org.springframework.data.mongodb.gridfs.GridFsResource.java Source code

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Here is the source code for org.springframework.data.mongodb.gridfs.GridFsResource.java

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/*
 * Copyright 2011-2019 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.data.mongodb.gridfs;

import java.io.ByteArrayInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.Optional;

import org.springframework.core.io.InputStreamResource;
import org.springframework.core.io.Resource;
import org.springframework.data.util.Optionals;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;

import com.mongodb.MongoGridFSException;
import com.mongodb.client.gridfs.model.GridFSFile;

/**
 * {@link GridFSFile} based {@link Resource} implementation.
 *
 * @author Oliver Gierke
 * @author Christoph Strobl
 * @author Hartmut Lang
 * @author Mark Paluch
 */
public class GridFsResource extends InputStreamResource {

    static final String CONTENT_TYPE_FIELD = "_contentType";
    private static final ByteArrayInputStream EMPTY_INPUT_STREAM = new ByteArrayInputStream(new byte[0]);

    private final @Nullable GridFSFile file;
    private final String filename;

    /**
     * Creates a new, absent {@link GridFsResource}.
     *
     * @param filename filename of the absent resource.
     * @since 2.1
     */
    private GridFsResource(String filename) {

        super(EMPTY_INPUT_STREAM, String.format("GridFs resource [%s]", filename));

        this.file = null;
        this.filename = filename;
    }

    /**
     * Creates a new {@link GridFsResource} from the given {@link GridFSFile}.
     *
     * @param file must not be {@literal null}.
     */
    public GridFsResource(GridFSFile file) {
        this(file, new ByteArrayInputStream(new byte[] {}));
    }

    /**
     * Creates a new {@link GridFsResource} from the given {@link GridFSFile} and {@link InputStream}.
     *
     * @param file must not be {@literal null}.
     * @param inputStream must not be {@literal null}.
     */
    public GridFsResource(GridFSFile file, InputStream inputStream) {

        super(inputStream, String.format("GridFs resource [%s]", file.getFilename()));

        this.file = file;
        this.filename = file.getFilename();
    }

    /**
     * Obtain an absent {@link GridFsResource}.
     *
     * @param filename filename of the absent resource, must not be {@literal null}.
     * @return never {@literal null}.
     * @since 2.1
     */
    public static GridFsResource absent(String filename) {

        Assert.notNull(filename, "Filename must not be null");

        return new GridFsResource(filename);
    }

    /*
     * (non-Javadoc)
     * @see org.springframework.core.io.InputStreamResource#getInputStream()
     */
    @Override
    public InputStream getInputStream() throws IOException, IllegalStateException {

        verifyExists();
        return super.getInputStream();
    }

    /*
     * (non-Javadoc)
     * @see org.springframework.core.io.AbstractResource#contentLength()
     */
    @Override
    public long contentLength() throws IOException {

        verifyExists();
        return getGridFSFile().getLength();
    }

    /*
     * (non-Javadoc)
     * @see org.springframework.core.io.AbstractResource#getFilename()
     */
    @Override
    public String getFilename() throws IllegalStateException {
        return this.filename;
    }

    /*
     * (non-Javadoc)
     * @see org.springframework.core.io.AbstractResource#exists()
     */
    @Override
    public boolean exists() {
        return this.file != null;
    }

    /*
     * (non-Javadoc)
     * @see org.springframework.core.io.AbstractResource#lastModified()
     */
    @Override
    public long lastModified() throws IOException {

        verifyExists();
        return getGridFSFile().getUploadDate().getTime();
    }

    /*
     * (non-Javadoc)
     * @see org.springframework.core.io.AbstractResource#getDescription()
     */
    @Override
    public String getDescription() {
        return String.format("GridFs resource [%s]", this.getFilename());
    }

    /**
     * Returns the {@link Resource}'s id.
     *
     * @return never {@literal null}.
     * @throws IllegalStateException if the file does not {@link #exists()}.
     */
    public Object getId() {

        Assert.state(exists(), () -> String.format("%s does not exist.", getDescription()));

        return getGridFSFile().getId();
    }

    /**
     * @return the underlying {@link GridFSFile}. Can be {@literal null} if absent.
     * @since 2.2
     */
    @Nullable
    public GridFSFile getGridFSFile() {
        return this.file;
    }

    /**
     * Returns the {@link Resource}'s content type.
     *
     * @return never {@literal null}.
     * @throws com.mongodb.MongoGridFSException in case no content type declared on {@link GridFSFile#getMetadata()} nor
     *           provided via {@link GridFSFile#getContentType()}.
     * @throws IllegalStateException if the file does not {@link #exists()}.
     */
    @SuppressWarnings("deprecation")
    public String getContentType() {

        Assert.state(exists(), () -> String.format("%s does not exist.", getDescription()));

        return Optionals
                .firstNonEmpty(
                        () -> Optional.ofNullable(getGridFSFile().getMetadata())
                                .map(it -> it.get(CONTENT_TYPE_FIELD, String.class)),
                        () -> Optional.ofNullable(getGridFSFile().getContentType()))
                .orElseThrow(() -> new MongoGridFSException("No contentType data for this GridFS file"));
    }

    private void verifyExists() throws FileNotFoundException {

        if (!exists()) {
            throw new FileNotFoundException(String.format("%s does not exist.", getDescription()));
        }
    }
}