mongo创建服务器连接及简单查询

来源:转载


1.     Java语言连接mongo库需要mongo提供的驱动包,类似于传统数据库使用的jdbc包。

一般将连接的参数写在配置文件中,这些参数有:

#是否重试

autoConnectRetry=true

#连接池大小

poolSize=50

#主机地址

hosts=ip:port

#数据库名称

dbName=dbname

#数据库连接用户名

userName= username

#连接密码

password=password

#表名称

tableName=emailSent

所以,连接mongo的Java代码如下:

import java.util.ArrayList;

import java.util.Properties;

 

import com.mongodb.DB;

import com.mongodb.DBCollection;

import com.mongodb.MongoClient;

import com.mongodb.MongoClientOptions;

import com.mongodb.MongoClientOptions.Builder;

import com.mongodb.ServerAddress;

 

public class MongoDBUtil {

 

         private static final String AUTO_CONNECT_RETRY ="autoConnectRetry";

         private static final String POOL_SIZE ="poolSize";

         private static final String HOSTS ="hosts";

         private static final String DB_NAME ="dbName";

         private static final String USERNAME ="userName";

         private static final String PASSWORD ="password";

         private static final String CONFIG ="ubd_esp_conf.properties";

         private static final Properties prop =new Properties();

         private static MongoClient client =null;

         private static ArrayList<ServerAddress> address =new ArrayList<ServerAddress>();

         private static DB db = null;

        

         static {

                   try{

                            prop.load(MongoDBUtil.class.getClassLoader().getResourceAsStream(CONFIG));

                            //对配置文件中的多个ip地址进行遍历

                            for(String hostIP :prop.getProperty(HOSTS).split(";")){

                                     //虑空

                                     hostIP= hostIP.trim();

                                     //获得ip

                                     Stringip = hostIP.split(":")[0];

                                     //获得端口

                                     int  port= Integer.parseInt(hostIP.split(":")[1]);

                                     //添加地址

                                     address.add(new ServerAddress(ip,port));

                            }

                            mongoDBInit(address);

                   }catch(Exception e){

                            e.getStackTrace();

                   }

         }

        

         /**

          * 初始化MongoDB连接

          * @param address

          * @throws Exception

          */

         private static void mongoDBInit(ArrayList<ServerAddress> address)throws Exception{

                   Builderbuilder = new MongoClientOptions.Builder();

                   builder.autoConnectRetry(Boolean.parseBoolean(prop.getProperty(AUTO_CONNECT_RETRY)));

                   builder.connectionsPerHost(Integer.parseInt(prop.getProperty(POOL_SIZE)));

                   client =new MongoClient(address,builder.build());

                   db =client.getDB(prop.getProperty(DB_NAME));

                   if(!db.isAuthenticated()){

                            if(prop.getProperty(USERNAME)==null||prop.getProperty(PASSWORD)==null){

                                     thrownew Exception("the username or password is null in"+CONFIG);

                            }

                            db.authenticate(prop.getProperty(USERNAME),prop.getProperty(PASSWORD).toCharArray());

                   }

         }

        

         /**

          * 返回collection

          * @param tableName

          * @return

          */

         public static DBCollection getCollection(String tableName){

                   returndb.getCollection(tableName);

         }

}

2.     给出一个简单的mongo查询示例,将mongo查询的结果写入一个文件,并且按/001分隔,以备接下来使用Hadoop处理。

import java.io.BufferedWriter;

import java.io.File;

import java.io.FileWriter;

import java.io.IOException;

import java.util.Date;

import java.util.Properties;

 

importcom.dangdang.ubd.esp.help.MongoDBUtil;

import com.dangdang.ubd.esp.help.TimeTool;

import com.mongodb.BasicDBObject;

import com.mongodb.DBCollection;

import com.mongodb.DBCursor;

import com.mongodb.DBObject;

import com.mongodb.QueryOperators;

 

public class GetEmailData {

 

   privatestatic final String TABLE_NAME ="tableName";

   privatestatic final String FILE_DIR = "fileDir";

   privatestatic Properties prop = new Properties();

   privatestatic final String CONFIG = "ubd_esp_conf.properties";

   privatestatic int before = 0;

  

   static{

            try{

                     prop.load(GetEmailData.class.getClassLoader().getResourceAsStream(CONFIG));

                     before= Integer.parseInt(prop.getProperty("before"));

            }catch (IOException e) {

                     e.printStackTrace();

            }

   }

  

   publicstatic void getDataToFile(String sDate,String eDate,String tableName,StringfileName){

            //文件

            Filefile = new File(fileName);

           

            if(file.exists()){

                     file.delete();

            }

           

            if(!file.getParentFile().exists()) {

                               file.getParentFile().mkdirs();

                       }

             try {

                       file.createNewFile();

                     }catch (IOException e) {

                        e.printStackTrace();

              }

                      

            BufferedWriterbw = null;

            try{

                     bw= new BufferedWriter(new FileWriter(file));

                     //获取到collection

                     DBCollectiondbCollection = MongoDBUtil.getCollection(tableName);

                    

                     //查询条件为lastChangedTime距离现在为90天以内的并且打开的

                     DBObjectquery = new BasicDBObject();

                     DBObjectcondition = new BasicDBObject();

                     condition.put(QueryOperators.GTE,TimeTool.strToDate(sDate));

                     condition.put(QueryOperators.LT,TimeTool.strToDate(eDate));

                     query.put("lastChangedTime",condition);

                     query.put("open",true);

                    

                     //执行查询

                     DBCursorcursor = dbCollection.find(query);

                     intcount = 0;

                     while(cursor.hasNext()){

                               DBObjectdbObject = cursor.next();

                               Stringinfo = getLineStr(dbObject);

                               bw.write(info);

                               bw.newLine();

                               count++;

                     }

                     bw.flush();

                     System.out.println(count);

            }catch(Exceptione){

                     e.printStackTrace();

            }finally{

                     if(bw!=null){

                               try{

                                        bw.close();

                               }catch (IOException e) {

                                        e.printStackTrace();

                               }

                     }

            }

   }

  

   /**

    * 将mongo查询结果转换成hdfs存放的串

    * @param jsonStr

    * @return

    */

   publicstatic String getLineStr (DBObject jsonStr){

            StringBuffersb = new StringBuffer();

 

            if(jsonStr.containsField("open")){

                     sb.append("/001"+ jsonStr.get("open"));

            }else{

                     sb.append("/001"+ "false");

            }

            if(jsonStr.containsField("openTime")) {

                     sb.append("/001"+ TimeTool.dateToStr((Date)jsonStr.get("openTime")));

            }else{

                     sb.append("/001"+ "1000-00-00 00:00:00");

            }

           

            returnsb.toString();

   }

 

   publicstatic void main(String[] args) {

            try{

                     Stringedate = args[0];

                     Stringsdate = TimeTool.getBeforDate(edate, before);

                     StringtableName = prop.getProperty(TABLE_NAME);

                     StringfileDir = prop.getProperty(FILE_DIR);

                     StringfileName = fileDir+"ubd_esp_email_chg_log";

                     getDataToFile(sdate,edate,tableName,fileName);

            }catch(Exceptione){

                     e.printStackTrace();

                     System.exit(-1);

            }

   }

}

 



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