Android学习五：Content Provider 使用

public class MainActivity extends Activity {
	private ListView listView = null;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);

		listView = (ListView) this.findViewById(R.id.listView);
		// 查询系统中的所有联系人
		Uri uri = Uri.parse("content://com.android.contacts/contacts");
		Cursor cursor = getContentResolver().query(uri, null, null, null, null);
		// 根据Cursor创建SimpleCursorAdapter对象
		SimpleCursorAdapter simpleCursorAdapter = new SimpleCursorAdapter(this,
				android.R.layout.simple_list_item_1, cursor,
				new String[] { ContactsContract.Contacts.DISPLAY_NAME },
				new int[] { android.R.id.text1 },
				CursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER);
		// 在ListVIew中显示联系人列表
		listView.setAdapter(simpleCursorAdapter);
	}
}

<uses-permission android:name="android.permission.READ_CONTACTS" />

public class DBOpenHelper extends SQLiteOpenHelper {
	public DBOpenHelper(Context context) {
		/**
		 * postgrade.db 数据库的名字 ；null 表示使用默认的游标工厂 ；1 表示一开始的版本，建议设置为1
		 */
		super(context, "postgrade.db", null, 1);
	}

	@Override
	public void onCreate(SQLiteDatabase db) {
		// 该方法在第一次创建数据库的时候被调用
		// 因此可以在这个地方创建表之类的操作
		db.execSQL("CREATE TABLE student(id INTEGER PRIMARY KEY AUTOINCREMENT, name VARCHAR(20))");
	}

	@Override
	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
		// 修改数据库的版本会触发此函数
		// 在这里可以添加新的表或者修改表的字段
	}
}

public class StuProvider extends ContentProvider {
	private DBOpenHelper dbOpenHelper = null;

	private static final UriMatcher MATCHER;
	private static final int STU = 0;// 匹配成功后的返回值
	private static final String AUTHORITY;// 域名[主机名]
	private static final String STUDENT;// 路径名

	static {
		// 在不匹配的时候，返回-1，即UriMatcher.NO_MATCH
		MATCHER = new UriMatcher(UriMatcher.NO_MATCH);
		AUTHORITY = "org.tonny.providers.stuprovider";
		STUDENT = "student";
		MATCHER.addURI(AUTHORITY, STUDENT, STU);
	}

	@Override
	public boolean onCreate() {
		// 在创建实例的时候调用，只会被调用一次；用作数据的初始化操作
		dbOpenHelper = new DBOpenHelper(getContext());
		return false;
	}

	@Override
	public String getType(Uri uri) {
		// 返回当前要操作的数据的内容类型如txt-->plain/text html -->html/text
		return null;
	}

	@Override
	public Uri insert(Uri uri, ContentValues values) {
		// 允许外部的应用向内容提供者插入数据
		SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
		switch (MATCHER.match(uri)) {
		case STU:
			// 調用自身的方法，第二個參數爲插入空值时候的列名
			long rowId = db.insert("student", null, values);
			Uri insertUri = ContentUris.withAppendedId(uri, rowId);

			// 也可以使用这种方式
			// Uri insertUri =
			// Uri.parse("content://org.tonny.test.providers.stuprovider/student/"+
			// rowId);
			return insertUri;
		default:
			throw new IllegalArgumentException("This is an unknown Uri:" + uri);
		}
	}

	@Override
	public int delete(Uri uri, String selection, String[] selectionArgs) {
		// TODO Auto-generated method stub
		return 0;
	}

	@Override
	public int update(Uri uri, ContentValues values, String selection,
			String[] selectionArgs) {
		// TODO Auto-generated method stub
		return 0;
	}

	@Override
	public Cursor query(Uri uri, String[] projection, String selection,
			String[] selectionArgs, String sortOrder) {
		// TODO Auto-generated method stub
		return null;
	}

}

package org.tonny.domain;

public class Student {
	private int id;
	private String name;

	public Student() {

	}

	public Student(int id, String name) {
		this.id = id;
		this.name = name;
	}

	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 class StudentService {

	private DBOpenHelper dbHelper = null;

	public StudentService(Context context) {
		this.dbHelper = new DBOpenHelper(context);
	}

	public void insert(Student stu) {
		// 内部有緩存功能，使用的是同一個句柄,如果数据库满了，则返回一个只读的句柄
		SQLiteDatabase db = dbHelper.getWritableDatabase();
		// 使用占位符號‘?’，防止特殊字符
		db.execSQL("INSERT INTO student VALUES(?,?)",
				new Object[] { stu.getId(), stu.getName() });
	}

	public void delete(Integer id) {
		SQLiteDatabase db = dbHelper.getReadableDatabase();
		db.execSQL("DELETE FROM student WHERE id = ?",
				new String[] { String.valueOf(id) });
	}

	public void update(Student stu) {
		SQLiteDatabase db = dbHelper.getWritableDatabase();
		db.execSQL("UPDATE student SET name = ? WHERE id = ?", new String[] {
				stu.getName(), String.valueOf(stu.getId()) });
	}

	public Student query(Integer id) {
		SQLiteDatabase db = dbHelper.getReadableDatabase();
		String sql = "SELECT * FROM student WHERE id = ?";
		Cursor cursor = db.rawQuery(sql, new String[] { String.valueOf(id) });
		if (cursor.moveToFirst()) {
			int stuId = cursor.getInt(cursor.getColumnIndex("id"));
			String stuName = cursor.getString(cursor.getColumnIndex("name"));
			return new Student(stuId, stuName);
		}
		return null;
	}
}

public class MainActivity extends Activity {
	private EditText _txtId = null;
	private EditText _txtName = null;
	private StudentService _service = null;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		_txtId = (EditText) this.findViewById(R.id.txtId);
		_txtName = (EditText) this.findViewById(R.id.txtName);
		_service = new StudentService(getApplicationContext());
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}

	public void onBtnOK(View v) {
		int id = Integer.valueOf(_txtId.getText().toString());
		String name = _txtName.getText().toString();
		Student stu = new Student(id, name);
		_service.insert(stu);
	}

}

<provider
            android:name="org.tonny.db.StuProvider"
            android:authorities="org.tonny.providers.stuprovider"
            android:exported="true"
            tools:ignore="ExportedContentProvider" />