使用mongodb存取lbs数据

1，在mongodb中创建lbs_db数据库，collection名称lbs_info，要使用lbs查询功能，需要对二维数据列建立索引

db.lbs_info.ensureIndex( { locs : "2d" } );

2，Servlet源码如下：

package com.ciaos.lbs;

import java.io.IOException;
import java.net.UnknownHostException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.mongodb.BasicDBList;
import com.mongodb.BasicDBObject;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.DBObject;
import com.mongodb.Mongo;

public class LBSServlet extends HttpServlet {

    /**
     *
     */
    private static final long serialVersionUID = 1L;
    private Mongo mongo = null;

    final private String MongoDbIp = "127.0.0.1";
    final private Integer MongoDbPort = 27017;
    final private String MongoDbName = "lbs_db";

    @Override
    public void init() throws ServletException {
        // TODO Auto-generated method stub
        try {
            mongo=new Mongo(MongoDbIp, MongoDbPort);
        } catch (UnknownHostException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            System.exit(-1);
        }
        super.init();
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {

        String uid = req.getParameter("uid");
        String lon = req.getParameter("lon");
        String lat = req.getParameter("lat");
        if(uid == null || lon == null || lat == null){
            resp.sendError(400,"bad request");
            return;
        }
        int skip = 0, limit = 10;
        try{
            skip = Integer.parseInt(req.getParameter("skip"));
            limit = Integer.parseInt(req.getParameter("limit"));
        }
        catch(Exception ex){
            skip = 0;
            limit = 10;
        }
        try{
            DB db=mongo.getDB(MongoDbName);
            DBCollection col = db.getCollection("lbs_info");
            BasicDBList dbl = new BasicDBList();
            dbl.add(Double.parseDouble(lon));
            dbl.add(Double.parseDouble(lat));
            BasicDBObject query = new BasicDBObject("locs", new BasicDBObject("$near", dbl));
            BasicDBObject filters = new BasicDBObject("_id", false);
            DBCursor cursor = col.find(query, filters).skip(skip).limit(limit);
            resp.getWriter().println(cursor.toArray().toString());
            resp.getWriter().flush();
        }catch(Exception ex){
            resp.sendError(500,"internal server error");
            return;
        }
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {

        String uid = req.getParameter("uid");
        String lon = req.getParameter("lon");
        String lat = req.getParameter("lat");
        if(uid == null || lon == null || lat == null){
            resp.sendError(400,"bad request");
            return;
        }
        try{
            DB db=mongo.getDB(MongoDbName);
            DBCollection col = db.getCollection("lbs_info");

            BasicDBList dbl = new BasicDBList();
            dbl.add(Double.parseDouble(lon));
            dbl.add(Double.parseDouble(lat));
            BasicDBObject query = new BasicDBObject("uid", uid);
            DBObject setValue=new BasicDBObject();
            setValue.put("utime", System.currentTimeMillis());
            setValue.put("locs", dbl);

            DBObject upsertValue=new BasicDBObject("$set",setValue);
            col.update(query, upsertValue, true, true);
            resp.getWriter().println("ok");
            resp.getWriter().flush();
        }catch(Exception ex){
            resp.sendError(500,"internal server error");
            return;
        }
    }
}

3，使用示例

1，插入或更新数据
curl -XPOST -v "http://127.0.0.1:8080/lbs?uid=1001&lon=1&lat=1"
curl -XPOST -v "http://127.0.0.1:8080/lbs?uid=1002&lon=2&lat=2"
curl -XPOST -v "http://127.0.0.1:8080/lbs?uid=1003&lon=3&lat=3"
curl -XPOST -v "http://127.0.0.1:8080/lbs?uid=1004&lon=4&lat=4"
curl -XPOST -v "http://127.0.0.1:8080/lbs?uid=1005&lon=5&lat=5"

2，查询距离最近的数据
curl -XGET -v "http://127.0.0.1:8080/lbs?uid=1006&lon=3&lat=3
[{ "_id" : { "$oid" : "532786efb84743574afdd26f"} , "locs" : [ 3.0 , 3.0] , "uid" : "1003" , "utime" : 1395476404876}, { "_id" : { "$oid" : "532786e8b84743574afdd26e"} , "locs" : [ 2.0 , 2.0] , "uid" : "1002" , "utime" : 1395476397434}, { "_id" : { "$oid" : "532786f8b84743574afdd270"} , "locs" : [ 4.0 , 4.0] , "uid" : "1004" , "utime" : 1395476413299}, { "_id" : { "$oid" : "5327868db84743574afdd26d"} , "locs" : [ 1.0 , 1.0] , "uid" : "1001" , "utime" : 1395476436048}, { "_id" : { "$oid" : "5327885db84743574afdd271"} , "locs" : [ 6.0 , 6.0] , "uid" : "1006" , "utime" : 1395476769272}]

3，mongodb命令行查询
rs0:PRIMARY> db.lbs_info.find();
{ "_id" : ObjectId("5327868db84743574afdd26d"), "locs" : [ 1, 1 ], "uid" : "1001", "utime" : NumberLong("1395476436048") }
{ "_id" : ObjectId("532786e8b84743574afdd26e"), "locs" : [ 2, 2 ], "uid" : "1002", "utime" : NumberLong("1395476397434") }
{ "_id" : ObjectId("532786efb84743574afdd26f"), "locs" : [ 3, 3 ], "uid" : "1003", "utime" : NumberLong("1395476404876") }
{ "_id" : ObjectId("532786f8b84743574afdd270"), "locs" : [ 4, 4 ], "uid" : "1004", "utime" : NumberLong("1395476413299") }
{ "_id" : ObjectId("5327885db84743574afdd271"), "locs" : [ 6, 6 ], "uid" : "1006", "utime" : NumberLong("1395476769272") }

rs0:PRIMARY> db.lbs_info.find( { locs : {$near:[0,0]}, uid: {$gt:"1001"}}).limit(3)
{ "_id" : ObjectId("532786e8b84743574afdd26e"), "locs" : [ 2, 2 ], "uid" : "1002", "utime" : NumberLong("1395476397434") }
{ "_id" : ObjectId("532786efb84743574afdd26f"), "locs" : [ 3, 3 ], "uid" : "1003", "utime" : NumberLong("1395476404876") }
{ "_id" : ObjectId("532786f8b84743574afdd270"), "locs" : [ 4, 4 ], "uid" : "1004", "utime" : NumberLong("1395476413299") }