Android内容提供者(Content provider)
来源:互联网 发布:java字符数组赋值 编辑:程序博客网 时间:2024/05/18 03:51
使用ContentProvider共享数据
当应用继承ContentProvider类,并重写该类用于提供数据和存储数据的方法,就可以向其他应用共享其数据。虽然使用其他方法也可以对外共享数据,但数据访问方式会因数据存储的方式而不同,如:采用文件方式对外共享数据,需要进行文件操作读写数据;采用sharedpreferences共享数据,需要使用sharedpreferences API读写数据。而使用ContentProvider共享数据的好处是统一了数据访问方式。
当应用需要通过ContentProvider对外共享数据时,第一步需要继承ContentProvider并重写下面方法:
public class PersonContentProvider extends ContentProvider{
public boolean onCreate()
public Uri insert(Uri uri, ContentValues values)
public int delete(Uri uri, String selection, String[] selectionArgs)
public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs)
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder)
public String getType(Uri uri)}
第二步需要在AndroidManifest.xml使用<provider>对该ContentProvider进行配置,为了能让其他应用找到该ContentProvider , ContentProvider 采用了authorities(主机名/域名)对它进行唯一标识,你可以把 ContentProvider看作是一个网站(想想,网站也是提供数据者),authorities 就是他的域名:
<manifest .... >
<application android:icon="@drawable/icon" android:label="@string/app_name">
<provider android:name=".PersonContentProvider" android:authorities="com.jbridge.provider.personprovider"/>
</application>
</manifest>
注意:一旦应用继承了ContentProvider类,后面我们就会把这个应用称为ContentProvider(内容提供者)。
Uri介绍
Uri代表了要操作的数据,Uri主要包含了两部分信息:1》需要操作的ContentProvider ,2》对ContentProvider中的什么数据进行操作,一个Uri由以下几部分组成:
ContentProvider(内容提供者)的scheme已经由Android所规定, scheme为:content://
ContentProvider示例程序
我们为《Android之SQlite存储》示例程序添加一个ContentProvider,供其他应用来访问我们的数据。
1.为SQLite示例程序添加ContentProvider类
package com.jbridge.db;import com.jbridge.service.DataBaseOpenHelper;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 android.text.TextUtils;public class PersonContentProvider extends ContentProvider {private DataBaseOpenHelper dbOpenHelper;private static final int ALLPERSON = 1;private static final int PERSON = 2;private static final UriMatcher sMatcher = new UriMatcher(UriMatcher.NO_MATCH);static {sMatcher.addURI("com.jbridge.provider.personprovider", "person",ALLPERSON);sMatcher.addURI("com.jbridge.provider.personprovider", "person/#",PERSON);}@Overridepublic int delete(Uri uri, String selection, String[] selectionArgs) {SQLiteDatabase db = dbOpenHelper.getWritableDatabase();int count = 0;switch (sMatcher.match(uri)) {case ALLPERSON:// com.jbridge.provider.personprovider/personcount=db.delete("person", selection,selectionArgs);break;case PERSON:// com.jbridge.provider.personprovider/person/10long personid=ContentUris.parseId(uri);//防止他输入时String selection, String[] selectionArgs参数为空,这样就会修改表的所有数据了String where=TextUtils.isEmpty(selection)?"personid=?":selection+" and personid=?";String[] params=new String[]{String.valueOf(personid)}; if (!TextUtils.isEmpty(selection)&&selectionArgs!=null) {params=new String[selectionArgs.length+1];for (int i=0;i<selectionArgs.length;i++) {params[i]=selectionArgs[i];}params[selectionArgs.length]=String.valueOf(personid);}count = db.delete("person", where,params);break;default:throw new IllegalArgumentException("Unknow Uri:" + uri);}return count;}@Overridepublic String getType(Uri uri) {switch (sMatcher.match(uri)) {case ALLPERSON:// //数据集的MIME类型字符串则应该以vnd.android.cursor.dir/开头return "vnd.android.cursor.dir/personprovider.person";case PERSON://单一数据的MIME类型字符串应该以vnd.android.cursor.item/开头return "vnd.android.cursor.item/personprovider.person";default:throw new IllegalArgumentException("Unknow Uri:" + uri);}}@Overridepublic Uri insert(Uri uri, ContentValues values) {SQLiteDatabase db = dbOpenHelper.getWritableDatabase();long id = 0;switch (sMatcher.match(uri)) {case ALLPERSON:// com.jbridge.provider.personprovider/personid = db.insert("person", "name", values);// 返回值是记录的行号,主键为int实际上就是主键值,主键为text则为行号return ContentUris.withAppendedId(uri, id);case PERSON:// com.jbridge.provider.personprovider/person/10id = db.insert("person", "name", values);// 返回值是记录的行号,主键为int实际上就是主键值,主键为text则为行号String path = uri.toString();return Uri.parse(path.substring(0, path.lastIndexOf("/")) + id);default:throw new IllegalArgumentException("Unknow Uri:" + uri);}}@Overridepublic boolean onCreate() {dbOpenHelper=new DataBaseOpenHelper(this.getContext());return false;}@Overridepublic Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,String sortOrder) {SQLiteDatabase db = dbOpenHelper.getWritableDatabase();switch (sMatcher.match(uri)) {case ALLPERSON:// com.jbridge.provider.personprovider/personreturn db.query("person",projection, selection, selectionArgs,null, null, sortOrder);case PERSON:// com.jbridge.provider.personprovider/person/10long personid=ContentUris.parseId(uri);//防止他输入时String selection, String[] selectionArgs参数为空,这样就会修改表的所有数据了String where=TextUtils.isEmpty(selection)?"personid=?":selection+" and personid=?";String[] params=new String[]{String.valueOf(personid)}; if (!TextUtils.isEmpty(selection)&&selectionArgs!=null) {params=new String[selectionArgs.length+1];for (int i=0;i<selectionArgs.length;i++) {params[i]=selectionArgs[i];}params[selectionArgs.length]=String.valueOf(personid);}return db.query("person",projection, where, params,null, null, sortOrder);default:throw new IllegalArgumentException("Unknow Uri:" + uri);}}@Override//返回值为影响的记录数public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {SQLiteDatabase db = dbOpenHelper.getWritableDatabase();int count = 0;switch (sMatcher.match(uri)) {case ALLPERSON:// com.jbridge.provider.personprovider/personcount = db.update("person", values, selection,selectionArgs);break;case PERSON:// com.jbridge.provider.personprovider/person/10long personid=ContentUris.parseId(uri);//防止他输入时String selection, String[] selectionArgs参数为空,这样就会修改表的所有数据了String where=TextUtils.isEmpty(selection)?"personid=?":selection+" and personid=?";String[] params=new String[]{String.valueOf(personid)}; if (!TextUtils.isEmpty(selection)&&selectionArgs!=null) {params=new String[selectionArgs.length+1];for (int i=0;i<selectionArgs.length;i++) {params[i]=selectionArgs[i];}params[selectionArgs.length]=String.valueOf(personid);}count = db.update("person", values, where,params);break;default:throw new IllegalArgumentException("Unknow Uri:" + uri);}return count;}}
2.添加ContentProvider配置
<provider android:name=".PersonContentProvider" android:authorities="com.jbridge.provider.personprovider" android:permission="android.permission.READ_PERSON_DB"/>
3.测试SQLite示例程序的ContentProvider,建立项目contentProviderUser
Project name: contentProviderUser
BuildTarget:Android2.2
Application name: 内容使用者
Package name: com.jbridge.user
Create Activity: ContentProviderUserActivity
Min SDK Version:8
package com.jbridge.user;import android.R.string;import android.app.Activity;import android.content.ContentResolver;import android.content.ContentValues;import android.database.Cursor;import android.net.Uri;import android.os.Bundle;import android.provider.ContactsContract;import android.util.Log;public class ContentProviderUserActivity extends Activity {private static final String TAG="ContentProviderUserActivity";/* @Override //向数据库插入数据 public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); ContentResolver contentResolver=this.getContentResolver(); Uri uri=Uri.parse("content://com.jbridge.provider.personprovider/person"); ContentValues values=new ContentValues(); values.put("name", "刘德华"); values.put("age",(short)55); contentResolver.insert(uri, values); }*/ /* @Override //向数据库修改数据 public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); ContentResolver contentResolver=this.getContentResolver(); Uri uri=Uri.parse("content://com.jbridge.provider.personprovider/person/4"); ContentValues values=new ContentValues(); values.put("name", "haha"); values.put("age",(short)55); contentResolver.update(uri, values, null, null); }*/ /*@Override //向数据库删除数据 public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); ContentResolver contentResolver=this.getContentResolver(); Uri uri=Uri.parse("content://com.jbridge.provider.personprovider/person"); contentResolver.delete(uri, "personid>?",new String[]{String.valueOf(18)} );// contentResolver.delete(uri,null,null ); }*//*@Override //向数据库查询数据 public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); ContentResolver contentResolver=this.getContentResolver(); Uri uri=Uri.parse("content://com.jbridge.provider.personprovider/person"); Cursor cursor=contentResolver.query(uri, new String[]{"personid","name","age"}, null, null, "personid desc"); while (cursor.moveToNext()) {Log.i(TAG, "personid "+cursor.getInt(0));} cursor.close();}*/@Override //向电话本取得数据 public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); ContentResolver contentResolver=this.getContentResolver(); Cursor cursor=contentResolver.query(ContactsContract.Contacts.CONTENT_URI,null, null, null, null); while (cursor.moveToNext()) {int contactID=cursor.getInt(cursor.getColumnIndex(ContactsContract.Contacts._ID));String name=cursor.getString(cursor.getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME));Log.i(TAG, "contactid="+contactID+",name="+name);Cursor phones=contentResolver.query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null,ContactsContract.CommonDataKinds.Phone.CONTACT_ID+"="+contactID,null, null);StringBuilder sb=new StringBuilder();while (phones.moveToNext()) {String phoneNumber=phones.getString(phones.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));sb.append(phoneNumber).append(",");}sb.deleteCharAt(sb.lastIndexOf(","));phones.close();Log.i(TAG, sb.toString()); Cursor emails = getContentResolver().query(ContactsContract.CommonDataKinds.Email.CONTENT_URI, null, ContactsContract.CommonDataKinds.Email.CONTACT_ID + " = " + contactID, null, null); while (emails.moveToNext()) { // This would allow you get several email addresses String emailAddress = emails.getString(emails.getColumnIndex(ContactsContract.CommonDataKinds.Email.DATA)); Log.i(TAG, "emailAddress="+ emailAddress); } emails.close(); cursor.close();}}}
<uses-permission android:name="android.permission.READ_CONTACTS"/> <uses-permission android:name="android.permission.READ_PERSON_DB"/>
- Android开发--内容提供者(Content provider)
- Android内容提供者(Content provider)
- Android内容提供者(Content provider)
- Android 内容提供者(Content provider)
- Android内容提供者(Content provider)
- Android内容提供者(Content provider)
- Android内容提供者(Content provider)
- Android内容提供者(Content provider)
- Android内容提供者(Content provider)
- Android内容提供者(Content provider)
- Android Content Provider(内容提供者)
- content Provider 内容提供者
- Content Provider内容提供者
- Content Provider 内容提供者
- 内容提供者-Content Provider
- Android四大组件之Content Provider(内容提供者)
- android content provider(内容提供者) 学习总结
- 【android学习】四大组件-Content Provider(内容提供者)
- TCP、UDP、IP 协议分析
- 读写SharedPreferences中的数据
- 【Linux】中TCP的握手与挥手
- [DP优化] POJ 1160 Post Office
- Android之SQlite存储
- Android内容提供者(Content provider)
- TST运行报错解决
- java udp简单例子
- java tcp简单例子
- Linux_博客-端口分类调研
- defy手机 小技能 问题
- spring mvc maven
- java关于多线程的面试题(三道)--参考答案
- JAVA启动参数大全之三:非Stable参数