Define APIs for loading rules

Define fine-grained APIs for loading rules to be used by the rule
evaluation engine. The loader supports loading rules based on some app
install metadata keys such as PackageName, AppCertificate, InstallerName, and
InstallerCertificate.

Bug: 141970289
Test: N/A
Change-Id: Iec171974f9e9a63049cac10464a97116eea20b2b

services/core/java/com/android/server/integrity/engine/RuleLoader.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.integrity.engine;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * A helper class for loading rules to the rule evaluation engine.
+ *
+ * <p>Expose fine-grained APIs for loading rules to be passed to the rule evaluation engine.
+ *
+ * <p>It supports:
+ * <ul>
+ *     <li>Loading rules based on some keys, such as PACKAGE_NAME and APP_CERT.</li>
+ * </ul>
+ *
+ * <p>It does NOT support:
+ * <ul>
+ *     <li>Loading the list of all rules.</li>
+ *     <li>Merging rules resulting from different APIs.</li>
+ * </ul>
+ */
+final class RuleLoader {
+
+    List<String> loadRulesByPackageName(String packageName) {
+        // TODO: Add logic based on rule storage.
+        return new ArrayList<>();
+    }
+
+    List<String> loadRulesByAppCertificate(String appCertificate) {
+        // TODO: Add logic based on rule storage.
+        return new ArrayList<>();
+    }
+
+    List<String> loadRulesByInstallerName(String installerName) {
+        // TODO: Add logic based on rule storage.
+        return new ArrayList<>();
+    }
+
+    List<String> loadRulesByInstallerCertificate(String installerCertificate) {
+        // TODO: Add logic based on rule storage.
+        return new ArrayList<>();
+    }
+}