成语展示

新建一个db包，在其下新建一个DBOpenHelper类

package happyidiom.bztc.edu.com.happyidiom.db; import android.content.Context; import android.database.sqlite.SQLiteDatabase; import android.os.Environment; import android.util.Log; import java.io.File; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import happyidiom.bztc.edu.com.happyidiom.R; /** * Created by Administrator on 2017/5/4. */ public class DBOpenHelper { private final int BUFFER_SIZE = 400000; public static final String DB_NAME = "idioms.db"; public static final String PACKAGE_NAME = "happyidiom.bztc.edu.com.happyidiom"; 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 openDatabase() { 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", "File not found"); e.printStackTrace(); } catch (IOException e) { Log.e("Database", "IO exception"); e.printStackTrace(); } return null; } }

搭建AndroidManifest.xml文件

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

新建一个test包，在其下新建DBOpenHelperTest继承AndroidTestCase

package happyidiom.bztc.edu.com.happyidiom.test; import android.test.AndroidTestCase; import happyidiom.bztc.edu.com.happyidiom.db.DBOpenHelper; /** * Created by Administrator on 2017/5/4. */ public class DBOpenHelperTest extends AndroidTestCase { public void testDBCopy(){ DBOpenHelper dbOpenHelper=new DBOpenHelper(getContext()); dbOpenHelper.openDatabase(); } }

新建一个entity包，在entity包下新建一个Animal类

package happyidiom.bztc.edu.com.happyidiom.entity; /** * Created by Administrator on 2017/5/4. */ public class Animal { private int id; private String name; private String pronounce; private String explain; private String antonym; private String homoionym; private String derivation; private String examples; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getPronounce() { return pronounce; } public void setPronounce(String pronounce) { this.pronounce = pronounce; } public String getExplain() { return explain; } public void setExplain(String explain) { this.explain = explain; } public String getAntonym() { return antonym; } public void setAntonym(String antonym) { this.antonym = antonym; } public String getHomoionym() { return homoionym; } public void setHomoionym(String homoionym) { this.homoionym = homoionym; } public String getDerivation() { return derivation; } public void setDerivation(String derivation) { this.derivation = derivation; } public String getExamples() { return examples; } public void setExamples(String examples) { this.examples = examples; } }

在entity包下再创建一个AnimalDao类

package happyidiom.bztc.edu.com.happyidiom.entity; import android.content.Context; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import java.util.ArrayList; import java.util.List; import happyidiom.bztc.edu.com.happyidiom.db.DBOpenHelper; /** * Created by Administrator on 2017/5/5. */ public class AnimalDao { private static AnimalDao animalDao; private SQLiteDatabase db; private AnimalDao(Context context) { DBOpenHelper dbHelper = new DBOpenHelper(context); db=dbHelper.openDatabase(); } 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<>(); Cursor cursor=db.query("animal",null,null,null,null,null,null); if (cursor.moveToFirst()) { do { Animal animal=new Animal(); animal.setId(cursor.getInt(cursor.getColumnIndex("_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; } }

编写单元测试类AnimalDaoTest 继承 AndroidTestCase

package happyidiom.bztc.edu.com.happyidiom.test; import android.test.AndroidTestCase; import java.util.List; import happyidiom.bztc.edu.com.happyidiom.entity.Animal; import happyidiom.bztc.edu.com.happyidiom.entity.AnimalDao; /** * Created by Administrator on 2017/5/5. */ public class AnimalDaoTest extends AndroidTestCase{ public void testGetAllAnimals(){ AnimalDao animalDao= AnimalDao.getInstance(getContext()); List<Animal> animals=animalDao.getAllAnimals(); System.out.println(animals.size()); for(Animal animal:animals){ System.out.println(animal.getName()); } } }

在layout下新建activity_animal.xml文件，主要添加了一个ListView控件

<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:background="@drawable/bg_animal" android:orientation="vertical"> <ListView android:id="@+id/lvAnimalList" android:layout_width="match_parent" android:layout_height="wrap_content" android:layoutAnimation="@anim/anim_layout_listview" android:listSelector="#00000000" /> </LinearLayout>

在layout目录下新建animal_item.xml

<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:padding="10dp"> <TextView android:text="助人为乐" android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/tvName" android:layout_alignParentLeft="true" android:layout_alignParentTop="true" android:gravity="center" android:textAppearance="?android:attr/textAppearanceLarge" /> <ImageButton android:id="@+id/btnSave" android:layout_width="wrap_content" android:layout_height="wrap_content" android:background="@null" android:layout_alignParentRight="true" android:layout_alignTop="@+id/tvName" android:src="@drawable/btnsave" /> </RelativeLayout>

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>

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>

创建adapter包，在其下创建一个AnimalAdapter类

package happyidiom.bztc.edu.com.happyidiom.adapter; import android.content.Context; import android.support.annotation.NonNull; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.ArrayAdapter; import android.widget.ImageButton; import android.widget.TextView; import java.util.List; import happyidiom.bztc.edu.com.happyidiom.R; import happyidiom.bztc.edu.com.happyidiom.entity.Animal; /** * Created by Administrator on 2017/5/4. */ public class AnimalAdapter extends ArrayAdapter<Animal> { private int resourceId; public AnimalAdapter(Context context, int resource, List<Animal> objects) { super(context, resource, objects); resourceId=resource; } @NonNull @Override 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()); viewHolder.btnSave.setFocusable(false); viewHolder.btnSave.setFocusableInTouchMode(false); return view; } class ViewHolder { TextView tvName; ImageButton btnSave; } }

在activity包下新建StudyAnimalActivity继承自Activity

package happyidiom.bztc.edu.com.happyidiom.activity; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.widget.AdapterView; import android.widget.ListView; import java.util.List; import happyidiom.bztc.edu.com.happyidiom.R; import happyidiom.bztc.edu.com.happyidiom.adapter.AnimalAdapter; import happyidiom.bztc.edu.com.happyidiom.entity.Animal; import happyidiom.bztc.edu.com.happyidiom.entity.AnimalDao; import happyidiom.bztc.edu.com.happyidiom.unil.DialogUtil; /** * Created by Administrator on 2017/5/5. */ public class StudyAnimalActivity extends Activity { private List<Animal> animalList; private AnimalDao animalDao; private ListView lvAnimalList; @Override 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); 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(); } }

在layout下新建布局文件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:id="@+id/tvIdiomInfo" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="Medium Text" android:textAppearance="?android:attr/textAppearanceMedium" /> </LinearLayout> </ScrollView>

在util包下新建DialogUtil类

package happyidiom.bztc.edu.com.happyidiom.unil; import android.app.AlertDialog; import android.content.Context; import android.content.DialogInterface; import android.view.LayoutInflater; import android.view.View; import android.widget.TextView; import happyidiom.bztc.edu.com.happyidiom.R; /** * Created by Administrator on 2017/5/5. */ 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(); } }

实验结果

实验过程遇到的问题

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.database.Cursor android.database.sqlite.SQLiteDatabase.query(java.lang.String, java.lang.String[], java.lang.String, java.lang.String[], java.lang.String, java.lang.String, java.lang.String)' on a null object reference at happyidiom.bztc.edu.com.happyidiom.entity.AnimalDao.getAllAnimals(AnimalDao.java:34) at happyidiom.bztc.edu.com.happyidiom.activity.StudyAnimalActivity.initAnimals(StudyAnimalActivity.java:52) at happyidiom.bztc.edu.com.happyidiom.activity.StudyAnimalActivity.onCreate(StudyAnimalActivity.java:30) at android.app.Activity.performCreate(Activity.java:6664) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)? at android.app.ActivityThread.-wrap12(ActivityThread.java)? at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)? at android.os.Handler.dispatchMessage(Handler.java:102)? at android.os.Looper.loop(Looper.java:154)? at android.app.ActivityThread.main(ActivityThread.java:6077)? at java.lang.reflect.Method.invoke(Native Method)? at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)? at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)?

出现问题的原因：DBOpenHelper中的包名路径与实际建立的包名的路径不同，所以调试不成功