source: josm/trunk/src/org/openstreetmap/josm/io/MirroredInputStream.java@ 1472

// License: GPL. Copyright 2007 by Immanuel Scholz and others
package org.openstreetmap.josm.io;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.IOException;
import java.net.URL;
import java.net.URLConnection;

import org.openstreetmap.josm.Main;

/**
 * Mirrors a file to a local file.
 * <p>
 * The file mirrored is only downloaded if it has been more than one day since last download
 */
public class MirroredInputStream extends InputStream {
    InputStream fs = null;

    public MirroredInputStream(String name) throws IOException
    {
        this(name, null, -1L);
    }

    public MirroredInputStream(String name, long maxTime) throws IOException
    {
        this(name, null, maxTime);
    }

    public MirroredInputStream(String name, String destDir, long maxTime) throws IOException
    {
        URL url;
        File file = null;
        try
        {
            url = new URL(name);
            if(url.getProtocol().equals("file"))
            {
                file = new File(name.substring("file:/".length()));
                if(!file.exists())
                    file = new File(name.substring("file://".length()));
            }
            else
                file = checkLocal(url, destDir, maxTime);
        }
        catch(java.net.MalformedURLException e)
        {
            if(name.startsWith("resource://"))
            {
                fs = getClass().getResourceAsStream(
                name.substring("resource:/".length()));
                return;
            }
            else
                file = new File(name);
        }
        if(file == null)
            throw new IOException();
        fs = new FileInputStream(file);
    }

    private File checkLocal(URL url, String destDir, long maxTime)
    {
        String localPath = Main.pref.get("mirror." + url);
        File file = null;
        if(localPath != null && localPath.length() > 0)
        {
            String[] lp = localPath.split(";");
            file = new File(lp[1]);
            if(maxTime <= 0)
                maxTime = Main.pref.getInteger("mirror.maxtime", 7*24*60*60);
            if(System.currentTimeMillis() - Long.parseLong(lp[0]) < maxTime*1000)
            {
                if(file.exists())
                {
                    return file;
                }
            }
        }
        if(destDir == null)
            destDir = Main.pref.getPreferencesDir();

        File destDirFile = new File(destDir);
        if(!destDirFile.exists() )
            destDirFile.mkdirs();

        localPath = "mirror_" + new File(url.getPath()).getName();
        destDirFile = new File(destDir, localPath + ".tmp");
        BufferedOutputStream bos = null;
        BufferedInputStream bis = null;
        try
        {
            URLConnection conn = url.openConnection();
            conn.setConnectTimeout(5000);
            bis = new BufferedInputStream(conn.getInputStream());
            bos = new BufferedOutputStream( new FileOutputStream(destDirFile));
            byte[] buffer = new byte[4096];
            int length;
            while((length = bis.read(buffer)) > -1)
                bos.write(buffer, 0, length);
        }
        catch(IOException ioe)
        {
            if(file != null)
                return file;
            else
                return null;
        }
        finally
        {
            if(bis != null)
            {
                try
                {
                    bis.close();
                }
                catch (IOException e)
                {
                    e.printStackTrace();
                }
            }
            if(bos != null)
            {
                try
                {
                    bos.close();
                }
                catch (IOException e)
                {
                    e.printStackTrace();
                }
            }
            file = new File(destDir, localPath);
            destDirFile.renameTo(file);
            Main.pref.put("mirror." + url, System.currentTimeMillis() + ";" + file);
        }

        return file;
    }
    public int available() throws IOException
    { return fs.available(); }
    public void close() throws IOException
    { fs.close(); }
    public int read() throws IOException
    { return fs.read(); }
    public int read(byte[] b) throws IOException
    { return fs.read(b); }
    public int read(byte[] b, int off, int len) throws IOException
    { return fs.read(b,off, len); }
    public long skip(long n) throws IOException
    { return fs.skip(n); }
}