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 
AssetJsonWriter()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      */
writeFieldLower(String key, String value)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      */
writeArrayUpper(String key, List<String> values)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      */
closeAndGetString()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