Java tutorial
/* * Copyright 2011 the original author or authors. * 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.jayway.jsonpath.spi.json; import java.io.InputStream; import java.io.InputStreamReader; import java.io.UnsupportedEncodingException; import java.math.BigDecimal; import java.util.ArrayList; import java.util.Collection; import java.util.List; import java.util.Map; import com.google.gson.Gson; import com.google.gson.JsonArray; import com.google.gson.JsonElement; import com.google.gson.JsonObject; import com.google.gson.JsonParser; import com.google.gson.JsonPrimitive; import com.google.gson.internal.LazilyParsedNumber; import com.jayway.jsonpath.InvalidJsonException; import com.jayway.jsonpath.JsonPathException; public class GsonJsonProvider extends AbstractJsonProvider { private static final JsonParser PARSER = new JsonParser(); private final Gson gson; /** * Initializes the {@code GsonJsonProvider} using the default {@link Gson} object. */ public GsonJsonProvider() { this(new Gson()); } /** * Initializes the {@code GsonJsonProvider} using a customized {@link Gson} object. * * @param gson the customized Gson object. */ public GsonJsonProvider(final Gson gson) { this.gson = gson; } public Object unwrap(final Object o) { if (o == null) { return null; } if (!(o instanceof JsonElement)) { return o; } JsonElement e = (JsonElement) o; if (e.isJsonNull()) { return null; } else if (e.isJsonPrimitive()) { JsonPrimitive p = e.getAsJsonPrimitive(); if (p.isString()) { return p.getAsString(); } else if (p.isBoolean()) { return p.getAsBoolean(); } else if (p.isNumber()) { return unwrapNumber(p.getAsNumber()); } } return o; } private static Number unwrapNumber(final Number n) { Number unwrapped; if (n instanceof LazilyParsedNumber) { LazilyParsedNumber lpn = (LazilyParsedNumber) n; BigDecimal bigDecimal = new BigDecimal(lpn.toString()); if (bigDecimal.scale() <= 0) { if (bigDecimal.compareTo(new BigDecimal(Integer.MAX_VALUE)) <= 0) { unwrapped = bigDecimal.intValue(); } else { unwrapped = bigDecimal.longValue(); } } else { unwrapped = bigDecimal.doubleValue(); } } else { unwrapped = n; } return unwrapped; } @Override public Object parse(final String json) throws InvalidJsonException { return PARSER.parse(json); } @Override public Object parse(final InputStream jsonStream, final String charset) throws InvalidJsonException { try { return PARSER.parse(new InputStreamReader(jsonStream, charset)); } catch (UnsupportedEncodingException e) { throw new JsonPathException(e); } } @Override public String toJson(final Object obj) { return gson.toJson(obj); } @Override public Object createArray() { return new JsonArray(); } @Override public Object createMap() { return new JsonObject(); } @Override public boolean isArray(final Object obj) { return (obj instanceof JsonArray || obj instanceof List); } @Override public Object getArrayIndex(final Object obj, final int idx) { return toJsonArray(obj).get(idx); } @Override public void setArrayIndex(final Object array, final int index, final Object newValue) { if (!isArray(array)) { throw new UnsupportedOperationException(); } else { JsonArray arr = toJsonArray(array); if (index == arr.size()) { arr.add(createJsonElement(newValue)); } else { arr.set(index, createJsonElement(newValue)); } } } @Override public Object getMapValue(final Object obj, final String key) { JsonObject jsonObject = toJsonObject(obj); Object o = jsonObject.get(key); if (!jsonObject.has(key)) { return UNDEFINED; } else { return unwrap(o); } } @Override public void setProperty(final Object obj, final Object key, final Object value) { if (isMap(obj)) { toJsonObject(obj).add(key.toString(), createJsonElement(value)); } else { JsonArray array = toJsonArray(obj); int index; if (key != null) { index = key instanceof Integer ? (Integer) key : Integer.parseInt(key.toString()); } else { index = array.size(); } if (index == array.size()) { array.add(createJsonElement(value)); } else { array.set(index, createJsonElement(value)); } } } @SuppressWarnings("unchecked") public void removeProperty(final Object obj, final Object key) { if (isMap(obj)) { toJsonObject(obj).remove(key.toString()); } else { JsonArray array = toJsonArray(obj); int index = key instanceof Integer ? (Integer) key : Integer.parseInt(key.toString()); array.remove(index); } } @Override public boolean isMap(final Object obj) { // return (obj instanceof JsonObject || obj instanceof Map); return (obj instanceof JsonObject); } @Override public Collection<String> getPropertyKeys(final Object obj) { List<String> keys = new ArrayList<String>(); for (Map.Entry<String, JsonElement> entry : toJsonObject(obj).entrySet()) { keys.add(entry.getKey()); } return keys; } @Override public int length(final Object obj) { if (isArray(obj)) { return toJsonArray(obj).size(); } else if (isMap(obj)) { return toJsonObject(obj).entrySet().size(); } else { if (obj instanceof JsonElement) { JsonElement element = toJsonElement(obj); if (element.isJsonPrimitive()) { return element.toString().length(); } } } throw new JsonPathException( "length operation can not applied to " + obj != null ? obj.getClass().getName() : "null"); } @Override public Iterable<?> toIterable(final Object obj) { JsonArray arr = toJsonArray(obj); List<Object> values = new ArrayList<Object>(arr.size()); for (Object o : arr) { values.add(unwrap(o)); } return values; } private JsonElement createJsonElement(final Object o) { return gson.toJsonTree(o); } private JsonArray toJsonArray(final Object o) { return (JsonArray) o; } private JsonObject toJsonObject(final Object o) { return (JsonObject) o; } private JsonElement toJsonElement(final Object o) { return (JsonElement) o; } }