SpringMVC-解析对象
如果参数是对象且没有注解，则参数由ServletModelAttributeMethodProcessor解析。解析如下参数：
@PostMapping("/userParam0")
@ResponseBody
public User handleUserByParam0(User user) {
return user;
}
ModelAttributeMethodProcessor.supportsParameter(MethodParameter parameter)
public boolean supportsParameter(MethodParameter parameter) {
return (parameter.hasParameterAnnotation(ModelAttribute.class) ||
(this.annotationNotRequired && !BeanUtils.isSimpleProperty(parameter.getParameterType())));
}
如果参数有@ModelAttribute或者annotationNotRequired为true且参数类型不是简单类型。
BeanUtils.isSimpleProperty(Class<?> type)
public static boolean isSimpleProperty(Class<?> type) {
Assert.notNull(type, "'type' must not be null");
return isSimpleValueType(type) || (type.isArray() && isSimpleValueType(type.getComponentType()));
}
public static boolean isSimpleValueType(Class<?> type) {
return (Void.class != type && void.class != type &&
(ClassUtils.isPrimitiveOrWrapper(type) ||
Enum.class.isAssignableFrom(type) ||
CharSequence.class.isAssignableFrom(type) ||
Number.class.isAssignableFrom(type) ||
Date.class.isAssignableFrom(type) ||
Temporal.class.isAssignableFrom(type) ||
URI.class == type ||
URL.class == type ||
Locale.class == type ||
Class.class == type));
}
如果参数是以上类型或以上类型的数组则认为是简单类型。
ModelAttributeMethodProcessor.resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory)
public final Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception {
Assert.state(mavContainer != null, "ModelAttributeMethodProcessor requires ModelAndViewContainer");
Assert.state(binderFactory != null, "ModelAttributeMethodProcessor requires WebDataBinderFactory");
String name = ModelFactory.getNameForParameter(parameter);
ModelAttribute ann = parameter.getParameterAnnotation(ModelAttribute.class);
if (ann != null) {
mavContainer.setBinding(name, ann.binding());
}
Object attribute = null;
BindingResult bindingResult = null;
if (mavContainer.containsAttribute(name)) {
attribute = mavContainer.getModel().get(name);
}
else {
// Create attribute instance
try {
attribute = createAttribute(name, parameter, binderFactory, webRequest);
}
catch (BindException ex) {
if (isBindExceptionRequired(parameter)) {
// No BindingResult parameter -> fail with BindException
throw ex;
}
// Otherwise, expose null/empty value and associated BindingResult
if (parameter.getParameterType() == Optional.class) {
attribute = Optional.empty();
}
else {
attribute = ex.getTarget();
}
bindingResult = ex.getBindingResult();
}
}
if (bindingResult == null) {
// Bean property binding and validation;
// skipped in case of binding failure on construction.
WebDataBinder binder = binderFactory.createBinder(webRequest, attribute, name);
if (binder.getTarget() != null) {
if (!mavContainer.isBindingDisabled(name)) {
bindRequestParameters(binder, webRequest);
}
validateIfApplicable(binder, parameter);
if (binder.getBindingResult().hasErrors() && isBindExceptionRequired(binder, parameter)) {
throw new BindException(binder.getBindingResult());
}
}
// Value type adaptation, also covering java.util.Optional
if (!parameter.getParameterType().isInstance(attribute)) {
attribute = binder.convertIfNecessary(binder.getTarget(), parameter.getParameterType(), parameter);
}
bindingResult = binder.getBindingResult();
}
// Add resolved attribute and BindingResult at the end of the model
Map<String, Object> bindingResultModel = bindingResult.getModel();
mavContainer.removeAttributes(bindingResultModel);
mavContainer.addAllAttributes(bindingResultModel);
return attribute;
}
1、获取参数名，首先从@ModelAttribute获取value属性，如果没有获取参数名
2、如果ModelAndViewContainer有属性值则从ModelAndViewContainer获取
3、createAttribute创建属性值
4、如果bindingResult为null，bindRequestParameters绑定参数
ServletModelAttributeMethodProcessor.createAttribute(String attributeName, MethodParameter parameter,
WebDataBinderFactory binderFactory, NativeWebRequest request)
protected final Object createAttribute(String attributeName, MethodParameter parameter,
WebDataBinderFactory binderFactory, NativeWebRequest request) throws Exception {
String value = getRequestValueForAttribute(attributeName, request);
if (value != null) {
Object attribute = createAttributeFromRequestValue(
value, attributeName, parameter, binderFactory, request);
if (attribute != null) {
return attribute;
}
}
return super.createAttribute(attributeName, parameter, binderFactory, request);
}
1、从request中获取属性值
2、如果存在属性值调用createAttributeFromRequestValue进行值的类型转换
3、否则调用父类createAttribute
ServletModelAttributeMethodProcessor.getRequestValueForAttribute(String attributeName, NativeWebRequest request)
protected String getRequestValueForAttribute(String attributeName, NativeWebRequest request) {
Map<String, String> variables = getUriTemplateVariables(request);
String variableValue = variables.get(attributeName);
if (StringUtils.hasText(variableValue)) {
return variableValue;
}
String parameterValue = request.getParameter(attributeName);
if (StringUtils.hasText(parameterValue)) {
return parameterValue;
}
return null;
}
1、从uri模板变量中获取属性值，存在则返回
2、通过属性名从request获取属性值
ModelAttributeMethodProcessor.createAttribute(String attributeName, MethodParameter parameter,
WebDataBinderFactory binderFactory, NativeWebRequest webRequest)
protected Object createAttribute(String attributeName, MethodParameter parameter,
WebDataBinderFactory binderFactory, NativeWebRequest webRequest) throws Exception {
MethodParameter nestedParameter = parameter.nestedIfOptional();
Class<?> clazz = nestedParameter.getNestedParameterType();
Constructor<?> ctor = BeanUtils.getResolvableConstructor(clazz);
Object attribute = constructAttribute(ctor, attributeName, parameter, binderFactory, webRequest);
if (parameter != nestedParameter) {
attribute = Optional.of(attribute);
}
return attribute;
}
1、BeanUtils.getResolvableConstructor解析参数类型构造函数
2、constructAttribute实例化对象
ServletModelAttributeMethodProcessor.bindRequestParameters(WebDataBinder binder, NativeWebRequest request)
protected void bindRequestParameters(WebDataBinder binder, NativeWebRequest request) {
ServletRequest servletRequest = request.getNativeRequest(ServletRequest.class);
Assert.state(servletRequest != null, "No ServletRequest");
ServletRequestDataBinder servletBinder = (ServletRequestDataBinder) binder;
servletBinder.bind(servletRequest);
}
ServletRequestDataBinder调用bind绑定参数值
ServletRequestDataBinder.bind(ServletRequest request)
public void bind(ServletRequest request) {
MutablePropertyValues mpvs = new ServletRequestParameterPropertyValues(request);
MultipartRequest multipartRequest = WebUtils.getNativeRequest(request, MultipartRequest.class);
if (multipartRequest != null) {
bindMultipart(multipartRequest.getMultiFileMap(), mpvs);
}
else if (StringUtils.startsWithIgnoreCase(request.getContentType(), "multipart/")) {
HttpServletRequest httpServletRequest = WebUtils.getNativeRequest(request, HttpServletRequest.class);
if (httpServletRequest != null) {
StandardServletPartUtils.bindParts(httpServletRequest, mpvs, isBindEmptyMultipartFiles());
}
}
addBindValues(mpvs, request);
doBind(mpvs);
}
1、创建ServletRequestParameterPropertyValues将request中的参数值转成MutablePropertyValues
2、解析Multipart请求
3、addBindValues将uri模板变量加入MutablePropertyValues
4、doBind绑定参数值
WebDataBinder.doBind(MutablePropertyValues mpvs)
protected void doBind(MutablePropertyValues mpvs) {
checkFieldDefaults(mpvs);
checkFieldMarkers(mpvs);
adaptEmptyArrayIndices(mpvs);
super.doBind(mpvs);
}
调用父类doBind。
DataBinder.doBind(MutablePropertyValues mpvs)
protected void doBind(MutablePropertyValues mpvs) {
checkAllowedFields(mpvs);
checkRequiredFields(mpvs);
applyPropertyValues(mpvs);
}
applyPropertyValues填充参数值
AbstractPropertyAccessor.setPropertyValues(PropertyValues pvs, boolean ignoreUnknown, boolean ignoreInvalid)
public void setPropertyValues(PropertyValues pvs, boolean ignoreUnknown, boolean ignoreInvalid)
throws BeansException {
List<PropertyAccessException> propertyAccessExceptions = null;
List<PropertyValue> propertyValues = (pvs instanceof MutablePropertyValues ?
((MutablePropertyValues) pvs).getPropertyValueList() : Arrays.asList(pvs.getPropertyValues()));
if (ignoreUnknown) {
this.suppressNotWritablePropertyException = true;
}
try {
for (PropertyValue pv : propertyValues) {
// setPropertyValue may throw any BeansException, which won't be caught
// here, if there is a critical failure such as no matching field.
// We can attempt to deal only with less serious exceptions.
try {
setPropertyValue(pv);
}
catch (NotWritablePropertyException ex) {
if (!ignoreUnknown) {
throw ex;
}
// Otherwise, just ignore it and continue...
}
catch (NullValueInNestedPathException ex) {
if (!ignoreInvalid) {
throw ex;
}
// Otherwise, just ignore it and continue...
}
catch (PropertyAccessException ex) {
if (propertyAccessExceptions == null) {
propertyAccessExceptions = new ArrayList<>();
}
propertyAccessExceptions.add(ex);
}
}
}
finally {
if (ignoreUnknown) {
this.suppressNotWritablePropertyException = false;
}
}
// If we encountered individual exceptions, throw the composite exception.
if (propertyAccessExceptions != null) {
PropertyAccessException[] paeArray = propertyAccessExceptions.toArray(new PropertyAccessException[0]);
throw new PropertyBatchUpdateException(paeArray);
}
}
遍历参数列表，调用setPropertyValue设置参数值。
AbstractNestablePropertyAccessor.setPropertyValue(PropertyValue pv)
public void setPropertyValue(PropertyValue pv) throws BeansException {
PropertyTokenHolder tokens = (PropertyTokenHolder) pv.resolvedTokens;
if (tokens == null) {
String propertyName = pv.getName();
AbstractNestablePropertyAccessor nestedPa;
try {
nestedPa = getPropertyAccessorForPropertyPath(propertyName);
}
catch (NotReadablePropertyException ex) {
throw new NotWritablePropertyException(getRootClass(), this.nestedPath + propertyName,
"Nested property in path '" + propertyName + "' does not exist", ex);
}
tokens = getPropertyNameTokens(getFinalPath(nestedPa, propertyName));
if (nestedPa == this) {
pv.getOriginalPropertyValue().resolvedTokens = tokens;
}
nestedPa.setPropertyValue(tokens, pv);
}
else {
setPropertyValue(tokens, pv);
}
}
如果tokens为null，调用AbstractNestablePropertyAccessor.setPropertyValue设置属性值。否则调用setPropertyValue设置属性值。
AbstractNestablePropertyAccessor.setPropertyValue(PropertyTokenHolder tokens, PropertyValue pv)
protected void setPropertyValue(PropertyTokenHolder tokens, PropertyValue pv) throws BeansException {
if (tokens.keys != null) {
processKeyedProperty(tokens, pv);
}
else {
processLocalProperty(tokens, pv);
}
}
如果keys不为null调用processKeyedProperty否则调用processLocalProperty。
AbstractNestablePropertyAccessor.processLocalProperty(PropertyTokenHolder tokens, PropertyValue pv)
private void processLocalProperty(PropertyTokenHolder tokens, PropertyValue pv) {
PropertyHandler ph = getLocalPropertyHandler(tokens.actualName);
if (ph == null || !ph.isWritable()) {
if (pv.isOptional()) {
if (logger.isDebugEnabled()) {
logger.debug("Ignoring optional value for property '" + tokens.actualName +
"' - property not found on bean class [" + getRootClass().getName() + "]");
}
return;
}
if (this.suppressNotWritablePropertyException) {
// Optimization for common ignoreUnknown=true scenario since the
// exception would be caught and swallowed higher up anyway...
return;
}
throw createNotWritablePropertyException(tokens.canonicalName);
}
Object oldValue = null;
try {
Object originalValue = pv.getValue();
Object valueToApply = originalValue;
if (!Boolean.FALSE.equals(pv.conversionNecessary)) {
if (pv.isConverted()) {
valueToApply = pv.getConvertedValue();
}
else {
if (isExtractOldValueForEditor() && ph.isReadable()) {
try {
oldValue = ph.getValue();
}
catch (Exception ex) {
if (ex instanceof PrivilegedActionException) {
ex = ((PrivilegedActionException) ex).getException();
}
if (logger.isDebugEnabled()) {
logger.debug("Could not read previous value of property '" +
this.nestedPath + tokens.canonicalName + "'", ex);
}
}
}
valueToApply = convertForProperty(
tokens.canonicalName, oldValue, originalValue, ph.toTypeDescriptor());
}
pv.getOriginalPropertyValue().conversionNecessary = (valueToApply != originalValue);
}
ph.setValue(valueToApply);
}
catch (TypeMismatchException ex) {
throw ex;
}
catch (InvocationTargetException ex) {
PropertyChangeEvent propertyChangeEvent = new PropertyChangeEvent(
getRootInstance(), this.nestedPath + tokens.canonicalName, oldValue, pv.getValue());
if (ex.getTargetException() instanceof ClassCastException) {
throw new TypeMismatchException(propertyChangeEvent, ph.getPropertyType(), ex.getTargetException());
}
else {
Throwable cause = ex.getTargetException();
if (cause instanceof UndeclaredThrowableException) {
// May happen e.g. with Groovy-generated methods
cause = cause.getCause();
}
throw new MethodInvocationException(propertyChangeEvent, cause);
}
}
catch (Exception ex) {
PropertyChangeEvent pce = new PropertyChangeEvent(
getRootInstance(), this.nestedPath + tokens.canonicalName, oldValue, pv.getValue());
throw new MethodInvocationException(pce, ex);
}
}
从PropertyValue中获取属性值类型转换后并设置。
