/*
* Copyright 2002-2019 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
*
* https://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 org.springframework.messaging.handler.annotation.support;
import java.lang.annotation.Annotation;
import org.springframework.core.MethodParameter;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.lang.Nullable;
import org.springframework.messaging.Message;
import org.springframework.messaging.converter.MessageConversionException;
import org.springframework.messaging.converter.MessageConverter;
import org.springframework.messaging.converter.SmartMessageConverter;
import org.springframework.messaging.handler.annotation.Payload;
import org.springframework.messaging.handler.invocation.HandlerMethodArgumentResolver;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;
import org.springframework.validation.BeanPropertyBindingResult;
import org.springframework.validation.BindingResult;
import org.springframework.validation.ObjectError;
import org.springframework.validation.SmartValidator;
import org.springframework.validation.Validator;
import org.springframework.validation.annotation.Validated;
/**
* A resolver to extract and convert the payload of a message using a
* {@link MessageConverter}. It also validates the payload using a
* {@link Validator} if the argument is annotated with a Validation annotation.
*
* <p>This {@link HandlerMethodArgumentResolver} should be ordered last as it
* supports all types and does not require the {@link Payload} annotation.
*
* @author Rossen Stoyanchev
* @author Juergen Hoeller
* @author Brian Clozel
* @author Stephane Nicoll
* @since 5.2
*/
public class PayloadMethodArgumentResolver implements HandlerMethodArgumentResolver {
private final MessageConverter converter;
@Nullable
private final Validator validator;
private final boolean useDefaultResolution;
/**
* Create a new {@code PayloadArgumentResolver} with the given
* {@link MessageConverter}.
* @param messageConverter the MessageConverter to use (required)
*/
public PayloadMethodArgumentResolver(MessageConverter messageConverter) {
this(messageConverter, null);
}
/**
* Create a new {@code PayloadArgumentResolver} with the given
* {@link MessageConverter} and {@link Validator}.
* @param messageConverter the MessageConverter to use (required)
* @param validator the Validator to use (optional)
*/
public PayloadMethodArgumentResolver(MessageConverter messageConverter, @Nullable Validator validator) {
this(messageConverter, validator, true);
}
/**
* Create a new {@code PayloadArgumentResolver} with the given
* {@link MessageConverter} and {@link Validator}.
* @param messageConverter the MessageConverter to use (required)
* @param validator the Validator to use (optional)
* @param useDefaultResolution if "true" (the default) this resolver supports
* all parameters; if "false" then only arguments with the {@code @Payload}
* annotation are supported.
*/
public PayloadMethodArgumentResolver(MessageConverter messageConverter, @Nullable Validator validator,
boolean useDefaultResolution) {
Assert.notNull(messageConverter, "MessageConverter must not be null");
this.converter = messageConverter;
this.validator = validator;
this.useDefaultResolution = useDefaultResolution;
}
@Override
public boolean supportsParameter(MethodParameter parameter) {
return (parameter.hasParameterAnnotation(Payload.class) || this.useDefaultResolution);
}
@Override
@Nullable
public Object resolveArgument(MethodParameter parameter, Message<?> message) throws Exception {
Payload ann = parameter.getParameterAnnotation(Payload.class);
if (ann != null && StringUtils.hasText(ann.expression())) {
throw new IllegalStateException("@Payload SpEL expressions not supported by this resolver");
}
Object payload = message.getPayload();
if (isEmptyPayload(payload)) {
if (ann == null || ann.required()) {
String paramName = getParameterName(parameter);
BindingResult bindingResult = new BeanPropertyBindingResult(payload, paramName);
bindingResult.addError(new ObjectError(paramName, "Payload value must not be empty"));
throw new MethodArgumentNotValidException(message, parameter, bindingResult);
}
else {
return null;
}
}
Class<?> targetClass = resolveTargetClass(parameter, message);
Class<?> payloadClass = payload.getClass();
if (ClassUtils.isAssignable(targetClass, payloadClass)) {
validate(message, parameter, payload);
return payload;
}
else {
if (this.converter instanceof SmartMessageConverter) {
SmartMessageConverter smartConverter = (SmartMessageConverter) this.converter;
payload = smartConverter.fromMessage(message, targetClass, parameter);
}
else {
payload = this.converter.fromMessage(message, targetClass);
}
if (payload == null) {
throw new MessageConversionException(message, "Cannot convert from [" +
payloadClass.getName() + "] to [" + targetClass.getName() + "] for " + message);
}
validate(message, parameter, payload);
return payload;
}
}
private String getParameterName(MethodParameter param) {
String paramName = param.getParameterName();
return (paramName != null ? paramName : "Arg " + param.getParameterIndex());
}
/**
* Specify if the given {@code payload} is empty.
* @param payload the payload to check (can be {@code null})
*/
protected boolean isEmptyPayload(@Nullable Object payload) {
if (payload == null) {
return true;
}
else if (payload instanceof byte[]) {
return ((byte[]) payload).length == 0;
}
else if (payload instanceof String) {
return !StringUtils.hasText((String) payload);
}
else {
return false;
}
}
/**
* Resolve the target class to convert the payload to.
* <p>By default this is simply {@link MethodParameter#getParameterType()}
* but that can be overridden to select a more specific target type after
* also taking into account the "Content-Type", e.g. return {@code String}
* if target type is {@code Object} and {@code "Content-Type:text/**"}.
* @param parameter the target method parameter
* @param message the message bring processed
* @return the target type to use
* @since 5.2
*/
protected Class<?> resolveTargetClass(MethodParameter parameter, Message<?> message) {
return parameter.getParameterType();
}
/**
* Validate the payload if applicable.
* <p>The default implementation checks for {@code @javax.validation.Valid},
* Spring's {@link Validated},
* and custom annotations whose name starts with "Valid".
* @param message the currently processed message
* @param parameter the method parameter
* @param target the target payload object
* @throws MethodArgumentNotValidException in case of binding errors
*/
protected void validate(Message<?> message, MethodParameter parameter, Object target) {
if (this.validator == null) {
return;
}
for (Annotation ann : parameter.getParameterAnnotations()) {
Validated validatedAnn = AnnotationUtils.getAnnotation(ann, Validated.class);
if (validatedAnn != null || ann.annotationType().getSimpleName().startsWith("Valid")) {
Object hints = (validatedAnn != null ? validatedAnn.value() : AnnotationUtils.getValue(ann));
Object[] validationHints = (hints instanceof Object[] ? (Object[]) hints : new Object[] {hints});
BeanPropertyBindingResult bindingResult =
new BeanPropertyBindingResult(target, getParameterName(parameter));
if (!ObjectUtils.isEmpty(validationHints) && this.validator instanceof SmartValidator) {
((SmartValidator) this.validator).validate(target, bindingResult, validationHints);
}
else {
this.validator.validate(target, bindingResult);
}
if (bindingResult.hasErrors()) {
throw new MethodArgumentNotValidException(message, parameter, bindingResult);
}
break;
}
}
}
}
