1 /*
2 * Copyright (C) 2017, David Pursehouse <david.pursehouse@gmail.com> and others
3 *
4 * This program and the accompanying materials are made available under the
5 * terms of the Eclipse Distribution License v. 1.0 which is available at
6 * https://www.eclipse.org/org/documents/edl-v10.php.
7 *
8 * SPDX-License-Identifier: BSD-3-Clause
9 */
10
11 package org.eclipse.jgit.lfs.server.internal;
12
13 import java.io.Reader;
14
15 import com.google.gson.FieldNamingPolicy;
16 import com.google.gson.Gson;
17 import com.google.gson.GsonBuilder;
18 import com.google.gson.JsonIOException;
19 import com.google.gson.JsonSyntaxException;
20
21 /**
22 * Wrapper for {@link com.google.gson.Gson} used by LFS servlets.
23 */
24 public class LfsGson {
25 private static final Gson gson = new GsonBuilder()
26 .setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES)
27 .disableHtmlEscaping()
28 .create();
29
30 /**
31 * Wrapper class only used for serialization of error messages.
32 */
33 static class Error {
34 String message;
35
36 Error(String m) {
37 this.message = m;
38 }
39 }
40
41 /**
42 * Serializes the specified object into its equivalent Json representation.
43 *
44 * @param src
45 * the object for which Json representation is to be created. If
46 * this is a String, it is wrapped in an instance of
47 * {@link org.eclipse.jgit.lfs.server.internal.LfsGson.Error}.
48 * @param writer
49 * Writer to which the Json representation needs to be written
50 * @throws com.google.gson.JsonIOException
51 * if there was a problem writing to the writer
52 * @see Gson#toJson(Object, Appendable)
53 */
54 public static void toJson(Object src, Appendable writer)
55 throws JsonIOException {
56 if (src instanceof String) {
57 gson.toJson(new Error((String) src), writer);
58 } else {
59 gson.toJson(src, writer);
60 }
61 }
62
63 /**
64 * Deserializes the Json read from the specified reader into an object of
65 * the specified type.
66 *
67 * @param json
68 * reader producing json from which the object is to be
69 * deserialized
70 * @param classOfT
71 * specified type to deserialize
72 * @return an Object of type T
73 * @throws com.google.gson.JsonIOException
74 * if there was a problem reading from the Reader
75 * @throws com.google.gson.JsonSyntaxException
76 * if json is not a valid representation for an object of type
77 * @see Gson#fromJson(Reader, java.lang.reflect.Type)
78 * @param <T>
79 * a T object.
80 */
81 public static <T> T fromJson(Reader json, Class<T> classOfT)
82 throws JsonSyntaxException, JsonIOException {
83 return gson.fromJson(json, classOfT);
84 }
85 }