Java example source code file (URLStreamHandler.java)
The URLStreamHandler.java Java example source code/*
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package java.net;
import java.io.IOException;
import java.io.InputStream;
import java.io.File;
import java.io.OutputStream;
import java.util.Hashtable;
import sun.net.util.IPAddressUtil;
import sun.net.www.ParseUtil;
/**
* The abstract class {@code URLStreamHandler} is the common
* superclass for all stream protocol handlers. A stream protocol
* handler knows how to make a connection for a particular protocol
* type, such as {@code http} or {@code https}.
* <p>
* In most cases, an instance of a {@code URLStreamHandler}
* subclass is not created directly by an application. Rather, the
* first time a protocol name is encountered when constructing a
* {@code URL}, the appropriate stream protocol handler is
* automatically loaded.
*
* @author James Gosling
* @see java.net.URL#URL(java.lang.String, java.lang.String, int, java.lang.String)
* @since JDK1.0
*/
public abstract class URLStreamHandler {
/**
* Opens a connection to the object referenced by the
* {@code URL} argument.
* This method should be overridden by a subclass.
*
* <p>If for the handler's protocol (such as HTTP or JAR), there
* exists a public, specialized URLConnection subclass belonging
* to one of the following packages or one of their subpackages:
* java.lang, java.io, java.util, java.net, the connection
* returned will be of that subclass. For example, for HTTP an
* HttpURLConnection will be returned, and for JAR a
* JarURLConnection will be returned.
*
* @param u the URL that this connects to.
* @return a {@code URLConnection} object for the {@code URL}.
* @exception IOException if an I/O error occurs while opening the
* connection.
*/
abstract protected URLConnection openConnection(URL u) throws IOException;
/**
* Same as openConnection(URL), except that the connection will be
* made through the specified proxy; Protocol handlers that do not
* support proxying will ignore the proxy parameter and make a
* normal connection.
*
* Calling this method preempts the system's default ProxySelector
* settings.
*
* @param u the URL that this connects to.
* @param p the proxy through which the connection will be made.
* If direct connection is desired, Proxy.NO_PROXY
* should be specified.
* @return a {@code URLConnection} object for the {@code URL}.
* @exception IOException if an I/O error occurs while opening the
* connection.
* @exception IllegalArgumentException if either u or p is null,
* or p has the wrong type.
* @exception UnsupportedOperationException if the subclass that
* implements the protocol doesn't support this method.
* @since 1.5
*/
protected URLConnection openConnection(URL u, Proxy p) throws IOException {
throw new UnsupportedOperationException("Method not implemented.");
}
/**
* Parses the string representation of a {@code URL} into a
* {@code URL} object.
* <p>
* If there is any inherited context, then it has already been
* copied into the {@code URL} argument.
* <p>
* The {@code parseURL} method of {@code URLStreamHandler}
* parses the string representation as if it were an
* {@code http} specification. Most URL protocol families have a
* similar parsing. A stream protocol handler for a protocol that has
* a different syntax must override this routine.
*
* @param u the {@code URL} to receive the result of parsing
* the spec.
* @param spec the {@code String} representing the URL that
* must be parsed.
* @param start the character index at which to begin parsing. This is
* just past the '{@code :}' (if there is one) that
* specifies the determination of the protocol name.
* @param limit the character position to stop parsing at. This is the
* end of the string or the position of the
* "{@code #}" character, if present. All information
* after the sharp sign indicates an anchor.
*/
protected void parseURL(URL u, String spec, int start, int limit) {
// These fields may receive context content if this was relative URL
String protocol = u.getProtocol();
String authority = u.getAuthority();
String userInfo = u.getUserInfo();
String host = u.getHost();
int port = u.getPort();
String path = u.getPath();
String query = u.getQuery();
// This field has already been parsed
String ref = u.getRef();
boolean isRelPath = false;
boolean queryOnly = false;
// FIX: should not assume query if opaque
// Strip off the query part
if (start < limit) {
int queryStart = spec.indexOf('?');
queryOnly = queryStart == start;
if ((queryStart != -1) && (queryStart < limit)) {
query = spec.substring(queryStart+1, limit);
if (limit > queryStart)
limit = queryStart;
spec = spec.substring(0, queryStart);
}
}
int i = 0;
// Parse the authority part if any
boolean isUNCName = (start <= limit - 4) &&
(spec.charAt(start) == '/') &&
(spec.charAt(start + 1) == '/') &&
(spec.charAt(start + 2) == '/') &&
(spec.charAt(start + 3) == '/');
if (!isUNCName && (start <= limit - 2) && (spec.charAt(start) == '/') &&
(spec.charAt(start + 1) == '/')) {
start += 2;
i = spec.indexOf('/', start);
if (i < 0) {
i = spec.indexOf('?', start);
if (i < 0)
i = limit;
}
host = authority = spec.substring(start, i);
int ind = authority.indexOf('@');
if (ind != -1) {
userInfo = authority.substring(0, ind);
host = authority.substring(ind+1);
} else {
userInfo = null;
}
if (host != null) {
// If the host is surrounded by [ and ] then its an IPv6
// literal address as specified in RFC2732
if (host.length()>0 && (host.charAt(0) == '[')) {
if ((ind = host.indexOf(']')) > 2) {
String nhost = host ;
host = nhost.substring(0,ind+1);
if (!IPAddressUtil.
isIPv6LiteralAddress(host.substring(1, ind))) {
throw new IllegalArgumentException(
"Invalid host: "+ host);
}
port = -1 ;
if (nhost.length() > ind+1) {
if (nhost.charAt(ind+1) == ':') {
++ind ;
// port can be null according to RFC2396
if (nhost.length() > (ind + 1)) {
port = Integer.parseInt(nhost.substring(ind+1));
}
} else {
throw new IllegalArgumentException(
"Invalid authority field: " + authority);
}
}
} else {
throw new IllegalArgumentException(
"Invalid authority field: " + authority);
}
} else {
ind = host.indexOf(':');
port = -1;
if (ind >= 0) {
// port can be null according to RFC2396
if (host.length() > (ind + 1)) {
port = Integer.parseInt(host.substring(ind + 1));
}
host = host.substring(0, ind);
}
}
} else {
host = "";
}
if (port < -1)
throw new IllegalArgumentException("Invalid port number :" +
port);
start = i;
// If the authority is defined then the path is defined by the
// spec only; See RFC 2396 Section 5.2.4.
if (authority != null && authority.length() > 0)
path = "";
}
if (host == null) {
host = "";
}
// Parse the file path if any
if (start < limit) {
if (spec.charAt(start) == '/') {
path = spec.substring(start, limit);
} else if (path != null && path.length() > 0) {
isRelPath = true;
int ind = path.lastIndexOf('/');
String seperator = "";
if (ind == -1 && authority != null)
seperator = "/";
path = path.substring(0, ind + 1) + seperator +
spec.substring(start, limit);
} else {
String seperator = (authority != null) ? "/" : "";
path = seperator + spec.substring(start, limit);
}
} else if (queryOnly && path != null) {
int ind = path.lastIndexOf('/');
if (ind < 0)
ind = 0;
path = path.substring(0, ind) + "/";
}
if (path == null)
path = "";
if (isRelPath) {
// Remove embedded /./
while ((i = path.indexOf("/./")) >= 0) {
path = path.substring(0, i) + path.substring(i + 2);
}
// Remove embedded /../ if possible
i = 0;
while ((i = path.indexOf("/../", i)) >= 0) {
/*
* A "/../" will cancel the previous segment and itself,
* unless that segment is a "/../" itself
* i.e. "/a/b/../c" becomes "/a/c"
* but "/../../a" should stay unchanged
*/
if (i > 0 && (limit = path.lastIndexOf('/', i - 1)) >= 0 &&
(path.indexOf("/../", limit) != 0)) {
path = path.substring(0, limit) + path.substring(i + 3);
i = 0;
} else {
i = i + 3;
}
}
// Remove trailing .. if possible
while (path.endsWith("/..")) {
i = path.indexOf("/..");
if ((limit = path.lastIndexOf('/', i - 1)) >= 0) {
path = path.substring(0, limit+1);
} else {
break;
}
}
// Remove starting .
if (path.startsWith("./") && path.length() > 2)
path = path.substring(2);
// Remove trailing .
if (path.endsWith("/."))
path = path.substring(0, path.length() -1);
}
setURL(u, protocol, host, port, authority, userInfo, path, query, ref);
}
/**
* Returns the default port for a URL parsed by this handler. This method
* is meant to be overidden by handlers with default port numbers.
* @return the default port for a {@code URL} parsed by this handler.
* @since 1.3
*/
protected int getDefaultPort() {
return -1;
}
/**
* Provides the default equals calculation. May be overidden by handlers
* for other protocols that have different requirements for equals().
* This method requires that none of its arguments is null. This is
* guaranteed by the fact that it is only called by java.net.URL class.
* @param u1 a URL object
* @param u2 a URL object
* @return {@code true} if the two urls are
* considered equal, ie. they refer to the same
* fragment in the same file.
* @since 1.3
*/
protected boolean equals(URL u1, URL u2) {
String ref1 = u1.getRef();
String ref2 = u2.getRef();
return (ref1 == ref2 || (ref1 != null && ref1.equals(ref2))) &&
sameFile(u1, u2);
}
/**
* Provides the default hash calculation. May be overidden by handlers for
* other protocols that have different requirements for hashCode
* calculation.
* @param u a URL object
* @return an {@code int} suitable for hash table indexing
* @since 1.3
*/
protected int hashCode(URL u) {
int h = 0;
// Generate the protocol part.
String protocol = u.getProtocol();
if (protocol != null)
h += protocol.hashCode();
// Generate the host part.
InetAddress addr = getHostAddress(u);
if (addr != null) {
h += addr.hashCode();
} else {
String host = u.getHost();
if (host != null)
h += host.toLowerCase().hashCode();
}
// Generate the file part.
String file = u.getFile();
if (file != null)
h += file.hashCode();
// Generate the port part.
if (u.getPort() == -1)
h += getDefaultPort();
else
h += u.getPort();
// Generate the ref part.
String ref = u.getRef();
if (ref != null)
h += ref.hashCode();
return h;
}
/**
* Compare two urls to see whether they refer to the same file,
* i.e., having the same protocol, host, port, and path.
* This method requires that none of its arguments is null. This is
* guaranteed by the fact that it is only called indirectly
* by java.net.URL class.
* @param u1 a URL object
* @param u2 a URL object
* @return true if u1 and u2 refer to the same file
* @since 1.3
*/
protected boolean sameFile(URL u1, URL u2) {
// Compare the protocols.
if (!((u1.getProtocol() == u2.getProtocol()) ||
(u1.getProtocol() != null &&
u1.getProtocol().equalsIgnoreCase(u2.getProtocol()))))
return false;
// Compare the files.
if (!(u1.getFile() == u2.getFile() ||
(u1.getFile() != null && u1.getFile().equals(u2.getFile()))))
return false;
// Compare the ports.
int port1, port2;
port1 = (u1.getPort() != -1) ? u1.getPort() : u1.handler.getDefaultPort();
port2 = (u2.getPort() != -1) ? u2.getPort() : u2.handler.getDefaultPort();
if (port1 != port2)
return false;
// Compare the hosts.
if (!hostsEqual(u1, u2))
return false;
return true;
}
/**
* Get the IP address of our host. An empty host field or a DNS failure
* will result in a null return.
*
* @param u a URL object
* @return an {@code InetAddress} representing the host
* IP address.
* @since 1.3
*/
protected synchronized InetAddress getHostAddress(URL u) {
if (u.hostAddress != null)
return u.hostAddress;
String host = u.getHost();
if (host == null || host.equals("")) {
return null;
} else {
try {
u.hostAddress = InetAddress.getByName(host);
} catch (UnknownHostException ex) {
return null;
} catch (SecurityException se) {
return null;
}
}
return u.hostAddress;
}
/**
* Compares the host components of two URLs.
* @param u1 the URL of the first host to compare
* @param u2 the URL of the second host to compare
* @return {@code true} if and only if they
* are equal, {@code false} otherwise.
* @since 1.3
*/
protected boolean hostsEqual(URL u1, URL u2) {
InetAddress a1 = getHostAddress(u1);
InetAddress a2 = getHostAddress(u2);
// if we have internet address for both, compare them
if (a1 != null && a2 != null) {
return a1.equals(a2);
// else, if both have host names, compare them
} else if (u1.getHost() != null && u2.getHost() != null)
return u1.getHost().equalsIgnoreCase(u2.getHost());
else
return u1.getHost() == null && u2.getHost() == null;
}
/**
* Converts a {@code URL} of a specific protocol to a
* {@code String}.
*
* @param u the URL.
* @return a string representation of the {@code URL} argument.
*/
protected String toExternalForm(URL u) {
// pre-compute length of StringBuffer
int len = u.getProtocol().length() + 1;
if (u.getAuthority() != null && u.getAuthority().length() > 0)
len += 2 + u.getAuthority().length();
if (u.getPath() != null) {
len += u.getPath().length();
}
if (u.getQuery() != null) {
len += 1 + u.getQuery().length();
}
if (u.getRef() != null)
len += 1 + u.getRef().length();
StringBuffer result = new StringBuffer(len);
result.append(u.getProtocol());
result.append(":");
if (u.getAuthority() != null && u.getAuthority().length() > 0) {
result.append("//");
result.append(u.getAuthority());
}
if (u.getPath() != null) {
result.append(u.getPath());
}
if (u.getQuery() != null) {
result.append('?');
result.append(u.getQuery());
}
if (u.getRef() != null) {
result.append("#");
result.append(u.getRef());
}
return result.toString();
}
/**
* Sets the fields of the {@code URL} argument to the indicated values.
* Only classes derived from URLStreamHandler are able
* to use this method to set the values of the URL fields.
*
* @param u the URL to modify.
* @param protocol the protocol name.
* @param host the remote host value for the URL.
* @param port the port on the remote machine.
* @param authority the authority part for the URL.
* @param userInfo the userInfo part of the URL.
* @param path the path component of the URL.
* @param query the query part for the URL.
* @param ref the reference.
* @exception SecurityException if the protocol handler of the URL is
* different from this one
* @see java.net.URL#set(java.lang.String, java.lang.String, int, java.lang.String, java.lang.String)
* @since 1.3
*/
protected void setURL(URL u, String protocol, String host, int port,
String authority, String userInfo, String path,
String query, String ref) {
if (this != u.handler) {
throw new SecurityException("handler for url different from " +
"this handler");
}
// ensure that no one can reset the protocol on a given URL.
u.set(u.getProtocol(), host, port, authority, userInfo, path, query, ref);
}
/**
* Sets the fields of the {@code URL} argument to the indicated values.
* Only classes derived from URLStreamHandler are able
* to use this method to set the values of the URL fields.
*
* @param u the URL to modify.
* @param protocol the protocol name. This value is ignored since 1.2.
* @param host the remote host value for the URL.
* @param port the port on the remote machine.
* @param file the file.
* @param ref the reference.
* @exception SecurityException if the protocol handler of the URL is
* different from this one
* @deprecated Use setURL(URL, String, String, int, String, String, String,
* String);
*/
@Deprecated
protected void setURL(URL u, String protocol, String host, int port,
String file, String ref) {
/*
* Only old URL handlers call this, so assume that the host
* field might contain "user:passwd@host". Fix as necessary.
*/
String authority = null;
String userInfo = null;
if (host != null && host.length() != 0) {
authority = (port == -1) ? host : host + ":" + port;
int at = host.lastIndexOf('@');
if (at != -1) {
userInfo = host.substring(0, at);
host = host.substring(at+1);
}
}
/*
* Assume file might contain query part. Fix as necessary.
*/
String path = null;
String query = null;
if (file != null) {
int q = file.lastIndexOf('?');
if (q != -1) {
query = file.substring(q+1);
path = file.substring(0, q);
} else
path = file;
}
setURL(u, protocol, host, port, authority, userInfo, path, query, ref);
}
}
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