org.springframework.web.method.annotation.AbstractNamedValueMethodArgumentResolver Maven / Gradle / Ivy
/*
* Copyright 2002-2018 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
*
* 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 org.springframework.web.method.annotation;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import javax.servlet.ServletException;
import org.springframework.beans.ConversionNotSupportedException;
import org.springframework.beans.TypeMismatchException;
import org.springframework.beans.factory.config.BeanExpressionContext;
import org.springframework.beans.factory.config.BeanExpressionResolver;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.core.MethodParameter;
import org.springframework.lang.Nullable;
import org.springframework.web.bind.ServletRequestBindingException;
import org.springframework.web.bind.WebDataBinder;
import org.springframework.web.bind.annotation.ValueConstants;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.context.request.RequestScope;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.ModelAndViewContainer;
/**
* Abstract base class for resolving method arguments from a named value.
* Request parameters, request headers, and path variables are examples of named
* values. Each may have a name, a required flag, and a default value.
*
* Subclasses define how to do the following:
*
* - Obtain named value information for a method parameter
*
- Resolve names into argument values
*
- Handle missing argument values when argument values are required
*
- Optionally handle a resolved value
*
*
* A default value string can contain ${...} placeholders and Spring Expression
* Language #{...} expressions. For this to work a
* {@link ConfigurableBeanFactory} must be supplied to the class constructor.
*
*
A {@link WebDataBinder} is created to apply type conversion to the resolved
* argument value if it doesn't match the method parameter type.
*
* @author Arjen Poutsma
* @author Rossen Stoyanchev
* @author Juergen Hoeller
* @since 3.1
*/
public abstract class AbstractNamedValueMethodArgumentResolver implements HandlerMethodArgumentResolver {
@Nullable
private final ConfigurableBeanFactory configurableBeanFactory;
@Nullable
private final BeanExpressionContext expressionContext;
private final Map namedValueInfoCache = new ConcurrentHashMap<>(256);
public AbstractNamedValueMethodArgumentResolver() {
this.configurableBeanFactory = null;
this.expressionContext = null;
}
/**
* Create a new {@link AbstractNamedValueMethodArgumentResolver} instance.
* @param beanFactory a bean factory to use for resolving ${...} placeholder
* and #{...} SpEL expressions in default values, or {@code null} if default
* values are not expected to contain expressions
*/
public AbstractNamedValueMethodArgumentResolver(@Nullable ConfigurableBeanFactory beanFactory) {
this.configurableBeanFactory = beanFactory;
this.expressionContext =
(beanFactory != null ? new BeanExpressionContext(beanFactory, new RequestScope()) : null);
}
@Override
@Nullable
public final Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception {
NamedValueInfo namedValueInfo = getNamedValueInfo(parameter);
MethodParameter nestedParameter = parameter.nestedIfOptional();
Object resolvedName = resolveStringValue(namedValueInfo.name);
if (resolvedName == null) {
throw new IllegalArgumentException(
"Specified name must not resolve to null: [" + namedValueInfo.name + "]");
}
Object arg = resolveName(resolvedName.toString(), nestedParameter, webRequest);
if (arg == null) {
if (namedValueInfo.defaultValue != null) {
arg = resolveStringValue(namedValueInfo.defaultValue);
}
else if (namedValueInfo.required && !nestedParameter.isOptional()) {
handleMissingValue(namedValueInfo.name, nestedParameter, webRequest);
}
arg = handleNullValue(namedValueInfo.name, arg, nestedParameter.getNestedParameterType());
}
else if ("".equals(arg) && namedValueInfo.defaultValue != null) {
arg = resolveStringValue(namedValueInfo.defaultValue);
}
if (binderFactory != null) {
WebDataBinder binder = binderFactory.createBinder(webRequest, null, namedValueInfo.name);
try {
arg = binder.convertIfNecessary(arg, parameter.getParameterType(), parameter);
}
catch (ConversionNotSupportedException ex) {
throw new MethodArgumentConversionNotSupportedException(arg, ex.getRequiredType(),
namedValueInfo.name, parameter, ex.getCause());
}
catch (TypeMismatchException ex) {
throw new MethodArgumentTypeMismatchException(arg, ex.getRequiredType(),
namedValueInfo.name, parameter, ex.getCause());
}
}
handleResolvedValue(arg, namedValueInfo.name, parameter, mavContainer, webRequest);
return arg;
}
/**
* Obtain the named value for the given method parameter.
*/
private NamedValueInfo getNamedValueInfo(MethodParameter parameter) {
NamedValueInfo namedValueInfo = this.namedValueInfoCache.get(parameter);
if (namedValueInfo == null) {
namedValueInfo = createNamedValueInfo(parameter);
namedValueInfo = updateNamedValueInfo(parameter, namedValueInfo);
this.namedValueInfoCache.put(parameter, namedValueInfo);
}
return namedValueInfo;
}
/**
* Create the {@link NamedValueInfo} object for the given method parameter. Implementations typically
* retrieve the method annotation by means of {@link MethodParameter#getParameterAnnotation(Class)}.
* @param parameter the method parameter
* @return the named value information
*/
protected abstract NamedValueInfo createNamedValueInfo(MethodParameter parameter);
/**
* Create a new NamedValueInfo based on the given NamedValueInfo with sanitized values.
*/
private NamedValueInfo updateNamedValueInfo(MethodParameter parameter, NamedValueInfo info) {
String name = info.name;
if (info.name.isEmpty()) {
name = parameter.getParameterName();
if (name == null) {
throw new IllegalArgumentException(
"Name for argument type [" + parameter.getNestedParameterType().getName() +
"] not available, and parameter name information not found in class file either.");
}
}
String defaultValue = (ValueConstants.DEFAULT_NONE.equals(info.defaultValue) ? null : info.defaultValue);
return new NamedValueInfo(name, info.required, defaultValue);
}
/**
* Resolve the given annotation-specified value,
* potentially containing placeholders and expressions.
*/
@Nullable
private Object resolveStringValue(String value) {
if (this.configurableBeanFactory == null) {
return value;
}
String placeholdersResolved = this.configurableBeanFactory.resolveEmbeddedValue(value);
BeanExpressionResolver exprResolver = this.configurableBeanFactory.getBeanExpressionResolver();
if (exprResolver == null || this.expressionContext == null) {
return value;
}
return exprResolver.evaluate(placeholdersResolved, this.expressionContext);
}
/**
* Resolve the given parameter type and value name into an argument value.
* @param name the name of the value being resolved
* @param parameter the method parameter to resolve to an argument value
* (pre-nested in case of a {@link java.util.Optional} declaration)
* @param request the current request
* @return the resolved argument (may be {@code null})
* @throws Exception in case of errors
*/
@Nullable
protected abstract Object resolveName(String name, MethodParameter parameter, NativeWebRequest request)
throws Exception;
/**
* Invoked when a named value is required, but {@link #resolveName(String, MethodParameter, NativeWebRequest)}
* returned {@code null} and there is no default value. Subclasses typically throw an exception in this case.
* @param name the name for the value
* @param parameter the method parameter
* @param request the current request
* @since 4.3
*/
protected void handleMissingValue(String name, MethodParameter parameter, NativeWebRequest request)
throws Exception {
handleMissingValue(name, parameter);
}
/**
* Invoked when a named value is required, but {@link #resolveName(String, MethodParameter, NativeWebRequest)}
* returned {@code null} and there is no default value. Subclasses typically throw an exception in this case.
* @param name the name for the value
* @param parameter the method parameter
*/
protected void handleMissingValue(String name, MethodParameter parameter) throws ServletException {
throw new ServletRequestBindingException("Missing argument '" + name +
"' for method parameter of type " + parameter.getNestedParameterType().getSimpleName());
}
/**
* A {@code null} results in a {@code false} value for {@code boolean}s or an exception for other primitives.
*/
@Nullable
private Object handleNullValue(String name, @Nullable Object value, Class paramType) {
if (value == null) {
if (Boolean.TYPE.equals(paramType)) {
return Boolean.FALSE;
}
else if (paramType.isPrimitive()) {
throw new IllegalStateException("Optional " + paramType.getSimpleName() + " parameter '" + name +
"' is present but cannot be translated into a null value due to being declared as a " +
"primitive type. Consider declaring it as object wrapper for the corresponding primitive type.");
}
}
return value;
}
/**
* Invoked after a value is resolved.
* @param arg the resolved argument value
* @param name the argument name
* @param parameter the argument parameter type
* @param mavContainer the {@link ModelAndViewContainer} (may be {@code null})
* @param webRequest the current request
*/
protected void handleResolvedValue(@Nullable Object arg, String name, MethodParameter parameter,
@Nullable ModelAndViewContainer mavContainer, NativeWebRequest webRequest) {
}
/**
* Represents the information about a named value, including name, whether it's required and a default value.
*/
protected static class NamedValueInfo {
private final String name;
private final boolean required;
@Nullable
private final String defaultValue;
public NamedValueInfo(String name, boolean required, @Nullable String defaultValue) {
this.name = name;
this.required = required;
this.defaultValue = defaultValue;
}
}
}