mongodb web_MongoDB和Web应用程序

mongodb web

当今时代是数据以非常大的速度增长的时代。数据存储不是问题，是的，但是它的结构化和存储方式可能会增加或减少所需数据块的查找时间。

不断增长的非结构化数据的用例

脸书：
- 活跃用户达7.5亿，互联网用户中有三分之一拥有Facebook帐户
- 每月共享的内容超过300亿条（Web链接，新闻报道，博客文章，便笺，相册等）。
- 容纳30PB数据进行分析，每天增加12 TB压缩数据
推特
- 2亿用户，每日2亿条推文
- 每天有16亿个搜索查询
- 每天生成7 TB数据用于分析

在这样的规模下，传统的数据存储，技术和分析工具不起作用！

当前方案要求需要NoSQL数据库（例如Apache Cassandra，Mongo DB）来处理不断增长的非结构化数据。 NoSQL数据库提供比传统RDBMS宽松的一致性模型，用于存储和检索数据。 NoSQL数据库将数据存储为高度优化的键值对，这导致简单的检索和附加操作，从而在低延迟和高吞吐量方面提高了性能。

NoSQL数据库在开发和维护大数据和实时Web应用程序的行业中起着重要作用。

Mongo DB和Web应用程序的用例

让我们想象一下，我们想在后端使用JSF2.0和Mongo DB创建一个汽车注册门户。将有两个功能

汽车登记
查看已注册汽车的报告

图1描述了要进行的项目的流程。

假设：

Mongo DB已安装并作为服务运行
Eclipse靛蓝或更高版本
Tomcat 7.0或更高版本
存在必需的jar文件（JSF2.0 jars jsf-api.jar，jsf-impl），mongo-java-driver-2.10.1.jar或任何合适的版本

应用程序具有三个页面，即Home.xhtml，AddCar.xhtml，Report.xhtml。

Home.xhtml的实现如下：

Home.xhtml

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"xmlns:f="http://java.sun.com/jsf/core"xmlns:h="http://java.sun.com/jsf/html"xmlns:j="http://java.sun.com/jsp/jstl/core">
<h:head><meta http-equiv="content-type" content="text/html; charset=utf-8" /></h:head><h:body><f:view>
<h:form><center>
<h2> MSD Car Portal</h2><h4><h:outputLink value="AddCar.xhtml">Add Car</h:outputLink><br/><br/>
<h:commandLink action="#{carBean.getCarDetails}" >See Registered Cars</h:commandLink></h4></center></h:form>
</f:view></h:body>
</html>

单击“ 添加汽车”链接后 ，将加载AddCar.xhtml并执行以下代码行。

AddCar.xhtml

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"xmlns:f="http://java.sun.com/jsf/core"xmlns:h="http://java.sun.com/jsf/html"xmlns:j="http://java.sun.com/jsp/jstl/core">
<h:head><meta http-equiv="content-type" content="text/html; charset=utf-8" /></h:head><h:body><f:view>
<h:form><center><h2>MSD Car Portal</h2>
<h3>Add a Car</h3><h:panelGrid border="2" columns="2"><h:outputText value="CarName"></h:outputText>
<h:inputText value="#{carBean.carTO.carName}"></h:inputText><h:outputText value="Company"></h:outputText>
<h:inputText value="#{carBean.carTO.company}"></h:inputText><h:outputText value="Model"></h:outputText>
<h:inputText value="#{carBean.carTO.model}">
<f:convertDateTime pattern="dd-MMM-yyyy"></f:convertDateTime>
</h:inputText><h:outputText value="CC"></h:outputText>
<h:inputText value="#{carBean.carTO.cc}"></h:inputText><h:outputText value="Price"></h:outputText>
<h:inputText value="#{carBean.carTO.price}"></h:inputText></h:panelGrid><h:commandButton action="#{carBean.addCar}" value="Add Car"></h:commandButton><br/><h:outputText value="#{carBean.message}"></h:outputText><br/><h:outputLink value="Home.xhtml">Home</h:outputLink></center></h:form>
</f:view></h:body>
</html>

点击“ 添加汽车”按钮后，将调用CarBean （后备bean）的动作处理程序，并在后备Bean 中将CarTO （Car Transfer Object）发送到CarService的insertData函数，此处将CarTO值的值插入文档中并将文档添加到集合中。并单击Home Home.xhtml。以下清单显示了CarBean的代码。

CarBean.java

package mongo.db.bean;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.List;
import javax.faces.bean.ManagedBean;
import mongo.db.service.CarService;
import mongo.db.to.CarTO;
@ManagedBean
public class CarBean {private List<CarTO> list = new ArrayList<CarTO>();private String message;private CarTO carTO= new CarTO();/**Action handler to save the data in the collection*/public String addCar(){try {/**Inserting the data to the Service class to insert it intoMongo DB*/message= new CarService().insertData("testdb","MyNewJAVATableCollection3",carTO);/**Message property is shown on the Page to show successmessage on the page*/} catch (UnknownHostException e) {message= e.getMessage();}return "samePage";}/**Action handler to get the data from the collection*/public String getCarDetails(){try {/**Reading the data From the Service class which further readthe data from the  Mongo DB */list = new CarService().findData("testdb","MyNewJAVATableCollection3");if(list.size()==0){message="No records Exist";}} catch (UnknownHostException e) {message= e.getMessage();}return "success";}
/*Getters  and setters to be coded*/
}

服务类的代码如下：

CarService.java

package mongo.db.service;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import mongo.db.to.CarTO;
import com.mongodb.BasicDBObject;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.DBObject;
import com.mongodb.MongoClient;public class CarService {/**Utility to Get the Connection from the database*/
public static DBCollection getConnection(String dbName, String collectionName)throws UnknownHostException {/** Connecting to MongoDB */MongoClient mongo = new MongoClient("localhost", 27017);/**Gets database, incase if the database is not existingMongoDB Creates it for you*/DB db = mongo.getDB(dbName);/**Gets collection / table from database specified ifcollection doesn't exists, MongoDB will create it foryou*/DBCollection table = db.getCollection(collectionName);return table;}/**function to insert the data to the database */
public  String insertData(String dbName, String collectionName, CarTO carTO) throws UnknownHostException {/**Connecting to MongoDB*/
DBCollection table =CarService.getConnection(dbName, collectionName);/**creating a document to store as key and value*/BasicDBObject document = new BasicDBObject();document.put("carName", carTO.getCarName());document.put("company", carTO.getCompany());document.put("model", carTO.getModel());document.put("cc", carTO.getCc());document.put("Price", carTO.getPrice());/** inserting to the document to collection or table*/table.insert(document);return "Car added successfully with the record number :"+table.count();
}/**function to get Details from the database*/
public  List<CarTO> findData(String dbName, String collectionName) throws UnknownHostException {/**Connecting to database*/
DBCollection table= CarService.getConnection(dbName, collectionName);/**getting results from the database*/
DBCursor cursor = table.find();
List<CarTO>list= new ArrayList<CarTO>();/**iterating over the documents got from the database*/
while (cursor.hasNext()) {DBObject obj= cursor.next();/**documentToMapUtility is coded to convert the document received from database to key value pairs and put it inside a map*/
Map map=CarService.documentToMapUtility(obj.toString());/**Map having values is iterated using entry set and CarTO is populated and CarTO is added in the List<CarTO> and this list returned*//**Getting the Entery Set from the map  */
Set<Entry<String,String>> set= map.entrySet();/**Getting the Iterator to iterate the entry Set*/
Iterator<Entry<String,String>> itr= set.iterator();CarTO carTO = new CarTO();/**loop to put ever Key value pair to CarTO object*/       while(itr.hasNext()){Entry<String, String> entry = itr.next();String key=entry.getKey();/**Removing the unwanted from the keys*/key = CarService.subStringUtility(key);String value=entry.getValue();if(key.equalsIgnoreCase("carName")){carTO.setCarName(value.substring(2,value.length()-2));}else if(key.equalsIgnoreCase("company")){carTO.setCompany(value.substring(2,value.length()-2));}else if(key.equalsIgnoreCase("model")){String date[]=value.split("-");int year=Integer.parseInt(date[0].substring(2));int month=Integer.parseInt(date[1]);int datemon=Integer.parseInt(date[2].substring(0, date.length-1));Calendar c= Calendar.getInstance();c.set(Calendar.YEAR, year);c.set(Calendar.MONTH, month);c.set(Calendar.DATE, datemon);carTO.setModel(c.getTime());}else if(key.equalsIgnoreCase("cc")){carTO.setCc(Integer.parseInt(value.trim()));}else if(key.equalsIgnoreCase("Price")){carTO.setPrice(Double.parseDouble(value.trim()));}}          /**inner While closed*/list.add(carTO);
}   /**while iterating over the cursor records closed here*/return list;
}/**Utility to remove un wanted contents*/public static String subStringUtility (String s){return s.substring(2,s.length()-2);}/**Utility to convert the document to map*/public static Map<String,String> documentToMapUtility (String s){s= s.substring(1,s.length()-1);String sArr[]= s.split(",");Map<String,String> map = new LinkedHashMap<String,String>();for(int i=1;i<sArr.length;i++){if(!sArr[i].contains("$date")){String keyValue[]= sArr[i].split(":");map.put(keyValue[0],keyValue[1]);System.out.println(keyValue[0]+","+keyValue[1]);}else{String keyValue[]= sArr[i].split(":");map.put(keyValue[0],keyValue[2]);}}return map;}}

以下清单显示了传输对象类CarTO的内容

CarTO.java

package mongo.db.to;
import java.util.Date;
public class CarTO {private String carName;private String company;private Integer cc;private Double price;private Date model;/*Getters and Setters to be coded*/
}

在单击主页上的“查看注册的汽车”链接时，因为它是命令链接，所以将执行CarBean的动作处理程序getCarDetails并在方法findData的帮助下从CarService类获取详细信息，请参阅动作处理程序getCarDetails的CarBean代码。下面的清单表示Report.xhtml的代码。

Report.xhtml.java

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"xmlns:f="http://java.sun.com/jsf/core"xmlns:h="http://java.sun.com/jsf/html"xmlns:j="http://java.sun.com/jsp/jstl/core">
<h:head><meta http-equiv="content-type" content="text/html; charset=utf-8" /></h:head><h:body><f:view>
<h:form><center>
<h2>MSD Car Portal</h2>
<h3>Car Details</h3><h:dataTable value="#{carBean.list}" var="item" border="2" rendered="#{not empty carBean.list}"><h:column>
<f:facet name="header">
<h:outputText value="CarName"></h:outputText>
</f:facet>
<h:outputText value="#{item.carName}"></h:outputText>
</h:column><h:column>
<f:facet name="header">
<h:outputText value="Company"></h:outputText>
</f:facet>
<h:outputText value="#{item.company}"></h:outputText>
</h:column><h:column>
<f:facet name="header">
<h:outputText value="Model"></h:outputText>
</f:facet>
<h:outputText value="#{item.model.time}">
<f:convertDateTime pattern="dd-MMM-yyyy"></f:convertDateTime>
</h:outputText>
</h:column><h:column>
<f:facet name="header">
<h:outputText value="CC"></h:outputText>
</f:facet>
<h:outputText value="#{item.cc}"></h:outputText>
</h:column><h:column>
<f:facet name="header">
<h:outputText value="Price"></h:outputText>
</f:facet>
<h:outputText value="#{item.price}"></h:outputText>
</h:column></h:dataTable><br/><h:outputText value="#{carBean.message}"></h:outputText><br/><h:outputLink value="Home.xhtml">Home</h:outputLink>
</center></h:form>
</f:view></h:body>
</html>

结论

从给定的示例中可以很明显地看出，MongoDb可以与现有的Web框架集成，并且可以用于制作可以轻松处理大数据问题的Web应用程序。

参考：

http://www.rabidgremlin.com/data20/
http://docs.mongodb.org/manual/tutorial/install-mongodb-on-windows/
http://docs.oracle.com/javaee/6/tutorial/doc/bnaph.html

翻译自: https://www.javacodegeeks.com/2013/09/mongodb-and-web-applications.html

mongodb web