treesetsort.java

数据库的加密以及密态查询

import java.util.TreeSet;
import java.util.Comparator;
import java.util.Vector;
import java.util.Collections;
import java.sql.Date;

public class TreeSetSort implements Comparator {
	public int compare(Object a, Object b) {
		int i, j, k;
		String adate, bdate;
		adate = (String)a;
		bdate = (String)b;
		// find index of beginning of last name
		i = adate.indexOf(',');
		j = bdate.indexOf(',');
		k = adate.substring(0, i).compareTo(bdate.substring(0, j));
		if (k == 0) // last names match, check entire name
			return adate.compareTo(bdate);
		else
			return k;
	}

    public static void main(String[] args) {
        TreeSet ts = new TreeSet(new TreeSetSort());
        ts.add("1984-01-23, 1");
	ts.add("1983-01-23, 2");
	ts.add("1984-08-15, 3");
	ts.add("1988-09-8, 3");
	ts.add("1997-04-27, 4");
	ts.add("1984-08-15, 7");
	//Collections.sort(ts, new TreeSetSort());
        System.out.println(ts.toString());
    }
}