Android 音乐播放器的开发教程（十二）SQLite的使用及我的最爱歌曲的实现 ----- 小达
SQLite的使用及我的最爱歌曲的实现
早上好~~~~各位,今天接着昨天的android上数据库SQLite的使用来说说,怎么在昨天的基础上,实现歌曲添加入我的最爱.先上理想的效果图,进入播放界面之后就可以点击爱心添加为最爱歌曲,并放入数据库,在我的最爱栏目也可以看的到,再次点击红心就可以取消我的最爱,丛数据库再拿出来(讲解的话,主要在代码的注释里面):
先来实现点击主界面上的我的最爱后切换至我的最爱fragment,一个MyFavoriteFragment.java和一个fragment_favorite_layout.xml,先给出布局文件:
package com.example.dada.myapplication;
import android.app.Activity;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.net.Uri;
import android.os.Bundle;
import android.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ListView;
public class MyFavoriteFragment extends Fragment {
private OnFragmentInteractionListener mListener;
public static MyFavoriteFragment newInstance() {
MyFavoriteFragment fragment = new MyFavoriteFragment();
Bundle args = new Bundle();
fragment.setArguments(args);
return fragment;
}
public MyFavoriteFragment() {
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_my_favorite, container, false);
initialize(rootView); //自定义初始化函数
return rootView;
}
private void initialize(View rootView){
rootView.findViewById(R.id.favorite_fragment_to_main_fragment) //回到主Fragment
.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
MainFragment mainFragment = new MainFragment();
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.fragment_layout, mainFragment);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
}
});
((ListView) rootView.findViewById(R.id.favorite_music_list)).setOnItemClickListener( //我的最爱列表点击事件
new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView parent, View view, int position, long id) {
mListener.onFavoriteFragmentInteraction(AppConstant.PlayerMsg.LIST_CLICK,position);
}
}
);
/*
更新列表的adapter
给列表设置一个新的adapter
*/
MainActivity.myDataBase.Update_adapter();
MainActivity.myDataBase.SetAdapter((ListView)rootView.findViewById(R.id.favorite_music_list));
}
public void onButtonPressed() {
if (mListener != null) {
}
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
try {
mListener = (OnFragmentInteractionListener) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement OnFragmentInteractionListener");
}
}
@Override
public void onDetach() {
super.onDetach();
mListener = null;
}
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
public void onFavoriteFragmentInteraction(int msg,int position);
}
}
在 PlayFragment的界面上有颗爱心,根据当前歌曲是否为喜爱的歌曲来显示状态,直接放在PlayFragment.java的onCreateView方法里面即可:
if(MainActivity.isFavorite){
(v.findViewById(R.id.my_favorite_button)).setBackgroundResource(R.drawable.img_favourite_selected);
}
else{
(v.findViewById(R.id.my_favorite_button)).setBackgroundResource(R.drawable.img_favourite_normal);
}
(v.findViewById(R.id.my_favorite_button))
.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(MainActivity.isFavorite){
Toast.makeText(getActivity().getApplicationContext(),"已经取消我的最爱",Toast.LENGTH_SHORT).show();
(v.findViewById(R.id.my_favorite_button)).setBackgroundResource(R.drawable.img_favourite_normal);
mListener.onPlayFragmentInteraction(AppConstant.PlayerMsg.DELETE_FROM_FAVORITE);
}
else{
Toast.makeText(getActivity().getApplicationContext(),"已经加入我的最爱",Toast.LENGTH_SHORT).show();
(v.findViewById(R.id.my_favorite_button)).setBackgroundResource(R.drawable.img_favourite_selected);
mListener.onPlayFragmentInteraction(AppConstant.PlayerMsg.ADD_TO_FAVORITE);
}
}
});在MainFragment.java中添加点击事件的相应,代码添加进onCreateView方法里:
rootView.findViewById(R.id.myFavoriteButton). //切换至我的最爱Fragment
setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
MyFavoriteFragment myFavoriteFragment = new MyFavoriteFragment();
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction(); fragmentTransaction.replace(R.id.fragment_layout, myFavoriteFragment);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
}
});在MainActivity中的部分代码如下(这些代码分布在不同的地方,我会详细的说明的):
public static boolean isFavorite = false; //声明一个静态的boolean变量,用来记录当前的播放歌曲是否为我的最爱
public void onPlayFragmentInteraction(int message){ //PlayFragment的回调函数
Mp3Info mp3_Info = mp3Infos.get(music_position); //得到当前歌曲类(自定义类)的实例
switch (message){
case AppConstant.PlayerMsg.DISMISS_CLICK: //回退到MainFragmnet
myMusicFragment = new MyMusicFragment();
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction(); fragmentTransaction.replace(R.id.fragment_layout, mainFragment);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
break;
case AppConstant.PlayerMsg.ADD_TO_FAVORITE: //将当前歌曲添加到我的最爱列表里
isFavorite = true;
mp3_Info.setFavorite(isFavorite);
myDataBase.AddData( //添加入数据库的表格中
MyDataBase.TABLE_NAME_FAVORITE,
(int)mp3_Info.getId(),
mp3_Info.getTitle(),
mp3_Info.getArtist(),
mp3_Info.getDuration(),
mp3_Info.getUrl(),
(int)mp3_Info.getAlbum_id()
);
break;
case AppConstant.PlayerMsg.DELETE_FROM_FAVORITE: //从数据库对应表格里面删除
isFavorite = false;
mp3Infos.get(music_position).setFavorite(isFavorite);
myDataBase.DeleteData(
MyDataBase.TABLE_NAME_FAVORITE,
(int)mp3_Info.getId());
break;
}
}
public void onFavoriteFragmentInteraction(int msg,int position){ //点击我的最爱列表里的歌曲实现播放 if(msg == AppConstant.PlayerMsg.LIST_CLICK){
if (mp3Infos != null) {
isPause = false;
initService(position);
}
}
}
isFavorite = mp3_Info.getFavorite(); //这句话加入到changeMusic函数里面去,因为每切一首歌,都要重置activity中的这个变量,以保证该变量指示的是当前播放歌曲,可以同步那个红心的显示上面有两个涉及到数据库操作的函数,下面就给出MyDataBase.java的全部代码,红色是在昨天的基础上添加的新的部分,代码有点多,大家选重点的看哈:
package com.example.dada.myapplication;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.widget.Adapter;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
import java.util.ArrayList;
import java.util.List;
public class MyDataBase {
private int dataCount;
private static Context context;
public static ListAdapter adapter;
/*
下面一大串是需要用到的常量
直接弄成了静态final的
*/
public final static String DATABASE_NAME = "MyMusicDataBase";
public final static String TABLE_NAME = "RecentlyPlayTable1";
public final static String TABLE_NAME_FAVORITE = "FavoriteTable";
public final static String TABLE_NAME_PLAYLIST = "PlayListTable";
public final static String TABLE_MUSIC_ID = "_id";
public final static String TABLE_MUSIC_TITLE = "music_title";
public final static String TABLE_ARTIST = "artist";
public final static String TABLE_DURATION = "druation";
public final static String TABLE_MUSIC_URL = "music_url";
public final static String TABLE_ALBUM_ID = "album_id";
public final static String TABLE_CURRENT_TIME = "current_time";
public final static String TABLE_LIST_NAME = "list_name";
/*
创建数据库的语句
写好了直接可以执行的
*/
public final static String CREATE_TABLE = "CREATE TABLE IF NOT EXISTS " +
TABLE_NAME + " (" + TABLE_MUSIC_ID + " INTEGER PRIMARY KEY,"
+ TABLE_MUSIC_TITLE + " STRING," + TABLE_ARTIST + " STRING,"
+ TABLE_DURATION + " LONG," + TABLE_MUSIC_URL + " STRING,"
+ TABLE_ALBUM_ID + " INTEGER," + TABLE_CURRENT_TIME + " LONG)";
public final static String CREATE_FAVORITE_TABLE = "CREATE TABLE IF NOT EXISTS " +
TABLE_NAME_FAVORITE + " (" + TABLE_MUSIC_ID + " INTEGER PRIMARY KEY,"
+ TABLE_MUSIC_TITLE + " STRING," + TABLE_ARTIST + " STRING,"
+ TABLE_DURATION + " LONG," + TABLE_MUSIC_URL + " STRING,"
+ TABLE_ALBUM_ID + " INTEGER," + TABLE_CURRENT_TIME + " LONG)";
/*
直接持有一个SQLiteDatabase的实例
后面就直接对这个实例进行操作
*/
public static SQLiteDatabase recentPlaySQLiteDatabase = null; //最近播放的数据库
public MyDataBase(Context context,ListView listView){
this.context = context;
this.dataCount = 0;
this.adapter = null;
}
/*
自定义的创建数据库函数
在activity的onCreate()里面调用
*/
public static void CreateDataBase(){
recentPlaySQLiteDatabase = context.openOrCreateDatabase(DATABASE_NAME,Context.MODE_PRIVATE,null);
recentPlaySQLiteDatabase.execSQL(CREATE_TABLE);
recentPlaySQLiteDatabase.execSQL(CREATE_FAVORITE_TABLE);
}
/*
向数据库的表格中添加数据
这里用到的是添加的其中一种方法
利用ContentValues将数据封装好了之后再添加
另外一种是直接用SQL语句向表格里面插入
*/
public static void AddData(String table_name,int music_id,String music_title,
String music_artist,long music_duration,
String music_url,int album_id,long current_time){
ContentValues cv = new ContentValues();
cv.put(TABLE_MUSIC_ID,music_id);
cv.put(TABLE_MUSIC_TITLE,music_title);
cv.put(TABLE_ARTIST,music_artist);
cv.put(TABLE_DURATION,MusicListAdapter.formatTime(music_duration));
cv.put(TABLE_MUSIC_URL,music_url);
cv.put(TABLE_ALBUM_ID,album_id);
cv.put(TABLE_CURRENT_TIME,current_time);
recentPlaySQLiteDatabase.insert(table_name,null,cv);
}
/*这部分代码和上面那个函数功能是差不多的注释就看上面的*/
public static void AddData(String table_name,int music_id,String music_title,
String music_artist,long music_duration,
String music_url,int album_id){
ContentValues cv = new ContentValues();
cv.put(TABLE_MUSIC_ID,music_id);
cv.put(TABLE_MUSIC_TITLE,music_title);
cv.put(TABLE_ARTIST,music_artist);
cv.put(TABLE_DURATION,MusicListAdapter.formatTime(music_duration));
cv.put(TABLE_MUSIC_URL,music_url);
cv.put(TABLE_ALBUM_ID,album_id);
recentPlaySQLiteDatabase.insert(table_name,null,cv);
}
/*
由于在最近播放里面可能会存在一首歌曲播放两次
所以在AddData之前需要先查询是否存在歌曲
存在的话直接UpdateData()更新歌曲播放的时间
不存在就插入数据
*/
public static void UpdateData(String table_name,int music_id,long current_time){
String str = "UPDATE " + table_name + " SET " + TABLE_CURRENT_TIME + "=" + current_time + " WHERE "
+ TABLE_MUSIC_ID + "=" + music_id;
recentPlaySQLiteDatabase.execSQL(str);
}
public static boolean IsExistData(String table_name,int music_id){
String str = "SELECT * FROM " + table_name + " WHERE " + TABLE_MUSIC_ID + "=" +music_id;
if(recentPlaySQLiteDatabase.rawQuery(str,null).getCount() == 0)
return false;
else
return true;
}
/*
更新列表的adapter
可以更新列表的显示
里面用到了Cursor,执行query后,返回了一个Cursor对象
通过解析这个对象来获取需要的信息
*/
public static void UpdateAdapter(){
try{
Cursor cur = recentPlaySQLiteDatabase.
query(TABLE_NAME,new String[] {
TABLE_MUSIC_ID,
TABLE_MUSIC_TITLE,
TABLE_ARTIST,
TABLE_DURATION,
TABLE_MUSIC_URL,
TABLE_ALBUM_ID}
,null,null,null,null,null);
/*
这里的adapter用到了simpleCursorAdapter
关于SimpleCursorAdapter的使用需要注意的是，在我们的结果集中必须要包含一个“_id”的列
小达先开始在创建表格的时候,根本没有_id这一列,经常报错
卡了好久好久的,对于这个问题有三种解决办法:
第一，建表时根据规范去做
第二，查询时用别名，例如：SELECT id AS _id FROM person
第三，在CursorWrapper里做文章,在代码后面讲解下.
*/
if(cur !=null && cur.getCount() >= 0){
adapter = new SimpleCursorAdapter(
context,
R.layout.recently_play_item_layout,
cur,
new String[] {
TABLE_MUSIC_TITLE,
TABLE_ARTIST,
TABLE_DURATION},
new int[] {R.id.recently_play_music_title,
R.id.recently_play_music_Artist,
R.id.recently_play_music_duration}
);
}
MainActivity.mp3Infos.clear();
while(cur.moveToNext()){
Mp3Info mp3Info = new Mp3Info();
mp3Info.setUrl(cur.getString(cur.getColumnIndex(TABLE_MUSIC_URL)));
//mp3Info.setAlbum_id(cur.getLong(cur.getColumnIndex(TABLE_ALBUM_ID)));
mp3Info.setArtist(cur.getString(cur.getColumnIndex(TABLE_ARTIST)));
String time = cur.getString(cur.getColumnIndex(TABLE_DURATION));
long Time = changeTime(time);
mp3Info.setDuration(Time);
mp3Info.setId(cur.getInt(cur.getColumnIndex(TABLE_MUSIC_ID)));
mp3Info.setTitle(cur.getString(cur.getColumnIndex(TABLE_MUSIC_TITLE)));
MainActivity.mp3Infos.add(mp3Info);
}
}
catch(Exception e){
e.printStackTrace();
}
}
/*
从我的最爱列表里面删除该歌曲
也就是取消我的最爱收藏
直接执行数据库语句DELETE
*/
public static void DeleteData(String table_name,int music_id){
String str = "DELETE FROM " + MyDataBase.TABLE_NAME_FAVORITE +
" WHERE " + MyDataBase.TABLE_MUSIC_ID + "=" +music_id;
recentPlaySQLiteDatabase.execSQL(str);
}
public static void SetAdapter(ListView listView){
listView.setAdapter(adapter);
}
/*
更新我的最爱列表的adapter
*/
public static void Update_adapter(){
try{
Cursor cur = recentPlaySQLiteDatabase.
query(TABLE_NAME_FAVORITE,new String[] {
TABLE_MUSIC_ID,
TABLE_MUSIC_TITLE,
TABLE_ARTIST,
TABLE_DURATION,
TABLE_MUSIC_URL,
TABLE_ALBUM_ID}
,null,null,null,null,null);
if(cur !=null && cur.getCount() >= 0){
adapter = new SimpleCursorAdapter(
context,
R.layout.recently_play_item_layout,
cur,
new String[] {
TABLE_MUSIC_TITLE,
TABLE_ARTIST,
TABLE_DURATION},
new int[] {R.id.recently_play_music_title,
R.id.recently_play_music_Artist,
R.id.recently_play_music_duration}
);
}
/*
这里是将Activity中的List清空,
将我的最爱列表里的歌曲全部放入里面
为我的最爱列表点击做准备
*/
MainActivity.mp3Infos.clear();
while(cur.moveToNext()){
Mp3Info mp3Info = new Mp3Info();
mp3Info.setUrl(cur.getString(cur.getColumnIndex(TABLE_MUSIC_URL)));
mp3Info.setAlbum_id(cur.getLong(cur.getColumnIndex(TABLE_ALBUM_ID)));
mp3Info.setArtist(cur.getString(cur.getColumnIndex(TABLE_ARTIST)));
String time = cur.getString(cur.getColumnIndex(TABLE_DURATION));
long Time = changeTime(time);
mp3Info.setDuration(Time);
mp3Info.setId(cur.getInt(cur.getColumnIndex(TABLE_MUSIC_ID)));
mp3Info.setTitle(cur.getString(cur.getColumnIndex(TABLE_MUSIC_TITLE)));
MainActivity.mp3Infos.add(mp3Info);
}
}
catch(Exception e){
e.printStackTrace();
}
}
private static long changeTime(String time){ //将歌曲的时间转换为分秒的制度
long Time = 0;
String[] str = time.split(":");
Time = (Integer.valueOf(str[0])*60 + Integer.valueOf(str[1]))*1000;
return Time;
}
}
上面的一大批代码加注释,现在的播放器就能实现我们在最开始的理想功能咯,各位上手试试把 ,代码搞得有点乱,可能会有什么地方漏掉了一点东西,如果有问题直接给我留言,我会尽快改掉的~~~.
其实到这里,整个播放器的教程也就做完了,分了十二期博客将这个东西讲完了,刚开始写的时候感觉还有好多好多东西要弄上去,结果自己一点点的往上写,慢慢的播放器原型就出来了,感觉自己也把整个开发的流程复习了一变,好多知识点又有了新的认识.
先没感觉写博客的好处,真的投入到其中了才会享受这个过程,理清自己思路的一个过程,个人很推荐大家都将自己的经验或者经历同大家分享,双利的好处只有经历过的人才会懂,身为程序员的我们更应该如此.好咯,不废话了.整个专栏就到这里结束了,小达以后再有什么好的东西,一定会拿上来和大家分享的,.
还是栏目刚开始的那句话,不能怂,就是干,怂就输一半儿~~~~~~,大家一起加油把,嘿嘿.