XQuery创建BaseX数据库实例

文章目录

• XQuery创建BaseX数据库实例
• • 1、准备工作
  • 2、demo目录结构
  • 3、IDEA配置BaseX
  • 4、工具类BaseXClient
  • 5、Example

1、准备工作

开发工具：

• IDEA
• Oxygen

技术：

• Java
• BaseX
• Xpath
• Xquery

BaseX需要阅读的文档：

• https://github.com/BaseXdb/basex/blob/9/basex-examples/src/main/java/org/basex/examples/api/Example.java
• https://docs.basex.org/wiki/Table_of_Contents

2、demo目录结构

Base X相当于一个工具类，Example是我们写的创建XML数据库的例子。

3、IDEA配置BaseX

4、工具类BaseXClient

package com.linghu.util;import java.io.*;import java.net.InetSocketAddress;import java.net.Socket;import java.nio.charset.Charset;import java.security.MessageDigest;import java.security.NoSuchAlgorithmException;import java.util.ArrayList;/** * Java client for BaseX. * Works with BaseX 7.0 and later * * Documentation: https://docs.basex.org/wiki/Clients * * (C) BaseX Team 2005-22, BSD License */public final class BaseXClient implements Closeable {/** UTF-8 charset. */private static final Charset UTF8 = Charset.forName("UTF-8");/** Output stream. */private final OutputStream out;/** Input stream (buffered). */private final BufferedInputStream in;/** Socket. */private final Socket socket;/** Command info. */private String info;/** * Constructor. * @param host server name * @param port server port * @param username user name * @param password password * @throws */public BaseXClient(final String host, final int port, final String username, final String password) throws IOException {socket = new Socket();socket.setTcpNoDelay(true);socket.connect(new InetSocketAddress(host, port), 5000);in = new BufferedInputStream(socket.getInputStream());out = socket.getOutputStream();// receive server responsefinal String[] response = receive().split(":");final String code, nonce;if(response.length > 1) {// support for digest authenticationcode = username + ':' + response[0] + ':' + password;nonce = response[1];} else {// support for cram-md5 (Version < 8.0)code = password;nonce = response[0];}send(username);send(md5(md5(code) + nonce));// receive success flagif(!ok()) throw new IOException("Access denied.");}/** * Executes a command and serializes the result to an output stream. * @param command command * @param output output stream * @throws IOException Exception */public void execute(final String command, final OutputStream output) throws IOException {// send {Command}0send(command);receive(in, output);info = receive();if(!ok()) throw new IOException(info);}/** * Executes a command and returns the result. * @param command command * @return result * @throws IOException Exception */public String execute(final String command) throws IOException {final ByteArrayOutputStream os = new ByteArrayOutputStream();execute(command, os);return new String(os.toByteArray(), UTF8);}/** * Creates a query object. * @param query query string * @return query * @throws IOException Exception */public Query query(final String query) throws IOException {return new Query(query);}/** * Creates a database. * @param name name of database * @param input xml input * @throws IOException I/O exception */public void create(final String name, final InputStream input) throws IOException {send(8, name, input);}/** * Adds a document to a database. * @param path path to resource * @param input xml input * @throws IOException I/O exception */public void add(final String path, final InputStream input) throws IOException {send(9, path, input);}/** * Replaces a document in a database. * @param path path to resource * @param input xml input * @throws IOException I/O exception */public void replace(final String path, final InputStream input) throws IOException {send(12, path, input);}/** * Stores a binary resource in a database. * @param path path to resource * @param input xml input * @throws IOException I/O exception */public void store(final String path, final InputStream input) throws IOException {send(13, path, input);}/** * Returns command information. * @return string info */public String info() {return info;}/** * Closes the session. * @throws IOException Exception */@Overridepublic void close() throws IOException, IOException {send("exit");out.flush();socket.close();}/** * Checks the next success flag. * @return value of check * @throws IOException Exception */private boolean ok() throws IOException {out.flush();return in.read() == 0;}/** * Returns the next received string. * @return String result or info * @throws IOException I/O exception */private String receive() throws IOException {final ByteArrayOutputStream os = new ByteArrayOutputStream();receive(in, os);return new String(os.toByteArray(), UTF8);}/** * Sends a string to the server. * @param string string to be sent * @throws IOException I/O exception */private void send(final String string) throws IOException {out.write((string + '\0').getBytes(UTF8));}/** * Receives a string and writes it to the specified output stream. * @param input input stream * @param output output stream * @throws IOException I/O exception */private static void receive(final InputStream input, final OutputStream output)throws IOException {for(int b; (b = input.read()) > 0;) {// read next byte if 0xFF is receivedoutput.write(b == 0xFF " />.read() : b);}}/** * Sends a command, argument, and input. * @param code command code * @param path name, or path to resource * @param input xml input * @throws IOException I/O exception */private void send(final int code, final String path, final InputStream input) throws IOException {out.write(code);send(path);send(input);}/** * Sends an input stream to the server. * @param input xml input * @throws IOException I/O exception */private void send(final InputStream input) throws IOException {final BufferedInputStream bis = new BufferedInputStream(input);final BufferedOutputStream bos = new BufferedOutputStream(out);for(int b; (b = bis.read()) != -1;) {// 0x00 and 0xFF will be prefixed by 0xFFif(b == 0x00 || b == 0xFF) bos.write(0xFF);bos.write(b);}bos.write(0);bos.flush();info = receive();if(!ok()) throw new IOException(info);}/** * Returns an MD5 hash. * @param pw String * @return String */private static String md5(final String pw) {final StringBuilder sb = new StringBuilder();try {final MessageDigest md = MessageDigest.getInstance("MD5");md.update(pw.getBytes());for(final byte b : md.digest()) {final String s = Integer.toHexString(b & 0xFF);if(s.length() == 1) sb.append('0');sb.append(s);}} catch(final NoSuchAlgorithmException ex) {// should not occurex.printStackTrace();}return sb.toString();}/** * Inner class for iterative query execution. */public class Query implements Closeable {/** Query id. */private final String id;/** Cached results. */private ArrayList<byte[]> cache;/** Cache pointer. */private int pos;/** * Standard constructor. * @param query query string * @throws IOException I/O exception */Query(final String query) throws IOException {id = exec(0, query);}/** * Binds a value to an external variable. * @param name name of variable * @param value value * @throws IOException I/O exception */public void bind(final String name, final String value) throws IOException {bind(name, value, "");}/** * Binds a value with the specified type to an external variable. * @param name name of variable * @param value value * @param type type (can be an empty string) * @throws IOException I/O exception */public void bind(final String name, final String value, final String type) throws IOException {cache = null;exec(3, id + '\0' + name + '\0' + value + '\0' + type);}/** * Binds a value to the context item. * @param value value * @throws IOException I/O exception */public void context(final String value) throws IOException {context(value, "");}/** * Binds a value with the specified type to the context item. * @param value value * @param type type (can be an empty string) * @throws IOException I/O exception */public void context(final String value, final String type) throws IOException {cache = null;exec(14, id + '\0' + value + '\0' + type);}/** * Checks for the next item. * @return result of check * @throws IOException I/O exception */public boolean more() throws IOException {if(cache == null) {out.write(4);send(id);cache = new ArrayList<>();final ByteArrayOutputStream os = new ByteArrayOutputStream();while(in.read() > 0) {receive(in, os);cache.add(os.toByteArray());os.reset();}if(!ok()) throw new IOException(receive());pos = 0;}if(pos < cache.size()) return true;cache = null;return false;}/** * Returns the next item. * @return item string * @throws IOException I/O Exception */public String next() throws IOException {return more() ? new String(cache.set(pos++, null), UTF8) : null;}/** * Returns the whole result of the query. * @return query result * @throws IOException I/O Exception */public String execute() throws IOException {return exec(5, id);}/** * Returns query info in a string. * @return query info * @throws IOException I/O exception */public String info() throws IOException {return exec(6, id);}/** * Returns serialization parameters in a string. * @return query info * @throws IOException I/O exception */public String options() throws IOException {return exec(7, id);}/** * Closes the query. * @throws IOException I/O exception */@Overridepublic void close() throws IOException {exec(2, id);}/** * Executes the specified command. * @param code command code * @param arg argument * @return resulting string * @throws IOException I/O exception */private String exec(final int code, final String arg) throws IOException {out.write(code);send(arg);final String s = receive();if(!ok()) throw new IOException(receive());return s;}}}

5、Example

接下来开始创建数据库

package com.linghu.util;import java.io.IOException;import java.io.OutputStream;/** * This example shows how commands can be executed on a server. * * This example requires a running database server instance. * Documentation: https://docs.basex.org/wiki/Clients * * @author BaseX Team 2005-22, BSD License */public final class Example {/** * Main method. * @param args command-line arguments * @throws IOException I/O exception */public static void main(final String... args) throws IOException {// create sessiontry(BaseXClient session = new BaseXClient("localhost", 1984, "admin", "admin")) {session.query("db:create('Zhang')").execute();}}}