org.springframework.web.method.annotation.ModelMethodProcessor.java Source code

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Here is the source code for org.springframework.web.method.annotation.ModelMethodProcessor.java

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/*
 * Copyright 2002-2017 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.web.method.annotation;

import org.springframework.core.MethodParameter;
import org.springframework.lang.Nullable;
import org.springframework.ui.Model;
import org.springframework.util.Assert;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.HandlerMethodReturnValueHandler;
import org.springframework.web.method.support.ModelAndViewContainer;

/**
 * Resolves {@link Model} arguments and handles {@link Model} return values.
 *
 * <p>A {@link Model} return type has a set purpose. Therefore this handler
 * should be configured ahead of handlers that support any return value type
 * annotated with {@code @ModelAttribute} or {@code @ResponseBody} to ensure
 * they don't take over.
 *
 * @author Rossen Stoyanchev
 * @since 3.1
 */
public class ModelMethodProcessor implements HandlerMethodArgumentResolver, HandlerMethodReturnValueHandler {

    @Override
    public boolean supportsParameter(MethodParameter parameter) {
        return Model.class.isAssignableFrom(parameter.getParameterType());
    }

    @Override
    @Nullable
    public Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
            NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception {

        Assert.state(mavContainer != null, "ModelAndViewContainer is required for model exposure");
        return mavContainer.getModel();
    }

    @Override
    public boolean supportsReturnType(MethodParameter returnType) {
        return Model.class.isAssignableFrom(returnType.getParameterType());
    }

    @Override
    public void handleReturnValue(@Nullable Object returnValue, MethodParameter returnType,
            ModelAndViewContainer mavContainer, NativeWebRequest webRequest) throws Exception {

        if (returnValue == null) {
            return;
        } else if (returnValue instanceof Model) {
            mavContainer.addAllAttributes(((Model) returnValue).asMap());
        } else {
            // should not happen
            throw new UnsupportedOperationException("Unexpected return type: "
                    + returnType.getParameterType().getName() + " in method: " + returnType.getMethod());
        }
    }

}