原文地址：http://www.mkyong.com/mongodb/java-mongodb-hello-world-example/

A simple Java + MongoDB hello world example – how to connect, create database, collection and document, save, update, remove, get and display document (data).

Tools and technologies used :

MongoDB 2.2.3

MongoDB-Java-Driver 2.10.1

JDK 1.6

Maven 3.0.3

Eclipse 4.2

P.S Maven and Eclipse are both optional, just my personal favorite development tool.

1. Create a Java Project

Create a?simple Java project?with Maven.

mvn archetype:generate -DgroupId=com.mkyong.core -DartifactId=mongodb -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false

2. Get Mongo Java Driver

Download mongo-java driver from?github. For Maven users, declares mongo-java driver in?pom.xml.

pom.xml <project ...><dependencies><dependency><groupId>org.mongodb</groupId><artifactId>mongo-java-driver</artifactId><version>2.10.1</version></dependency></dependencies><build><plugins><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId><version>2.3.1</version><configuration><source>1.6</source><target>1.6</target></configuration></plugin><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-eclipse-plugin</artifactId><configuration><downloadSources>true</downloadSources><downloadJavadocs>true</downloadJavadocs></configuration></plugin></plugins></build></project>

. Mongo Connection

Connect to MongoDB server. For MongoDB version >= 2.10.0, uses?MongoClient.

// Old version, uses MongoMongo mongo = new Mongo("localhost", 27017);// Since 2.10.0, uses MongoClientMongoClient mongo = new MongoClient( "localhost" , 27017 );

If MongoDB in secure mode, authentication is required.

MongoClient mongoClient = new MongoClient();DB db = mongoClient.getDB("database name");boolean auth = db.authenticate("username", "password".toCharArray());

4. Mongo Database

Get database. If the database doesn’t exist, MongoDB will create it for you.

DB db = mongo.getDB("database name");

Display all databases.

List<String> dbs = mongo.getDatabaseNames();for(String db : dbs){System.out.println(db);}

5. Mongo Collection

Get collection / table.

DB db = mongo.getDB("testdb");DBCollection table = db.getCollection("user");

Display all collections from selected database.

DB db = mongo.getDB("testdb");Set<String> tables = db.getCollectionNames();for(String coll : tables){System.out.println(coll);} Note
In RDBMS, collection is equal to table.

6. Save example

Save a document (data) into a collection (table) named “user”.

DBCollection table = db.getCollection("user");BasicDBObject document = new BasicDBObject();document.put("name", "mkyong");document.put("age", 30);document.put("createdDate", new Date());table.insert(document);

Refer to this?Java MongoDB insert example.

7. Update example

Update a document where “name=mkyong”.

DBCollection table = db.getCollection("user");BasicDBObject query = new BasicDBObject();query.put("name", "mkyong");BasicDBObject newDocument = new BasicDBObject();newDocument.put("name", "mkyong-updated");BasicDBObject updateObj = new BasicDBObject();updateObj.put("$set", newDocument);table.update(query, updateObj);

Refer to this?Java MongoDB update example.

8. Find example

Find document where “name=mkyong”, and display it with DBCursor

DBCollection table = db.getCollection("user");BasicDBObject searchQuery = new BasicDBObject();searchQuery.put("name", "mkyong");DBCursor cursor = table.find(searchQuery);while (cursor.hasNext()) {System.out.println(cursor.next());}

Refer to this?Java MongoDB search query example.

9. Delete example

Find document where “name=mkyong”, and delete it.

DBCollection table = db.getCollection("user");BasicDBObject searchQuery = new BasicDBObject();searchQuery.put("name", "mkyong");table.remove(searchQuery);

Refer to this?Java MongoDB delete example.

10. Hello World

Let review a complete Java + MongoDB example, see comments for self-explanatory.

App.java package com.mkyong.core;import java.net.UnknownHostException; import java.util.Date; import com.mongodb.BasicDBObject; import com.mongodb.DB; import com.mongodb.DBCollection; import com.mongodb.DBCursor; import com.mongodb.MongoClient; import com.mongodb.MongoException;/*** Java + MongoDB Hello world Example* */ public class App {public static void main(String[] args) {try {/**** Connect to MongoDB ****/// Since 2.10.0, uses MongoClientMongoClient mongo = new MongoClient("localhost", 27017);/**** Get database ****/// if database doesn't exists, MongoDB will create it for youDB db = mongo.getDB("testdb");/**** Get collection / table from 'testdb' ****/// if collection doesn't exists, MongoDB will create it for youDBCollection table = db.getCollection("user");/**** Insert ****/// create a document to store key and valueBasicDBObject document = new BasicDBObject();document.put("name", "mkyong");document.put("age", 30);document.put("createdDate", new Date());table.insert(document);/**** Find and display ****/BasicDBObject searchQuery = new BasicDBObject();searchQuery.put("name", "mkyong");DBCursor cursor = table.find(searchQuery);while (cursor.hasNext()) {System.out.println(cursor.next());}/**** Update ****/// search document where name="mkyong" and update it with new valuesBasicDBObject query = new BasicDBObject();query.put("name", "mkyong");BasicDBObject newDocument = new BasicDBObject();newDocument.put("name", "mkyong-updated");BasicDBObject updateObj = new BasicDBObject();updateObj.put("$set", newDocument);table.update(query, updateObj);/**** Find and display ****/BasicDBObject searchQuery2 = new BasicDBObject().append("name", "mkyong-updated");DBCursor cursor2 = table.find(searchQuery2);while (cursor2.hasNext()) {System.out.println(cursor2.next());}/**** Done ****/System.out.println("Done");} catch (UnknownHostException e) {e.printStackTrace();} catch (MongoException e) {e.printStackTrace();}} }

Output…

{ "_id" : { "$oid" : "51398e6e30044a944cc23e2e"} , "name" : "mkyong" , "age" : 30 , "createdDate" : { "$date" : "2013-03-08T07:08:30.168Z"}} { "_id" : { "$oid" : "51398e6e30044a944cc23e2e"} , "age" : 30 , "createdDate" : { "$date" : "2013-03-08T07:08:30.168Z"} , "name" : "mkyong-updated"} Done

Let use?mongo?console to check the created database “testdb”, collection “user”, and document.

$ mongo MongoDB shell version: 2.2.3 connecting to: test> show dbs testdb 0.203125GB> use testdb switched to db testdb> show collections system.indexes user > db.user.find() { "_id" : ObjectId("51398e6e30044a944cc23e2e"), "age" : 30, "createdDate" : ISODate("2013-03-08T07:08:30.168Z"), "name" : "mkyong-updated" }

?

轉載于:https://www.cnblogs.com/davidwang456/p/4360016.html

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