Android中的ContentProvider问题 - 黑马程序员技术交流社区

package com.sharpandroid.activity;
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;
import com.sharpandroid.activity.dao.DBHelper;
public class PersonProvider extends ContentProvider {
private DBHelper dbHelper;
//路径的识别器 UriMatcher
private static final UriMatcher matcher = new UriMatcher(UriMatcher.NO_MATCH);//UriMatcher.NO_MATCH表示不匹配的话返回的码 -1
private static final int PERSONS = 1;
private static final int PERSON = 2;
static{
//为UriMatcher对象添加需要匹配的路径
matcher.addURI("com.sharpandroid.provider.personprovider", "person", PERSONS);
matcher.addURI("com.sharpandroid.provider.personprovider", "person/#", PERSON);
}
//onCreate方法在ContentProvider创建后就会被调用
@Override
public boolean onCreate() {
//实例化dbHelper
dbHelper = new DBHelper(this.getContext());
return true;
}
@Override
public Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) {
SQLiteDatabase db = dbHelper.getReadableDatabase();
switch(matcher.match(uri)){
case PERSONS:
//查询数据库中所有的数据
return db.query("person", projection, selection, selectionArgs, null, null, sortOrder);
case PERSON:
//查询数据库中特定的数据
//从Uri中提取id
long id = ContentUris.parseId(uri);
//创建查询条件
String whereClause = "personid="+id;
if(selection!=null&&!"".equals(selection.trim())){
whereClause += "and"+selection;
}
return db.query("person", projection, whereClause, selectionArgs, null, null, null);
default:
throw new IllegalArgumentException("Unknow Uri"+uri);
}
}
@Override
public String getType(Uri uri) {
return null;
}
@Override
public Uri insert(Uri uri, ContentValues values) {
return null;
}
@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
return 0;
}
@Override
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs) {
return 0;
}
}

复制代码

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.sharpandroid.activity"
android:versionCode="1"
android:versionName="1.0">
<uses-sdk android:minSdkVersion="10" />
<application android:icon="@drawable/icon" android:label="@string/app_name">
<uses-library android:name="android.test.runner"/>
<activity android:name=".PersonActivity"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<provider
android:name=".PersonProvider"
android:authorities="com.sharpandroid.provider.personprovider"/>
</application>
<instrumentation
android:name="android.test.InstrumentationTestRunner"
android:targetPackage="com.sharpandroid.activity"
android:label="Tests for My App">
</instrumentation>
</manifest>

复制代码

package com.example.other;
import android.content.ContentResolver;
import android.database.Cursor;
import android.net.Uri;
import android.test.AndroidTestCase;
import android.util.Log;
/**
* AccessContentProvider可以对PersonProvider中的数据进行操作时，
* 可以使用ContentResolver类完成
* @author Administrator
*
*/
public class AccessContentProvider extends AndroidTestCase {
private static final String TAG = "AccessContentProvider";
public void testQuery()throws Exception{
//获取ContentResolver对象
ContentResolver resolver = this.getContext().getContentResolver();
//定义Uri,查询所有的记录
Uri uri = Uri.parse("content://com.sharpandroid.provider.personprovider/person");
Cursor cursor = resolver.query(uri, null, null, null, null);
while(cursor.moveToNext()){
int id = cursor.getInt(cursor.getColumnIndex("personid"));
String name = cursor.getString(cursor.getColumnIndex("name"));
int age = cursor.getInt(cursor.getColumnIndex("age"));
//显示查询结果
Log.i(TAG, id+":"+name+":"+age);
}
//关闭游标
cursor.close();
}
}

复制代码