标签： url uri file path
File to URI:
File file = ...;
URI uri = file.toURI();

File to URL:
File file = ...;
URL url = file.toURI().URL();

URL to File:
URL url = ...;
File file = new Path(url.getPath()).toFile();

URI to URL:
URI uri = ...;
URL url = uri.toURL();

URL to URI:
URL url = ...;
URI uri = url.toURI();

一般情况下采用上述方式都可以安全的使用.

但是, 当处理本地路径且有空格,或者特殊字符,比如汉字等. 路径在相互的转换过程中, 可能会出现转换的无效字符错误异常.
所以, 可以使用Eclipse提供的工具类org.eclipse.core.runtime.URIUtil (插件: org.eclipse.equinox.simpleconfigurator)来进行转换.
URL <wbr>URI <wbr>File <wbr>Path <wbr>转换(原创)

比如URL to File:
URL url = ...;
File file = URIUtil.toFile(URIUtil.toURI(url));

当URL, URI直接互相转换时,也可以使用该URIUtil工具类.

toURI

toURL

还有一个工具类,就是org.eclipse.core.runtime.FileLocator(插件: org.eclipse.equinox.common) 也可以对URL进行File的格式化. 比如toFileURL方法.

附源码:

package org.eclipse.equinox.internal.simpleconfigurator.utils;

import java.io.File;
import java.net.*;

public class URIUtil {

private static final String SCHEME_FILE = "file"; //$NON-NLS-1$
private static final String UNC_PREFIX = "//"; //$NON-NLS-1$


public static URI append(URI base, String extension) {
    try {
        String path = base.getPath();
        if (path == null)
            return appendOpaque(base, extension);
        //if the base is already a directory then resolve will just do the right thing
        if (path.endsWith("/")) {//$NON-NLS-1$
            URI result = base.resolve(extension);
            //Fix UNC paths that are incorrectly normalized by URI#resolve (see Java bug 4723726)
            String resultPath = result.getPath();
            if (path.startsWith(UNC_PREFIX) && (resultPath == null || !resultPath.startsWith(UNC_PREFIX)))
                result = new URI(result.getScheme(), "///" + result.getSchemeSpecificPart(), result.getFragment()); //$NON-NLS-1$
            return result;
        }
        path = path + "/" + extension; //$NON-NLS-1$
        return new URI(base.getScheme(), base.getUserInfo(), base.getHost(), base.getPort(), path, base.getQuery(), base.getFragment());
    } catch (URISyntaxException e) {
        //shouldn't happen because we started from a valid URI
        throw new RuntimeException(e);
    }
}


private static URI appendOpaque(URI base, String extension) throws URISyntaxException {
    String ssp = base.getSchemeSpecificPart();
    if (ssp.endsWith("/")) //$NON-NLS-1$
        ssp += extension;
    else
        ssp = ssp + "/" + extension; //$NON-NLS-1$
    return new URI(base.getScheme(), ssp, base.getFragment());
}


public static URI fromString(String uriString) throws URISyntaxException {
    int colon = uriString.indexOf(':');
    int hash = uriString.lastIndexOf('#');
    boolean noHash = hash < 0;
    if (noHash)
        hash = uriString.length();
    String scheme = colon < 0 ? null : uriString.substring(0, colon);
    String ssp = uriString.substring(colon + 1, hash);
    String fragment = noHash ? null : uriString.substring(hash + 1);
    //use java.io.File for constructing file: URIs
    if (scheme != null && scheme.equals(SCHEME_FILE)) {
        File file = new File(uriString.substring(5));
        if (file.isAbsolute())
            return file.toURI();
        scheme = null;
        if (File.separatorChar != '/')
            ssp = ssp.replace(File.separatorChar, '/');
    }
    return new URI(scheme, ssp, fragment);
}


public static boolean sameURI(URI url1, URI url2) {
    if (url1 == url2)
        return true;
    if (url1 == null || url2 == null)
        return false;
    if (url1.equals(url2))
        return true;

    if (url1.isAbsolute() != url2.isAbsolute())
        return false;

    // check if we have two local file references that are case variants
    File file1 = toFile(url1);
    return file1 == null ? false : file1.equals(toFile(url2));
}


public static File toFile(URI uri) {
    try {
        if (!SCHEME_FILE.equalsIgnoreCase(uri.getScheme()))
            return null;
        //assume all illegal characters have been properly encoded, so use URI class to unencode
        return new File(uri);
    } catch (IllegalArgumentException e) {
        //File constructor does not support non-hierarchical URI
        String path = uri.getPath();
        //path is null for non-hierarchical URI such as file:c:/tmp
        if (path == null)
            path = uri.getSchemeSpecificPart();
        return new File(path);
    }
}


public static String toUnencodedString(URI uri) {
    StringBuffer result = new StringBuffer();
    String scheme = uri.getScheme();
    if (scheme != null)
        result.append(scheme).append(':');
    //there is always a ssp
    result.append(uri.getSchemeSpecificPart());
    String fragment = uri.getFragment();
    if (fragment != null)
        result.append('#').append(fragment);
    return result.toString();
}


public static URI toURI(URL url) throws URISyntaxException {
    //URL behaves differently across platforms so for file: URLs we parse from string form
    if (SCHEME_FILE.equals(url.getProtocol())) {
        String pathString = url.toExternalForm().substring(5);
        //ensure there is a leading slash to handle common malformed URLs such as file:c:/tmp
        if (pathString.indexOf('/') != 0)
            pathString = '/' + pathString;
        else if (pathString.startsWith(UNC_PREFIX) && !pathString.startsWith(UNC_PREFIX, 2)) {
            //URL encodes UNC path with two slashes, but URI uses four (see bug 207103)
            pathString = UNC_PREFIX + pathString;
        }
        return new URI(SCHEME_FILE, null, pathString, null);
    }
    try {
        return new URI(url.toExternalForm());
    } catch (URISyntaxException e) {
        //try multi-argument URI constructor to perform encoding
        return new URI(url.getProtocol(), url.getUserInfo(), url.getHost(), url.getPort(), url.getPath(), url.getQuery(), url.getRef());
    }
}


public static URL toURL(URI uri) throws MalformedURLException {
    return new URL(uri.toString());
}

}