Java中使用mongodb實現增刪改查
Java
安裝
要想在 Java 程式中使用 MongoDB,需要先確定是否安裝了 MongoDB JDBC 驅動,並且要在機器上安裝了 Java。檢視 Java 教程來確保在機器上安裝好 Java。下面來介紹如何安裝 MongoDB JDBC 驅動。
- 從路徑 Download mongo.jar 處下載 jar 檔案,注意下載最新版本。
- 在類路徑中包括 mongo.jar 檔案。
連線資料庫
為了連線資料庫,需要指定資料庫名稱,如果資料庫不存在,mongodb 就會自動建立它。
連線資料庫的程式碼段如下所示:
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() ); } } }
下面編譯並執行上面的程式,以便測試資料庫。可以針對每個需求改變路徑。假設當前 JDBC 驅動版本 mongo-2.10.1.jar 可用於當前路徑。
$javac MongoDBJDBC.java $java -classpath ".:mongo-2.10.1.jar" MongoDBJDBC Connect to database successfully Authentication: true
如果想使用 Windows 系統的機器,則編譯並執行程式碼如下:
$javac MongoDBJDBC.java $java -classpath ".;mongo-2.10.1.jar" MongoDBJDBC Connect to database successfully Authentication: true
如果選定資料庫的使用者名稱及密碼有效,則 auth 值為 true。
建立集合
建立集合需要使用 com.mongodb.DB
類的 createCollection()
方法。
建立集合的程式碼段如下所示:
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() ); } } }
編譯並執行該程式,結果如下所示:
Connect to database successfully Authentication: true Collection created successfully
獲取/選擇一個集合
從資料庫中獲取/選擇一個集合,使用 com.mongodb.DBCollection
類的 getCollection()
方法。程式碼段如下:
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() ); } } }
編譯並執行該程式,結果如下所示:
Connect to database successfully Authentication: true Collection created successfully Collection mycol selected successfully
插入文件
插入文件使用 com.mongodb.DBCollection
類的 insert()
方法。程式碼段如下所示:
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() ); } } }
編譯並執行該程式,結果如下所示
Connect to database successfully Authentication: true Collection mycol selected successfully Document inserted successfully
檢索所有文件
選擇集合中的所有文件,使用 com.mongodb.DBCollection
類的 find()
方法。該方法返回一個遊標,所以需要迭代該遊標。
選擇所有文件的程式碼如下所示:
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() ); } } }
編譯並執行程式的結果如下:
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" }
更新文件
更新集合中的文件,使用 com.mongodb.DBCollection
類的 update()
方法。程式碼如下所示:
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() ); } } }
程式編譯及執行結果如下:
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" }
刪除第一個文件
刪除集合中的第一個文件,需要使用 findOne()
方法選中第一個文件,然後使用 com.mongodb.DBCollection
類的remove
方法將其刪除。程式碼範例如下:
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() ); } } }