Java實現讀取Doxygen查詢功能的索引檔案。

Doxygen的Search功能的前端是使用search.php實現的。我使用java代替php,讀取search.idx

用Doxygen產生原始碼的文檔需要設定檔，設定檔內有search選項：

#---------------------------------------------------------------------------
# Configuration::additions related to the search engine  
#---------------------------------------------------------------------------
SEARCHENGINE           = YES

如果YES，則在產生文檔時會產生search.idx索引檔案和search.php查詢介面。

search.php會將要查詢的字串作為輸入參數調用用php實現的查詢function search($file,$word,&$statsList)

我將該方法以及該方法調用的其他方法翻譯成java語言,如下：

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.util.TreeMap;
import java.util.ArrayList;
import java.util.StringTokenizer;
/**
 * @author tyrone
 *
 * TODO To change the template for this generated type comment go to
 * Window - Preferences - Java - Code Style - Code Templates
 */
public class Search {
 /**讀取search.idx*/
 public Search(File fp){
     String content="";
     try{
      BufferedInputStream In = new BufferedInputStream(new FileInputStream( fp ));
      int len=In.available();
      this.Content=new byte[len];
      In.read(this.Content);
      Scontent=new String(this.Content);
     }catch(Exception ex){
      ex.printStackTrace();
     }
     this.Scontent=new String(this.Content);
     //this.Content=content.getBytes();
 }
 private byte[] Content;
 
 private String Scontent;
 
 private int Index;
 
 private void setIndex(int index){
  this.Index=index;
 }
 
 private int getIndex(){
  return this.Index;
 }
 
 private byte[] getContent(){
  return this.Content;
 }
 private String getScontent(){
  return this.Scontent;
 }
 /**
  * 查詢
  * @param word
  * @param statsList
  * @return
  */
 public ArrayList Searching(String word,ArrayList statsList){
  this.setIndex(computeIndex(word));

  TreeMap stat=new TreeMap();
  int start=0;
  int count=0;
  byte[] buf=new byte[4];
  if (this.getIndex()!=-1) // found a valid index
  {
      int totalHi=0;
      int totalFreqHi=0;
      int totalFreqLo=0;

   //read 4 bytes skip header
      int index=readInt(this.getIndex()*4+4);
      //int index=readInt(8,this.getIn());
      if (index>0){// found words matching the hash key
        start=statsList.size();
        count=start;
        String w=readString(index);
        while (w.length()!=0){
          int statIdx = readInt(this.getIndex());
          if (w.compareTo(word)>=0){
              // found word that matches (as substring)
           stat.put("word",word);
           stat.put("match",w);
           stat.put("index",new Integer(statIdx));
           if (w.length()==word.length())
            stat.put("full","true");
           else
            stat.put("full","false");
           statsList.add(stat);
          }
          w = readString(this.getIndex());
        }

        for (count=start;count<statsList.size();count++)
        {
         TreeMap statInfo = (TreeMap)statsList.get(count);
          int multiplier = 1;
          // whole word matches have a double weight
          String full=(String)statInfo.get("full");
          if (full.compareTo("true")==0) multiplier=2;
          Integer inte=(Integer)statInfo.get("index");
          int numDocs = readInt(inte.intValue());
          TreeMap[] docInfo =new TreeMap[numDocs];
          // read docs info + occurrence frequency of the word
          for (int i=0;i<numDocs;i++)
          {
            int idx=readInt(this.getIndex());
            int freq=readInt(this.getIndex());
            docInfo[i]=new TreeMap();
            docInfo[i].put("idx",new Integer(idx));
            docInfo[i].put("freq",new Integer(freq>>1));
            docInfo[i].put("rank",new Double(0.0));
            docInfo[i].put("hi",new Integer(freq&1));
            if ((freq&1)>0) // word occurs in high priority doc
            {
              totalHi++;
              totalFreqHi+=freq*multiplier;
            }
            else // word occurs in low priority doc
            {
              totalFreqLo+=freq*multiplier;
            }
          }
          // read name and url info for the doc
          for (int i=0;i<numDocs;i++)
          {
            Integer idx=(Integer)docInfo[i].get("idx");
            docInfo[i].put("name",readString(idx.intValue()));
            docInfo[i].put("url",readString(this.getIndex()));
          }
          statInfo.put("docs",docInfo);
        }
       
        int totalFreq=(totalHi+1)*totalFreqLo +totalFreqHi;
        for (count=start;count<statsList.size();count++)
        {
         TreeMap statInfo =(TreeMap)statsList.get(count);
          int multiplier = 1;
          // whole word matches have a double weight
          String full=(String)statInfo.get("full");
          if (full.compareTo("true")==0) multiplier=2;
          TreeMap[] docInfo=(TreeMap[])statInfo.get("docs");
          for (int i=0;i<docInfo.length;i++)
          {
            // compute frequency rank of the word in each doc
            Integer inte=(Integer)docInfo[i].get("freq");
            int freq=inte.intValue();
            inte=(Integer)docInfo[i].get("hi");
            if (inte.intValue()>0){
             docInfo[i].put("rank",new Double((freq*multiplier+totalFreqLo)/totalFreq));
            }else{
             docInfo[i].put("rank",new Double((freq*multiplier)/totalFreq));
            }
          }
        }
      }
    }
    return statsList;
 } 

private int readInt(int index){
  
  byte[] buf1;
  int b1,b2,b3,b4;
  try{
   b1=this.getContent()[index];
   b2=this.getContent()[index+1];
   b3=this.getContent()[index+2];
   b4=this.getContent()[index+3];

/**費了好大勁，才知道java的byte轉化為ASCII碼是16位，而idx存的是8位的。*/
   b1=b1&0xff;
   b2=b2&0xff;
   b3=b3&0xff;
   b4=b4&0xff;
   index=index+4;
   this.setIndex(index);
   return (b1<<24)|(b2<<16)|(b3<<8)|(b4);
  }catch(Exception ex){
   
  }
  return -1;
 }
 private String readString(int index){
  String result="";
  byte[] re=new byte[60];
  int i=0;
  byte ind;
  while((ind=this.getContent()[index])!=0){
   re[i]=ind;
   if (i==59){
    result=result+new String(re);
    i=0;
   }else{
    i++;
   }
   index++;
  }
  result=result+new String(re,0,i);
  this.setIndex(++index);
  return result;
 }
 /**
  *
  * @param word
  * @return
  */
 private int computeIndex(String word)
 {
  int hi;
  int lo;
  if (word.length()<2) return -1;
  // high char of the index
    hi =word.charAt(0);
    if (hi==0) return -1;
    // low char of the index
    lo =word.charAt(1);
    if (lo==0) return -1;
    // return index
    return hi*256+lo;
 }
 

/**args[0]=search.idx, args[1]="word1+word2+... " ,如何顯示statsList 結果已經不重要了*/

public static void main(String[] args){
  Search se=new Search(new File(args[0]));
  StringTokenizer st = new StringTokenizer(args[1],"+");
  ArrayList result=new ArrayList();
  while (st.hasMoreTokens()){
   result=se.Searching(st.nextToken(),result);
  }
  for(int i=0;i<result.size();i++){
   TreeMap tm=(TreeMap)result.get(i);
   TreeMap[] docs=(TreeMap[])tm.get("docs");
   for (int l=0;l<docs.length;l++){
    System.out.println((String)docs[l].get("name"));
    System.out.println((String)docs[l].get("url"));    
   }
  }
 }
}