mongo创建服务器连接及简单查询

最新推荐文章于 2025-02-16 22:06:32 发布

lgdlxc

最新推荐文章于 2025-02-16 22:06:32 发布

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分类专栏： MongoDB 文章标签： mongodb

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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){

throw new 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){

return db.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);

}