初涉Android之ContentProvider

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;}@Overridepublic 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

<?xml version="1.0" encoding="utf-8"?>

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")));}}}

更多相关文章

随机推荐