Android-数据存储与访问：快乐动物成语

本次任务是完成一款成语介绍的app，界面为成语选择，点击想要明白的成语，会出现此成语的解释





首先先将已经得到的成语数据库存入手机内存中，即在db包下建立一个DBOpenHelper类

public class DBOpenHelper {
private final int BUFFER_SIZE = 400000;//缓冲区大小
public static final String DB_NAME = "idioms.db"; // 保存的数据库文件名
public static final String PACKAGE_NAME = "cn.edu.bzu.happyidiom";// 应用的包名
public static final String DB_PATH ="/data"+ Environment.getDataDirectory().getAbsolutePath()+"/"+PACKAGE_NAME+"/databases";
private Context context;

public DBOpenHelper(Context context){
this.context=context;
}
public SQLiteDatabase openDatabases(){
try{
File myDataPath=new File(DB_PATH);
if (!myDataPath.exists()){
myDataPath.mkdirs();
}
String dbfile=myDataPath+"/"+DB_NAME;
if (!(new File(dbfile).exists())){
InputStream is=context.getResources().openRawResource(R.raw.idioms);
FileOutputStream fos=new FileOutputStream(dbfile);
byte[]buffer=new byte[BUFFER_SIZE];
int count=0;
while((count=is.read(buffer))>0){
fos.write(buffer,0,count);
}
fos.close();
is.close();
}
SQLiteDatabase db=SQLiteDatabase.openOrCreateDatabase(dbfile,null);
return db;
}catch (FileNotFoundException e){
Log.e("Database","Filenotfound");
e.printStackTrace();
}catch (IOException e){
Log.e("Database","IOexception");
e.printStackTrace();
}
return null;
}
}

搭建单元测试环境，测试数据库有没有创建到指定路径下

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="cn.edu.bzu.happyidiom"
android:versionCode="1"
android:versionName="1.0">
<uses-sdk
android:minSdkVersion="14"
android:targetSdkVersion="18"/>
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<uses-library android:name="android.test.runner"/>
<activity android:name=".activity.StudyAnimalActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
<instrumentation        android:name="android.test.InstrumentationTestRunner"
android:targetPackage="cn.edu.bzu.happyidiom"></instrumentation>
</manifest>

接下来新建一个DBOpenHelperTest类，继承AndroidTestCase，封装一个test方法，调用了DBOpenHelper类的openDatabase方法

public class DBOpenHelperTest extends AndroidTestCase {
public void testDBCopy(){
DBOpenHelper dbOpenHelper=new DBOpenHelper(getContext());
dbOpenHelper.openDatabases();
}
}

构建Animal实体类，以及AnimalDao类，将一些常用的数据库操作封装起来，将他的构造方法私有化

public class AnimalDao {
private static AnimalDao animalDao;
private SQLiteDatabase db;
private AnimalDao(Context context){
DBOpenHelper dbHelper=new DBOpenHelper(context);
db=dbHelper.openDatabases();
}
public synchronized static AnimalDao getInstance(Context context){
if (animalDao==null){
animalDao=new AnimalDao(context);
}
return animalDao;
}
public List<Animal> getAllAnimals() {
List<Animal> list = new ArrayList<Animal>();
Cursor cursor = db.query("animal", null, null, null, null, null, null);
if (cursor.moveToFirst()) {
do {
Animal animal = new Animal();                animal.setId(cursor.getInt(cursor.getColumnInd
ce71
ex("_id")));
animal.setName(cursor.getString(cursor
.getColumnIndex("name")));
animal.setPronounce(cursor.getString(cursor
.getColumnIndex("pronounce")));
animal.setAntonym(cursor.getString(cursor
.getColumnIndex("antonym")));
animal.setHomoionym(cursor.getString(cursor
.getColumnIndex("homoionym")));
animal.setDerivation(cursor.getString                       (cursor.getColumnIndex("derivation")));
animal.setExamples(cursor.getString                        (cursor.getColumnIndex("examples")));
list.add(animal);
} while (cursor.moveToNext());
}
return list;
}
}

接下来呢，我们开始写主界面，将数据库中所有的动物类成语显示在界面上activity_animal.xml和animal_item.xml。

为了使界面载入过程生动形象，我们可以增加淡入淡出的动画效果

在res目录下新建anim目录，在下面创建anim_listview.xml文件

<?xml version="1.0" encoding="utf-8"?>
<alpha xmlns:android="http://schemas.android.com/apk/res/android"
android:duration="1000"
android:fromAlpha="0.0"
android:toAlpha="1.0"
>
</alpha>

设置了一个Alpha动画，从无到有的过程。

创建anim_layout_listview.xml文件，

<?xml version="1.0" encoding="utf-8"?>
<layoutAnimation xmlns:android="http://schemas.android.com/apk/res/android"
android:animation="@anim/anim_listview"
android:animationOrder="random"
android:delay="0.2"
>
</layoutAnimation>

上述代码主要是设置了布局动画，引用了之前的Alpha动画，设置每一项出现的时间间隔和出现的顺序。

接下来，我们创建一个自定义的适配器，这个适配器继承自ArrayAdapter，泛型指定为Animal类

public class AnimalAdapter extends ArrayAdapter<Animal> {
private int resourceId;
public AnimalAdapter(Context context, int resource, List<Animal>objects) {
super(context, resource, objects);
resourceId=resource;
}
public View getView(int position, View convertView, ViewGroup parent){
Animal animal=getItem(position);
View view;
ViewHolder viewHolder;
if (convertView==null){
view= LayoutInflater.from(getContext()).inflate(resourceId,null);
viewHolder=new ViewHolder();
viewHolder.tvName=(TextView)view.findViewById(R.id.tvName);
viewHolder.btnSave=(ImageButton)view.findViewById(R.id.btnSave);
view.setTag(viewHolder);
}else{
view=convertView;
viewHolder=(ViewHolder)view.getTag();
}
viewHolder.tvName.setText(animal.getName());
//取消获取焦点的组件，为了实现点击每个成语从而弹出对话框
viewHolder.btnSave.setFocusable(false);
viewHolder.btnSave.setFocusableInTouchMode(false);

return view;
}
class ViewHolder {
TextView tvName;
ImageButton btnSave;
}
}

下面在activity包下新建StudyAnimalActivity继承自Activity

public class StudyAnimalActivity extends Activity {
private List<Animal>animalList;
private AnimalDao animalDao;
private ListView lvAnimalList;

protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_animal);
initAnimals();
lvAnimalList=(ListView)findViewById(R.id.lvAnimalList);
AnimalAdapter animalAdapter=new AnimalAdapter(this,R.layout.animal_item,animalList);
lvAnimalList.setAdapter(animalAdapter);
//增加点击事件处理
lvAnimalList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?>adapterView, View view, int position, long id) {
Animal animal=animalList.get(position);
String result=animal.getName()+"\n"+animal.getPronounce()+"\n【解释】: "+ animal.getExplain()
+ "\n【近义词】: " +animal.getHomoionym()+
"\n【反义词】: " + animal.getAntonym() +
"\n【来源】: "+ animal.getDerivation() +
"\n【示例】: " + animal.getExamples();
DialogUtil.showDialog(result,StudyAnimalActivity.this);
}
});
}
private void initAnimals() {
animalDao=AnimalDao.getInstance(this);
animalList=animalDao.getAllAnimals();
}
}

可以看出来，这里添加了一个initAnimal（）方法，用于初始化所有动物数据。

这里DialogUtil.showDialog()方法是自定义的方法。

public class DialogUtil {
public static void showDialog(String result, Context context){
AlertDialog.Builder builder=new AlertDialog.Builder(context);
LayoutInflater layoutInflater=LayoutInflater.from(context);
View view=layoutInflater.inflate(R.layout.dialog_info,null);
builder.setView(view);
TextView tvIdiomInfo=(TextView)view.findViewById(R.id.tvIdiomInfo);
tvIdiomInfo.setText(result);
builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
}
});
builder.create().show();
}
}

然后获取ListView控件，建立AnimalAdapter关联子布局及数据，调用ListView控件的setAdapter()方法与关联数据，这样定制ListView界面的任务就完成了。

接下来，该做实现点击每条成语以对话框的形式显示该成语的详细信息：dialog_info.xml

<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/bg_ling"
android:orientation="vertical">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/tvIdiomInfo"
android:text="MediumText"
android:textAppearance="?android:attr/textAppearanceMedium"/>
</LinearLayout>
</ScrollView>

可以看到，最外层是ScrollView组件，当内容较多时会自动出现垂直滚动条。

这样这个快乐动物成语app就完成了，步骤很复杂，连环实现一套程序，才能达到需要的结果，做程序的就是不能怕麻烦，一点一点的做下来，最后终会成功！