Java + MongoDB 实现 hello world 例子（译）

 

原文出自：http://www.mkyong.com/mongodb/java-mongodb-hello-world-example/

返回目录：http://ysj5125094.iteye.com/blog/2192754 

 

 

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).

译：一个简单的利用Java + MongoDB实现hello world例子 —— 如何连接，创建数据库、集合和文档，保存、更新、删除、获取和显示文档（数据）。

 

Tools and technologies used :

译：使用的工具和技术：

1. MongoDB 2.2.3
2. MongoDB-Java-Driver 2.10.1
3. JDK 1.6
4. Maven 3.0.3
5. Eclipse 4.2

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

译：P.S Maven和Eclipse是可选的，只是我个人最喜欢的开发工具。

 

1. Create a Java Project

Create a simple Java project with Maven.

译：创建一个简单的Maven Java project项目。

 

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.

译：从github下载mongo-java驱动。mgongo-java驱动声明在pom.xml文件中。

<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>

 

3. Mongo Connection

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

译：使用MongoClient连接MongoDB server。MongoDB版本 >= 2.10.0

 

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

 

If MongoDB in secure mode, authentication is required.

译：如果已经在安全模式下，认证是必需的。

 

	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.

译：获取数据库。如果数据库不存在，那么MongoDB会自动创建。

 

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

 

Display all databases.

译：显示所有数据库。

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

 

5. Mongo Collection

Get collection / table.

译：获取集合 / 表。

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

 

Display all collections from selected database.

译：从选择的数据库中显示所有集合。

	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.

在关系型数据库中，集合 = 表。

 

6. Save example

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

译：在"user"集合（表）中保存一个文档（数据）

	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.

译：请参数这个Java MongoDB插入的例子。

 

7. Update example

Update a document where “name=mkyong”.

译：更新条件为“name=mkyong”的文档。

	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

译：查询条件为"name=mkyong"的文档，并显示所有数据游标内容。

	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.

译：查询条件为"name=mkyong"的文档并删除他。

	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.

译：让我们一起来审查已完成的Java + MongoDB例子，

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 MongoClient
	MongoClient mongo = new MongoClient("localhost", 27017);
 
	/**** Get database ****/
	// if database doesn't exists, MongoDB will create it for you
	DB db = mongo.getDB("testdb");
 
	/**** Get collection / table from 'testdb' ****/
	// if collection doesn't exists, MongoDB will create it for you
	DBCollection table = db.getCollection("user");
 
	/**** Insert ****/
	// create a document to store key and value
	BasicDBObject 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 values
	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);
 
	/**** 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.

译：让我们用mongo控制台来检查创建的数据库"testdb"，集合"user"和文档。

$ 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" }

 

Download Source Code

附件可以下载源代码

 

References

1. Getting started with Java driver
2. Java-MongoDB driver