Package org.springframework.web.bind.annotation.support

Source Code of org.springframework.web.bind.annotation.support.HandlerMethodInvoker

/*
* Copyright 2002-2010 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.bind.annotation.support;

import java.lang.annotation.Annotation;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.core.BridgeMethodResolver;
import org.springframework.core.Conventions;
import org.springframework.core.GenericTypeResolver;
import org.springframework.core.MethodParameter;
import org.springframework.core.ParameterNameDiscoverer;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpInputMessage;
import org.springframework.http.MediaType;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.ui.ExtendedModelMap;
import org.springframework.ui.Model;
import org.springframework.util.ClassUtils;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.util.ReflectionUtils;
import org.springframework.validation.BindException;
import org.springframework.validation.BindingResult;
import org.springframework.validation.Errors;
import org.springframework.web.HttpMediaTypeNotSupportedException;
import org.springframework.web.bind.WebDataBinder;
import org.springframework.web.bind.annotation.CookieValue;
import org.springframework.web.bind.annotation.InitBinder;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestHeader;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ValueConstants;
import org.springframework.web.bind.support.DefaultSessionAttributeStore;
import org.springframework.web.bind.support.SessionAttributeStore;
import org.springframework.web.bind.support.SessionStatus;
import org.springframework.web.bind.support.SimpleSessionStatus;
import org.springframework.web.bind.support.WebArgumentResolver;
import org.springframework.web.bind.support.WebBindingInitializer;
import org.springframework.web.bind.support.WebRequestDataBinder;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.context.request.WebRequest;
import org.springframework.web.multipart.MultipartRequest;

/**
* Support class for invoking an annotated handler method. Operates on the introspection results of a {@link
* HandlerMethodResolver} for a specific handler type.
*
* <p>Used by {@link org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter} and {@link
* org.springframework.web.portlet.mvc.annotation.AnnotationMethodHandlerAdapter}.
*
* @author Juergen Hoeller
* @author Arjen Poutsma
* @since 2.5.2
* @see #invokeHandlerMethod
*/
public class HandlerMethodInvoker {

  /** We'll create a lot of these objects, so we don't want a new logger every time. */
  private static final Log logger = LogFactory.getLog(HandlerMethodInvoker.class);

  private final HandlerMethodResolver methodResolver;

  private final WebBindingInitializer bindingInitializer;

  private final SessionAttributeStore sessionAttributeStore;

  private final ParameterNameDiscoverer parameterNameDiscoverer;

  private final WebArgumentResolver[] customArgumentResolvers;

  private final HttpMessageConverter[] messageConverters;

  private final SimpleSessionStatus sessionStatus = new SimpleSessionStatus();


  public HandlerMethodInvoker(HandlerMethodResolver methodResolver) {
    this(methodResolver, null);
  }

  public HandlerMethodInvoker(HandlerMethodResolver methodResolver, WebBindingInitializer bindingInitializer) {
    this(methodResolver, bindingInitializer, new DefaultSessionAttributeStore(), null, null, null);
  }

  public HandlerMethodInvoker(HandlerMethodResolver methodResolver, WebBindingInitializer bindingInitializer,
      SessionAttributeStore sessionAttributeStore, ParameterNameDiscoverer parameterNameDiscoverer,
      WebArgumentResolver[] customArgumentResolvers, HttpMessageConverter[] messageConverters) {

    this.methodResolver = methodResolver;
    this.bindingInitializer = bindingInitializer;
    this.sessionAttributeStore = sessionAttributeStore;
    this.parameterNameDiscoverer = parameterNameDiscoverer;
    this.customArgumentResolvers = customArgumentResolvers;
    this.messageConverters = messageConverters;
  }


  public final Object invokeHandlerMethod(Method handlerMethod, Object handler,
      NativeWebRequest webRequest, ExtendedModelMap implicitModel) throws Exception {

    Method handlerMethodToInvoke = BridgeMethodResolver.findBridgedMethod(handlerMethod);
    try {
      boolean debug = logger.isDebugEnabled();
      for (String attrName : this.methodResolver.getActualSessionAttributeNames()) {
        Object attrValue = this.sessionAttributeStore.retrieveAttribute(webRequest, attrName);
        if (attrValue != null) {
          implicitModel.addAttribute(attrName, attrValue);
        }
      }
      for (Method attributeMethod : this.methodResolver.getModelAttributeMethods()) {
        Method attributeMethodToInvoke = BridgeMethodResolver.findBridgedMethod(attributeMethod);
        Object[] args = resolveHandlerArguments(attributeMethodToInvoke, handler, webRequest, implicitModel);
        if (debug) {
          logger.debug("Invoking model attribute method: " + attributeMethodToInvoke);
        }
        String attrName = AnnotationUtils.findAnnotation(attributeMethodToInvoke, ModelAttribute.class).value();
        if (!"".equals(attrName) && implicitModel.containsAttribute(attrName)) {
          continue;
        }
        Object attrValue = doInvokeMethod(attributeMethodToInvoke, handler, args);
        if ("".equals(attrName)) {
          Class resolvedType =
              GenericTypeResolver.resolveReturnType(attributeMethodToInvoke, handler.getClass());
          attrName =
              Conventions.getVariableNameForReturnType(attributeMethodToInvoke, resolvedType, attrValue);
        }
        if (!implicitModel.containsAttribute(attrName)) {
          implicitModel.addAttribute(attrName, attrValue);
        }
      }
      Object[] args = resolveHandlerArguments(handlerMethodToInvoke, handler, webRequest, implicitModel);
      if (debug) {
        logger.debug("Invoking request handler method: " + handlerMethodToInvoke);
      }
      return doInvokeMethod(handlerMethodToInvoke, handler, args);
    }
    catch (IllegalStateException ex) {
      // Throw exception with full handler method context...
      throw new HandlerMethodInvocationException(handlerMethodToInvoke, ex);
    }
  }

  @SuppressWarnings("unchecked")
  private Object[] resolveHandlerArguments(Method handlerMethod, Object handler,
      NativeWebRequest webRequest, ExtendedModelMap implicitModel) throws Exception {

    Class[] paramTypes = handlerMethod.getParameterTypes();
    Object[] args = new Object[paramTypes.length];

    for (int i = 0; i < args.length; i++) {
      MethodParameter methodParam = new MethodParameter(handlerMethod, i);
      methodParam.initParameterNameDiscovery(this.parameterNameDiscoverer);
      GenericTypeResolver.resolveParameterType(methodParam, handler.getClass());
      String paramName = null;
      String headerName = null;
      boolean requestBodyFound = false;
      String cookieName = null;
      String pathVarName = null;
      String attrName = null;
      boolean required = false;
      String defaultValue = null;
      boolean validate = false;
      int found = 0;
      Annotation[] paramAnns = methodParam.getParameterAnnotations();

      for (Annotation paramAnn : paramAnns) {
        if (RequestParam.class.isInstance(paramAnn)) {
          RequestParam requestParam = (RequestParam) paramAnn;
          paramName = requestParam.value();
          required = requestParam.required();
          defaultValue = parseDefaultValueAttribute(requestParam.defaultValue());
          found++;
        }
        else if (RequestHeader.class.isInstance(paramAnn)) {
          RequestHeader requestHeader = (RequestHeader) paramAnn;
          headerName = requestHeader.value();
          required = requestHeader.required();
          defaultValue = parseDefaultValueAttribute(requestHeader.defaultValue());
          found++;
        }
        else if (RequestBody.class.isInstance(paramAnn)) {
          requestBodyFound = true;
          found++;
        }
        else if (CookieValue.class.isInstance(paramAnn)) {
          CookieValue cookieValue = (CookieValue) paramAnn;
          cookieName = cookieValue.value();
          required = cookieValue.required();
          defaultValue = parseDefaultValueAttribute(cookieValue.defaultValue());
          found++;
        }
        else if (PathVariable.class.isInstance(paramAnn)) {
          PathVariable pathVar = (PathVariable) paramAnn;
          pathVarName = pathVar.value();
          found++;
        }
        else if (ModelAttribute.class.isInstance(paramAnn)) {
          ModelAttribute attr = (ModelAttribute) paramAnn;
          attrName = attr.value();
          found++;
        }
        else if (Value.class.isInstance(paramAnn)) {
          defaultValue = ((Value) paramAnn).value();
        }
        else if ("Valid".equals(paramAnn.annotationType().getSimpleName())) {
          validate = true;
        }
      }

      if (found > 1) {
        throw new IllegalStateException("Handler parameter annotations are exclusive choices - " +
            "do not specify more than one such annotation on the same parameter: " + handlerMethod);
      }

      if (found == 0) {
        Object argValue = resolveCommonArgument(methodParam, webRequest);
        if (argValue != WebArgumentResolver.UNRESOLVED) {
          args[i] = argValue;
        }
        else if (defaultValue != null) {
          args[i] = resolveDefaultValue(defaultValue);
        }
        else {
          Class paramType = methodParam.getParameterType();
          if (Model.class.isAssignableFrom(paramType) || Map.class.isAssignableFrom(paramType)) {
            args[i] = implicitModel;
          }
          else if (SessionStatus.class.isAssignableFrom(paramType)) {
            args[i] = this.sessionStatus;
          }
          else if (Errors.class.isAssignableFrom(paramType)) {
            throw new IllegalStateException("Errors/BindingResult argument declared " +
                "without preceding model attribute. Check your handler method signature!");
          }
          else if (BeanUtils.isSimpleProperty(paramType)) {
            paramName = "";
          }
          else {
            attrName = "";
          }
        }
      }

      if (paramName != null) {
        args[i] = resolveRequestParam(paramName, required, defaultValue, methodParam, webRequest, handler);
      }
      else if (headerName != null) {
        args[i] = resolveRequestHeader(headerName, required, defaultValue, methodParam, webRequest, handler);
      }
      else if (requestBodyFound) {
        args[i] = resolveRequestBody(methodParam, webRequest, handler);
      }
      else if (cookieName != null) {
        args[i] = resolveCookieValue(cookieName, required, defaultValue, methodParam, webRequest, handler);
      }
      else if (pathVarName != null) {
        args[i] = resolvePathVariable(pathVarName, methodParam, webRequest, handler);
      }
      else if (attrName != null) {
        WebDataBinder binder =
            resolveModelAttribute(attrName, methodParam, implicitModel, webRequest, handler);
        boolean assignBindingResult = (args.length > i + 1 && Errors.class.isAssignableFrom(paramTypes[i + 1]));
        if (binder.getTarget() != null) {
          doBind(binder, webRequest, validate, !assignBindingResult);
        }
        args[i] = binder.getTarget();
        if (assignBindingResult) {
          args[i + 1] = binder.getBindingResult();
          i++;
        }
        implicitModel.putAll(binder.getBindingResult().getModel());
      }
    }

    return args;
  }

  protected void initBinder(Object handler, String attrName, WebDataBinder binder, NativeWebRequest webRequest)
      throws Exception {

    if (this.bindingInitializer != null) {
      this.bindingInitializer.initBinder(binder, webRequest);
    }
    if (handler != null) {
      Set<Method> initBinderMethods = this.methodResolver.getInitBinderMethods();
      if (!initBinderMethods.isEmpty()) {
        boolean debug = logger.isDebugEnabled();
        for (Method initBinderMethod : initBinderMethods) {
          Method methodToInvoke = BridgeMethodResolver.findBridgedMethod(initBinderMethod);
          String[] targetNames = AnnotationUtils.findAnnotation(methodToInvoke, InitBinder.class).value();
          if (targetNames.length == 0 || Arrays.asList(targetNames).contains(attrName)) {
            Object[] initBinderArgs =
                resolveInitBinderArguments(handler, methodToInvoke, binder, webRequest);
            if (debug) {
              logger.debug("Invoking init-binder method: " + methodToInvoke);
            }
            Object returnValue = doInvokeMethod(methodToInvoke, handler, initBinderArgs);
            if (returnValue != null) {
              throw new IllegalStateException(
                  "InitBinder methods must not have a return value: " + methodToInvoke);
            }
          }
        }
      }
    }
  }

  private Object[] resolveInitBinderArguments(Object handler, Method initBinderMethod,
      WebDataBinder binder, NativeWebRequest webRequest) throws Exception {

    Class[] initBinderParams = initBinderMethod.getParameterTypes();
    Object[] initBinderArgs = new Object[initBinderParams.length];

    for (int i = 0; i < initBinderArgs.length; i++) {
      MethodParameter methodParam = new MethodParameter(initBinderMethod, i);
      methodParam.initParameterNameDiscovery(this.parameterNameDiscoverer);
      GenericTypeResolver.resolveParameterType(methodParam, handler.getClass());
      String paramName = null;
      boolean paramRequired = false;
      String paramDefaultValue = null;
      String pathVarName = null;
      Annotation[] paramAnns = methodParam.getParameterAnnotations();

      for (Annotation paramAnn : paramAnns) {
        if (RequestParam.class.isInstance(paramAnn)) {
          RequestParam requestParam = (RequestParam) paramAnn;
          paramName = requestParam.value();
          paramRequired = requestParam.required();
          paramDefaultValue = requestParam.defaultValue();
          break;
        }
        else if (ModelAttribute.class.isInstance(paramAnn)) {
          throw new IllegalStateException(
              "@ModelAttribute is not supported on @InitBinder methods: " + initBinderMethod);
        }
        else if (PathVariable.class.isInstance(paramAnn)) {
          PathVariable pathVar = (PathVariable) paramAnn;
          pathVarName = pathVar.value();
        }
      }

      if (paramName == null && pathVarName == null) {
        Object argValue = resolveCommonArgument(methodParam, webRequest);
        if (argValue != WebArgumentResolver.UNRESOLVED) {
          initBinderArgs[i] = argValue;
        }
        else {
          Class paramType = initBinderParams[i];
          if (paramType.isInstance(binder)) {
            initBinderArgs[i] = binder;
          }
          else if (BeanUtils.isSimpleProperty(paramType)) {
            paramName = "";
          }
          else {
            throw new IllegalStateException(
                "Unsupported argument [" + paramType.getName() + "] for @InitBinder method: " +
                    initBinderMethod);
          }
        }
      }

      if (paramName != null) {
        initBinderArgs[i] =
            resolveRequestParam(paramName, paramRequired, paramDefaultValue, methodParam, webRequest, null);
      }
      else if (pathVarName != null) {
        initBinderArgs[i] = resolvePathVariable(pathVarName, methodParam, webRequest, null);
      }
    }

    return initBinderArgs;
  }

  @SuppressWarnings("unchecked")
  private Object resolveRequestParam(String paramName, boolean required, String defaultValue,
      MethodParameter methodParam, NativeWebRequest webRequest, Object handlerForInitBinderCall)
      throws Exception {

    Class<?> paramType = methodParam.getParameterType();
    if (Map.class.isAssignableFrom(paramType)) {
      return resolveRequestParamMap((Class<? extends Map>) paramType, webRequest);
    }
    if (paramName.length() == 0) {
      paramName = getRequiredParameterName(methodParam);
    }
    Object paramValue = null;
    if (webRequest.getNativeRequest() instanceof MultipartRequest) {
      paramValue = ((MultipartRequest) webRequest.getNativeRequest()).getFile(paramName);
    }
    if (paramValue == null) {
      String[] paramValues = webRequest.getParameterValues(paramName);
      if (paramValues != null && !paramType.isArray()) {
        paramValue = (paramValues.length == 1 ? paramValues[0] : paramValues);
      }
      else {
        paramValue = paramValues;
      }
    }
    if (paramValue == null) {
      if (defaultValue != null) {
        paramValue = resolveDefaultValue(defaultValue);
      }
      else if (required) {
        raiseMissingParameterException(paramName, paramType);
      }
      paramValue = checkValue(paramName, paramValue, paramType);
    }
    WebDataBinder binder = createBinder(webRequest, null, paramName);
    initBinder(handlerForInitBinderCall, paramName, binder, webRequest);
    return binder.convertIfNecessary(paramValue, paramType, methodParam);
  }

  private Map resolveRequestParamMap(Class<? extends Map> mapType, NativeWebRequest webRequest) {
    Map<String, String[]> parameterMap = webRequest.getParameterMap();
    if (MultiValueMap.class.isAssignableFrom(mapType)) {
      MultiValueMap<String, String> result = new LinkedMultiValueMap<String, String>(parameterMap.size());
      for (Map.Entry<String, String[]> entry : parameterMap.entrySet()) {
        for (String value : entry.getValue()) {
          result.add(entry.getKey(), value);
        }
      }
      return result;
    }
    else {
      Map<String, String> result = new LinkedHashMap<String, String>(parameterMap.size());
      for (Map.Entry<String, String[]> entry : parameterMap.entrySet()) {
        if (entry.getValue().length > 0) {
          result.put(entry.getKey(), entry.getValue()[0]);
        }
      }
      return result;
    }
  }

  @SuppressWarnings("unchecked")
  private Object resolveRequestHeader(String headerName, boolean required, String defaultValue,
      MethodParameter methodParam, NativeWebRequest webRequest, Object handlerForInitBinderCall)
      throws Exception {

    Class<?> paramType = methodParam.getParameterType();
    if (Map.class.isAssignableFrom(paramType)) {
      return resolveRequestHeaderMap((Class<? extends Map>) paramType, webRequest);
    }
    if (headerName.length() == 0) {
      headerName = getRequiredParameterName(methodParam);
    }
    Object headerValue = null;
    String[] headerValues = webRequest.getHeaderValues(headerName);
    if (headerValues != null) {
      headerValue = (headerValues.length == 1 ? headerValues[0] : headerValues);
    }
    if (headerValue == null) {
      if (defaultValue != null) {
        headerValue = resolveDefaultValue(defaultValue);
      }
      else if (required) {
        raiseMissingHeaderException(headerName, paramType);
      }
      headerValue = checkValue(headerName, headerValue, paramType);
    }
    WebDataBinder binder = createBinder(webRequest, null, headerName);
    initBinder(handlerForInitBinderCall, headerName, binder, webRequest);
    return binder.convertIfNecessary(headerValue, paramType, methodParam);
  }

  private Map resolveRequestHeaderMap(Class<? extends Map> mapType, NativeWebRequest webRequest) {
    if (MultiValueMap.class.isAssignableFrom(mapType)) {
      MultiValueMap<String, String> result;
      if (HttpHeaders.class.isAssignableFrom(mapType)) {
        result = new HttpHeaders();
      }
      else {
        result = new LinkedMultiValueMap<String, String>();
      }
      for (Iterator<String> iterator = webRequest.getHeaderNames(); iterator.hasNext();) {
        String headerName = iterator.next();
        for (String headerValue : webRequest.getHeaderValues(headerName)) {
          result.add(headerName, headerValue);
        }
      }
      return result;
    }
    else {
      Map<String, String> result = new LinkedHashMap<String, String>();
      for (Iterator<String> iterator = webRequest.getHeaderNames(); iterator.hasNext();) {
        String headerName = iterator.next();
        String headerValue = webRequest.getHeader(headerName);
        result.put(headerName, headerValue);
      }
      return result;
    }
  }

  /**
   * Resolves the given {@link RequestBody @RequestBody} annotation.
   */
  @SuppressWarnings("unchecked")
  protected Object resolveRequestBody(MethodParameter methodParam, NativeWebRequest webRequest, Object handler)
      throws Exception {

    HttpInputMessage inputMessage = createHttpInputMessage(webRequest);
    Class paramType = methodParam.getParameterType();
    MediaType contentType = inputMessage.getHeaders().getContentType();
    if (contentType == null) {
      StringBuilder builder = new StringBuilder(ClassUtils.getShortName(methodParam.getParameterType()));
      String paramName = methodParam.getParameterName();
      if (paramName != null) {
        builder.append(' ');
        builder.append(paramName);
      }
      throw new HttpMediaTypeNotSupportedException(
          "Cannot extract @RequestBody parameter (" + builder.toString() + "): no Content-Type found");
    }
    List<MediaType> allSupportedMediaTypes = new ArrayList<MediaType>();
    if (this.messageConverters != null) {
      for (HttpMessageConverter<?> messageConverter : this.messageConverters) {
        allSupportedMediaTypes.addAll(messageConverter.getSupportedMediaTypes());
        if (messageConverter.canRead(paramType, contentType)) {
          return messageConverter.read(paramType, inputMessage);
        }
      }
    }
    throw new HttpMediaTypeNotSupportedException(contentType, allSupportedMediaTypes);
  }

  private Object resolveCookieValue(String cookieName, boolean required, String defaultValue,
      MethodParameter methodParam, NativeWebRequest webRequest, Object handlerForInitBinderCall)
      throws Exception {

    Class<?> paramType = methodParam.getParameterType();
    if (cookieName.length() == 0) {
      cookieName = getRequiredParameterName(methodParam);
    }
    Object cookieValue = resolveCookieValue(cookieName, paramType, webRequest);
    if (cookieValue == null) {
      if (defaultValue != null) {
        cookieValue = resolveDefaultValue(defaultValue);
      }
      else if (required) {
        raiseMissingCookieException(cookieName, paramType);
      }
      cookieValue = checkValue(cookieName, cookieValue, paramType);
    }
    WebDataBinder binder = createBinder(webRequest, null, cookieName);
    initBinder(handlerForInitBinderCall, cookieName, binder, webRequest);
    return binder.convertIfNecessary(cookieValue, paramType, methodParam);
  }

  /**
   * Resolves the given {@link CookieValue @CookieValue} annotation.
   * <p>Throws an UnsupportedOperationException by default.
   */
  protected Object resolveCookieValue(String cookieName, Class paramType, NativeWebRequest webRequest)
      throws Exception {

    throw new UnsupportedOperationException("@CookieValue not supported");
  }

  private Object resolvePathVariable(String pathVarName, MethodParameter methodParam,
      NativeWebRequest webRequest, Object handlerForInitBinderCall) throws Exception {

    Class<?> paramType = methodParam.getParameterType();
    if (pathVarName.length() == 0) {
      pathVarName = getRequiredParameterName(methodParam);
    }
    String pathVarValue = resolvePathVariable(pathVarName, paramType, webRequest);
    WebDataBinder binder = createBinder(webRequest, null, pathVarName);
    initBinder(handlerForInitBinderCall, pathVarName, binder, webRequest);
    return binder.convertIfNecessary(pathVarValue, paramType, methodParam);
  }

  /**
   * Resolves the given {@link PathVariable @PathVariable} annotation.
   * <p>Throws an UnsupportedOperationException by default.
   */
  protected String resolvePathVariable(String pathVarName, Class paramType, NativeWebRequest webRequest)
      throws Exception {

    throw new UnsupportedOperationException("@PathVariable not supported");
  }

  private String getRequiredParameterName(MethodParameter methodParam) {
    String name = methodParam.getParameterName();
    if (name == null) {
      throw new IllegalStateException(
          "No parameter name specified for argument of type [" + methodParam.getParameterType().getName() +
              "], and no parameter name information found in class file either.");
    }
    return name;
  }

  private Object checkValue(String name, Object value, Class paramType) {
    if (value == null) {
      if (boolean.class.equals(paramType)) {
        return Boolean.FALSE;
      }
      else if (paramType.isPrimitive()) {
        throw new IllegalStateException("Optional " + paramType + " parameter '" + name +
            "' is not 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;
  }

  private WebDataBinder resolveModelAttribute(String attrName, MethodParameter methodParam,
      ExtendedModelMap implicitModel, NativeWebRequest webRequest, Object handler) throws Exception {

    // Bind request parameter onto object...
    String name = attrName;
    if ("".equals(name)) {
      name = Conventions.getVariableNameForParameter(methodParam);
    }
    Class<?> paramType = methodParam.getParameterType();
    Object bindObject;
    if (implicitModel.containsKey(name)) {
      bindObject = implicitModel.get(name);
    }
    else if (this.methodResolver.isSessionAttribute(name, paramType)) {
      bindObject = this.sessionAttributeStore.retrieveAttribute(webRequest, name);
      if (bindObject == null) {
        raiseSessionRequiredException("Session attribute '" + name + "' required - not found in session");
      }
    }
    else {
      bindObject = BeanUtils.instantiateClass(paramType);
    }
    WebDataBinder binder = createBinder(webRequest, bindObject, name);
    initBinder(handler, name, binder, webRequest);
    return binder;
  }

  @SuppressWarnings("unchecked")
  public final void updateModelAttributes(Object handler, Map<String, Object> mavModel,
      ExtendedModelMap implicitModel, NativeWebRequest webRequest) throws Exception {

    if (this.methodResolver.hasSessionAttributes() && this.sessionStatus.isComplete()) {
      for (String attrName : this.methodResolver.getActualSessionAttributeNames()) {
        this.sessionAttributeStore.cleanupAttribute(webRequest, attrName);
      }
    }

    // Expose model attributes as session attributes, if required.
    // Expose BindingResults for all attributes, making custom editors available.
    Map<String, Object> model = (mavModel != null ? mavModel : implicitModel);
    for (String attrName : new HashSet<String>(model.keySet())) {
      Object attrValue = model.get(attrName);
      boolean isSessionAttr =
          this.methodResolver.isSessionAttribute(attrName, (attrValue != null ? attrValue.getClass() : null));
      if (isSessionAttr && !this.sessionStatus.isComplete()) {
        this.sessionAttributeStore.storeAttribute(webRequest, attrName, attrValue);
      }
      if (!attrName.startsWith(BindingResult.MODEL_KEY_PREFIX) &&
          (isSessionAttr || isBindingCandidate(attrValue))) {
        String bindingResultKey = BindingResult.MODEL_KEY_PREFIX + attrName;
        if (mavModel != null && !model.containsKey(bindingResultKey)) {
          WebDataBinder binder = createBinder(webRequest, attrValue, attrName);
          initBinder(handler, attrName, binder, webRequest);
          mavModel.put(bindingResultKey, binder.getBindingResult());
        }
      }
    }
  }

  /**
   * Determine whether the given value qualifies as a "binding candidate", i.e. might potentially be subject to
   * bean-style data binding later on.
   */
  protected boolean isBindingCandidate(Object value) {
    return (value != null && !value.getClass().isArray() && !(value instanceof Collection) &&
        !(value instanceof Map) && !BeanUtils.isSimpleValueType(value.getClass()));
  }

  private Object doInvokeMethod(Method method, Object target, Object[] args) throws Exception {
    ReflectionUtils.makeAccessible(method);
    try {
      return method.invoke(target, args);
    }
    catch (InvocationTargetException ex) {
      ReflectionUtils.rethrowException(ex.getTargetException());
    }
    throw new IllegalStateException("Should never get here");
  }

  protected void raiseMissingParameterException(String paramName, Class paramType) throws Exception {
    throw new IllegalStateException("Missing parameter '" + paramName + "' of type [" + paramType.getName() + "]");
  }

  protected void raiseMissingHeaderException(String headerName, Class paramType) throws Exception {
    throw new IllegalStateException("Missing header '" + headerName + "' of type [" + paramType.getName() + "]");
  }

  protected void raiseMissingCookieException(String cookieName, Class paramType) throws Exception {
    throw new IllegalStateException(
        "Missing cookie value '" + cookieName + "' of type [" + paramType.getName() + "]");
  }

  protected void raiseSessionRequiredException(String message) throws Exception {
    throw new IllegalStateException(message);
  }

  protected WebDataBinder createBinder(NativeWebRequest webRequest, Object target, String objectName)
      throws Exception {

    return new WebRequestDataBinder(target, objectName);
  }

  private void doBind(WebDataBinder binder, NativeWebRequest webRequest, boolean validate, boolean failOnErrors)
      throws Exception {

    doBind(binder, webRequest);
    if (validate) {
      binder.validate();
    }
    if (failOnErrors && binder.getBindingResult().hasErrors()) {
      throw new BindException(binder.getBindingResult());
    }
  }

  protected void doBind(WebDataBinder binder, NativeWebRequest webRequest) throws Exception {
    ((WebRequestDataBinder) binder).bind(webRequest);
  }

  /**
   * Return a {@link HttpInputMessage} for the given {@link NativeWebRequest}.
   * <p>Throws an UnsupportedOperationException by default.
   */
  protected HttpInputMessage createHttpInputMessage(NativeWebRequest webRequest) throws Exception {
    throw new UnsupportedOperationException("@RequestBody not supported");
  }

  protected String parseDefaultValueAttribute(String value) {
    return (ValueConstants.DEFAULT_NONE.equals(value) ? null : value);
  }

  protected Object resolveDefaultValue(String value) {
    return value;
  }

  protected Object resolveCommonArgument(MethodParameter methodParameter, NativeWebRequest webRequest)
      throws Exception {

    // Invoke custom argument resolvers if present...
    if (this.customArgumentResolvers != null) {
      for (WebArgumentResolver argumentResolver : this.customArgumentResolvers) {
        Object value = argumentResolver.resolveArgument(methodParameter, webRequest);
        if (value != WebArgumentResolver.UNRESOLVED) {
          return value;
        }
      }
    }

    // Resolution of standard parameter types...
    Class paramType = methodParameter.getParameterType();
    Object value = resolveStandardArgument(paramType, webRequest);
    if (value != WebArgumentResolver.UNRESOLVED && !ClassUtils.isAssignableValue(paramType, value)) {
      throw new IllegalStateException(
          "Standard argument type [" + paramType.getName() + "] resolved to incompatible value of type [" +
              (value != null ? value.getClass() : null) +
              "]. Consider declaring the argument type in a less specific fashion.");
    }
    return value;
  }

  protected Object resolveStandardArgument(Class parameterType, NativeWebRequest webRequest) throws Exception {
    if (WebRequest.class.isAssignableFrom(parameterType)) {
      return webRequest;
    }
    return WebArgumentResolver.UNRESOLVED;
  }

  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);
  }

}
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