com.google.api.client.json.JsonObjectParser Maven / Gradle / Ivy
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/*
* Copyright (c) 2012 Google 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.google.api.client.json;
import com.google.api.client.util.ObjectParser;
import com.google.api.client.util.Preconditions;
import com.google.api.client.util.Sets;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.lang.reflect.Type;
import java.nio.charset.Charset;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
/**
* Parses JSON data into an data class of key/value pairs.
*
* Implementation is thread-safe.
*
*
Sample usage:
*
*
*
* static void setParser(HttpRequest request) {
* request.setParser(new JsonObjectParser(new JacksonFactory()));
* }
*
*
*
* @author Matthias Linder (mlinder)
* @since 1.10
*/
public class JsonObjectParser implements ObjectParser {
/** JSON factory. */
private final JsonFactory jsonFactory;
/** Wrapper keys for the JSON content or empty for none. */
private final Set wrapperKeys;
/** @param jsonFactory JSON factory */
public JsonObjectParser(JsonFactory jsonFactory) {
this(new Builder(jsonFactory));
}
/**
* @param builder builder
* @since 1.14
*/
protected JsonObjectParser(Builder builder) {
jsonFactory = builder.jsonFactory;
wrapperKeys = new HashSet(builder.wrapperKeys);
}
@SuppressWarnings("unchecked")
public T parseAndClose(InputStream in, Charset charset, Class dataClass)
throws IOException {
return (T) parseAndClose(in, charset, (Type) dataClass);
}
public Object parseAndClose(InputStream in, Charset charset, Type dataType) throws IOException {
JsonParser parser = jsonFactory.createJsonParser(in, charset);
initializeParser(parser);
return parser.parse(dataType, true);
}
@SuppressWarnings("unchecked")
public T parseAndClose(Reader reader, Class dataClass) throws IOException {
return (T) parseAndClose(reader, (Type) dataClass);
}
public Object parseAndClose(Reader reader, Type dataType) throws IOException {
JsonParser parser = jsonFactory.createJsonParser(reader);
initializeParser(parser);
return parser.parse(dataType, true);
}
/** Returns the JSON factory. */
public final JsonFactory getJsonFactory() {
return jsonFactory;
}
/**
* Returns the unmodifiable set of wrapper keys for the JSON content.
*
* @since 1.14
*/
public Set getWrapperKeys() {
return Collections.unmodifiableSet(wrapperKeys);
}
/**
* Initialize the parser to skip to wrapped keys (if any).
*
* @param parser JSON parser
*/
private void initializeParser(JsonParser parser) throws IOException {
if (wrapperKeys.isEmpty()) {
return;
}
boolean failed = true;
try {
String match = parser.skipToKey(wrapperKeys);
Preconditions.checkArgument(
match != null && parser.getCurrentToken() != JsonToken.END_OBJECT,
"wrapper key(s) not found: %s",
wrapperKeys);
failed = false;
} finally {
if (failed) {
parser.close();
}
}
}
/**
* Builder.
*
* Implementation is not thread-safe.
*
* @since 1.14
*/
public static class Builder {
/** JSON factory. */
final JsonFactory jsonFactory;
/** Wrapper keys for the JSON content or empty for none. */
Collection wrapperKeys = Sets.newHashSet();
/** @param jsonFactory JSON factory */
public Builder(JsonFactory jsonFactory) {
this.jsonFactory = Preconditions.checkNotNull(jsonFactory);
}
/** Returns a new instance of a JSON object parser. */
public JsonObjectParser build() {
return new JsonObjectParser(this);
}
/** Returns the JSON factory. */
public final JsonFactory getJsonFactory() {
return jsonFactory;
}
/** Returns the wrapper keys for the JSON content. */
public final Collection getWrapperKeys() {
return wrapperKeys;
}
/**
* Sets the wrapper keys for the JSON content.
*
* Overriding is only supported for the purpose of calling the super implementation and
* changing the return type, but nothing else.
*/
public Builder setWrapperKeys(Collection wrapperKeys) {
this.wrapperKeys = wrapperKeys;
return this;
}
}
}