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.
<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 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.
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);
}
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.
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.
$ 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" }