VersionInfo.java

package org.mapfish.print;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.jar.Attributes;
import java.util.jar.Manifest;
import javax.annotation.Nullable;
import javax.annotation.PostConstruct;
import javax.servlet.ServletContext;

/**
 * Allows to access version information (from the manifest).
 *
 * Works only in a servlet context.
 */
public class VersionInfo {
    private static final Logger LOGGER = LoggerFactory.getLogger(VersionInfo.class);

    private static final String MAPFISH_PRINT_VERSION = "Mapfish-Print-Version";
    private static final String GIT_VERSION = "Git-Revision";

    @Nullable
    private Attributes attrs;

    @Autowired
    private ServletContext servletContext;

    /**
     * Output the version on the logs.
     */
    @PostConstruct
    public final void init() {
        this.attrs = getAttributes();
        LOGGER.warn("Starting print version {} ({})", getVersion(), getGitHash());
    }

    /**
     * @return The version
     */
    public final String getVersion() {
        return getValue(MAPFISH_PRINT_VERSION);
    }

    /**
     * @return The GIT hash
     */
    public final String getGitHash() {
        return getValue(GIT_VERSION);
    }

    private String getValue(final String name) {
        if (this.attrs != null) {
            final String value = this.attrs.getValue(name);
            return value != null ? value : "?";
        } else {
            return "?";
        }
    }

    private Attributes getAttributes() {
        if (this.servletContext == null) {
            return null;
        }
        try {
            final String path = this.servletContext.getRealPath("/META-INF/MANIFEST.MF");
            if (path != null) {
                final InputStream stream = new FileInputStream(path);
                try {
                    return new Manifest(stream).getMainAttributes();
                } finally {
                    stream.close();
                }
            }
        } catch (FileNotFoundException e) {
            LOGGER.warn("Cannot find servlet manifest");
        } catch (IOException e) {
            LOGGER.warn("Cannot read servlet manifest", e);
        }
        return null;
    }
}