用有向图拓扑排序整理foreign key table create顺序

package neoe.tool;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
public class FindSqlCreateOrder {
	/**
	 * @param args
	 * @throws Exception
	 */
	public static void main(String[] args) throws Exception {
		new FindSqlCreateOrder().run();
	}
	private void run() throws Exception {
		File[] fs = new File("C:/DBscript/")
				.listFiles();
		for (File f : fs) {
			String fn = f.getName();
			if (fn.endsWith(".SQL")) {
				parseCreateSql(f);
			}
		}
		findOrder();
	}
	private void findOrder() {
		while (true) {
			List<String> out = new ArrayList<String>();
			for (String tab : tables) {
				if (noRef(tab)) {
					out.add(tab);
					delRef(tab);
				}
			}
			if (out.size() == 0) {
				break;
			}
			order.addAll(out);
			tables.removeAll(out);
		}
		if (tables.size() != 0) {
			System.out.println("remain " + tables);
		}
		for (String s : order) {
			System.out.println(s);
		}
		Collections.reverse(order);
		System.out.println("---rev-----");
		for (String s : order) {
			System.out.println("drop table "+s+";");
		}
	}
	private void delRef(String tab) {
		for (int i=refs1.size()-1;i>=0;i--){
			if (refs1.get(i).equals(tab)){
				refs1.remove(i);
				refs2.remove(i);
			}
		}		
	}
	private boolean noRef(String tab) {
		return !refs2.contains(tab);
	}
	private void parseCreateSql(File f) throws Exception {
		String table = f.getName().substring(0, f.getName().length() - 4)
				.toUpperCase();
		addTable(table);
		BufferedReader in = new BufferedReader(new FileReader(f));
		String line;
		while ((line = in.readLine()) != null) {
			if (line.indexOf("FOREIGN KEY") >= 0) {
				int p1 = line.indexOf("REFERENCES");
				int p2 = line.indexOf(" ", p1 + "REFERENCES".length() + 1);
				String ref = line.substring(p1 + "REFERENCES".length() + 1, p2);
				addRef(table, ref);
			}
		}
		in.close();
	}
	private void addRef(String table, String ref) {
		System.out.println(table + "<" + ref);
		if (!table.equals(ref)){
			refs1.add(ref);
			refs2.add(table);	
		}		
	}
	private void addTable(String table) {
		System.out.println("#" + table);
		tables.add(table);
	}
	List<String> order = new ArrayList<String>();
	private List<String> tables = new ArrayList<String>();
	private List<String> refs1 = new ArrayList<String>();
	private List<String> refs2 = new ArrayList<String>();
}