com.google.web.bindery.requestfactory.shared.DefaultProxyStore Maven / Gradle / Ivy
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/*
* Copyright 2010 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.web.bindery.requestfactory.shared;
import com.google.web.bindery.autobean.shared.AutoBean;
import com.google.web.bindery.autobean.shared.AutoBeanCodex;
import com.google.web.bindery.autobean.shared.Splittable;
import com.google.web.bindery.requestfactory.shared.impl.MessageFactoryHolder;
import com.google.web.bindery.requestfactory.shared.messages.OperationMessage;
import java.util.HashMap;
import java.util.Map;
/**
* An in-memory ProxyStore store that can encode its state as a JSON object
* literal.
*/
public class DefaultProxyStore implements ProxyStore {
/**
* Provide a little bit of future-proofing to at least detect an encoded
* payload that can't be decoded.
*/
private static final String EXPECTED_VERSION = "211";
private final AutoBean messageBean;
private final Map map;
private int nextId;
/**
* Construct an empty DefaultProxyStore.
*/
public DefaultProxyStore() {
messageBean = MessageFactoryHolder.FACTORY.operation();
map = new HashMap();
OperationMessage message = messageBean.as();
message.setPropertyMap(map);
message.setVersion(EXPECTED_VERSION);
}
/**
* Construct a DefaultProxyStore using the a value returned from
* {@link #encode()}.
*
* @param payload a String previously returned from {@link #encode()}
* @throws IllegalArgumentException if the payload cannot be parsed
*/
public DefaultProxyStore(String payload) throws IllegalArgumentException {
messageBean =
AutoBeanCodex.decode(MessageFactoryHolder.FACTORY, OperationMessage.class, payload);
OperationMessage message = messageBean.as();
if (!EXPECTED_VERSION.equals(message.getVersion())) {
throw new IllegalArgumentException("Unexpected version string in payload "
+ message.getVersion());
}
map = message.getPropertyMap();
// #encode() saves nextId + 1, so we remove 1 here; see rationale below.
nextId = message.getSyntheticId() - 1;
if (nextId < 0) {
/*
* In case this is a message generated by a pre-2.5 DefaultProxyStore,
* getSyntheticId will be '0', so we initialize the nextId to our best
* guess (that only works because the store is append-only, and it could
* break if nextId() was called on the original DefaultProxyStore more
* times than put()).
* Post-2.5 DefaultProxyStore never stores a '0' (see #encode()).
*/
nextId = map.size();
}
}
/**
* Return a JSON object literal with the contents of the store.
*/
public String encode() {
// Backwards-compat: never store a '0' (see constructor)
assert nextId >= 0;
messageBean.as().setSyntheticId(nextId + 1);
return AutoBeanCodex.encode(messageBean).getPayload();
}
public Splittable get(String key) {
return map.get(key);
}
public int nextId() {
return nextId++;
}
public void put(String key, Splittable value) {
map.put(key, value);
}
}