ExifParser.java

package culmat.photo;
import static java.util.Arrays.asList;
import static java.util.Arrays.stream;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
import java.util.function.Consumer;

public class ExifParser implements AutoCloseable {

	final String EOO = "{ready77}";
    final List<String> args = new LinkedList<>(asList("exiftool","-q","-stay_open","True","-@","-"));
    Process lazyProc;
    IO lazyIO;
    boolean closed;
    byte[] newLine = System.getProperty("line.separator").getBytes();
    byte[] blank = " ".getBytes();
    byte[] execute = (System.getProperty("line.separator")+"-execute77"+System.getProperty("line.separator")).getBytes();
    
	class IO implements AutoCloseable{
		final BufferedReader err, out;
		public IO(OutputStream in, InputStream out, InputStream err) {
			this.in = in;
			this.out = new BufferedReader(new InputStreamReader(out));
			this.err = new BufferedReader(new InputStreamReader(err));
		}
		final OutputStream in;
		
		@Override
		public void close() throws Exception {
			in.close();
			out.close();
			err.close();
		}
		
	}

    private IO IO() throws IOException {
    	if(lazyProc == null) {
    		lazyProc = new ProcessBuilder(args).start();
    		lazyIO = new IO(
    		lazyProc.getOutputStream(),
    		lazyProc.getInputStream(),
    		lazyProc.getErrorStream());
    	}
    	return lazyIO;
    }
    
    public ExifParser(String ... commonargs) {
    	if(commonargs.length > 0) {
    		// common args must be at the end of the arg list
    		args.add("-common_args");
    		args.addAll(asList(commonargs));
    	}
	}

    public Map<String, String> getTags(Path path, String ... tags) throws IOException {
    	final Map<String, String> ret = new TreeMap<>();
		getMeta(path, (s)-> {
			String[] pair = s.split("\\s*:\\s*",2);
			ret.put(pair[0], pair[1]);
		}, stream(tags).map(s -> "-"+s).toList().toArray(new String[0]));
    	return ret;
    }
    
    @SuppressWarnings("resource")
	public void getMeta(Path path, Consumer<String> consumer, String ... args) throws IOException {
    	if(closed) throw new IllegalStateException("parser already closed");
    	for (String a : args) {
    		IO().in.write(a.getBytes());
			IO().in.write(newLine);
		}
    	IO().in.write(path.toAbsolutePath().normalize().toString().getBytes());
    	IO().in.write(execute);
    	IO().in.flush();
    	String line;
    	while (!(line = IO().out.readLine()).equals(EOO) ) {
			consumer.accept(line);
		}
	}
    
    @SuppressWarnings("resource")
    @Override
    public void close() throws Exception {
    	if(lazyProc != null) {
    		IO().in.write("-stay_open\nFalse\n".getBytes());
    		IO().in.flush();
    		lazyIO.close();
    		lazyProc.destroy();
    	}
    	lazyProc = null;
    	lazyIO = null;
    	closed = true;
    }
    

	public static void main(String[] args) throws Exception {
    	Path image = Paths.get("/home/XYZ/Pictures/2015/07/2015-07-03_22-41-14_250.jpg");
      
    	try (ExifParser exifTool = new ExifParser("-s")) {
        	for (int i = 0; i < 2; i++) {
				exifTool.getMeta(
						image,
						System.out::println,
						"-ShutterCount","-SerialNumber");
				System.out.println(exifTool.getTags(
						image,
						"ShutterCount","SerialNumber"));
        	}
        	exifTool.getMeta(
        			image,
        			System.out::println);
        }
    }

}