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MongoDB和Web应用程序

發(fā)布時間：2023/12/3 编程问答 39 豆豆

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當(dāng)今時代是數(shù)據(jù)大規(guī)模增長的時代。數(shù)據(jù)存儲不是問題，是的，但是結(jié)構(gòu)化和存儲的方式可能會增加或減少所需數(shù)據(jù)塊的查找時間。

不斷增長的非結(jié)構(gòu)化數(shù)據(jù)的用例

臉書：
- 7.5億用戶處于活躍狀態(tài)，三分之一的互聯(lián)網(wǎng)用戶擁有Facebook帳戶
- 每月共享的內(nèi)容超過300億條（Web鏈接，新聞報道，博客文章，便箋，相冊等）。
- 容納30PB數(shù)據(jù)進行分析，每天增加12 TB壓縮數(shù)據(jù)
推特
- 2億用戶，每日2億條推文
- 每天有16億個搜索查詢
- 每天生成7 TB數(shù)據(jù)用于分析

在這樣的規(guī)模下，傳統(tǒng)的數(shù)據(jù)存儲，技術(shù)和分析工具不起作用！

當(dāng)前方案要求需要NoSQL數(shù)據(jù)庫（例如Apache Cassandra，Mongo DB）來處理不斷增長的非結(jié)構(gòu)化數(shù)據(jù)。 NoSQL數(shù)據(jù)庫提供比傳統(tǒng)RDBMS寬松的一致性模型，用于存儲和檢索數(shù)據(jù)。 NoSQL數(shù)據(jù)庫將數(shù)據(jù)存儲為高度優(yōu)化的鍵值對，這導(dǎo)致簡單的檢索和附加操作，從而在低延遲和高吞吐量方面提高了性能。

在開發(fā)和維護大數(shù)據(jù)和實時Web應(yīng)用程序的行業(yè)中，NoSQL數(shù)據(jù)庫發(fā)揮著重要作用。

Mongo數(shù)據(jù)庫和Web應(yīng)用程序的用例

讓我們想象一下，我們想在后端使用JSF2.0和Mongo DB創(chuàng)建一個汽車注冊門戶。將有兩個功能

汽車登記
查看已注冊汽車的報告

圖1描繪了要進行的項目的流程。

假設(shè)：

Mongo DB已安裝并作為服務(wù)運行
Eclipse靛藍或更高版本
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或任何合適的版本

應(yīng)用程序具有三個頁面，即Home.xhtml，AddCar.xhtml，Report.xhtml。

Home.xhtml的實現(xiàn)如下：

Home.xhtml

單擊“ 添加汽車”鏈接后，將加載AddCar.xhtml并執(zhí)行以下代碼行。

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>

點擊“ 添加汽車”按鈕后，將調(diào)用CarBean （后備bean）的動作處理程序，并在后備Bean 中將CarTO （Car Transfer Object）發(fā)送到CarService的insertData函數(shù)，此處將CarTO值的值插入文檔中并將文檔添加到集合中。然后單擊“ 主頁 Home.xhtml”。以下清單顯示了CarBean的代碼。

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*/ }

服務(wù)類的代碼如下：

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;}}

以下清單顯示了傳輸對象類CarTO的內(nèi)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*/ }

單擊主頁上的“查看注冊的汽車”鏈接時，因為它是命令鏈接，所以將執(zhí)行CarBean的動作處理程序getCarDetails并在方法findData的幫助下從CarService類獲取詳細信息，請參閱動作處理程序getCarDetails的CarBean代碼。下面的清單表示Report.xhtml的代碼。

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>

結(jié)論

從給定的示例中可以很明顯地看出，MongoDb可以與現(xiàn)有的Web框架集成，并且可以用于制作可以輕松處理大數(shù)據(jù)問題的Web應(yīng)用程序。

參考：

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

翻譯自: https://www.javacodegeeks.com/2013/09/mongodb-and-web-applications.html

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