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(); 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(); resolver.delete(uri, "name=?", new String[] { "哈哈" }); } public void update(View view) { ContentResolver resolver = getContentResolver(); 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(); ContentValues values = new ContentValues(); values.put("name", "大哥"); values.put("age", 100); resolver.insert(uri, values); } |
