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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 import android.util.JsonToken;
     21 
     22 import org.json.JSONArray;
     23 import org.json.JSONException;
     24 import org.json.JSONObject;
     25 
     26 import java.io.IOException;
     27 import java.util.ArrayList;
     28 import java.util.List;
     29 
     30 /**
     31  * A helper class that creates a {@link JSONObject} from a {@link JsonReader}.
     32  */
     33 public final class JsonParser {
     34 
     35     private JsonParser() {}
     36 
     37     /**
     38      * Consumes and parses exactly one JSON object from the {@link JsonReader}.
     39      * The object's fields can only be objects, strings or arrays of strings.
     40      */
     41     public static JSONObject parse(JsonReader reader) throws IOException, JSONException {
     42         JSONObject output = new JSONObject();
     43         String errorMsg = null;
     44 
     45         reader.beginObject();
     46         while (reader.hasNext()) {
     47             String fieldName = reader.nextName();
     48 
     49             if (output.has(fieldName)) {
     50                 errorMsg = "Duplicate field name.";
     51                 reader.skipValue();
     52                 continue;
     53             }
     54 
     55             JsonToken token = reader.peek();
     56             if (token.equals(JsonToken.BEGIN_ARRAY)) {
     57                 output.put(fieldName, new JSONArray(parseArray(reader)));
     58             } else if (token.equals(JsonToken.STRING)) {
     59                 output.put(fieldName, reader.nextString());
     60             } else if (token.equals(JsonToken.BEGIN_OBJECT)) {
     61                 try {
     62                     output.put(fieldName, parse(reader));
     63                 } catch (JSONException e) {
     64                     errorMsg = e.getMessage();
     65                 }
     66             } else {
     67                 reader.skipValue();
     68                 errorMsg = "Unsupported value type.";
     69             }
     70         }
     71         reader.endObject();
     72 
     73         if (errorMsg != null) {
     74             throw new JSONException(errorMsg);
     75         }
     76 
     77         return output;
     78     }
     79 
     80     /**
     81      * Parses one string array from the {@link JsonReader}.
     82      */
     83     public static List<String> parseArray(JsonReader reader) throws IOException {
     84         ArrayList<String> output = new ArrayList<>();
     85 
     86         reader.beginArray();
     87         while (reader.hasNext()) {
     88             output.add(reader.nextString());
     89         }
     90         reader.endArray();
     91 
     92         return output;
     93     }
     94 }
     95