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 * Copyright 2014 Red Hat, Inc., and individual contributors
 * as indicated by the @author tags.
 *
 * 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
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 *  distributed under the License is distributed on an "AS IS" BASIS,
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 *  See the License for the specific language governing permissions and
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package io.undertow.server.handlers;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import io.undertow.attribute.ExchangeAttribute;
import io.undertow.attribute.ExchangeAttributeParser;
import io.undertow.attribute.ExchangeAttributes;
import io.undertow.attribute.NullAttribute;
import io.undertow.attribute.ReadOnlyAttributeException;
import io.undertow.server.HandlerWrapper;
import io.undertow.server.HttpHandler;
import io.undertow.server.HttpServerExchange;
import io.undertow.server.ResponseCommitListener;
import io.undertow.server.handlers.builder.HandlerBuilder;

Handler that can set an arbitrary attribute on the exchange. Both the attribute and the value to set are expressed as exchange attributes.
Author:Stuart Douglas
/** * Handler that can set an arbitrary attribute on the exchange. Both the attribute and the * value to set are expressed as exchange attributes. * * * @author Stuart Douglas */
public class SetAttributeHandler implements HttpHandler { private final HttpHandler next; private final ExchangeAttribute attribute; private final ExchangeAttribute value; private final boolean preCommit; public SetAttributeHandler(HttpHandler next, ExchangeAttribute attribute, ExchangeAttribute value) { this(next, attribute, value, false); } public SetAttributeHandler(HttpHandler next, final String attribute, final String value) { this.next = next; ExchangeAttributeParser parser = ExchangeAttributes.parser(getClass().getClassLoader()); this.attribute = parser.parseSingleToken(attribute); this.value = parser.parse(value); this.preCommit = false; } public SetAttributeHandler(HttpHandler next, final String attribute, final String value, final ClassLoader classLoader) { this.next = next; ExchangeAttributeParser parser = ExchangeAttributes.parser(classLoader); this.attribute = parser.parseSingleToken(attribute); this.value = parser.parse(value); this.preCommit = false; } public SetAttributeHandler(HttpHandler next, ExchangeAttribute attribute, ExchangeAttribute value, boolean preCommit) { this.next = next; this.attribute = attribute; this.value = value; this.preCommit = preCommit; } public SetAttributeHandler(HttpHandler next, final String attribute, final String value, boolean preCommit) { this.next = next; this.preCommit = preCommit; ExchangeAttributeParser parser = ExchangeAttributes.parser(getClass().getClassLoader()); this.attribute = parser.parseSingleToken(attribute); this.value = parser.parse(value); } public SetAttributeHandler(HttpHandler next, final String attribute, final String value, final ClassLoader classLoader, boolean preCommit) { this.next = next; this.preCommit = preCommit; ExchangeAttributeParser parser = ExchangeAttributes.parser(classLoader); this.attribute = parser.parseSingleToken(attribute); this.value = parser.parse(value); } public ExchangeAttribute getValue() { return value; } @Override public String toString() { return "set( attribute='" + attribute.toString() + "', value='" + value.toString() + "' )"; } @Override public void handleRequest(HttpServerExchange exchange) throws Exception { if(preCommit) { exchange.addResponseCommitListener(new ResponseCommitListener() { @Override public void beforeCommit(HttpServerExchange exchange) { try { attribute.writeAttribute(exchange, value.readAttribute(exchange)); } catch (ReadOnlyAttributeException e) { throw new RuntimeException(e); } } }); } else { attribute.writeAttribute(exchange, value.readAttribute(exchange)); } next.handleRequest(exchange); } public static class Builder implements HandlerBuilder { @Override public String name() { return "set"; } @Override public Map<String, Class<?>> parameters() { Map<String, Class<?>> parameters = new HashMap<>(); parameters.put("value", ExchangeAttribute.class); parameters.put("attribute", ExchangeAttribute.class); parameters.put("pre-commit", Boolean.class); return parameters; } @Override public Set<String> requiredParameters() { final Set<String> req = new HashSet<>(); req.add("value"); req.add("attribute"); return req; } @Override public String defaultParameter() { return null; } @Override public HandlerWrapper build(final Map<String, Object> config) { final ExchangeAttribute value = (ExchangeAttribute) config.get("value"); final ExchangeAttribute attribute = (ExchangeAttribute) config.get("attribute"); final Boolean preCommit = (Boolean) config.get("pre-commit"); return new HandlerWrapper() { @Override public HttpHandler wrap(HttpHandler handler) { return new SetAttributeHandler(handler, attribute, value, preCommit == null ? false : preCommit); } }; } } public static class ClearBuilder implements HandlerBuilder { @Override public String name() { return "clear"; } @Override public Map<String, Class<?>> parameters() { Map<String, Class<?>> parameters = new HashMap<>(); parameters.put("attribute", ExchangeAttribute.class); parameters.put("pre-commit", Boolean.class); return parameters; } @Override public Set<String> requiredParameters() { final Set<String> req = new HashSet<>(); req.add("attribute"); return req; } @Override public String defaultParameter() { return "attribute"; } @Override public HandlerWrapper build(final Map<String, Object> config) { final ExchangeAttribute attribute = (ExchangeAttribute) config.get("attribute"); final Boolean preCommit = (Boolean) config.get("pre-commit"); return new HandlerWrapper() { @Override public HttpHandler wrap(HttpHandler handler) { return new SetAttributeHandler(handler, attribute, NullAttribute.INSTANCE, preCommit == null ? false : preCommit); } }; } } }