Home | History | Annotate | Download | only in retriever 
      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.JsonWriter;
     20 
     21 import java.io.IOException;
     22 import java.io.StringWriter;
     23 import java.util.List;
     24 import java.util.Locale;
     25 
     26 /**
     27  * Creates a Json string where the order of the fields can be specified.
     28  */
     29 /* package private */ final class AssetJsonWriter {
     30 
     31     private StringWriter mStringWriter = new StringWriter();
     32     private JsonWriter mWriter;
     33     private boolean mClosed = false;
     34 
     35     public AssetJsonWriter() {
     36         mWriter = new JsonWriter(mStringWriter);
     37         try {
     38             mWriter.beginObject();
     39         } catch (IOException e) {
     40             throw new AssertionError("Unreachable exception.");
     41         }
     42     }
     43 
     44     /**
     45      * Appends a field to the output, putting both the key and value in lowercase. Null values are
     46      * not written.
     47      */
     48     public void writeFieldLower(String key, String value) {
     49         if (mClosed) {
     50             throw new IllegalArgumentException(
     51                     "Cannot write to an object that has already been closed.");
     52         }
     53 
     54         if (value != null) {
     55             try {
     56                 mWriter.name(key.toLowerCase(Locale.US));
     57                 mWriter.value(value.toLowerCase(Locale.US));
     58             } catch (IOException e) {
     59                 throw new AssertionError("Unreachable exception.");
     60             }
     61         }
     62     }
     63 
     64     /**
     65      * Appends an array to the output, putting both the key and values in lowercase. If {@code
     66      * values} is null, this field will not be written. Individual values in the list must not be
     67      * null.
     68      */
     69     public void writeArrayUpper(String key, List<String> values) {
     70         if (mClosed) {
     71             throw new IllegalArgumentException(
     72                     "Cannot write to an object that has already been closed.");
     73         }
     74 
     75         if (values != null) {
     76             try {
     77                 mWriter.name(key.toLowerCase(Locale.US));
     78                 mWriter.beginArray();
     79                 for (String value : values) {
     80                     mWriter.value(value.toUpperCase(Locale.US));
     81                 }
     82                 mWriter.endArray();
     83             } catch (IOException e) {
     84                 throw new AssertionError("Unreachable exception.");
     85             }
     86         }
     87     }
     88 
     89     /**
     90      * Returns the string representation of the constructed json. After calling this method, {@link
     91      * #writeFieldLower} can no longer be called.
     92      */
     93     public String closeAndGetString() {
     94         if (!mClosed) {
     95             try {
     96                 mWriter.endObject();
     97             } catch (IOException e) {
     98                 throw new AssertionError("Unreachable exception.");
     99             }
    100             mClosed = true;
    101         }
    102         return mStringWriter.toString();
    103     }
    104 }
    105