The HostIdentifier.java Java example source code
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* accompanied this code).
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package sun.jvmstat.monitor;
import java.net.*;
/**
* An abstraction that identifies a target host and communications
* protocol. The HostIdentifier, or hostid, provides a convenient string
* representation of the information needed to locate and communicate with
* a target host. The string, based on a {@link URI}, may specify the
* the communications protocol, host name, and protocol specific information
* for a target host. The format for a HostIdentifier string is:
* <pre>
* [<I>protocol:][[//]hostname][:port][/servername]
* </pre>
* There are actually no required components of this string, as a null string
* is interpreted to mean a local connection to the local host and is equivalent
* to the string <em>local://localhost. The components of the
* HostIdentifier are:
* <ul>
* <li>protocol - The communications protocol. If omitted,
* and a hostname is not specified, then default local protocol,
* <em>local:, is assumed. If the protocol is omitted and a
* hostname is specified then the default remote protocol,
* <em>rmi: is assumed.
* </p>
* <li>
hostname - The hostname. If omitted, then
* <em>localhost is assumed. If the protocol is also omitted,
* then default local protocol <em>local: is also assumed.
* If the hostname is not omitted but the protocol is omitted,
* then the default remote protocol, <em>rmi: is assumed.
* </p>
* <li>
port - The port for the communications protocol.
* Treatment of the <tt>port parameter is implementation
* (protocol) specific. It is unused by the default local protocol,
* <em>local:. For the default remote protocol, rmi:,
* <tt>port indicates the port number of the rmiregistry
* on the target host and defaults to port 1099.
* </p>
* <li>
servername - The treatment of the Path, Query, and
* Fragment components of the HostIdentifier are implementation
* (protocol) dependent. These components are ignored by the
* default local protocol, <em>local:. For the default remote
* protocol, <em>rmi, the Path component is interpreted as
* the name of the RMI remote object. The Query component may
* contain an access mode specifier <em>?mode= specifying
* <em>"r" or "rw" access (write access currently
* ignored). The Fragment part is ignored.
* </p>
* </ul>
* <p>
* All HostIdentifier objects are represented as absolute, hierarchical URIs.
* The constructors accept relative URIs, but these will generally be
* transformed into an absolute URI specifying a default protocol. A
* HostIdentifier differs from a URI in that certain contractions and
* illicit syntactical constructions are allowed. The following are all
* valid HostIdentifier strings:
*
* <ul>
* <li>
< null > - transformed into "//localhost"
* <li>localhost - transformed into "//localhost"
* <li>hostname - transformed into "//hostname"
* <li>hostname:port - transformed into "//hostname:port"
* <li>proto:hostname - transformed into "proto://hostname"
* <li>proto:hostname:port - transformed into
* "proto://hostname:port"</p>
* <li>
proto://hostname:port
* </ul>
* </p>
*
* @see URI
* @see VmIdentifier
*
* @author Brian Doherty
* @since 1.5
*/
public class HostIdentifier {
private URI uri;
/**
* creates a canonical representation of the uriString. This method
* performs certain translations depending on the type of URI generated
* by the string.
*/
private URI canonicalize(String uriString) throws URISyntaxException {
if ((uriString == null) || (uriString.compareTo("localhost") == 0)) {
uriString = "//localhost";
return new URI(uriString);
}
URI u = new URI(uriString);
if (u.isAbsolute()) {
if (u.isOpaque()) {
/*
* this code is here to deal with a special case. For ease of
* use, we'd like to be able to handle the case where the user
* specifies hostname:port, not requiring the scheme part.
* This introduces some subtleties.
* hostname:port - scheme = hostname
* - schemespecificpart = port
* - hostname = null
* - userinfo=null
* however, someone could also enter scheme:hostname:port and
* get into this code. the strategy is to consider this
* syntax illegal and provide some code to defend against it.
* Basically, we test that the string contains only one ":"
* and that the ssp is numeric. If we get two colons, we will
* attempt to insert the "//" after the first colon and then
* try to create a URI from the resulting string.
*/
String scheme = u.getScheme();
String ssp = u.getSchemeSpecificPart();
String frag = u.getFragment();
URI u2 = null;
int c1index = uriString.indexOf(":");
int c2index = uriString.lastIndexOf(":");
if (c2index != c1index) {
/*
* this is the scheme:hostname:port case. Attempt to
* transform this to scheme://hostname:port. If a path
* part is part of the original strings, it will be
* included in the SchemeSpecificPart. however, the
* fragment part must be handled separately.
*/
if (frag == null) {
u2 = new URI(scheme + "://" + ssp);
} else {
u2 = new URI(scheme + "://" + ssp + "#" + frag);
}
return u2;
}
/*
* here we have the <string>: case, possibly with
* optional path and fragment components. we assume that
* the part following the colon is a number. we don't check
* this condition here as it will get detected later anyway.
*/
u2 = new URI("//" + uriString);
return u2;
} else {
return u;
}
} else {
/*
* This is the case where we were given a hostname followed
* by a path part, fragment part, or both a path and fragment
* part. The key here is that no scheme part was specified.
* For this case, if the scheme specific part does not begin
* with "//", then we prefix the "//" to the given string and
* attempt to create a URI from the resulting string.
*/
String ssp = u.getSchemeSpecificPart();
if (ssp.startsWith("//")) {
return u;
} else {
return new URI("//" + uriString);
}
}
}
/**
* Create a HostIdentifier instance from a string value.
*
* @param uriString a string representing a target host. The syntax of
* the string must conform to the rules specified in the
* class documentation.
*
* @throws URISyntaxException Thrown when the uriString or its canonical
* form is poorly formed. This exception may
* get encapsulated into a MonitorException in
* a future version.
*
*/
public HostIdentifier(String uriString) throws URISyntaxException {
uri = canonicalize(uriString);
}
/**
* Create a HostIdentifier instance from component parts of a URI.
*
* @param scheme the {@link URI#getScheme} component of a URI.
* @param authority the {@link URI#getAuthority} component of a URI.
* @param path the {@link URI#getPath} component of a URI.
* @param query the {@link URI#getQuery} component of a URI.
* @param fragment the {@link URI#getFragment} component of a URI.
*
* @throws URISyntaxException Thrown when the uriString or its canonical
* form is poorly formed. This exception may
* get encapsulated into a MonitorException in
* a future version.
* @see URI
*/
public HostIdentifier(String scheme, String authority, String path,
String query, String fragment)
throws URISyntaxException {
uri = new URI(scheme, authority, path, query, fragment);
}
/**
* Create a HostIdentifier instance from a VmIdentifier.
*
* The necessary components of the VmIdentifier are extracted and
* reassembled into a HostIdentifier. If a "file:" scheme (protocol)
* is specified, the the returned HostIdentifier will always be
* equivalent to HostIdentifier("file://localhost").
*
* @param vmid the VmIdentifier use to construct the HostIdentifier.
*/
public HostIdentifier(VmIdentifier vmid) {
/*
* Extract all components of the VmIdentifier URI except the
* user-info part of the authority (the lvmid).
*/
StringBuilder sb = new StringBuilder();
String scheme = vmid.getScheme();
String host = vmid.getHost();
String authority = vmid.getAuthority();
// check for 'file:' VmIdentifiers and handled as a special case.
if ((scheme != null) && (scheme.compareTo("file") == 0)) {
try {
uri = new URI("file://localhost");
} catch (URISyntaxException e) { };
return;
}
if ((host != null) && (host.compareTo(authority) == 0)) {
/*
* this condition occurs when the VmIdentifier specifies only
* the authority (i.e. the lvmid ), and not a host name.
*/
host = null;
}
if (scheme == null) {
if (host == null) {
scheme = "local"; // default local scheme
} else {
/*
* rmi is the default remote scheme. if the VmIdentifier
* specifies some other protocol, this default is overridden.
*/
scheme = "rmi";
}
}
sb.append(scheme).append("://");
if (host == null) {
sb.append("localhost"); // default host name
} else {
sb.append(host);
}
int port = vmid.getPort();
if (port != -1) {
sb.append(":").append(port);
}
String path = vmid.getPath();
if ((path != null) && (path.length() != 0)) {
sb.append(path);
}
String query = vmid.getQuery();
if (query != null) {
sb.append("?").append(query);
}
String frag = vmid.getFragment();
if (frag != null) {
sb.append("#").append(frag);
}
try {
uri = new URI(sb.toString());
} catch (URISyntaxException e) {
// shouldn't happen, as we were passed a valid VmIdentifier
throw new RuntimeException("Internal Error", e);
}
}
/**
* Resolve a VmIdentifier with this HostIdentifier. A VmIdentifier, such
* as <em>1234 or 1234@hostname or any other string that
* omits certain components of the URI string may be valid, but is certainly
* incomplete. They are missing critical information for identifying the
* the communications protocol, target host, or other parameters. A
* VmIdentifier of this form is considered <em>unresolved. This method
* uses components of the HostIdentifier to resolve the missing components
* of the VmIdentifier.
* <p>
* Specified components of the unresolved VmIdentifier take precedence
* over their HostIdentifier counterparts. For example, if the VmIdentifier
* indicates <em>1234@hostname:2099 and the HostIdentifier indicates
* <em>rmi://hostname:1099/, then the resolved VmIdentifier will
* be <em>rmi://1234@hostname:2099. Any component not explicitly
* specified or assumed by the HostIdentifier, will remain unresolved in
* resolved VmIdentifier.
* <p>
* A VmIdentifier specifying a <em>file: scheme (protocol), is
* not changed in any way by this method.
*
* @param vmid the unresolved VmIdentifier.
* @return VmIdentifier - the resolved VmIdentifier. If vmid was resolved
* on entry to this method, then the returned
* VmIdentifier will be equal, but not identical, to
* vmid.
*/
public VmIdentifier resolve(VmIdentifier vmid)
throws URISyntaxException, MonitorException {
String scheme = vmid.getScheme();
String host = vmid.getHost();
String authority = vmid.getAuthority();
if ((scheme != null) && (scheme.compareTo("file") == 0)) {
// don't attempt to resolve a file based VmIdentifier.
return vmid;
}
if ((host != null) && (host.compareTo(authority) == 0)) {
/*
* this condition occurs when the VmIdentifier specifies only
* the authority (i.e. an lvmid), and not a host name.
*/
host = null;
}
if (scheme == null) {
scheme = getScheme();
}
URI nuri = null;
StringBuffer sb = new StringBuffer();
sb.append(scheme).append("://");
String userInfo = vmid.getUserInfo();
if (userInfo != null) {
sb.append(userInfo);
} else {
sb.append(vmid.getAuthority());
}
if (host == null) {
host = getHost();
}
sb.append("@").append(host);
int port = vmid.getPort();
if (port == -1) {
port = getPort();
}
if (port != -1) {
sb.append(":").append(port);
}
String path = vmid.getPath();
if ((path == null) || (path.length() == 0)) {
path = getPath();
}
if ((path != null) && (path.length() > 0)) {
sb.append(path);
}
String query = vmid.getQuery();
if (query == null) {
query = getQuery();
}
if (query != null) {
sb.append("?").append(query);
}
String fragment = vmid.getFragment();
if (fragment == null) {
fragment = getFragment();
}
if (fragment != null) {
sb.append("#").append(fragment);
}
String s = sb.toString();
return new VmIdentifier(s);
}
/**
* Return the Scheme, or protocol, portion of this HostIdentifier.
*
* @return String - the scheme for this HostIdentifier.
* @see URI#getScheme()
*/
public String getScheme() {
return uri.isAbsolute() ? uri.getScheme() : null;
}
/**
* Return the Scheme Specific Part of this HostIdentifier.
*
* @return String - the scheme specific part for this HostIdentifier.
* @see URI#getSchemeSpecificPart()
*/
public String getSchemeSpecificPart() {
return uri.getSchemeSpecificPart();
}
/**
* Return the User Info part of this HostIdentifier.
*
* @return String - the user info part for this HostIdentifier.
* @see URI#getUserInfo()
*/
public String getUserInfo() {
return uri.getUserInfo();
}
/**
* Return the Host part of this HostIdentifier.
*
* @return String - the host part for this HostIdentifier, or
* "localhost" if the URI.getHost() returns null.
* @see URI#getUserInfo()
*/
public String getHost() {
return (uri.getHost() == null) ? "localhost" : uri.getHost();
}
/**
* Return the Port for of this HostIdentifier.
*
* @return String - the port for this HostIdentifier
* @see URI#getPort()
*/
public int getPort() {
return uri.getPort();
}
/**
* Return the Path part of this HostIdentifier.
*
* @return String - the path part for this HostIdentifier.
* @see URI#getPath()
*/
public String getPath() {
return uri.getPath();
}
/**
* Return the Query part of this HostIdentifier.
*
* @return String - the query part for this HostIdentifier.
* @see URI#getQuery()
*/
public String getQuery() {
return uri.getQuery();
}
/**
* Return the Fragment part of this HostIdentifier.
*
* @return String - the fragment part for this HostIdentifier.
* @see URI#getFragment()
*/
public String getFragment() {
return uri.getFragment();
}
/**
* Return the mode indicated in this HostIdentifier.
*
* @return String - the mode string. If no mode is specified, then "r"
* is returned. otherwise, the specified mode is returned.
*/
public String getMode() {
String query = getQuery();
if (query != null) {
String[] queryArgs = query.split("\\+");
for (int i = 0; i < queryArgs.length; i++) {
if (queryArgs[i].startsWith("mode=")) {
int index = queryArgs[i].indexOf('=');
return queryArgs[i].substring(index+1);
}
}
}
return "r";
}
/**
* Return the URI associated with the HostIdentifier.
*
* @return URI - the URI.
* @see URI
*/
public URI getURI() {
return uri;
}
/**
* Return the hash code for this HostIdentifier. The hash code is
* identical to the hash code for the contained URI.
*
* @return int - the hashcode.
* @see URI#hashCode()
*/
public int hashCode() {
return uri.hashCode();
}
/**
* Test for quality with other objects.
*
* @param object the object to be test for equality.
* @return boolean - returns true if the given object is of type
* HostIdentifier and its URI field is equal to this
* object's URI field. Otherwise, returns false.
*
* @see URI#equals(Object)
*/
public boolean equals(Object object) {
if (object == this) {
return true;
}
if (!(object instanceof HostIdentifier)) {
return false;
}
return uri.equals(((HostIdentifier)object).uri);
}
/**
* Convert to a string representation. Conversion is identical to
* calling getURI().toString(). This may change in a future release.
*
* @return String - a String representation of the HostIdentifier.
*
* @see URI#toString()
*/
public String toString() {
return uri.toString();
}
}
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