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Google App Engine compliant variation of FreeMarker. FreeMarker is a "template engine"; a generic tool to generate text output based on templates.
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/*
 * Copyright 2014 Attila Szegedi, Daniel Dekany, Jonathan Revusky
 * 
 * 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 freemarker.cache;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.net.JarURLConnection;
import java.net.URL;
import java.net.URLConnection;

/**
 * Wraps a java.net.URL, and implements methods required for a typical template source.
 */
class URLTemplateSource {
    private final URL url;
    private URLConnection conn;
    private InputStream inputStream;
    private Boolean useCaches;

    /**
     * @param useCaches {@code null} if this aspect wasn't set in the parent {@link TemplateLoader}.
     */
    URLTemplateSource(URL url, Boolean useCaches) throws IOException {
        this.url = url;
        this.conn = url.openConnection();
        this.useCaches = useCaches;
        if (useCaches != null) {
            conn.setUseCaches(useCaches.booleanValue());
        }
    }

    public boolean equals(Object o) {
        if (o instanceof URLTemplateSource) {
            return url.equals(((URLTemplateSource) o).url);
        } else {
            return false;
        }
    }

    public int hashCode() {
        return url.hashCode();
    }

    public String toString() {
        return url.toString();
    }
    
    long lastModified() {
        if (conn instanceof JarURLConnection) {
          // There is a bug in sun's jar url connection that causes file handle leaks when calling getLastModified()
          // Since the time stamps of jar file contents can't vary independent from the jar file timestamp, just use
          // the jar file timestamp
          URL jarURL=((JarURLConnection)conn).getJarFileURL();
          if (jarURL.getProtocol().equals("file")) {
            // Return the last modified time of the underlying file - saves some opening and closing
            return new File(jarURL.getFile()).lastModified();
          } else {
            // Use the URL mechanism
            URLConnection jarConn=null;
            try {
              jarConn=jarURL.openConnection();
              return jarConn.getLastModified();
            } catch (IOException e) {
              return -1;
            } finally {
              try {
                if (jarConn!=null) jarConn.getInputStream().close();
              } catch (IOException e) { }
            }
          }
        } else {
          long lastModified = conn.getLastModified();
          if (lastModified == -1L && url.getProtocol().equals("file")) {
              // Hack for obtaining accurate last modified time for
              // URLs that point to the local file system. This is fixed
              // in JDK 1.4, but prior JDKs returns -1 for file:// URLs.
              return new File(url.getFile()).lastModified();
          } else {
              return lastModified;
          }
        }
    }

    InputStream getInputStream() throws IOException {
        if (inputStream != null) {
            // Ensure that the returned InputStream reads from the beginning of the resource when getInputStream()
            // is called for the second time:
            try {
                inputStream.close();
            } catch (IOException e) {
                // Ignore; this is maybe because it was closed for the 2nd time now
            }
            this.conn = url.openConnection();
        }
        inputStream = conn.getInputStream();
        return inputStream;
    }

    void close() throws IOException {
        try {
          if (inputStream != null) {
              inputStream.close();
          } else {
              conn.getInputStream().close();
          }
        } finally {
          inputStream = null;
          conn = null;
        }
    }

    Boolean getUseCaches() {
        return useCaches;
    }

    void setUseCaches(boolean useCaches) {
        if (this.conn != null) {
            conn.setUseCaches(useCaches);
            this.useCaches = Boolean.valueOf(useCaches);
        }
    }
    
}