zkoss/zk

/* ServletContextLocator.java

    Purpose:
        
    Description:
        
    History:
        Wed Jul  6 15:16:05     2005, Created by tomyeh

Copyright (C) 2005 Potix Corporation. All Rights Reserved.

{{IS_RIGHT
    This program is distributed under LGPL Version 2.1 in the hope that
    it will be useful, but WITHOUT ANY WARRANTY.
}}IS_RIGHT
*/
package org.zkoss.web.util.resource;

import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.net.URL;

import javax.servlet.ServletContext;

import org.zkoss.lang.SystemException;
import org.zkoss.util.resource.Locator;
import org.zkoss.web.servlet.Servlets;

/**
 * Locator based on ServletContext.
 *
 * @author tomyeh
 */
public class ServletContextLocator implements Locator {
    private final ServletContext _ctx;
    private final String _dir, _prefix;
    private final boolean _acceptURL;
    private final String _externalPrefix;

    /** Constructor.
     * A short cut of ServletContextLocator(ctx, null, null, false)
     */
    public ServletContextLocator(ServletContext ctx) {
        this(ctx, null, null, false, null);
    }

    /** Constructor.
     * @param acceptURL whether to URL (such as file:/, http:// and
     * ftp://) are accepted. In other words, {@link Servlets#getResource}
     * will be used.
     * @see Servlets#getResource
     * @since 5.0.7
     */
    public ServletContextLocator(ServletContext ctx, boolean acceptURL) {
        this(ctx, null, null, acceptURL, null);
    }

    /** Constructor.
     * A short of ServletContextLocator(ctx, dir, null, false, null).
     * @param dir the directory used when relative path is specified
     * (for {@link #getResource} and {@link #getResourceAsStream}).
     * It must be null, empty, or starts with /.
     */
    public ServletContextLocator(ServletContext ctx, String dir) {
        this(ctx, dir, null, false, null);
    }

    /** Constructor.
     * A short cut of ServletContextLocator(ctx, dir, prefix, false, null).
     */
    public ServletContextLocator(ServletContext ctx, String dir, String prefix) {
        this(ctx, dir, prefix, false, null);
    }

    /** Constructor.
     * A short cut of ServletContextLocator(ctx, dir, prefix, acceptURL, null).
     */
    public ServletContextLocator(ServletContext ctx, String dir, String prefix, boolean acceptURL) {
        this(ctx, dir, prefix, acceptURL, null);
    }

    /** Constructor.
     * For example, if prefix is "/WEB-INF/cwr", then getResource("/abc") will
     * look for "/WEB-INF/cwr/abc" first, and then "/abc".
     *
     * <p>Another example, if prefix is "/WEB-INF/cwr" and dir is "/subdir",
     * then getResource("abc") will look for "/WEB-INF/cwr/subdir/abc".
     *
     * @param dir the directory used when relative path is specified
     * (for {@link #getResource} and {@link #getResourceAsStream}).
     * It must be null, empty, or starts with /.
     * @param prefix the directory to prefix each directory specified
     * (for {@link #getResource} and {@link #getResourceAsStream}).
     * It must be null, empty, or starts with /.
     * @param acceptURL whether to URL (such as file:/, http:// and
     * ftp://) are accepted. In other words, {@link Servlets#getResource}
     * will be used.
     */
    public ServletContextLocator(ServletContext ctx, String dir, String prefix, boolean acceptURL, String externalPrefix) {
        if (ctx == null)
            throw new IllegalArgumentException("null");
        if (dir != null) {
            final int len = dir.length();
            if (len == 0)
                dir = null;
            else {
                if (dir.charAt(0) != '/')
                    throw new IllegalArgumentException("Absolute path required: " + dir);
                if (dir.charAt(len - 1) != '/')
                    dir += '/';
            }
        }
        if (prefix != null) {
            final int len = prefix.length();
            if (len == 0)
                prefix = null;
            else {
                if (prefix.charAt(0) != '/')
                    throw new IllegalArgumentException("Absolute path required: " + prefix);
                if (len == 1)
                    prefix = null; // "/" only
                else if (prefix.charAt(len - 1) == '/')
                    prefix = prefix.substring(0, len - 1);
            }
        }

        _ctx = ctx;
        _dir = dir;
        _prefix = prefix;
        _acceptURL = acceptURL;
        _externalPrefix = externalPrefix;
    }

    /** Returns the servlet context. */
    public ServletContext getServletContext() {
        return _ctx;
    }

    private String fixName(String name, boolean prefix) {
        name = name.length() > 0 && name.charAt(0) != '/'
                ? _dir != null ? _dir + name : prefix && _prefix != null ? '/' + name : name : name;
        return prefix && _prefix != null ? _prefix + name : (_externalPrefix == null ?  "" : _externalPrefix) + name;
    }

    //-- Locator --//
    public String getDirectory() {
        return _dir;
    }

    public URL getResource(String name) {
        String relativePath = null;
        try {
            URL url = getResource0(relativePath = fixName(name, true));
            return url == null && _prefix != null ? getResource0(relativePath = fixName(name, false)) : url;
        } catch (java.net.MalformedURLException ex) {
            if (relativePath != null && !relativePath.startsWith("-")) {
                return null; // ignore relative path here for ZK-5215
            }
            throw new SystemException(ex);
        } catch (UnsupportedEncodingException e) {
            throw new SystemException(e);
        }
    }

    public InputStream getResourceAsStream(String name) {
        try {
            InputStream is = getResourceAsStream0(fixName(name, true));
            return is == null && _prefix != null ? getResourceAsStream0(fixName(name, false)) : is;
        } catch (java.io.IOException ex) {
            throw new SystemException(ex);
        }
    }

    private URL getResource0(String path) throws java.net.MalformedURLException, UnsupportedEncodingException {
        return _acceptURL ? Servlets.getResource(_ctx, path) : _ctx.getResource(path);
    }

    private InputStream getResourceAsStream0(String path) throws java.io.IOException {
        return _acceptURL ? Servlets.getResourceAsStream(_ctx, path) : _ctx.getResourceAsStream(path);
    }

    //-- Object --//
    public int hashCode() {
        return _ctx.hashCode();
    }

    public boolean equals(Object o) {
        if (this == o)
            return true;
        return o instanceof ServletContextLocator && ((ServletContextLocator) o)._ctx.equals(_ctx);
    }
}