io.grpc.internal.JsonParser Maven / Gradle / Ivy
/*
* Copyright 2018 The gRPC 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 io.grpc.internal;
import static com.google.common.base.Preconditions.checkState;
import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonToken;
import java.io.IOException;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* Parses JSON with as few preconceived notions as possible.
*/
public final class JsonParser {
private static final Logger logger = Logger.getLogger(JsonParser.class.getName());
private JsonParser() {}
/**
* Parses a json string, returning either a {@code Map}, {@code List},
* {@code String}, {@code Double}, {@code Boolean}, or {@code null}.
*/
public static Object parse(String raw) throws IOException {
JsonReader jr = new JsonReader(new StringReader(raw));
try {
return parseRecursive(jr);
} finally {
try {
jr.close();
} catch (IOException e) {
logger.log(Level.WARNING, "Failed to close", e);
}
}
}
private static Object parseRecursive(JsonReader jr) throws IOException {
checkState(jr.hasNext(), "unexpected end of JSON");
switch (jr.peek()) {
case BEGIN_ARRAY:
return parseJsonArray(jr);
case BEGIN_OBJECT:
return parseJsonObject(jr);
case STRING:
return jr.nextString();
case NUMBER:
return jr.nextDouble();
case BOOLEAN:
return jr.nextBoolean();
case NULL:
return parseJsonNull(jr);
default:
throw new IllegalStateException("Bad token: " + jr.getPath());
}
}
private static Map parseJsonObject(JsonReader jr) throws IOException {
jr.beginObject();
Map obj = new LinkedHashMap<>();
while (jr.hasNext()) {
String name = jr.nextName();
Object value = parseRecursive(jr);
obj.put(name, value);
}
checkState(jr.peek() == JsonToken.END_OBJECT, "Bad token: " + jr.getPath());
jr.endObject();
return Collections.unmodifiableMap(obj);
}
private static List parseJsonArray(JsonReader jr) throws IOException {
jr.beginArray();
List