初涉Android之ContentProvider

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初涉Android之ContentProvider

 

 

一、ContentProvider的作用，可以让其它应用访问本应用的数据

第一步：定义ContentProvider如下：

import android.content.ContentProvider;
import android.content.ContentUris;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;

public class PersonProvider extends ContentProvider {
	
	private DBOpenHelper helper = null;
	private static final UriMatcher MATCHER = new UriMatcher(UriMatcher.NO_MATCH);
	private static final int PERSONS = 1; 
	private static final int PERSON = 2;
	
	static {
		MATCHER.addURI("cn.hpu.edu.personprovider", "person", PERSONS);
		MATCHER.addURI("cn.hpu.edu.personprovider", "person/#", PERSON);
	}
	
	/**
	 * 删除数据库中相应的数据
	 */
	public int delete(Uri uri, String selection, String[] selectionArgs) {
		SQLiteDatabase db = helper.getWritableDatabase();
		int num = 0;
		switch(MATCHER.match(uri)) {
		case PERSONS :
			num = db.delete("person", selection, selectionArgs);
			break;
		case PERSON :
			long rowid = ContentUris.parseId(uri);
			String where = " id = " + rowid;
			if(selection != null && !"".equals(selection.trim())) {
				where += " and " + selection;
			}
			num = db.delete("person", where, selectionArgs);
			break;
		default :
			throw new IllegalArgumentException("this is An Unkown Uri : " + uri.toString());
		}
		return num;
	}

	@Override
	public String getType(Uri uri) {
		return null;
	}

	/**
	 * 向内容提供者里面插入数据
	 */
	public Uri insert(Uri uri, ContentValues values) {
		SQLiteDatabase db = helper.getWritableDatabase();
		switch(MATCHER.match(uri)) {
		case PERSONS:
			long rowid = db.insert("person", "name", values);
			Uri insertUri = ContentUris.withAppendedId(uri, rowid);
			return insertUri;
		default: 
			throw new IllegalArgumentException("this is An Unknown Uri:" + uri.toString());
		}
	}

	/**
	 * 该方法只调用一次用于初始化环境
	 */
	public boolean onCreate() {
		helper = new DBOpenHelper(this.getContext());
		return true;
	}

	/**
	 * 按条件查询结果集并返回游标
	 */
	public Cursor query(Uri uri, String[] projection, String selection,
			String[] selectionArgs, String sortOrder) {
		SQLiteDatabase db = helper.getReadableDatabase();
		switch(MATCHER.match(uri)) {
		case PERSONS : 
			return db.query("person", projection, selection, selectionArgs, null, null, sortOrder);
		case PERSON :
			long rawid = ContentUris.parseId(uri);
			String where = " id = " + rawid;
			if(selection != null && !"".equals(selection.trim())) {
				where += " and " + selection;
			}
			return db.query("person", projection, where, selectionArgs, null, null, sortOrder);
		default :
			throw new IllegalArgumentException("this is An Unknown Uri : " + uri.toString());
		}
	}

	/**
	 * 更新数据
	 */
	public int update(Uri uri, ContentValues values, String selection,
			String[] selectionArgs) {
		SQLiteDatabase db = helper.getWritableDatabase();
		int num = 0;
		switch(MATCHER.match(uri)) {
		case PERSONS :
			num = db.update("person", values, selection, selectionArgs);
			break;
		case PERSON :
			long rowid = ContentUris.parseId(uri);
			String where = " id = " + rowid;
			if(selection != null && !"".equals(selection.trim())) {
				where += " and " + selection;
			}
			num = db.update("person", values, where , selectionArgs);
			break;
		default :
			throw new IllegalArgumentException("this is An Unknown Uri : " + uri.toString());
		}
		return num;
	}

}

 

第二步：在本应用的AndroidManifest.xml里面声明Provider

 

 第三步：在另外一个应用里面添加如下测试：

import android.content.ContentResolver;
import android.content.ContentValues;
import android.database.Cursor;
import android.net.Uri;
import android.test.AndroidTestCase;
import android.util.Log;

public class TestAccessContentProvider extends AndroidTestCase {
	
	private static final String TAG = "TestAccessContentProvider";
	private static final String URI = "content://cn.hpu.edu.personprovider/person";
	
	public void testInsert() throws Exception {
		Uri uri = Uri.parse(URI);
		ContentResolver resolver = this.getContext().getContentResolver();
		ContentValues values = new ContentValues();
		values.put("id", 45);
		values.put("name", "qiernsdf");
		values.put("phone", "123456789");
		resolver.insert(uri, values);
	}
	
	public void testDelete() throws Exception {
		Uri uri = Uri.parse(URI + "/10");
		ContentResolver resolver = this.getContext().getContentResolver();
		resolver.delete(uri, null, null);
		
	}
	
	public void testUpdate() throws Exception {
		Uri uri = Uri.parse(URI + "/11");
		ContentResolver resolver = this.getContext().getContentResolver();
		ContentValues values = new ContentValues();
		values.put("name" , "updateValues");
		resolver.update(uri, values, null, null);
	}
	
	public void testFind() throws Exception {
		Uri uri = Uri.parse(URI);
		ContentResolver resolver = this.getContext().getContentResolver();
		Cursor cursor = resolver.query(uri, null, null, null, " id asc");
		while(cursor.moveToNext()) {
			Log.i(TAG ,cursor.getString(cursor.getColumnIndex("name")));
		}
	}
}