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      1 /*
      2  * Copyright (C) 2015 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.statementservice.retriever;
     18 
     19 import android.util.JsonReader;
     20 
     21 import org.json.JSONException;
     22 
     23 import java.io.IOException;
     24 import java.io.StringReader;
     25 
     26 /**
     27  * A handle representing the identity and address of some digital asset. An asset is an online
     28  * entity that typically provides some service or content. Examples of assets are websites, Android
     29  * apps, Twitter feeds, and Plus Pages.
     30  *
     31  * <p> Asset can be represented by a JSON string. For example, the web site https://www.google.com
     32  * can be represented by
     33  * <pre>
     34  * {"namespace": "web", "site": "https://www.google.com"}
     35  * </pre>
     36  *
     37  * <p> The Android app with package name com.google.test that is signed by a certificate with sha256
     38  * fingerprint 11:22:33 can be represented by
     39  * <pre>
     40  * {"namespace": "android_app",
     41  *  "package_name": "com.google.test",
     42  *  "sha256_cert_fingerprints": ["11:22:33"]}
     43  * </pre>
     44  *
     45  * <p>Given a signed APK, Java 7's commandline keytool can compute the fingerprint using:
     46  * {@code keytool -list -printcert -jarfile signed_app.apk}
     47  */
     48 public abstract class AbstractAsset {
     49 
     50     /**
     51      * Returns a JSON string representation of this asset. The strings returned by this function are
     52      * normalized -- they can be used for equality testing.
     53      */
     54     public abstract String toJson();
     55 
     56     /**
     57      * Returns a key that can be used by {@link AbstractAssetMatcher} to lookup the asset.
     58      *
     59      * <p> An asset will match an {@code AssetMatcher} only if the value of this method is equal to
     60      * {@code AssetMatcher.getMatchedLookupKey()}.
     61      */
     62     public abstract int lookupKey();
     63 
     64     /**
     65      * Creates a new Asset from its JSON string representation.
     66      *
     67      * @throws AssociationServiceException if the assetJson is not well formatted.
     68      */
     69     public static AbstractAsset create(String assetJson)
     70             throws AssociationServiceException {
     71         JsonReader reader = new JsonReader(new StringReader(assetJson));
     72         reader.setLenient(false);
     73         try {
     74             return AssetFactory.create(JsonParser.parse(reader));
     75         } catch (JSONException | IOException e) {
     76             throw new AssociationServiceException(
     77                     "Input is not a well formatted asset descriptor.", e);
     78         }
     79     }
     80 
     81     /**
     82      * If this is the source asset of a statement file, should the retriever follow
     83      * any insecure (non-HTTPS) include statements made by the asset.
     84      */
     85     public abstract boolean followInsecureInclude();
     86 }
     87