nameproxy.java

来自「java版ace,java程序员值得一看」· Java 代码 · 共 406 行

/*************************************************
 *
 * = PACKAGE
 *    netsvcs.Naming
 *
 * = FILENAME
 *    NameProxy.java
 *
 *************************************************/
package JACE.netsvcs.Naming;

import java.io.*;
import java.net.*;
import java.util.*;
import JACE.OS.*;
import JACE.SOCK_SAP.*;
import JACE.Connection.*;

/**
 * Proxy which clients can use to interact with the naming service.
 * Can be used with the Connector.
 *
 *@see JACE.Connection.Connector
 *@see NameAcceptor
 *@see NameHandler
 *
 *@author Everett Anderson
 */
public class NameProxy extends SvcHandler
{
  /**
   * Constructor, connects itself using a Connector.
   *
   *@param host name of the host of the naming service
   *@param port port to connect to on the host
   */
  public NameProxy (String host, int port)
    throws UnknownHostException, 
	   SocketException,
	   InstantiationException,
	   IllegalAccessException,
	   IOException
  {
    Connector c = new Connector ();
    c.open (host, port);
    c.connect (this);
  }

  /**
   * Default constructor.  Proxies created with this constructor must
   * be connected to use.
   */
  public NameProxy ()
  {
  }

  /**
   * Constructor taking a SOCKStream to use.
   *
   *@param sock SOCKStream already open to the naming service
   */
  public NameProxy (SOCKStream sock)
  {
    this.stream_ = sock;
  }

  /**
   * Initialize this proxy.  (Called by Connector)
   */
  public int open (Object obj)
  {
    connected_ = true;
    return 0;
  }

  /**
   * Close the proxy, shutting down the connection to the service.
   */
  public int close ()
  {
    if (!connected_)
      return 0;

    try {
      this.peer ().close ();
    } catch (IOException e) {
      return -1;
    } finally {
      connected_ = false;
    }

    return 0;
  }

  /**
   * Attempt to bind the given data pair
   * @param name      Name/key
   * @param value     Value to bind 
   *
   * @return   True iff bind is successful
   */
  public boolean bind(String name, String value) throws IOException
  {
    return this.bind(name, value, null, false);
  }

  /**
   * Attempt to bind the given data triplet
   * @param name      Name/key
   * @param value     Value to bind 
   * @param type      Type to bind (another string)
   *
   * @return   True iff the bind was successful
   */
  public boolean bind(String name, String value, String type) 
    throws IOException
  {
    return this.bind(name, value, type, false);
  }

  /**
   * The most generic of the bind methods.  Allows factoring out of 
   * common code.  Not public.
   */
  boolean bind (String name, String value, String type, boolean rebind) 
    throws IOException
  {
    // Create a new NameRequest with the desired info
    NameRequest request = 
      new NameRequest(rebind ? NameRequest.REBIND : NameRequest.BIND,
		      name,
		      value,
		      type,
		      null);

    // Send it to the naming service
    request.streamOutTo(this.stream_);

    // Create a reply
    NameReply reply = new NameReply();

    // Get the status of the bind from the naming service
    reply.streamInFrom(this.stream_);
      
    // Return true on success
    return (reply.type() == NameReply.SUCCESS ? true : false);
  }

  /**
   * Rebind a name and a value
   * @param name     Name/key
   * @param value    Bound value
   *
   * @return     True if the rebind was successful
   */
  public boolean rebind (String name, String value) throws IOException
  {
    return this.bind(name, value, null, true);
  }

  /** 
   * Rebind a name, value, and type
   * @param name     Name/key
   * @param value    Bound value
   * @param type     Bound type
   *
   * @return    True if rebind was successful
   */
  public boolean rebind (String name, String value, String type) 
    throws IOException
  {
    return this.bind(name, value, type, true);
  }
  /**
   * Look up information bound to the given key/name.
   *
   * @param  name     Name/key
   *
   * @return     Vector with three elements:
   *                 0   Name/key
   *                 1   Value
   *                 2   Type
   */
  public Vector resolve (String name) throws IOException
  {
    // Create a new NameRequest with the name & request type
    NameRequest request = new NameRequest(NameRequest.RESOLVE,
					  name,
					  null,
					  null,
					  null);

    // Send it to the naming service
    request.streamOutTo(this.stream_);

    // Get a response (hopefully with the value and type)
    request.streamInFrom(this.stream_);

    // Dump the result into a vector
    Vector result = new Vector();

    result.addElement(request.name());
    result.addElement(request.value());
    result.addElement(request.type());

      // Cut it down to the size we need
    result.trimToSize();

    return result;
  }

  /**
   * Remove the entry in the mapping corresponding to the given name/key.
   *
   * @param      name      Name/key
   *
   * @return     True if the unbind was successful
   */
  public boolean unbind (String name) throws IOException
  {
    NameRequest request = new NameRequest(NameRequest.UNBIND,
					  name,
					  null,
					  null,
					  null);
    // Send the request to the naming service
    request.streamOutTo(this.stream_);

    NameReply reply = new NameReply();

    // Get reply
    reply.streamInFrom(this.stream_);

    return (reply.type() == NameReply.SUCCESS ? true : false);
  }

  /**
   * Return a vector that's a list of names (Strings) that begin with
   * the given pattern
   * @param    pattern      Search pattern
   * @return   Vector       List of names
   */
  public Vector listNames (String pattern) throws IOException
  {
    return this.requestSimpleList(pattern, NameRequest.LIST_NAMES);
  }

  /**
   * Return a vector that's a list of types (Strings) that begin with
   * the given pattern
   * @param    pattern      Search pattern
   * @return   Vector       List of types
   */
  public Vector listTypes (String pattern) throws IOException
  {
    return this.requestSimpleList(pattern, NameRequest.LIST_TYPES);
  }

  /**
   * Return a vector that's a list of values (Strings) that begin with
   * the given pattern
   * @param    pattern      Search pattern
   * @return   Vector       List of values
   */
  public Vector listValues (String pattern) throws IOException
  {
    return this.requestSimpleList(pattern, NameRequest.LIST_VALUES);
  }

  /**
   * Non-public generic list gathering method
   */
  Vector requestSimpleList (String pattern, int type) throws IOException
  {
    // Make request for a list of the given type
    NameRequest request = new NameRequest(type,
					  pattern,
					  null,
					  null,
					  null);
    request.streamOutTo(this.stream_);

      // Allocate and reuse the DIS here rather than each time we call
      // streamInFrom
    DataInputStream dis = new DataInputStream(this.stream_.inputStream());

    request.streamInFrom(dis);
    Vector result = new Vector();

    // Add elements until there's a null message with the MAX_ENUM
    // request type
    while (request.requestType() != NameRequest.MAX_ENUM) {
      if (type == NameRequest.LIST_NAMES)
	result.addElement(new String(request.name()));
      else
	if (type == NameRequest.LIST_VALUES)
	  result.addElement(new String(request.value()));
	else
	  result.addElement(new String(request.type()));

      request.streamInFrom(dis);
    }

    // Adjust the vector to the minimal size
    result.trimToSize();

    return result;
  }

  /**
   * Get a vector with the entire data set for entries whose name begins with
   * the given pattern.  Each element in the vector is another vector
   * with the following layout:
   *               0     Name/key
   *               1     Value
   *               2     Type
   *
   * @param    pattern     Search pattern
   * @return   Vector of vectors
   */
  public Vector listNameEntries (String pattern) throws IOException
  {
    return this.requestComplexList(pattern, NameRequest.LIST_NAME_ENTRIES);
  }

  /**
   * Get a vector with the entire data set for entries whose value begins with
   * the given pattern.  Each element in the vector is another vector
   * with the following layout:
   *               0     Name/key
   *               1     Value
   *               2     Type
   *
   * @param    pattern     Search pattern
   * @return   Vector of vectors
   */
  public Vector listValueEntries (String pattern) throws IOException
  {
    return this.requestComplexList(pattern, NameRequest.LIST_VALUE_ENTRIES);
  }

  /**
   * Get a vector with the entire data set for entries whose type begins with
   * the given pattern.  Each element in the vector is another vector
   * with the following layout:
   *               0     Name/key
   *               1     Value
   *               2     Type
   *
   * @param    pattern     Search pattern
   * @return   Vector of vectors
   */

  public Vector listTypeEntries (String pattern) throws IOException
  {
    return this.requestComplexList(pattern, NameRequest.LIST_TYPE_ENTRIES);
  }

  /**
   * Non-public generic method for getting a a vector of vectors with the 
   * entire data set for entries fitting the given pattern.
   */
  Vector requestComplexList (String pattern, int type) throws IOException
  {
    // Create request with desired type
    NameRequest request = new NameRequest(type,
					  pattern,
					  null,
					  null,
					  null);
    // Send it to the naming service
    request.streamOutTo(this.stream_);

    // Allocate the DIS here and reuse
    DataInputStream dis = new DataInputStream(this.stream_.inputStream());

    // Get the first response
    request.streamInFrom(dis);
    Vector result = new Vector();

    // Loop while we don't see a null response with the MAX_ENUM 
    //request type
    while (request.requestType() != NameRequest.MAX_ENUM) {
      Vector entry = new Vector();

      // Create an element in the main vector
      entry.addElement(request.name());
      entry.addElement(request.value());
      entry.addElement(request.type());
      entry.trimToSize();
	
      // Add it to the result
      result.addElement(entry);

      // Get another NameRequest
      request.streamInFrom(dis);
    }

    result.trimToSize();

    return result;
  }

  private boolean connected_ = false;
}