Java tutorial
/* * Copyright Andrei Goumilevski * This file licensed under GPLv3 for non commercial projects * GPLv3 text http://www.gnu.org/licenses/gpl-3.0.html * For commercial usage please contact me * gmlvsk2@gmail.com * */ package com.cyslab.craftvm.rest.mongo; import static javax.servlet.http.HttpServletResponse.SC_BAD_REQUEST; import static javax.servlet.http.HttpServletResponse.SC_NOT_FOUND; import static javax.servlet.http.HttpServletResponse.SC_UNAUTHORIZED; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import com.mongodb.DB; import com.mongodb.DBCollection; import com.mongodb.DBCursor; import com.mongodb.DBObject; import com.mongodb.util.JSON; import com.mongodb.util.JSONParseException; @SuppressWarnings("serial") @WebServlet(name = "QueryServlet") public class AggregateServlet extends SkeletonMongodbServlet { private final static int MAX_FIELDS_TO_RETURN = 1000; private static final Logger log = LoggerFactory.getLogger(AggregateServlet.class); private ThreadLocal<StringBuilder> tl = new ThreadLocal<StringBuilder>() { @Override protected synchronized StringBuilder initialValue() { return new StringBuilder(1024 * 4); } }; // -------------------------------- @Override public void init() throws ServletException { String name = getServletName(); log.trace("init() " + name); } // -------------------------------- @Override public void destroy() { String name = getServletName(); log.trace("destroy() " + name); } // POST // ------------------------------------ @Override protected void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException { log.trace("doPost()"); if (!can_read(req)) { res.sendError(SC_UNAUTHORIZED); return; } InputStream is = req.getInputStream(); String db_name = req.getParameter("dbname"); String col_name = req.getParameter("colname"); if (db_name == null || col_name == null) { error(res, SC_BAD_REQUEST, Status.get("param name missing")); return; } String skip = req.getParameter("skip"); String limit = req.getParameter("limit"); DB db = mongo.getDB(db_name); DBCollection col = db.getCollection(col_name); BufferedReader r = null; DBObject q = null, sort = null; try { r = new BufferedReader(new InputStreamReader(is)); String data = r.readLine(); if (data == null) { error(res, SC_BAD_REQUEST, Status.get("no data")); return; } try { q = (DBObject) JSON.parse(data); } catch (JSONParseException e) { error(res, SC_BAD_REQUEST, Status.get("can not parse data")); return; } // sort param data = r.readLine(); if (data != null) { try { sort = (DBObject) JSON.parse(data); } catch (JSONParseException e) { error(res, SC_BAD_REQUEST, Status.get("can not parse sort arg")); return; } } } finally { if (r != null) r.close(); } DBCursor c; if (sort == null) c = col.find(q); else c = col.find(q).sort(sort); if (c == null) { error(res, SC_NOT_FOUND, Status.get("no documents found")); return; } res.setIntHeader("X-Documents-Count", c.count()); if (limit != null) { try { c.limit(Math.min(Integer.parseInt(limit), MAX_FIELDS_TO_RETURN)); } catch (NumberFormatException e) { error(res, SC_BAD_REQUEST, Status.get("can not parse limit")); c.close(); return; } } else c.limit(MAX_FIELDS_TO_RETURN); if (skip != null) { try { c.skip(Integer.parseInt(skip)); } catch (NumberFormatException e) { error(res, SC_BAD_REQUEST, Status.get("can not parse skip")); c.close(); return; } } StringBuilder buf = tl.get(); // reset buf buf.setLength(0); int no = 0; buf.append("["); while (c.hasNext()) { DBObject o = c.next(); JSON.serialize(o, buf); buf.append(","); no++; } if (no > 0) buf.setCharAt(buf.length() - 1, ']'); else buf.append(']'); res.setIntHeader("X-Documents-Returned", no); out_str(req, buf.toString(), "application/json"); } // GET // ------------------------------------ @Override protected void doGet(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException { log.trace("doGet()"); if (!can_read(req)) { res.sendError(SC_UNAUTHORIZED); return; } String db_name = req.getParameter("dbname"); String col_name = req.getParameter("colname"); if (db_name == null || col_name == null) { error(res, SC_BAD_REQUEST, Status.get("param name missing")); return; } String skip = req.getParameter("skip"); String limit = req.getParameter("limit"); DB db = mongo.getDB(db_name); DBCollection col = db.getCollection(col_name); DBCursor c = col.find(); if (c == null) { error(res, SC_NOT_FOUND, Status.get("no documents found")); return; } res.setIntHeader("X-Documents-Count", c.count()); if (limit != null) { try { c.limit(Math.min(Integer.parseInt(limit), MAX_FIELDS_TO_RETURN)); } catch (NumberFormatException e) { error(res, SC_BAD_REQUEST, Status.get("can not parse limit")); c.close(); return; } } else c.limit(MAX_FIELDS_TO_RETURN); if (skip != null) { try { c.skip(Integer.parseInt(skip)); } catch (NumberFormatException e) { error(res, SC_BAD_REQUEST, Status.get("can not parse skip")); c.close(); return; } } StringBuilder buf = tl.get(); buf.setLength(0); int no = 0; buf.append("["); while (c.hasNext()) { DBObject o = c.next(); JSON.serialize(o, buf); buf.append(","); no++; } if (no > 0) buf.setCharAt(buf.length() - 1, ']'); else buf.append(']'); res.setIntHeader("X-Documents-Returned", no); out_str(req, buf.toString(), "application/json"); } }