org.springframework.web.bind.annotation.ModelAttribute#value ( )源码实例Demo

private Object getErrors(MethodParameter parameter, BindingContext context) {
	Assert.isTrue(parameter.getParameterIndex() > 0,
			"Errors argument must be declared immediately after a model attribute argument");

	int index = parameter.getParameterIndex() - 1;
	MethodParameter attributeParam = MethodParameter.forExecutable(parameter.getExecutable(), index);
	ReactiveAdapter adapter = getAdapterRegistry().getAdapter(attributeParam.getParameterType());

	Assert.state(adapter == null, "An @ModelAttribute and an Errors/BindingResult argument " +
			"cannot both be declared with an async type wrapper. " +
			"Either declare the @ModelAttribute without an async wrapper type or " +
			"handle a WebExchangeBindException error signal through the async type.");

	ModelAttribute ann = parameter.getParameterAnnotation(ModelAttribute.class);
	String name = (ann != null && StringUtils.hasText(ann.value()) ?
			ann.value() : Conventions.getVariableNameForParameter(attributeParam));
	Object errors = context.getModel().asMap().get(BindingResult.MODEL_KEY_PREFIX + name);

	Assert.state(errors != null, () -> "An Errors/BindingResult argument is expected " +
			"immediately after the @ModelAttribute argument to which it applies. " +
			"For @RequestBody and @RequestPart arguments, please declare them with a reactive " +
			"type wrapper and use its onError operators to handle WebExchangeBindException: " +
			parameter.getMethod());

	return errors;
}
 

private Object getErrors(MethodParameter parameter, BindingContext context) {
	Assert.isTrue(parameter.getParameterIndex() > 0,
			"Errors argument must be declared immediately after a model attribute argument");

	int index = parameter.getParameterIndex() - 1;
	MethodParameter attributeParam = MethodParameter.forExecutable(parameter.getExecutable(), index);
	ReactiveAdapter adapter = getAdapterRegistry().getAdapter(attributeParam.getParameterType());

	Assert.state(adapter == null, "An @ModelAttribute and an Errors/BindingResult argument " +
			"cannot both be declared with an async type wrapper. " +
			"Either declare the @ModelAttribute without an async wrapper type or " +
			"handle a WebExchangeBindException error signal through the async type.");

	ModelAttribute ann = parameter.getParameterAnnotation(ModelAttribute.class);
	String name = (ann != null && StringUtils.hasText(ann.value()) ?
			ann.value() : Conventions.getVariableNameForParameter(attributeParam));
	Object errors = context.getModel().asMap().get(BindingResult.MODEL_KEY_PREFIX + name);

	Assert.state(errors != null, () -> "An Errors/BindingResult argument is expected " +
			"immediately after the @ModelAttribute argument to which it applies. " +
			"For @RequestBody and @RequestPart arguments, please declare them with a reactive " +
			"type wrapper and use its onError operators to handle WebExchangeBindException: " +
			parameter.getMethod());

	return errors;
}
 

/**
 * Derive the model attribute name for the given return value. Results will be
 * based on:
 * <ol>
 * <li>the method {@code ModelAttribute} annotation value
 * <li>the declared return type if it is more specific than {@code Object}
 * <li>the actual return value type
 * </ol>
 * @param returnValue the value returned from a method invocation
 * @param returnType a descriptor for the return type of the method
 * @return the derived name (never {@code null} or empty String)
 */
public static String getNameForReturnValue(@Nullable Object returnValue, MethodParameter returnType) {
	ModelAttribute ann = returnType.getMethodAnnotation(ModelAttribute.class);
	if (ann != null && StringUtils.hasText(ann.value())) {
		return ann.value();
	}
	else {
		Method method = returnType.getMethod();
		Assert.state(method != null, "No handler method");
		Class<?> containingClass = returnType.getContainingClass();
		Class<?> resolvedType = GenericTypeResolver.resolveReturnType(method, containingClass);
		return Conventions.getVariableNameForReturnType(method, resolvedType, returnValue);
	}
}
 

/**
 * Derive the model attribute name for the given return value. Results will be
 * based on:
 * <ol>
 * <li>the method {@code ModelAttribute} annotation value
 * <li>the declared return type if it is more specific than {@code Object}
 * <li>the actual return value type
 * </ol>
 * @param returnValue the value returned from a method invocation
 * @param returnType a descriptor for the return type of the method
 * @return the derived name (never {@code null} or empty String)
 */
public static String getNameForReturnValue(@Nullable Object returnValue, MethodParameter returnType) {
	ModelAttribute ann = returnType.getMethodAnnotation(ModelAttribute.class);
	if (ann != null && StringUtils.hasText(ann.value())) {
		return ann.value();
	}
	else {
		Method method = returnType.getMethod();
		Assert.state(method != null, "No handler method");
		Class<?> containingClass = returnType.getContainingClass();
		Class<?> resolvedType = GenericTypeResolver.resolveReturnType(method, containingClass);
		return Conventions.getVariableNameForReturnType(method, resolvedType, returnValue);
	}
}
 

/**
 * Derive the model attribute name for the given return value based on:
 * <ol>
 * <li>the method {@code ModelAttribute} annotation value
 * <li>the declared return type if it is more specific than {@code Object}
 * <li>the actual return value type
 * </ol>
 * @param returnValue the value returned from a method invocation
 * @param returnType a descriptor for the return type of the method
 * @return the derived name (never {@code null} or empty String)
 */
public static String getNameForReturnValue(Object returnValue, MethodParameter returnType) {
	ModelAttribute ann = returnType.getMethodAnnotation(ModelAttribute.class);
	if (ann != null && StringUtils.hasText(ann.value())) {
		return ann.value();
	}
	else {
		Method method = returnType.getMethod();
		Class<?> containingClass = returnType.getContainingClass();
		Class<?> resolvedType = GenericTypeResolver.resolveReturnType(method, containingClass);
		return Conventions.getVariableNameForReturnType(method, resolvedType, returnValue);
	}
}
 

protected final void addReturnValueAsModelAttribute(Method handlerMethod, Class<?> handlerType,
		Object returnValue, ExtendedModelMap implicitModel) {

	ModelAttribute attr = AnnotationUtils.findAnnotation(handlerMethod, ModelAttribute.class);
	String attrName = (attr != null ? attr.value() : "");
	if ("".equals(attrName)) {
		Class<?> resolvedType = GenericTypeResolver.resolveReturnType(handlerMethod, handlerType);
		attrName = Conventions.getVariableNameForReturnType(handlerMethod, resolvedType, returnValue);
	}
	implicitModel.addAttribute(attrName, returnValue);
}
 

/**
 * Derive the model attribute name for the given return value using one of:
 * <ol>
 * 	<li>The method {@code ModelAttribute} annotation value
 * 	<li>The declared return type if it is more specific than {@code Object}
 * 	<li>The actual return value type
 * </ol>
 * @param returnValue the value returned from a method invocation
 * @param returnType the return type of the method
 * @return the model name, never {@code null} nor empty
 */
public static String getNameForReturnValue(Object returnValue, MethodParameter returnType) {
	ModelAttribute annotation = returnType.getMethodAnnotation(ModelAttribute.class);
	if (annotation != null && StringUtils.hasText(annotation.value())) {
		return annotation.value();
	}
	else {
		Method method = returnType.getMethod();
		Class<?> resolvedType = GenericTypeResolver.resolveReturnType(method, returnType.getContainingClass());
		return Conventions.getVariableNameForReturnType(method, resolvedType, returnValue);
	}
}
 

protected final void addReturnValueAsModelAttribute(Method handlerMethod, Class<?> handlerType,
		Object returnValue, ExtendedModelMap implicitModel) {

	ModelAttribute attr = AnnotationUtils.findAnnotation(handlerMethod, ModelAttribute.class);
	String attrName = (attr != null ? attr.value() : "");
	if ("".equals(attrName)) {
		Class<?> resolvedType = GenericTypeResolver.resolveReturnType(handlerMethod, handlerType);
		attrName = Conventions.getVariableNameForReturnType(handlerMethod, resolvedType, returnValue);
	}
	implicitModel.addAttribute(attrName, returnValue);
}
 

/**
 * Derive the model attribute name for the given method parameter based on
 * a {@code @ModelAttribute} parameter annotation (if present) or falling
 * back on parameter type based conventions.
 * @param parameter a descriptor for the method parameter
 * @return the derived name
 * @see Conventions#getVariableNameForParameter(MethodParameter)
 */
public static String getNameForParameter(MethodParameter parameter) {
	ModelAttribute ann = parameter.getParameterAnnotation(ModelAttribute.class);
	String name = (ann != null ? ann.value() : null);
	return (StringUtils.hasText(name) ? name : Conventions.getVariableNameForParameter(parameter));
}
 

/**
 * Derive the model attribute name for the given method parameter based on
 * a {@code @ModelAttribute} parameter annotation (if present) or falling
 * back on parameter type based conventions.
 * @param parameter a descriptor for the method parameter
 * @return the derived name
 * @see Conventions#getVariableNameForParameter(MethodParameter)
 */
public static String getNameForParameter(MethodParameter parameter) {
	ModelAttribute ann = parameter.getParameterAnnotation(ModelAttribute.class);
	String name = (ann != null ? ann.value() : null);
	return (StringUtils.hasText(name) ? name : Conventions.getVariableNameForParameter(parameter));
}
 

/**
 * Derive the model attribute name for the given method parameter based on
 * a {@code @ModelAttribute} parameter annotation (if present) or falling
 * back on parameter type based conventions.
 * @param parameter a descriptor for the method parameter
 * @return the derived name
 * @see Conventions#getVariableNameForParameter(MethodParameter)
 */
public static String getNameForParameter(MethodParameter parameter) {
	ModelAttribute ann = parameter.getParameterAnnotation(ModelAttribute.class);
	String name = (ann != null ? ann.value() : null);
	return (StringUtils.hasText(name) ? name : Conventions.getVariableNameForParameter(parameter));
}
 

/**
 * Derive the model attribute name for the given method parameter based on
 * a {@code @ModelAttribute} parameter annotation (if present) or falling
 * back on parameter type based conventions.
 * @param parameter a descriptor for the method parameter
 * @return the derived name
 * @see Conventions#getVariableNameForParameter(MethodParameter)
 */
public static String getNameForParameter(MethodParameter parameter) {
	ModelAttribute ann = parameter.getParameterAnnotation(ModelAttribute.class);
	String name = (ann != null ? ann.value() : null);
	return (StringUtils.hasText(name) ? name : Conventions.getVariableNameForParameter(parameter));
}
 

/**
 * Derive the model attribute name for a method parameter based on:
 * <ol>
 * <li>the parameter {@code @ModelAttribute} annotation value
 * <li>the parameter type
 * </ol>
 * @param parameter a descriptor for the method parameter
 * @return the derived name (never {@code null} or empty String)
 */
public static String getNameForParameter(MethodParameter parameter) {
	ModelAttribute ann = parameter.getParameterAnnotation(ModelAttribute.class);
	String name = (ann != null ? ann.value() : null);
	return (StringUtils.hasText(name) ? name : Conventions.getVariableNameForParameter(parameter));
}
 

/**
 * Derives the model attribute name for a method parameter based on:
 * <ol>
 * 	<li>The parameter {@code @ModelAttribute} annotation value
 * 	<li>The parameter type
 * </ol>
 * @return the derived name; never {@code null} or an empty string
 */
public static String getNameForParameter(MethodParameter parameter) {
	ModelAttribute annot = parameter.getParameterAnnotation(ModelAttribute.class);
	String attrName = (annot != null) ? annot.value() : null;
	return StringUtils.hasText(attrName) ? attrName :  Conventions.getVariableNameForParameter(parameter);
}