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URL.javaAPI DocGlassfish v2 API22333Fri May 04 22:32:30 BST 2007org.apache.catalina.util

URL

public final class URL extends Object implements Serializable

URL is designed to provide public APIs for parsing and synthesizing Uniform Resource Locators as similar as possible to the APIs of java.net.URL, but without the ability to open a stream or connection. One of the consequences of this is that you can construct URLs for protocols for which a URLStreamHandler is not available (such as an "https" URL when JSSE is not installed).

WARNING - This class assumes that the string representation of a URL conforms to the spec argument as described in RFC 2396 "Uniform Resource Identifiers: Generic Syntax":

<scheme>//<authority><path>?<query>#<fragment>

FIXME - This class really ought to end up in a Commons package someplace.

author
Craig R. McClanahan
version
$Revision: 1.6 $ $Date: 2007/05/05 05:32:30 $

Fields Summary
private String
authority
The authority part of the URL.
private String
file
The filename part of the URL.
private String
host
The host name part of the URL.
private String
path
The path part of the URL.
private int
port
The port number part of the URL.
private String
protocol
The protocol name part of the URL.
private String
query
The query part of the URL.
private String
ref
The reference part of the URL.
private String
userInfo
The user info part of the URL.
Constructors Summary
public URL(String spec)
Create a URL object from the specified String representation.

param
spec String representation of the URL
exception
MalformedURLException if the string representation cannot be parsed successfully


        this(null, spec);

    
public URL(URL context, String spec)
Create a URL object by parsing a string representation relative to a specified context. Based on logic from JDK 1.3.1's java.net.URL.

param
context URL against which the relative representation is resolved
param
spec String representation of the URL (usually relative)
exception
MalformedURLException if the string representation cannot be parsed successfully


        String original = spec;
        int i, limit, c;
        int start = 0;
        String newProtocol = null;
        boolean aRef = false;

        try {

            // Eliminate leading and trailing whitespace
            limit = spec.length();
            while ((limit > 0) && (spec.charAt(limit - 1) <= ' ")) {
                limit--;
            }
            while ((start < limit) && (spec.charAt(start) <= ' ")) {
                start++;
            }

            // If the string representation starts with "url:", skip it
            if (spec.regionMatches(true, start, "url:", 0, 4)) {
                start += 4;
            }

            // Is this a ref relative to the context URL?
            if ((start < spec.length()) && (spec.charAt(start) == '#")) {
                aRef = true;
            }

            // Parse out the new protocol
            for (i = start; !aRef && (i < limit) &&
                     ((c = spec.charAt(i)) != '/"); i++) {
                if (c == ':") {
                    String s = spec.substring(start, i).toLowerCase();
                    // Assume all protocols are valid
                    newProtocol = s;
                    start = i + 1;
                    break;
                }
            }

            // Only use our context if the protocols match
            protocol = newProtocol;
            if ((context != null) && ((newProtocol == null) ||
                 newProtocol.equalsIgnoreCase(context.getProtocol()))) {
                // If the context is a hierarchical URL scheme and the spec
                // contains a matching scheme then maintain backwards
                // compatibility and treat it as if the spec didn't contain
                // the scheme; see 5.2.3 of RFC2396
                if ((context.getPath() != null) &&
                    (context.getPath().startsWith("/")))
                    newProtocol = null;
                if (newProtocol == null) {
                    protocol = context.getProtocol();
                    authority = context.getAuthority();
                    userInfo = context.getUserInfo();
                    host = context.getHost();
                    port = context.getPort();
                    file = context.getFile();
                    int question = file.lastIndexOf("?");
                    if (question < 0)
                        path = file;
                    else
                        path = file.substring(0, question);
                }
            }

            if (protocol == null)
                throw new MalformedURLException("no protocol: " + original);

            // Parse out any ref portion of the spec
            i = spec.indexOf('#", start);
            if (i >= 0) {
                ref = spec.substring(i + 1, limit);
                limit = i;
            }

            // Parse the remainder of the spec in a protocol-specific fashion
            parse(spec, start, limit);
            if (context != null)
                normalize();


        } catch (MalformedURLException e) {
            throw e;
        } catch (Exception e) {
            throw new MalformedURLException(e.toString());
        }

    
public URL(String protocol, String host, String file)
Create a URL object from the specified components. The default port number for the specified protocol will be used.

param
protocol Name of the protocol to use
param
host Name of the host addressed by this protocol
param
file Filename on the specified host
exception
MalformedURLException is never thrown, but present for compatible APIs


        this(protocol, host, -1, file);

    
public URL(String protocol, String host, int port, String file)
Create a URL object from the specified components. Specifying a port number of -1 indicates that the URL should use the default port for that protocol. Based on logic from JDK 1.3.1's java.net.URL.

param
protocol Name of the protocol to use
param
host Name of the host addressed by this protocol
param
port Port number, or -1 for the default port for this protocol
param
file Filename on the specified host
exception
MalformedURLException is never thrown, but present for compatible APIs


        this.protocol = protocol;
        this.host = host;
        this.port = port;

        int hash = file.indexOf('#");
        this.file = hash < 0 ? file : file.substring(0, hash);
        this.ref = hash < 0 ? null : file.substring(hash + 1);
        int question = file.lastIndexOf('?");
        if (question >= 0) {
            query = file.substring(question + 1);
            path = file.substring(0, question);
        } else
            path = file;

        if ((host != null) && (host.length() > 0))
            authority = (port == -1) ? host : host + ":" + port;

    
Methods Summary
private booleancompare(java.lang.String first, java.lang.String second)
Compare to String values for equality, taking appropriate care if one or both of the values are null.

param
first First string
param
second Second string


        if (first == null) {
            if (second == null)
                return (true);
            else
                return (false);
        } else {
            if (second == null)
                return (false);
            else
                return (first.equals(second));
        }

    
public booleanequals(java.lang.Object obj)
Compare two URLs for equality. The result is true if and only if the argument is not null, and is a URL object that represents the same URL as this object. Two URLs are equal if they have the same protocol and reference the same host, the same port number on the host, and the same file and anchor on the host.

param
obj The URL to compare against



    // --------------------------------------------------------- Public Methods


                                                                                
        

        if (obj == null)
            return (false);
        if (!(obj instanceof URL))
            return (false);
        URL other = (URL) obj;
        if (!sameFile(other))
            return (false);
        return (compare(ref, other.getRef()));

    
public java.lang.StringgetAuthority()
Return the authority part of the URL.


        return (this.authority);

    
public java.lang.StringgetFile()
Return the filename part of the URL. NOTE - For compatibility with java.net.URL, this value includes the query string if there was one. For just the path portion, call getPath() instead.


        if (file == null)
            return ("");
        return (this.file);

    
public java.lang.StringgetHost()
Return the host name part of the URL.


        return (this.host);

    
public java.lang.StringgetPath()
Return the path part of the URL.


        if (this.path == null)
            return ("");
        return (this.path);

    
public intgetPort()
Return the port number part of the URL.


        return (this.port);

    
public java.lang.StringgetProtocol()
Return the protocol name part of the URL.


        return (this.protocol);

    
public java.lang.StringgetQuery()
Return the query part of the URL.


        return (this.query);

    
public java.lang.StringgetRef()
Return the reference part of the URL.


        return (this.ref);

    
public java.lang.StringgetUserInfo()
Return the user info part of the URL.


        return (this.userInfo);

    
public inthashCode()
Returns the hash code value for this object.

return
a hash code value for this object.


        int hashCode = 0;

        if (getProtocol() != null) {
            hashCode += getProtocol().hashCode();
        } 

        if (getHost() != null) {
            hashCode += getHost().hashCode();
        }

        hashCode += getPort();

        if (getFile() != null) {
            hashCode += getFile().hashCode();
        }

        if (getRef() != null) {
            hashCode += getRef().hashCode();
        }

        return hashCode;
    
public voidnormalize()
Normalize the path (and therefore file) portions of this URL.

NOTE - This method is not part of the public API of java.net.URL, but is provided as a value added service of this implementation.

exception
MalformedURLException if a normalization error occurs, such as trying to move about the hierarchical root


        // Special case for null path
        if (path == null) {
            if (query != null)
                file = "?" + query;
            else
                file = "";
            return;
        }

        // Create a place for the normalized path
        String normalized = path;
        if (normalized.equals("/.")) {
            path = "/";
            if (query != null)
                file = path + "?" + query;
            else
                file = path;
            return;
        }

        // Normalize the slashes and add leading slash if necessary
        if (normalized.indexOf('\\") >= 0)
            normalized = normalized.replace('\\", '/");
        if (!normalized.startsWith("/"))
            normalized = "/" + normalized;

        // Resolve occurrences of "//" in the normalized path
        while (true) {
            int index = normalized.indexOf("//");
            if (index < 0)
                break;
            normalized = normalized.substring(0, index) +
                normalized.substring(index + 1);
        }

        // Resolve occurrences of "/./" in the normalized path
        while (true) {
            int index = normalized.indexOf("/./");
            if (index < 0)
                break;
            normalized = normalized.substring(0, index) +
                normalized.substring(index + 2);
        }

        // Resolve occurrences of "/../" in the normalized path
        while (true) {
            int index = normalized.indexOf("/../");
            if (index < 0)
                break;
            if (index == 0)
                throw new MalformedURLException
                    ("Invalid relative URL reference");
            int index2 = normalized.lastIndexOf('/", index - 1);
            normalized = normalized.substring(0, index2) +
                normalized.substring(index + 3);
        }

        // Resolve occurrences of "/." at the end of the normalized path
        if (normalized.endsWith("/."))
            normalized = normalized.substring(0, normalized.length() - 1);

        // Resolve occurrences of "/.." at the end of the normalized path
        if (normalized.endsWith("/..")) {
            int index = normalized.length() - 3;
            int index2 = normalized.lastIndexOf('/", index - 1);
            if (index2 < 0)
                throw new MalformedURLException
                    ("Invalid relative URL reference");
            normalized = normalized.substring(0, index2 + 1);
        }

        // Return the normalized path that we have completed
        path = normalized;
        if (query != null)
            file = path + "?" + query;
        else
            file = path;

    
private voidparse(java.lang.String spec, int start, int limit)
Parse the specified portion of the string representation of a URL, assuming that it has a format similar to that for http.

FIXME - This algorithm can undoubtedly be optimized for performance. However, that needs to wait until after sufficient unit tests are implemented to guarantee correct behavior with no regressions.

param
spec String representation being parsed
param
start Starting offset, which will be just after the ':' (if there is one) that determined the protocol name
param
limit Ending position, which will be the position of the '#' (if there is one) that delimited the anchor
exception
MalformedURLException if a parsing error occurs


        // Trim the query string (if any) off the tail end
        int question = spec.lastIndexOf('?", limit - 1);
        if ((question >= 0) && (question < limit)) {
            query = spec.substring(question + 1, limit);
            limit = question;
        } else {
            query = null;
        }

        // Parse the authority section
        if (spec.indexOf("//", start) == start) {
            int pathStart = spec.indexOf("/", start + 2);
            if ((pathStart >= 0) && (pathStart < limit)) {
                authority = spec.substring(start + 2, pathStart);
                start = pathStart;
            } else {
                authority = spec.substring(start + 2, limit);
                start = limit;
            }
            if (authority.length() > 0) {
                int at = authority.indexOf('@");
                if( at >= 0 ) {
                    userInfo = authority.substring(0,at);
                }
                int colon = authority.indexOf(':",at+1);
                if (colon >= 0) {
                    try {
                        port =
                            Integer.parseInt(authority.substring(colon + 1));
                    } catch (NumberFormatException e) {
                        throw new MalformedURLException(e.toString());
                    }
                    host = authority.substring(at+1, colon);
                } else {
                    host = authority.substring(at+1);
                    port = -1;
                }
            }
        }

        // Parse the path section
        if (spec.indexOf("/", start) == start) {     // Absolute path
            path = spec.substring(start, limit);
            if (query != null)
                file = path + "?" + query;
            else
                file = path;
            return;
        }

        // Resolve relative path against our context's file
        if (path == null) {
            if (query != null)
                file = "?" + query;
            else
                file = null;
            return;
        }
        if (!path.startsWith("/"))
            throw new MalformedURLException
                ("Base path does not start with '/'");
        if (!path.endsWith("/"))
            path += "/../";
        path += spec.substring(start, limit);
        if (query != null)
            file = path + "?" + query;
        else
            file = path;
        return;

    
public booleansameFile(org.apache.catalina.util.URL other)
Compare two URLs, excluding the "ref" fields. Returns true if this URL and the other argument both refer to the same resource. The two URLs might not both contain the same anchor.


        if (!compare(protocol, other.getProtocol()))
            return (false);
        if (!compare(host, other.getHost()))
            return (false);
        if (port != other.getPort())
            return (false);
        if (!compare(file, other.getFile()))
            return (false);
        return (true);

    
public java.lang.StringtoExternalForm()
Return a string representation of this URL. This follow the rules in RFC 2396, Section 5.2, Step 7.


        StringBuffer sb = new StringBuffer();
        if (protocol != null) {
            sb.append(protocol);
            sb.append(":");
        }
        if (authority != null) {
            sb.append("//");
            sb.append(authority);
        }
        if (path != null)
            sb.append(path);
        if (query != null) {
            sb.append('?");
            sb.append(query);
        }
        if (ref != null) {
            sb.append('#");
            sb.append(ref);
        }
        return (sb.toString());

    
public java.lang.StringtoString()
Return a string representation of this object.


        StringBuffer sb = new StringBuffer("URL[");
        sb.append("authority=");
        sb.append(authority);
        sb.append(", file=");
        sb.append(file);
        sb.append(", host=");
        sb.append(host);
        sb.append(", port=");
        sb.append(port);
        sb.append(", protocol=");
        sb.append(protocol);
        sb.append(", query=");
        sb.append(query);
        sb.append(", ref=");
        sb.append(ref);
        sb.append(", userInfo=");
        sb.append(userInfo);
        sb.append("]");
        return (sb.toString());

        //        return (toExternalForm());