Java Resource Path Get getResourceAsStream(String resourcePath, ClassLoader classLoader, Class clazz)

Description

Get the InputStream input stream to the resource given by the supplied path.

License

Apache License

Parameter

Parameter	Description
resourcePath	the logical path to the classpath, file, or URL resource
clazz	the class that should be used to load the resource as a stream; may be null
classLoader	the classloader that should be used to load the resource as a stream; may be null

Exception

Parameter	Description
IllegalArgumentException	if the resource path is null or empty

Return

an input stream to the resource; or null if the resource could not be found

Declaration

public static InputStream getResourceAsStream(String resourcePath, ClassLoader classLoader, Class<?> clazz) 

Method Source Code

//package com.java2s;
/*/*w  w  w.  j  a  v a 2 s.  co m*/
 * Copyright 2014 Red Hat, Inc. and/or its affiliates.
 *
 * Licensed under the Apache Software License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
 */

import java.io.BufferedInputStream;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;

import java.io.IOException;
import java.io.InputStream;

import java.net.MalformedURLException;
import java.net.URL;

public class Main {
    /**
     * Get the {@link InputStream input stream} to the resource given by the supplied path. If a class loader is supplied, the
     * method attempts to resolve the resource using the {@link ClassLoader#getResourceAsStream(String)} method; if the result is
     * non-null, it is returned. Otherwise, if a class is supplied, this method attempts to resolve the resource using the
     * {@link Class#getResourceAsStream(String)} method; if the result is non-null, it is returned. Otherwise, this method then
     * uses the Class' ClassLoader to load the resource; if non-null, it is returned . Otherwise, this method looks for an
     * existing and readable {@link File file} at the path; if found, a buffered stream to that file is returned. Otherwise, this
     * method attempts to parse the resource path into a valid {@link URL}; if this succeeds, the method attempts to open a stream
     * to that URL. If all of these fail, this method returns null.
     * 
     * @param resourcePath the logical path to the classpath, file, or URL resource
     * @param clazz the class that should be used to load the resource as a stream; may be null
     * @param classLoader the classloader that should be used to load the resource as a stream; may be null
     * @return an input stream to the resource; or null if the resource could not be found
     * @throws IllegalArgumentException if the resource path is null or empty
     */
    public static InputStream getResourceAsStream(String resourcePath, ClassLoader classLoader, Class<?> clazz) {
        if (resourcePath == null)
            throw new IllegalArgumentException("resourcePath may not be null");
        InputStream result = null;
        if (classLoader != null) {
            // Try using the class loader first ...
            result = classLoader.getResourceAsStream(resourcePath);
        }
        if (result == null && clazz != null) {
            // Not yet found, so try the class ...
            result = clazz.getResourceAsStream(resourcePath);
            if (result == null) {
                // Not yet found, so try the class's class loader ...
                result = clazz.getClassLoader().getResourceAsStream(resourcePath);
            }
        }
        if (result == null) {
            // Still not found, so see if this is an existing File ...
            try {
                File file = new File(resourcePath);
                if (file.exists() && file.canRead()) {
                    return new BufferedInputStream(new FileInputStream(file));
                }
            } catch (FileNotFoundException e) {
                // just continue ...
            }
        }
        if (result == null) {
            // Still not found, so try to construct a URL out of it ...
            try {
                URL url = new URL(resourcePath);
                return url.openStream();
            } catch (MalformedURLException e) {
                // just continue ...
            } catch (IOException err) {
                // just continue ...
            }
        }
        // Couldn't find it anywhere ...
        return result;
    }
}

Related

1. getResource(String relativePath)
2. getResource(String resourcePath)
3. getResourceAsFile(Object relativeTo, String relativePath)
4. getResourceAsFile(String relativePath)
5. getResourceAsStream(final String path)
6. getResourceAsString(String path)
7. getResourceFile(Class clazz, String relPath)
8. getResourceFile(final Class baseClass, final String path)
9. getResourceFile(String sResourcePath, Class cRefClass)