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环境配置
在Java程序中如果要使用MongoDB，你需要确保已经安装了Java环境及MongoDB JDBC 驱动。
你可以参考本站的Java教程来安装Java程序。现在让我们来检测你是否安装了 MongoDB JDBC 驱动。
连接数据库，你需要指定数据库名称，如果指定的数据库不存在，mongo会自动创建数据库。
连接数据库的Java代码如下：
import com.mongodb.MongoClient; import com.mongodb.MongoException; import com.mongodb.WriteConcern; import com.mongodb.DB; import com.mongodb.DBCollection; import com.mongodb.BasicDBObject; import com.mongodb.DBObject; import com.mongodb.DBCursor; import com.mongodb.ServerAddress; import java.util.Arrays; public class MongoDBJDBC{ public static void main( String args[] ){ try{ // 连接到 mongodb 服务 MongoClient mongoClient = new MongoClient( "localhost" , 27017 ); // 连接到数据库 DB db = mongoClient.getDB( "test" ); System.out.println("Connect to database successfully"); boolean auth = db.authenticate(myUserName, myPassword); System.out.println("Authentication: "+auth); }catch(Exception e){ System.err.println( e.getClass().getName() + ": " + e.getMessage() ); } } }
现在，让我们来编译运行程序并创建数据库test。
你可以更加你的实际环境改变MongoDB JDBC驱动的路径。
本实例将MongoDB JDBC启动包 mongo-2.10.1.jar 放在本地目录下:
$javac MongoDBJDBC.java $java -classpath ".:mongo-2.10.1.jar" MongoDBJDBC Connect to database successfully Authentication: true
如果你使用的是Window系统，你可以按以下命令来编译执行程序：
$javac MongoDBJDBC.java $java -classpath ".;mongo-2.10.1.jar" MongoDBJDBC Connect to database successfully Authentication: true
如果用户名及密码正确，则Authentication 的值为true。
我们可以使用com.mongodb.DB类中的createCollection()来创建集合
代码片段如下：
import com.mongodb.MongoClient; import com.mongodb.MongoException; import com.mongodb.WriteConcern; import com.mongodb.DB; import com.mongodb.DBCollection; import com.mongodb.BasicDBObject; import com.mongodb.DBObject; import com.mongodb.DBCursor; import com.mongodb.ServerAddress; import java.util.Arrays; public class MongoDBJDBC{ public static void main( String args[] ){ try{ // 连接到 mongodb 服务 MongoClient mongoClient = new MongoClient( "localhost" , 27017 ); // 连接到数据库 DB db = mongoClient.getDB( "test" ); System.out.println("Connect to database successfully"); boolean auth = db.authenticate(myUserName, myPassword); System.out.println("Authentication: "+auth); DBCollection coll = db.createCollection("mycol"); System.out.println("Collection created successfully"); }catch(Exception e){ System.err.println( e.getClass().getName() + ": " + e.getMessage() ); } } }
编译运行以上程序，输出结果如下:
Connect to database successfully Authentication: true Collection created successfully
我们可以使用com.mongodb.DBCollection类的 getCollection() 方法来获取一个集合
代码片段如下：
import com.mongodb.MongoClient; import com.mongodb.MongoException; import com.mongodb.WriteConcern; import com.mongodb.DB; import com.mongodb.DBCollection; import com.mongodb.BasicDBObject; import com.mongodb.DBObject; import com.mongodb.DBCursor; import com.mongodb.ServerAddress; import java.util.Arrays; public class MongoDBJDBC{ public static void main( String args[] ){ try{ // 连接到 mongodb 服务 MongoClient mongoClient = new MongoClient( "localhost" , 27017 ); // 连接到数据库 DB db = mongoClient.getDB( "test" ); System.out.println("Connect to database successfully"); boolean auth = db.authenticate(myUserName, myPassword); System.out.println("Authentication: "+auth); DBCollection coll = db.createCollection("mycol"); System.out.println("Collection created successfully"); DBCollection coll = db.getCollection("mycol"); System.out.println("Collection mycol selected successfully"); }catch(Exception e){ System.err.println( e.getClass().getName() + ": " + e.getMessage() ); } } }
编译运行以上程序，输出结果如下:
Connect to database successfully Authentication: true Collection created successfully Collection mycol selected successfully
我们可以使用com.mongodb.DBCollection类的 insert() 方法来插入一个文档
代码片段如下：
import com.mongodb.MongoClient; import com.mongodb.MongoException; import com.mongodb.WriteConcern; import com.mongodb.DB; import com.mongodb.DBCollection; import com.mongodb.BasicDBObject; import com.mongodb.DBObject; import com.mongodb.DBCursor; import com.mongodb.ServerAddress; import java.util.Arrays; public class MongoDBJDBC{ public static void main( String args[] ){ try{ // 连接到 mongodb 服务 MongoClient mongoClient = new MongoClient( "localhost" , 27017 ); // 连接到数据库 DB db = mongoClient.getDB( "test" ); System.out.println("Connect to database successfully"); boolean auth = db.authenticate(myUserName, myPassword); System.out.println("Authentication: "+auth); DBCollection coll = db.getCollection("mycol"); System.out.println("Collection mycol selected successfully"); BasicDBObject doc = new BasicDBObject("title", "MongoDB"). append("description", "database"). append("likes", 100). append("url", "http://www.shouce.ren/mongodb/"). append("by", "shouce.ren"); coll.insert(doc); System.out.println("Document inserted successfully"); }catch(Exception e){ System.err.println( e.getClass().getName() + ": " + e.getMessage() ); } } }
编译运行以上程序，输出结果如下:
Connect to database successfully Authentication: true Collection mycol selected successfully Document inserted successfully
我们可以使用com.mongodb.DBCollection类中的 find() 方法来获取集合中的所有文档。
此方法返回一个游标，所以你需要遍历这个游标。
代码片段如下：
import com.mongodb.MongoClient; import com.mongodb.MongoException; import com.mongodb.WriteConcern; import com.mongodb.DB; import com.mongodb.DBCollection; import com.mongodb.BasicDBObject; import com.mongodb.DBObject; import com.mongodb.DBCursor; import com.mongodb.ServerAddress; import java.util.Arrays; public class MongoDBJDBC{ public static void main( String args[] ){ try{ // 连接到 mongodb 服务 MongoClient mongoClient = new MongoClient( "localhost" , 27017 ); // 连接到数据库 DB db = mongoClient.getDB( "test" ); System.out.println("Connect to database successfully"); boolean auth = db.authenticate(myUserName, myPassword); System.out.println("Authentication: "+auth); DBCollection coll = db.getCollection("mycol"); System.out.println("Collection mycol selected successfully"); DBCursor cursor = coll.find(); int i=1; while (cursor.hasNext()) { System.out.println("Inserted Document: "+i); System.out.println(cursor.next()); i++; } }catch(Exception e){ System.err.println( e.getClass().getName() + ": " + e.getMessage() ); } } }
编译运行以上程序，输出结果如下:
Connect to database successfully Authentication: true Collection mycol selected successfully Inserted Document: 1 { "_id" : ObjectId(7df78ad8902c), "title": "MongoDB", "description": "database", "likes": 100, "url": "http://www.shouce.ren/mongodb/", "by": "shouce.ren" }
你可以使用 com.mongodb.DBCollection 类中的 update() 方法来更新集合中的文档。
代码片段如下：
import com.mongodb.MongoClient; import com.mongodb.MongoException; import com.mongodb.WriteConcern; import com.mongodb.DB; import com.mongodb.DBCollection; import com.mongodb.BasicDBObject; import com.mongodb.DBObject; import com.mongodb.DBCursor; import com.mongodb.ServerAddress; import java.util.Arrays; public class MongoDBJDBC{ public static void main( String args[] ){ try{ // 连接到Mongodb服务 MongoClient mongoClient = new MongoClient( "localhost" , 27017 ); // 连接到你的数据库 DB db = mongoClient.getDB( "test" ); System.out.println("Connect to database successfully"); boolean auth = db.authenticate(myUserName, myPassword); System.out.println("Authentication: "+auth); DBCollection coll = db.getCollection("mycol"); System.out.println("Collection mycol selected successfully"); DBCursor cursor = coll.find(); while (cursor.hasNext()) { DBObject updateDocument = cursor.next(); updateDocument.put("likes","200") col1.update(updateDocument); } System.out.println("Document updated successfully"); cursor = coll.find(); int i=1; while (cursor.hasNext()) { System.out.println("Updated Document: "+i); System.out.println(cursor.next()); i++; } }catch(Exception e){ System.err.println( e.getClass().getName() + ": " + e.getMessage() ); } } }
编译运行以上程序，输出结果如下:
Connect to database successfully Authentication: true Collection mycol selected successfully Document updated successfully Updated Document: 1 { "_id" : ObjectId(7df78ad8902c), "title": "MongoDB", "description": "database", "likes": 200, "url": "http://www.shouce.ren/mongodb/", "by": "shouce.ren" }
要删除集合中的第一个文档，首先你需要使用com.mongodb.DBCollection类中的 findOne()方法来获取第一个文档，然后使用remove 方法删除。
代码片段如下：
import com.mongodb.MongoClient; import com.mongodb.MongoException; import com.mongodb.WriteConcern; import com.mongodb.DB; import com.mongodb.DBCollection; import com.mongodb.BasicDBObject; import com.mongodb.DBObject; import com.mongodb.DBCursor; import com.mongodb.ServerAddress; import java.util.Arrays; public class MongoDBJDBC{ public static void main( String args[] ){ try{ // 连接到Mongodb服务 MongoClient mongoClient = new MongoClient( "localhost" , 27017 ); // 连接到你的数据库 DB db = mongoClient.getDB( "test" ); System.out.println("Connect to database successfully"); boolean auth = db.authenticate(myUserName, myPassword); System.out.println("Authentication: "+auth); DBCollection coll = db.getCollection("mycol"); System.out.println("Collection mycol selected successfully"); DBObject myDoc = coll.findOne(); col1.remove(myDoc); DBCursor cursor = coll.find(); int i=1; while (cursor.hasNext()) { System.out.println("Inserted Document: "+i); System.out.println(cursor.next()); i++; } System.out.println("Document deleted successfully"); }catch(Exception e){ System.err.println( e.getClass().getName() + ": " + e.getMessage() ); } } }
编译运行以上程序，输出结果如下:
Connect to database successfully Authentication: true Collection mycol selected successfully Document deleted successfully
你还可以使用 save(), limit(), skip(), sort() 等方法来操作MongoDB数据库。