简单实现自己的Content Provider（一）

项目中突然想用Content Provider实现跨应用操作数据的功能，虽然后来没有利用Content Provider来实现。但还是写了个简单demo程序，熟悉一下Content Provider的开发。这篇文章只是简单记录下，下一篇文章具体解释需要注意的问题

 

两个项目，一个继承Content Provider将数据库的CRUD操作显露给其他应用，另一个项目，则是进行CRUD操作。很简单的功能。

 

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项目1：

首先创建 DatabaseHelper

	private static String DATABASE_NAME = "db_name";
	public static String TABLE_NAME = "db_table_name";
	public static String COL_ID = "_id";
	public static String COL_TXT = "txt";

	public DatabaseHelper(Context context) {
		super(context, DATABASE_NAME, null, 1);

	}

	@Override
	public void onCreate(SQLiteDatabase db) {
		// TODO Auto-generated method stub
		db.execSQL("create table if not exists " + TABLE_NAME + "(" + COL_ID
				+ " integer primary key autoincrement, " + COL_TXT + " text )");
	}

	@Override
	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
		// TODO Auto-generated method stub

		db.execSQL("drop table if exists " + TABLE_NAME);

		onCreate(db);
	}

 

然后实现 Content Provider功能

private static final String TAG = "TestContentProvider";

	private DatabaseHelper dbHelper;

	// public constants for client development
	public static final String AUTHORITY = "info.zhegui.contentprovider.provider";
	public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY
			+ "/" + DatabaseHelper.TABLE_NAME);

	// helper constants for use with the UriMatcher
	private static final int LENTITEM_LIST = 1;
	private static final int LENTITEM_ID = 2;
	private static final UriMatcher URI_MATCHER;

	/**
	 * Column and content type definitions for the LentItemsProvider.
	 */
	public static interface LentItems extends BaseColumns {
		public static final String CONTENT_TYPE = ContentResolver.CURSOR_DIR_BASE_TYPE
				+ "/vnd.info.zhegui.provider." + DatabaseHelper.TABLE_NAME;
		public static final String CONTENT_ITEM_TYPE = ContentResolver.CURSOR_ITEM_BASE_TYPE
				+ "/vnd.info.zhegui.provider." + DatabaseHelper.TABLE_NAME;
	}

	static {
		URI_MATCHER = new UriMatcher(UriMatcher.NO_MATCH);
		URI_MATCHER.addURI(AUTHORITY, DatabaseHelper.TABLE_NAME, LENTITEM_LIST);
		URI_MATCHER.addURI(AUTHORITY, DatabaseHelper.TABLE_NAME + "/#",
				LENTITEM_ID);
	}

	@Override
	public int delete(Uri uri, String selection, String[] selectionArgs) {
		int rowNum = dbHelper.getWritableDatabase().delete(
				DatabaseHelper.TABLE_NAME, selection, selectionArgs);

		return rowNum;
	}

	@Override
	public String getType(Uri uri) {
		switch (URI_MATCHER.match(uri)) {
		case LENTITEM_LIST:
			return LentItems.CONTENT_TYPE;
		case LENTITEM_ID:
			return LentItems.CONTENT_ITEM_TYPE;
		default:
			throw new IllegalArgumentException("Unsupported URI: " + uri);
		}
	}

	@Override
	public Uri insert(Uri uri, ContentValues values) {

		long rowId = dbHelper.getWritableDatabase().insert(
				DatabaseHelper.TABLE_NAME, null, values);

		return Uri.parse(CONTENT_URI + "/" + rowId);
	}

	@Override
	public boolean onCreate() {
		dbHelper = new DatabaseHelper(getContext());

		return true;
	}

	@Override
	public Cursor query(Uri uri, String[] projection, String selection,
			String[] selectionArgs, String sortOrder) {
		if (URI_MATCHER.match(uri) != LENTITEM_LIST) {
			throw new IllegalArgumentException(
					"Unsupported URI for insertion: " + uri);
		}

		return dbHelper.getReadableDatabase().query(DatabaseHelper.TABLE_NAME,
				projection, selection, selectionArgs, null, null, null);
	}

	@Override
	public int update(Uri uri, ContentValues values, String selection,
			String[] selectionArgs) {

		int rowNum = dbHelper.getWritableDatabase().updateWithOnConflict(
				DatabaseHelper.TABLE_NAME, values, selection, selectionArgs,
				SQLiteDatabase.CONFLICT_FAIL);

		return rowNum;
	}

 

接下来在manifest中声明

        <provider
            android:name="TestContentProvider"
            android:authorities="info.zhegui.contentprovider.provider"
            android:exported="true" />

 

ok，项目就完成了。就是这么简单!

 

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项目2：

只是简单调用CRUD操作，直接上代码

public static String TABLE_NAME = "db_table_name";
	public static final String AUTHORITY = "info.zhegui.contentprovider.provider";
	public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY
			+ "/" + TABLE_NAME);

	public static String COL_ID = "_id";
	public static String COL_TXT = "txt";

	public static interface LentItems extends BaseColumns {
		public static final String CONTENT_TYPE = ContentResolver.CURSOR_DIR_BASE_TYPE
				+ "/vnd.info.zhegui.provider." + TABLE_NAME;
		public static final String CONTENT_ITEM_TYPE = ContentResolver.CURSOR_ITEM_BASE_TYPE
				+ "/vnd.info.zhegui.provider." + TABLE_NAME;
	}

	private EditText etIccid;
	private ListView listView;

	private CustomAdapter mAdapter;
	private Handler handler;

	private List<Item> listData = new ArrayList<Item>();

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

		handler = new Handler(this);

		etIccid = (EditText) findViewById(R.id.et);
		listView = (ListView) findViewById(R.id.listview);
		mAdapter = new CustomAdapter();
		((Button) findViewById(R.id.btn_add))
				.setOnClickListener(new View.OnClickListener() {

					@Override
					public void onClick(View v) {
						final String txt = etIccid.getEditableText().toString();
						if (!TextUtils.isEmpty(txt)) {
							new Thread() {
								public void run() {
									ContentValues values = new ContentValues();
									values.put(COL_TXT, txt);
									Uri uri = getContentResolver().insert(
											CONTENT_URI, values);
									if (uri != null) {
										getData();
									}
								}
							}.start();

						}
						etIccid.setText("");

					}
				});

		listView.setAdapter(mAdapter);

		getData();

	}

	private synchronized void getData() {
		new Thread() {
			public void run() {
				listData.clear();

				Cursor cursor = getContentResolver().query(CONTENT_URI, null,
						null, null, null);
				Log.i(TAG, "line 100 cursor:" + cursor);
				if (cursor != null) {
					while (cursor.moveToNext()) {
						long id = cursor.getLong(cursor.getColumnIndex(COL_ID));
						String str = cursor.getString(cursor
								.getColumnIndex(COL_TXT));

						listData.add(new Item(id, str));
					}
				}
				handler.sendEmptyMessage(0);
			}
		}.start();

	}

	@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 static class ViewHolder {
		EditText et;
		Button btnUpdate;
		Button btnDelete;
	}

	public class Item {
		long id;

		public Item(long id, String str) {
			this.id = id;
			this.txt = str;
		}

		public long getId() {
			return id;
		}

		public String getTxt() {
			return txt;
		}

		String txt;
	}

	public class CustomAdapter extends BaseAdapter {

		public CustomAdapter() {

		}

		@Override
		public int getCount() {
			return listData.size();
		}

		@Override
		public Object getItem(int position) {
			return listData.get(position);

		}

		@Override
		public long getItemId(int position) {
			return position;
		}

		@Override
		public View getView(final int position, View convertView,
				ViewGroup parent) {
			ViewHolder holder = null;

			if (convertView == null) {
				holder = new ViewHolder();
				convertView = LayoutInflater.from(MainActivity.this).inflate(
						R.layout.list_item, parent, false);
				holder.et = (EditText) convertView.findViewById(R.id.et_item);
				holder.btnUpdate = (Button) convertView
						.findViewById(R.id.btn_update);
				holder.btnDelete = (Button) convertView
						.findViewById(R.id.btn_delete);

				convertView.setTag(holder);

			} else {
				holder = (ViewHolder) convertView.getTag();
			}

			holder.et.setText(listData.get(position).getTxt());
			holder.et.setTag("et_" + position);
			holder.btnDelete.setOnClickListener(new View.OnClickListener() {

				@Override
				public void onClick(View v) {
					// listData.remove(position);
					// mAdapter.notifyDataSetChanged();

					int rowId = getContentResolver()
							.delete(CONTENT_URI,
									COL_ID + " =?  ",
									new String[] { listData.get(position)
											.getId() + "" });
					if (rowId != 0) {
						getData();
					}

				}
			});
			holder.btnUpdate.setOnClickListener(new View.OnClickListener() {
				@Override
				public void onClick(View v) {
					String et = ((EditText) listView.findViewWithTag("et_"
							+ position)).getText().toString();
					if (!TextUtils.isEmpty(et)) {
						// listData.set(position, et);
						// mAdapter.notifyDataSetChanged();
						ContentValues values = new ContentValues();
						values.put(COL_TXT, et);
						int rowId = getContentResolver().update(
								CONTENT_URI,
								values,
								COL_ID + " =?  ",
								new String[] { listData.get(position).getId()
										+ "" });
						if (rowId != 0) {
							getData();
						}

					}
				}
			});

			return convertView;
		}
	}

	@Override
	public boolean handleMessage(Message msg) {
		mAdapter.notifyDataSetChanged();

		return false;
	}

 

 

。

 

附2个项目源码