MXQuery的基本使用

最近在看XQuery，没到一个可以输入XML和XQuery显示结果的平台。用开源的MXQuery写了一个，以便可以看到结果学习XQuery的语法，函数，自定义函数等

package org.sz.xquery;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;

import ch.ethz.mxquery.contextConfig.CompilerOptions;
import ch.ethz.mxquery.contextConfig.Context;
import ch.ethz.mxquery.exceptions.MXQueryException;
import ch.ethz.mxquery.model.XDMIterator;
import ch.ethz.mxquery.query.PreparedStatement;
import ch.ethz.mxquery.query.XQCompiler;
import ch.ethz.mxquery.query.impl.CompilerImpl;
import ch.ethz.mxquery.xdmio.XDMSerializer;

public class XQTester {
	
	private static void testXQ(String query) throws Exception {
		boolean updateFiles = true;

		Context ctx = new Context();
		CompilerOptions options = new CompilerOptions();
		options.setSchemaAwareness(true);
		options.setUpdate(true);
		ctx.getStores().setUseUpdateStores(true);
		ctx.getStores().setSerializeStores(updateFiles);

		XQCompiler complier = new CompilerImpl();
		PreparedStatement statement;

		try {
			statement = complier.compile(ctx, query, options);
			XDMIterator result = statement.evaluate();

			XDMSerializer ip = new XDMSerializer();
			String _return = ip.eventsToXML(result);
			//去掉XML header
			int utf_end = _return.indexOf(">");
			_return = _return.substring(utf_end + 2, _return.length());
			log(_return);
		} catch (MXQueryException e) {
			MXQueryException.printErrorPosition(query, e.getLocation());
			System.err.println("Error:");
			throw e;
		}
	}
	
	private static<T extends Object> void log(T t) {
		//toString();
		System.out.println(t);
	}
	
	public static String getXQueryFromFile(URL url) {
		File file = new File(url.getFile());
		String suffix = getSuffix(file.getName());
		if (!suffix.equalsIgnoreCase("xq")) {
			throw new RuntimeException("目标文件不是.xq文件");
		}
		
		StringBuilder sb = new StringBuilder();
		
		try {
			String line = "";
			BufferedReader fis = new BufferedReader(new InputStreamReader
					(new FileInputStream(file)));
			while((line = fis.readLine()) != null) {
				sb.append(line);
				sb.append("\n");
			}
		} catch (FileNotFoundException e) {
			e.printStackTrace();
			throw new RuntimeException("目标不是文件");
		} catch (IOException ex) {
			ex.printStackTrace();
			throw new RuntimeException("目标文件错误");
		}
		return sb.toString();
	}
	
	private static String getSuffix(String fileName) {
		return fileName.substring(fileName.lastIndexOf(".") + 1);
	}
	
	public static void main(String[] args) throws Exception {
		//String queryPrices = "doc('prices.xml')//priceList[prod/@num = 557]" ;
		//String queryCatalog = "doc('catalog.xml')//name/substring(., 1, 3)";
		String  basePath = XQTester.class.getClassLoader().getResource(".").getPath();
		final String sep = File.separator;
		String xqString = "file:/" + basePath + "org" + sep + "sz" + sep + "fn" + sep + "add-element.xq"; 
		URL url = new URL(xqString);
		String fnDefine = getXQueryFromFile(url);
		String fnCall = fnDefine + "doc('catalog.xml')//product/functx:add-attribute(., 'attr', 1)";
		testXQ(fnCall);
	}
}

XQuery函数

declare namespace functx = "http://www.functx.com";
declare function functx:add-attribute
	($element as element(), $name as xs:string,
	 $value as xs:anyAtomicType?) as element() {
	 
	  element { node-name($element) }
	  		  { attribute {$name} {$value},
	  		    $element/@*,
	  		    $element/node() }
};