mmqueryhelper.java

数字图书馆的互操作接口

package dli2fe.helpers;

/**
 * Title:        Digial Library Interoperable Interface Fudan Edition
 * Description:  This project contains all the classes required for DLI2FE interface. Developers use these classes to implement the wrapper and client side codes. The basic functions of DLI2FE is as follows:
 * Search: Search a digital library source site.
 * Metadata: Fetch metadata for a site.
 * ResultAccess: Get results for a given query.
 * DLI2FE uses Dublin Core as the basic attribute model, DAV/DASL as the general XML-based query language and CORBA as distributed object transportation mechanism.
 * Copyright:    Copyright (c) 2001
 * Company:      Fudan University
 * @author Carl Tao
 * @version 1.0
 */
import java.util.*;
import dli2fe.DLI2FEException;
import java.net.*;
import java.io.*;
import dli2fe.sample.MultimediaMeta;

// 一次多媒体查询的接口类
public class MMQueryHelper {
  // 缓存每个服务对应的DID与素材对应表。
  static Hashtable serviceSampleURL = new Hashtable();

  String baseURL;
  //String prefixForID;
  Vector results;         // n_m(String类型) format result list
  Vector listDID;         // document id(Integer类型) list for result

  public MMQueryHelper(String queryURL) throws DLI2FEException {
    if (serviceSampleURL.get(queryURL)==null) {
      String url = queryURL + "ServiceType=" + MultimediaMeta.serviceTypeDID+ "&OID=001";
      try {
        URLConnection con = new URL(url).openConnection();
        con.setDefaultUseCaches(false);
        con.setUseCaches(false);
        con.setDoInput(true);
        con.connect();
        DataInputStream in = new DataInputStream(con.getInputStream());
        int num = in.readInt();
        // should not be zero for document 1
        if (num == 0)
          throw new DLI2FEException(DLI2FEException.NOT_IMPLEMENTED_EXC, "Multimediasearch service error: zero results");
        Hashtable ht = new Hashtable();
        Vector v = new Vector();
        for (int i = 0; i<num; i++) {
          String rURL = in.readUTF();
          v.add(rURL.substring(Math.max(rURL.lastIndexOf('/'), rURL.lastIndexOf('\\')) + 1, rURL.lastIndexOf('.')));
        }
        in.close();
        ht.put(new Integer(1), v);
        serviceSampleURL.put(queryURL, ht);
      } catch (IOException ex) {
        throw new DLI2FEException(DLI2FEException.NOT_IMPLEMENTED_EXC, "Multimediasearch service error: "+ ex.toString());
      }
    }

    baseURL = queryURL;
    results = new Vector();
    listDID = new Vector();
  }

  // 查询多媒体
  public void searchMultimedia(String sample, String pfeedback, String nfeedback) throws DLI2FEException {
    try {
      URLConnection con = new URL(baseURL + "ServiceType=" + MultimediaMeta.serviceType +
        "&SampleURL=" + noNull(sample) + "&PFeedback=" + noNull(pfeedback) + "&NFeedback=" + noNull(nfeedback)).openConnection();
      System.out.println("GET " + baseURL + "ServiceType=" + MultimediaMeta.serviceType +
        "&SampleURL=" + noNull(sample) + "&PFeedback=" + noNull(pfeedback) + "&NFeedback=" + noNull(nfeedback));
      con.setDefaultUseCaches(false);
      con.setUseCaches(false);
      con.setDoInput(true);
      con.connect();
      DataInputStream in = new DataInputStream(con.getInputStream());
      int num = in.readInt();
      results = new Vector();
      for (int i=0; i<num; i++) {
        String rURL = in.readUTF();
        results.add(rURL.substring(Math.max(rURL.lastIndexOf('/'), rURL.lastIndexOf('\\')) + 1, rURL.lastIndexOf('.')));
      }
    } catch (IOException ex) {
      throw new DLI2FEException(DLI2FEException.SERVER_ERROR_EXC, "Multimedia Search service error: " + ex.toString());
    }
    generateListDID();
  }

  // 根据文档标志符查询素材标志符
  public void getIdmms(int did) throws DLI2FEException {
    // 首先从缓存中去取
    Vector v = (Vector)((Hashtable)serviceSampleURL.get(baseURL)).get(new Integer(did));
    if (v != null) {
      results = v;
      generateListDID();
      return;
    }
    String strDID = String.valueOf(did);
    int len = strDID.length();
    for (int i=0; i<3-len; i++)
      strDID = "0"+strDID;
    try {
      URLConnection con = new URL(baseURL + "ServiceType=" + MultimediaMeta.serviceTypeDID + "&OID=" + strDID).openConnection();
      //System.out.println("GET " + baseURL + "ServiceType=" + MultimediaMeta.serviceTypeDID + "&OID=" + strDID);
      con.setDefaultUseCaches(false);
      con.setUseCaches(false);
      con.setDoInput(true);
      con.connect();
      DataInputStream in = new DataInputStream(con.getInputStream());
      int num = in.readInt();
      results = new Vector();
      for (int i=0; i<num; i++) {
        String rURL = in.readUTF();
        results.add(rURL.substring(Math.max(rURL.lastIndexOf('/'), rURL.lastIndexOf('\\')) + 1, rURL.lastIndexOf('.')));
      }
    } catch (IOException ex) {
      throw new DLI2FEException(DLI2FEException.SERVER_ERROR_EXC, "Multimedia SearchByDID service error: " + ex.toString());
    }
    ((Hashtable)serviceSampleURL.get(baseURL)).put(new Integer(did), results);
    generateListDID();
  }

  public Vector getResults() {
    return results;
  }

  public Vector getListDID() {
    return listDID;
  }

  String noNull(String inStr) {
    if (inStr == null)
      return "";
    return inStr;
  }
  void generateListDID() {
    listDID = new Vector();
    Hashtable ht = new Hashtable();
    for (int i=0; i<results.size(); i++) {
      String result = (String)results.elementAt(i);
      Integer did = new Integer(Integer.parseInt(result.substring(0, result.indexOf('_'))));
      if (ht.get(did) == null) {
        ht.put(did, result);
        listDID.add(did);     // only add the first time to form the order of documents
      }
    }
  }

  public static void main(String[] args) {
    try {
      MMQueryHelper mmqh = new MMQueryHelper("http://localhost:8080/multimediasearch/MultimediaSearch?");
      //mmqh.searchMultimedia("http://localhost:8080/multimediasearch/tempsample/first.jpg", "", "");
      mmqh.getIdmms(23);
      Vector results = mmqh.getResults();
      for (int i=0; i<results.size(); i++) {
        System.out.println((String)results.elementAt(i));
      }
    } catch (Exception ex) {
      ex.printStackTrace();
    }
  }
}