内容提供者ContentProvider

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。ContentProvider为存储和获取数据提供了统一的接口

 注意:  android:exported="true"

这个属性不是限制把服务暴露给其他应用程序的唯一方法。还可以使用权限来限制能够跟该服务交互的外部实体

在需要提供的应用程序AndroidManifest.xml文件章添加如下文件

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<!-- 配置内容提供者,android:authorities为该内容提供者取名作为在本应用中的唯一标识 -->        <provider            android:name="com.example.usersqllite.provider.UserProvider"            android:authorities="com.sanya.user.provider"            android:exported="true" >        </provider>

 内容提供者需要的代码:

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package com.example.usersqllite.provider;    import android.content.ContentProvider; import android.content.ContentValues; import android.content.UriMatcher; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import android.net.Uri;    import com.example.usersqllite.domain.UserSqlLiteHelp;    public class UserProvider extends ContentProvider {     private static final int QUERY = 1;     private static final int INSERT = 2;     private static final int DELETE = 3;     private static final int UPDATE = 4;     private SQLiteDatabase database;     // 创建uri匹配器     private static UriMatcher matcher = new UriMatcher(UriMatcher.NO_MATCH);        static {         // 建立 匹配规则         matcher.addURI("com.sanya.user.provider", "query", QUERY);         matcher.addURI("com.sanya.user.provider", "insert", INSERT);         matcher.addURI("com.sanya.user.provider", "delete", DELETE);         matcher.addURI("com.sanya.user.provider", "update", UPDATE);        }        @Override     public boolean onCreate() {         UserSqlLiteHelp help = new UserSqlLiteHelp(getContext());         database = help.getWritableDatabase();            return true;     }        @Override     public Cursor query(Uri uri, String[] projection, String selection,             String[] selectionArgs, String sortOrder) {         int match = matcher.match(uri);         if (match == QUERY) {             // 查询处理             UserSqlLiteHelp userSqlLiteHelp = new UserSqlLiteHelp(getContext());             SQLiteDatabase readableDatabase = userSqlLiteHelp                     .getReadableDatabase();             return readableDatabase.query("user", new String[] { "id", "name",                     "age" }, null, null, null, null, null);         }else{             throw new RuntimeException("查询出错,路径不能被识别");         }        }        @Override     public String getType(Uri uri) {         return null;     }        @Override     public Uri insert(Uri uri, ContentValues values) {            int match = matcher.match(uri);         if (match == INSERT) {             database.insert("user", null, values);            }else{             throw new RuntimeException("插入数据出错,路径不能被识别");         }         return null;     }        @Override     public int delete(Uri uri, String selection, String[] selectionArgs) {            int match = matcher.match(uri);         if (match == DELETE) {             database.delete("user", selection, selectionArgs);         }else{             throw new RuntimeException("删除数据出错,路径不能被识别");         }         return 0;     }        @Override     public int update(Uri uri, ContentValues values, String selection,             String[] selectionArgs) {            int match = matcher.match(uri);         if (match == UPDATE) {             database.update("user", values, selection, selectionArgs);         }else{             throw new RuntimeException("更新数据出错,路径不能被识别");         }         return 0;     }    }

 其他应用程序调用的测试代码:

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public void query(View view) {            ContentResolver resolver = getContentResolver();         Uri uri = Uri.parse("content://com.sanya.user.provider/query");         Cursor cursor = resolver.query(uri, null, null, null, null);         while (cursor.moveToNext()) {             int id = cursor.getInt(cursor.getColumnIndex("id"));                String name = cursor.getString(cursor.getColumnIndex("name"));             int age = cursor.getInt(cursor.getColumnIndex("age"));                System.out.println(id + "--" + name + "---" + age);         }            cursor.close();        }        public void delete(View view) {         ContentResolver resolver = getContentResolver();         Uri uri = Uri.parse("content://com.sanya.user.provider/delete");            resolver.delete(uri, "name=?", new String[] { "哈哈" });     }        public void update(View view) {         ContentResolver resolver = getContentResolver();         Uri uri = Uri.parse("content://com.sanya.user.provider/update");         ContentValues values = new ContentValues();         values.put("name", "嘿嘿");         values.put("age", 19);         resolver.update(uri, values, "name=?", new String[] { "三亚" });     }        public void insert(View view) {         ContentResolver resolver = getContentResolver();         Uri uri = Uri.parse("content://com.sanya.user.provider/insert");         ContentValues values = new ContentValues();         values.put("name", "大哥");         values.put("age", 100);         resolver.insert(uri, values);        }