如何在Java中制作一个小型搜索引擎

Question

I want to make a small search engine.consider that I have 5 text files and I want to find the word "book" in whole files.How should i start? I am a senior and I have a little information about trees and iterators and I have to use these concepts.could anyone help me with the code?

Answer 1

You do not need any knowledge about trees and iterators. It is all about recursive calls, no more.

Here is the pure Java code with no dependencies or frameworks used: just pass directory or file name and word you'd like to search as parameters when call it.

package com.mytests;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;

public class Sometest {

public static void main(String[] args) {

    if (null == args || args.length < 2) {
        System.err.println("Not enough parameters. Please provide searchPath and searchWord.");
        return;
    }

    String pathToSearch = args[0];
    String wordToSearch = args[1];

    System.out.println("Start search word " + wordToSearch + " in " + pathToSearch);

    File searchFile = new File(pathToSearch);

    if (!searchFile.exists()) {
        System.err.println("Cannot find given file or directory to search :" + pathToSearch + ": ");
    }

    int matchesCount = 0;
    matchesCount = searchWord(searchFile, wordToSearch, matchesCount);

    System.out.println("Search completed. Matches found : " + matchesCount);

}

private static int searchWord(File sourceFile, String wordToSearch, int matchesCount) {

    int count = matchesCount;
    if (sourceFile.isDirectory()) {
        String[] sourceFilesArray = sourceFile.list();

        for (String nextFileName : sourceFilesArray) {
            File nextFile = new File(sourceFile.getAbsolutePath() + System.getProperty("file.separator")
                    + nextFileName);
            count = searchWord(nextFile, wordToSearch, count);
        }
    } else {
        try {
            BufferedReader sourceFileReader = new BufferedReader(new FileReader(sourceFile));
            String nextLine = "";
            while (true) {
                nextLine = sourceFileReader.readLine();
                if (null == nextLine) {
                    break;
                }

                if (nextLine.contains(wordToSearch)) {
                    System.out.println("found in -> " + sourceFile.getCanonicalPath());
                    count++;
                }

            }
            sourceFileReader.close();
        } catch (Exception e) {
            System.err.println("Error while reading file " + sourceFile.getAbsolutePath() + " : " + e.getMessage());
        }
    }

    return count;
}

}

I'm just wondering what is a purpose? personal education?