net.eusashead.hateoas.response.impl.AbstractEntityResponseBuilder.java Source code

Introduction

Here is the source code for net.eusashead.hateoas.response.impl.AbstractEntityResponseBuilder.java

Source

package net.eusashead.hateoas.response.impl;

/*
 * #[license]
 * spring-responseentitybuilder
 * %%
 * Copyright (C) 2013 Eusa's Head
 * %%
 * 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.
 * %[license]
 */

import javax.servlet.http.HttpServletRequest;

import net.eusashead.hateoas.header.ETagHeaderStrategy;
import net.eusashead.hateoas.header.impl.HashingETagHeaderStrategy;

import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;

public abstract class AbstractEntityResponseBuilder<T, V> extends AbstractResponseBuilder<T> {

    protected V entity;

    public AbstractEntityResponseBuilder(HttpServletRequest request) {
        super(request);
    }

    protected void setEntity(V entity) {
        this.entity = entity;
        assertEntity();
    }

    protected void assertEntity() {
        if (entity == null) {
            throw new IllegalArgumentException("Entity T cannot be null.");
        }
    }

    protected void setEtagHeader() {
        assertEntity();
        this.headers.setETag(new HashingETagHeaderStrategy().extract(entity).toString());
    }

    protected void setEtagHeader(ETagHeaderStrategy etagStrategy) {
        assertEntity();
        this.headers.setETag(etagStrategy.extract(entity).toString());
    }

    protected ResponseEntity<V> buildResponseEntity(V body) {

        // ResponseEntity to return
        ResponseEntity<V> responseEntity;

        // Check ETag against request value
        if (headers.getETag() != null && compareEtagWithIfNoneMatch(headers.getETag())) {
            // Return 304 Not Modified
            responseEntity = new ResponseEntity<V>(headers, HttpStatus.NOT_MODIFIED);
        } else {
            // Is it a HEAD or a GET
            if (request.getMethod().equals("HEAD")) {
                // Return 204 and the headers
                responseEntity = new ResponseEntity<V>(headers, HttpStatus.NO_CONTENT);
            } else if (request.getMethod().equals("GET")) {
                // Return 200 and the entity
                responseEntity = new ResponseEntity<V>(body, headers, HttpStatus.OK);
            } else {
                throw new RuntimeException(String
                        .format("esponseBuilder does not handle verb %s, only GET or HEAD.", request.getMethod()));
            }
        }

        // Return the ResponseEntity
        return responseEntity;
    }

}