关于Contentprovider的小结

自定义contentprovider

contentprovider 操作的数据源为本程序中创建的表中的数据

很简单的创建SqlHelper.java

  //数据库创建public class SqlHelper extends SQLiteOpenHelper{public SqlHelper(Context context) {//"data"数据库名字super(context, "data", null, 1);}@Overridepublic void onCreate(SQLiteDatabase db) {String sql="create table test(_id INTEGER PRIMARY KEY AUTOINCREMENT,name text,age text)";db.execSQL(sql);}@Overridepublic void onUpgrade(SQLiteDatabase db, int arg1, int arg2) {}}

//自定义contentprovider

MyContentProvider.java

public class MyContentProvider extends ContentProvider{    //UriMatcher类用于匹配Uripublic final static UriMatcher uriMatcher=new UriMatcher(UriMatcher.NO_MATCH);//域名,Contentprovider的标识public final static String AUTHORIES="com.example.contentprovider.mydata";static{//添加要匹配的uri,  参数：域名、表名、返回匹配码（如果匹配正确则返回  1）uriMatcher.addURI(AUTHORIES, "test", 1); uriMatcher.addURI(AUTHORIES, "test/#", 2);//‘#’通配符号}public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORIES+ "/" + "test");private SqlHelper helper = new SqlHelper(getContext());@Overridepublic int delete(Uri uri,  String where, String[] whereArgs) {SQLiteDatabase database = helper.getWritableDatabase(); //uri进行匹配，只有匹配才执行对应的操作switch (uriMatcher.match(uri)) {case 1:int count=database.delete("test", where, whereArgs);//删除的记录的条数break;case 2:break;default:break;}getContext().getContentResolver().notifyChange(uri, null);return 0;}@Overridepublic String getType(Uri arg0) {return null;}//插入操作@Overridepublic Uri insert(Uri uri, ContentValues contentValues) {SQLiteDatabase database = helper.getWritableDatabase(); database.insert("test", "name", contentValues);//可以将“name”字段更改为其他字段都行getContext().getContentResolver().notifyChange(uri, null);return uri;}@Overridepublic boolean onCreate() {helper = new SqlHelper(getContext());return true;}@Overridepublic Cursor query(Uri arg0, String[] arg1, String arg2, String[] arg3,String arg4) {return null;}@Overridepublic int update(Uri arg0, ContentValues arg1, String arg2, String[] arg3) {return 0;}}

//配置文件中注册如下

  <!-- 注册ContentProvider -->        <provider               android:name="com.example.contentprovider.MyContentProvider"              android:authorities="com.example.contentprovider.mydata" />

//本程序的唯一一个javabean people.java

public class People {private  String age;private String name;private String id;public String getAge() {return age;}public void setAge(String age) {this.age = age;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getId() {return id;}public void setId(String id) {this.id = id;}}

//MainActivity.java

public class MainActivity extends Activity {public final static String AUTHORIES="com.example.contentprovider.mydata";//                          |  固定格式   |  |类似网站的域名|  |数据源，这里是表|final Uri uri = Uri.parse("content://" + AUTHORIES+ "/" + "test"); private Button button1;private Button button2;private ListView listView;private List<People> peoples;private DataAdapter dataAdapter;    @SuppressWarnings({ "unused", "unused" })@Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);                        button1=(Button)this.findViewById(R.id.button1);        button2=(Button)this.findViewById(R.id.button2);        listView = (ListView)this.findViewById(R.id.listview);                peoples = getData();        if (peoples == null) {peoples = new ArrayList<People>();}else { dataAdapter = new DataAdapter(peoples);}               listView.setAdapter(dataAdapter);                getContentResolver().registerContentObserver(uri, true, new DataObserver(new Handler()));//注册数据变化监听                //增加数据        button1.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View view) {      ContentValues contentValues = new ContentValues();    contentValues.put("name", "hh");    contentValues.put("age", "20");        getContentResolver().insert(uri, contentValues);//插入数据}});               //删除数据        button2.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View view) {Uri urif=ContentUris.withAppendedId(uri, 42);////getContentResolver().delete(uri, "_id=?", new String[]{" "+3});getContentResolver().delete(urif, null, null);}});            }        private List<People> getData(){        List<People> list= new ArrayList<People>();        SqlHelper sqlHelper = new SqlHelper(MainActivity.this);    SQLiteDatabase database = sqlHelper.getWritableDatabase();        Cursor cursor = database.rawQuery("select * from test",null);        while (cursor.moveToNext()) {      People people = new People();          people.setId(cursor.getString(cursor.getColumnIndex("_id")));          people.setName(cursor.getString(cursor.getColumnIndex("name")));          people.setAge(cursor.getString(cursor.getColumnIndex("age")));          list.add(people);}    return list;    }          //监听URI上的变化的类    public class DataObserver extends ContentObserver{public DataObserver(Handler handler) {super(handler);}@Overridepublic void onChange(boolean change) {//进行相应的处理List<People> getList = getData();    DataAdapter dataAdapter = new DataAdapter(getList);    listView.setAdapter(dataAdapter);    listView.setSelection(dataAdapter.getCount()-1);}    }            public class DataAdapter extends BaseAdapter{        List<People> list = new ArrayList<People>();        public DataAdapter(List<People> list){    this.list = list;    }@Overridepublic int getCount() {return list.size();}@Overridepublic Object getItem(int arg0) {return list.get(arg0);}@Overridepublic long getItemId(int arg0) {return arg0;}@Overridepublic View getView(int arg0, View view, ViewGroup arg2) {Viewholder viewholder=null;if (view == null) {viewholder=new Viewholder();view=LayoutInflater.from(MainActivity.this).inflate(R.layout.item, null);viewholder.idTextView = (TextView)view.findViewById(R.id.text);viewholder.nameTextView = (TextView)view.findViewById(R.id.name);viewholder.ageTextView = (TextView)view.findViewById(R.id.age);view.setTag(viewholder);}else {viewholder=(Viewholder)view.getTag();}    People people = list.get(arg0);    viewholder.idTextView.setText( people.getId());    viewholder.nameTextView.setText(people.getName());    viewholder.ageTextView.setText(people.getAge());return view;}        }        class Viewholder{        TextView idTextView;    TextView nameTextView;    TextView ageTextView;        }}

//效果图