定适配器
actv.setAdapter(dictionaryAdapter);
}
});
}
//自定义Adapter类
public class DictionaryAdapter extends CursorAdapter{
//对于一个没有被载入或者想要动态载入的界面，都需要使用LayoutInflater.inflate()来载入；
//对于一个已经载入的界面，就可以使用Activiyt.findViewById()方法来获得其中的界面元素。
private LayoutInflater layoutInflater;
public DictionaryAdapter(Context context, Cursor c, boolean autoRequery)
{
super(context, c, autoRequery);
layoutInflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
@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);
}
@Override
public View newView(Context context, Cursor cursor, ViewGroup arg2) {
View view = layoutInflater.inflate(R.layout.word_list_item, null);
setView(view, cursor);
return view;
}
}
/**
* @param 返回一个SQLiteDatabase对象
* @return
*/
private SQLiteDatabase openDateBase(){
try {
// 获得dictionary.db文件的绝对路径
String databaseFileName = DATEBASE_PATH + "/" + DATEBASE_NAME;
File dir = new File(DATEBASE_PATH);
// 如果/sdcard/dictionary目录存在，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[9128];
int count = 0;
// 开始复制dictionary.db文件
while((count = is.read(buffer))!=-1){
fos.write(buffer, 0, count);
}
//关闭文件流
is.close();
fos.close();
}
// 打开/sdcard/dictionary目录中的dictionary.db文件
SQLiteDatabase database = SQLiteDatabase.openOrCreateDatabase(
databaseFileName, null);
return database;
} catch (Exception e) {
// TODO: handle exception
}
return null;
}
}
<?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" />MainActivity.java
package com.example.mydicitonary;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import android.app.Activity;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.support.v4.widget.CursorAdapter;
import android.text.Editable;
import android.text.TextWatcher;
import android.util.Log;
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.TextView;
public class MainActivity extends Activity {
//定义Log标签
private static final String TAG = "DICITONARY";
//声明控件对象
private Button search;
private TextView show;
private AutoCompleteTextView actv;
//用到SQLiteDateBase
//定义数据库的存放路径
private static final String DATEBASE_PATH = android.os.Environment
.getExternalStorageDirectory().getAbsolutePath()
+ "/dictionary";
//定义数据库的名字
private static final String DATEBASE_NAME = "dictionary.db";
private SQLiteDatabase database;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.i(TAG, "DICITONARY is onCreate");
//获取布局中的控件
init();
//打开数据库
database = openDateBase();
//监听事件处理
listener();
}
/**
* @oaram 初始化控件
*/
private void init(){
search = (Button)this.findViewById(R.id.searchWord);
show = (TextView)this.findViewById(R.id.show);
actv = (AutoCompleteTextView)this.findViewById(R.id.word);
}
/**
* @param 处理监听事件
*/
private void listener(){
//按钮点击事件
search.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View arg0) {
String result = "未查到该单词信息";
//查询指定的单词
String sql = "select chinese from t_words where english=?";
Cursor cursor = database.rawQuery(sql, new String[]{
actv.getText().toString()
});
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
show.setText(actv.getText().toString() +"\n"+result);
}
});
//文本变动事件
actv.addTextChangedListener(new TextWatcher() {
@Override
public void onTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {
// TODO Auto-generated method stub
}
@Override
public void beforeTextChanged(CharSequence arg0, int arg1, int arg2,
int arg3) {
// TODO Auto-generated method stub
}
@Override
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(MainActivity.this,
cursor, true);
//绑定适配器
actv.setAdapter(dictionaryAdapter);
}
});
}
//自定义Adapter类
public class DictionaryAdapter extends CursorAdapter{
//对于一个没有被载入或者想要动态载入的界面，都需要使用LayoutInflater.inflate()来载入；
//对于一个已经载入的界面，就可以使用Activiyt.findViewById()方法来获得其中的界面元素。
private LayoutInflater layoutInflater;
public DictionaryAdapter(Context context, Cursor c, boolean autoRequery)
{
super(context, c, autoRequery);
layoutInflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
@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);
}
@Override
public View newView(Context context, Cursor cursor, ViewGroup arg2) {
View view = layoutInflater.inflate(R.layout.word_list_item, null);
setView(view, cursor);
return view;
}
}
/**
* @param 返回一个SQLiteDatabase对象
* @return
*/
private SQLiteDatabase openDateBase(){
try {
// 获得dictionary.db文件的绝对路径
String databaseFileName = DATEBASE_PATH + "/" + DATEBASE_NAME;
File dir = new File(DATEBASE_PATH);
// 如果/sdcard/dictionary目录存在，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[9128];
int count = 0;
// 开始复制dictionary.db文件
while((count = is.read(buffer))!=-1){
fos.write(buffer, 0, count);
}
//关闭文件流
is.close();
fos.close();
}
// 打开/sdcard/dictionary目录中的dictionary.db文件
SQLiteDatabase database = SQLiteDatabase.openOrCreateDatabase(
databaseFileName, null);
return database;
} catch (Exception e) {
// TODO: handle exception
}
return null;
}
}
我的Android案例—电子词典
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