在Java中使用MongoDB
2016-03-17 11:32
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源于:http://wiki.jikexueyuan.com/project/mongodb/mongodb-java.html
从路径 Download mongo.jar 处下载 jar 文件,注意下载最新版本。
在类路径中包括 mongo.jar 文件。
maven dependency
jar包下载(百度云盘)
连接数据库的代码段如下所示:
下面编译并运行上面的程序,以便测试数据库。可以针对每个需求改变路径。假设当前 JDBC 驱动版本 mongo-2.10.1.jar 可用于当前路径。
如果想使用 Windows 系统的机器,则编译并执行代码如下:
如果选定数据库的用户名及密码有效,则 auth 值为 true。
创建集合的代码段如下所示:
编译并执行该程序,结果如下所示:
编译并执行该程序,结果如下所示:
编译并执行该程序,结果如下所示:
选择所有文档的代码如下所示:
编译并执行程序的结果如下:
程序编译及运行结果如下:
程序编译并执行结果如下所示:
剩余的 mongodb 的 save()、limit()、skip()、sort() 等方法将在教程剩余部分予以介绍。
安装
要想在 Java 程序中使用 MongoDB,需要先确定是否安装了 MongoDB JDBC 驱动,并且要在机器上安装了 Java。查看 Java 教程来确保在机器上安装好 Java。下面来介绍如何安装 MongoDB JDBC 驱动。从路径 Download mongo.jar 处下载 jar 文件,注意下载最新版本。
在类路径中包括 mongo.jar 文件。
maven dependency
<dependency> <groupId>org.mongodb</groupId> <artifactId>mongo-java-driver</artifactId> <version>3.2.2</version> </dependency>
jar包下载(百度云盘)
连接数据库
为了连接数据库,需要指定数据库名称,如果数据库不存在,mongodb 就会自动创建它。连接数据库的代码段如下所示:
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{ // To connect to mongodb server MongoClient mongoClient = new MongoClient( "localhost" , 27017 ); // Now connect to your databases 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() ); } } }
下面编译并运行上面的程序,以便测试数据库。可以针对每个需求改变路径。假设当前 JDBC 驱动版本 mongo-2.10.1.jar 可用于当前路径。
$javac MongoDBJDBC.java $java -classpath ".:mongo-2.10.1.jar" MongoDBJDBC Connect to database successfully Authentication: true
如果想使用 Windows 系统的机器,则编译并执行代码如下:
$javac MongoDBJDBC.java $java -classpath ".;mongo-2.10.1.jar" MongoDBJDBC Connect to database successfully Authentication: true
如果选定数据库的用户名及密码有效,则 auth 值为 true。
创建集合
创建集合需要使用 com.mongodb.DB 类的 createCollection() 方法。创建集合的代码段如下所示:
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{ // To connect to mongodb server MongoClient mongoClient = new MongoClient( "localhost" , 27017 ); // Now connect to your databases 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() ); } } }
编译并执行该程序,结果如下所示:
Connect to database successfully Authentication: true Collection created successfully
获取/选择一个集合
从数据库中获取/选择一个集合,使用 com.mongodb.DBCollection 类的 getCollection() 方法。代码段如下: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{ // To connect to mongodb server MongoClient mongoClient = new MongoClient( "localhost" , 27017 ); // Now connect to your databases 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() ); } } }
编译并执行该程序,结果如下所示:
Connect to database successfully Authentication: true Collection created successfully
Collection mycol selected successfully
插入文档
插入文档使用 com.mongodb.DBCollection 类的 insert() 方法。代码段如下所示: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{ // To connect to mongodb server MongoClient mongoClient = new MongoClient( "localhost" , 27017 ); // Now connect to your databases 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() ); } } }
编译并执行该程序,结果如下所示:
Connect to database successfully Authentication: true Collection mycol selected successfully Document inserted successfully
检索所有文档
选择集合中的所有文档,使用 com.mongodb.DBCollection 类的 find() 方法。该方法返回一个游标,所以需要迭代该游标。选择所有文档的代码如下所示:
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{ // To connect to mongodb server MongoClient mongoClient = new MongoClient( "localhost" , 27017 ); // Now connect to your databases 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() ); } } }
编译并执行程序的结果如下:
Connect to database successfully Authentication: true Collection mycol selected successfully Document updated successfully Updated Document: 1 { "_id" : ObjectId(7df78ad8902c), "title": "MongoDB", "description": "database", "likes": 100, "url": "http://www.tutorialspoint.com/mongodb/", "by": "tutorials point" }
更新文档
更新集合中的文档,使用 com.mongodb.DBCollection 类的 update() 方法。代码如下所示: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{ // To connect to mongodb server MongoClient mongoClient = new MongoClient( "localhost" , 27017 ); // Now connect to your databases 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() ); } } }
程序编译及运行结果如下:
Connect to database successfully Authentication: true Collection mycol selected successfully Document updated successfully Updated Document: 1 { "_id" : ObjectId(7df78ad8902c), "title": "MongoDB", "description": "database", "likes": 100, "url": "http://www.tutorialspoint.com/mongodb/", "by": "tutorials point" }
删除第一个文档
删除集合中的第一个文档,需要使用 findOne() 方法选中第一个文档,然后使用 com.mongodb.DBCollection 类的 remove 方法将其删除。代码范例如下: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{ // To connect to mongodb server MongoClient mongoClient = new MongoClient( "localhost" , 27017 ); // Now connect to your databases 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() ); } } }
程序编译并执行结果如下所示:
Connect to database successfully Authentication: true Collection mycol selected successfully Document deleted successfully
剩余的 mongodb 的 save()、limit()、skip()、sort() 等方法将在教程剩余部分予以介绍。
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