Add example for custom JsonAdapter.

examples/src/main/java/com/squareup/moshi/recipes/CustomJsonAdapter.java

@@ -0,0 +1,136 @@
+/*
+ * Copyright (C) 2015 Square, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.squareup.moshi.recipes;
+
+import com.squareup.moshi.JsonAdapter;
+import com.squareup.moshi.JsonReader;
+import com.squareup.moshi.JsonWriter;
+import com.squareup.moshi.Moshi;
+
+import java.io.IOException;
+import java.text.DateFormat;
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.util.Date;
+
+public final class CustomJsonAdapter {
+
+    private static final DateFormat FORMAT_DATE_AND_TIME = new SimpleDateFormat("yyyyMMddHH:mm");
+    private static final DateFormat FORMAT_DATE = new SimpleDateFormat("yyyyMMdd");
+    private static final DateFormat FORMAT_TIME = new SimpleDateFormat("HH:mm");
+
+    public void run() throws Exception {
+        // for some reason our JSON has date and time as separate fields -
+        // we will use a custom JsonAdapter<Event> to clean that up during parsing
+        // also, we are not interested in "fooToken", so we'll ignore that
+        String json = ""
+                + "{\n"
+                + "  \"title\": \"Blackjack tournament\",\n"
+                + "  \"beginDateAndTime\": \"20151006\",\n"
+                + "  \"beginTime\": \"15:59\",\n"
+                + "  \"fooToken\": \"zih7wenvkqyqwer099qr\"\n"
+                + "}\n";
+
+        Moshi moshi = new Moshi.Builder()
+                .add(Event.class, new EventAdapter())
+                .build();
+        JsonAdapter<Event> jsonAdapter = moshi.adapter(Event.class);
+
+        Event event = jsonAdapter.fromJson(json);
+        System.out.println(event);
+        System.out.println(jsonAdapter.toJson(event));
+    }
+
+    public static void main(String[] args) throws Exception {
+        new CustomJsonAdapter().run();
+    }
+
+    public static final class EventAdapter extends JsonAdapter<Event> {
+        @Override
+        public Event fromJson(JsonReader jsonReader) throws IOException {
+            String title = null;
+            String beginDate = null;
+            String beginTime = null;
+
+            jsonReader.beginObject();
+            while (jsonReader.hasNext()) {
+                String name = jsonReader.nextName();
+                if (name.equals("title")) {
+                    title = jsonReader.nextString();
+                } else if (name.equals("beginDateAndTime")) {
+                    beginDate = jsonReader.nextString();
+                } else if (name.equals("beginTime")) {
+                    beginTime = jsonReader.nextString();
+                } else {
+                    // skip (e.g.) "fooToken"
+                    jsonReader.skipValue();
+                }
+            }
+            jsonReader.endObject();
+
+            Date beginDateAndTime;
+            if ((beginDate != null) && (beginTime != null)) {
+                try {
+                    beginDateAndTime = FORMAT_DATE_AND_TIME.parse(beginDate + beginTime);
+                } catch (ParseException e) {
+                    beginDateAndTime = null;
+                }
+            } else {
+                beginDateAndTime = null;
+            }
+
+            return new Event(title, beginDateAndTime);
+        }
+
+        @Override
+        public void toJson(JsonWriter jsonWriter, Event event) throws IOException {
+            jsonWriter.beginObject();
+
+            if (event.title != null) {
+                jsonWriter.name("title");
+                jsonWriter.value(event.title);
+            }
+
+            if (event.beginDateAndTime != null) {
+                jsonWriter.name("beginDateAndTime");
+                jsonWriter.value(FORMAT_DATE.format(event.beginDateAndTime));
+
+                jsonWriter.name("beginTime");
+                jsonWriter.value(FORMAT_TIME.format(event.beginDateAndTime));
+            }
+
+            jsonWriter.endObject();
+        }
+    }
+
+    public static final class Event {
+        public final String title;
+        public final Date beginDateAndTime;
+
+        public Event(String title, Date beginDateAndTime) {
+            this.title = title;
+            this.beginDateAndTime = beginDateAndTime;
+        }
+
+        @Override
+        public String toString() {
+            return "Event{" +
+                    "title='" + title + '\'' +
+                    ", beginDateAndTime=" + beginDateAndTime +
+                    '}';
+        }
+    }
+}