XQuery は BaseX データベース インスタンスを作成します
記事ディレクトリ
1. 準備
開発ツール:
IDEAOxygen
テクノロジー：
JavaBaseXXpathXquery
BaseX に関して読む必要があるドキュメント:
- 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. デモのディレクトリ構造
Base Xツールクラスに相当し、Example弊社で作成したXMLデータベースの作成例です。
3. IDEA が BaseX を構成する
4. ツールクラス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 response
final String[] response = receive().split(":");
final String code, nonce;
if(response.length > 1) {
// support for digest authentication
code = 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 flag
if(!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}0
send(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
*/
@Override
public 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 received
output.write(b == 0xFF ? input.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 0xFF
if(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 occur
ex.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
*/
@Override
public 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、例
次にデータベースの作成を開始します
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 session
try(BaseXClient session = new BaseXClient("localhost", 1984, "admin", "admin")) {
session.query("db:create('Zhang')").execute();
}
}
}
