MongoDB Java 连接配置

【前言】

由于处于线程安全等考虑，MongoDBJava从3.0开始已经打算废弃DB开头的类的使用，所以整体调用上有了较大的区别，特以此文志之

【正文】

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。

· 首先你必须下载mongo jar包，

Git下载地址：https://github.com/mongodb/mongo-java-driver/downloads,

国内快速下载地址：http://central.maven.org/maven2/org/mongodb/mongo-java-driver/

网盘下载地址：http://pan.baidu.com/s/1i3Mv0dn (这里测试使用3.2.2版)。

· 你需要将mongo.jar包含在你的 classpath中

连接数据库

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 java.util.ArrayList;
import java.util.List;
import com.mongodb.MongoClient;
import com.mongodb.MongoCredential;
import com.mongodb.ServerAddress;
import com.mongodb.client.MongoDatabase;
public class MongoDBJDBC {
public static void main(String[] args){
try {
//连接到MongoDB服务如果是远程连接可以替换“localhost”为服务器所在IP地址
//ServerAddress()两个参数分别为服务器地址和端口
ServerAddress serverAddress = new ServerAddress("localhost",27017);
List<ServerAddress> addrs = new ArrayList<ServerAddress>();
addrs.add(serverAddress);
//MongoCredential.createScramSha1Credential()三个参数分别为用户名数据库名称密码
MongoCredential credential = MongoCredential.createScramSha1Credential("username", "databaseName", "password".toCharArray());
List<MongoCredential> credentials = new ArrayList<MongoCredential>();
credentials.add(credential);
//通过连接认证获取MongoDB连接
MongoClient mongoClient = new MongoClient(addrs,credentials);
//连接到数据库
MongoDatabase mongoDatabase = mongoClient.getDatabase("databaseName");
System.out.println("Connect to database successfully");
} catch (Exception e) {
System.err.println( e.getClass().getName() + ": " + e.getMessage() );
}
}
}

创建集合

我们可以使用com.mongodb.client.MongoDatabase类中的createCollection()来创建集合

代码片段如下：

import java.util.ArrayList;
import java.util.List;
import com.mongodb.MongoClient;
import com.mongodb.MongoCredential;
import com.mongodb.ServerAddress;
import com.mongodb.client.MongoDatabase;
public class MongoDBJDBC {
public static void main(String[] args){
try {
//连接到MongoDB服务如果是远程连接可以替换“localhost”为服务器所在IP地址
//ServerAddress()两个参数分别为服务器地址和端口
ServerAddress serverAddress = new ServerAddress("localhost",27017);
List<ServerAddress> addrs = new ArrayList<ServerAddress>();
addrs.add(serverAddress);
//MongoCredential.createScramSha1Credential()三个参数分别为用户名数据库名称密码
MongoCredential credential = MongoCredential.createScramSha1Credential("username", "databaseName", "password".toCharArray());
List<MongoCredential> credentials = new ArrayList<MongoCredential>();
credentials.add(credential);
//通过连接认证获取MongoDB连接
MongoClient mongoClient = new MongoClient(addrs,credentials);
//连接到数据库
MongoDatabase mongoDatabase = mongoClient.getDatabase("databaseName");
System.out.println("Connect to database successfully");
//创建集合参数为 “集合名称”
mongoDatabase.createCollection("collectionName");
System.out.println("Collection created successfully");
} catch (Exception e) {
System.err.println( e.getClass().getName() + ": " + e.getMessage() );
}
}
}

获取集合

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 org.bson.Document;
import com.mongodb.MongoClient;
import com.mongodb.MongoCredential;
import com.mongodb.ServerAddress;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoDatabase;
public class MongoDBJDBC {
public static void main(String[] args){
try {
//连接到MongoDB服务如果是远程连接可以替换“localhost”为服务器所在IP地址
//ServerAddress()两个参数分别为服务器地址和端口
ServerAddress serverAddress = new ServerAddress("localhost",27017);
List<ServerAddress> addrs = new ArrayList<ServerAddress>();
addrs.add(serverAddress);
//MongoCredential.createScramSha1Credential()三个参数分别为用户名数据库名称密码
MongoCredential credential = MongoCredential.createScramSha1Credential("username", "databaseName", "password".toCharArray());
List<MongoCredential> credentials = new ArrayList<MongoCredential>();
credentials.add(credential);
//通过连接认证获取MongoDB连接
MongoClient mongoClient = new MongoClient(addrs,credentials);
//连接到数据库
MongoDatabase mongoDatabase = mongoClient.getDatabase("databaseName");
System.out.println("Connect to database successfully");
//获取集合参数为“集合名称”
MongoCollection<Document> mongoCollection = mongoDatabase.getCollection("collectionName");
System.out.println("Collection mycol selected successfully");
} catch (Exception e) {
System.err.println( e.getClass().getName() + ": " + e.getMessage() );
}
}
}

插入文档

我们可以使用com.mongodb.client.MongoCollection类的insert()方法来插入一个文档

代码片段如下：

import java.util.ArrayList;
import java.util.List;
import org.bson.Document;
import com.mongodb.MongoClient;
import com.mongodb.MongoCredential;
import com.mongodb.ServerAddress;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoDatabase;
public class MongoDBJDBC {
public static void main(String[] args){
try {
//连接到MongoDB服务如果是远程连接可以替换“localhost”为服务器所在IP地址
//ServerAddress()两个参数分别为服务器地址和端口
ServerAddress serverAddress = new ServerAddress("localhost",27017);
List<ServerAddress> addrs = new ArrayList<ServerAddress>();
addrs.add(serverAddress);
//MongoCredential.createScramSha1Credential()三个参数分别为用户名数据库名称密码
MongoCredential credential = MongoCredential.createScramSha1Credential("username", "databaseName", "password".toCharArray());
List<MongoCredential> credentials = new ArrayList<MongoCredential>();
credentials.add(credential);
//通过连接认证获取MongoDB连接
MongoClient mongoClient = new MongoClient(addrs,credentials);
//连接到数据库
MongoDatabase mongoDatabase = mongoClient.getDatabase("databaseName");
System.out.println("Connect to database successfully");
//获取集合参数为“集合名称”
MongoCollection<Document> mongoCollection = mongoDatabase.getCollection("collectionName");
System.out.println("Collection mycol selected successfully");
//插入文档
/**
* 1. 创建文档 org.bson.Document 参数为key-value的格式
* 2. 创建文档集合List<Document>
* 3. 将文档集合插入数据库集合中 mongoCollection.insertMany(List<Document>) 插入单个文档可以用 mongoCollection.insertOne(Document)
* */
Document document = new Document("title", "MongoDB").
append("description", "database").
append("likes", 100).
append("by", "Fly");
List<Document> documents = new ArrayList<Document>();
documents.add(document);
mongoCollection.insertMany(documents);
System.out.println("Document inserted successfully");
} catch (Exception e) {
System.err.println( e.getClass().getName() + ": " + e.getMessage() );
}
}
}

检索所有文档

我们可以使用com.mongodb.client.MongoCollection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 java.util.ArrayList;
import java.util.List;
import org.bson.Document;
import com.mongodb.MongoClient;
import com.mongodb.MongoCredential;
import com.mongodb.ServerAddress;
import com.mongodb.client.FindIterable;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoCursor;
import com.mongodb.client.MongoDatabase;
public class MongoDBJDBC {
public static void main(String[] args){
try {
//连接到MongoDB服务如果是远程连接可以替换“localhost”为服务器所在IP地址
//ServerAddress()两个参数分别为服务器地址和端口
ServerAddress serverAddress = new ServerAddress("localhost",27017);
List<ServerAddress> addrs = new ArrayList<ServerAddress>();
addrs.add(serverAddress);
//MongoCredential.createScramSha1Credential()三个参数分别为用户名数据库名称密码
MongoCredential credential = MongoCredential.createScramSha1Credential("username", "databaseName", "password".toCharArray());
List<MongoCredential> credentials = new ArrayList<MongoCredential>();
credentials.add(credential);
//通过连接认证获取MongoDB连接
MongoClient mongoClient = new MongoClient(addrs,credentials);
//连接到数据库
MongoDatabase mongoDatabase = mongoClient.getDatabase("databaseName");
System.out.println("Connect to database successfully");
//获取集合参数为“集合名称”
MongoCollection<Document> mongoCollection = mongoDatabase.getCollection("collectionName");
System.out.println("Collection mycol selected successfully");
//检索所有文档
/**
* 1. 获取迭代器FindIterable<Document>
* 2. 获取游标MongoCursor<Document>
* 3. 通过游标遍历检索出的文档集合
* */
FindIterable<Document> findIterable = mongoCollection.find();
MongoCursor<Document> mongoCursor = findIterable.iterator();
while(mongoCursor.hasNext()){
System.out.println(mongoCursor.next());
}
} catch (Exception e) {
System.err.println( e.getClass().getName() + ": " + e.getMessage() );
}
}
}

更新文档

你可以使用com.mongodb.client.MongoCollection类中的 updateOne()或updateMany()方法来更新集合中的文档。

代码片段如下：

import java.util.ArrayList;
import java.util.List;
import org.bson.Document;
import com.mongodb.MongoClient;
import com.mongodb.MongoCredential;
import com.mongodb.ServerAddress;
import com.mongodb.client.FindIterable;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoCursor;
import com.mongodb.client.MongoDatabase;
import com.mongodb.client.model.Filters;
public class MongoDBJDBC {
public static void main(String[] args){
try {
//连接到MongoDB服务如果是远程连接可以替换“localhost”为服务器所在IP地址
//ServerAddress()两个参数分别为服务器地址和端口
ServerAddress serverAddress = new ServerAddress("localhost",27017);
List<ServerAddress> addrs = new ArrayList<ServerAddress>();
addrs.add(serverAddress);
//MongoCredential.createScramSha1Credential()三个参数分别为用户名数据库名称密码
MongoCredential credential = MongoCredential.createScramSha1Credential("userName", "databaseName", "password".toCharArray());
List<MongoCredential> credentials = new ArrayList<MongoCredential>();
credentials.add(credential);
//通过连接认证获取MongoDB连接
MongoClient mongoClient = new MongoClient(addrs,credentials);
//连接到数据库
MongoDatabase mongoDatabase = mongoClient.getDatabase("databaseName");
System.out.println("Connect to database successfully");
//获取集合参数为“集合名称”
MongoCollection<Document> mongoCollection = mongoDatabase.getCollection("collectionName");
System.out.println("Collection mycol selected successfully");
//更新文档将文档中likes=100的文档修改为likes=200
mongoCollection.updateMany(Filters.eq("likes", 100), new Document("$set",new Document("likes",200)));
//检索查看结果
FindIterable<Document> findIterable = mongoCollection.find();
MongoCursor<Document> mongoCursor = findIterable.iterator();
while(mongoCursor.hasNext()){
System.out.println(mongoCursor.next());
}
} catch (Exception e) {
System.err.println( e.getClass().getName() + ": " + e.getMessage() );
}
}
}

删除文档

要删除集合中符合条件的文档，需要使用com.mongodb.client.MongoCollection类中的deleteOne ()或deleteMany()方法。分别表示删除第一个符合条件的文档和删除所有符合条件的文档。

代码片段如下：

import java.util.ArrayList;
import java.util.List;
import org.bson.Document;
import com.mongodb.MongoClient;
import com.mongodb.MongoCredential;
import com.mongodb.ServerAddress;
import com.mongodb.client.FindIterable;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoCursor;
import com.mongodb.client.MongoDatabase;
import com.mongodb.client.model.Filters;
public class MongoDBJDBC {
public static void main(String[] args){
try {
//连接到MongoDB服务如果是远程连接可以替换“localhost”为服务器所在IP地址
//ServerAddress()两个参数分别为服务器地址和端口
ServerAddress serverAddress = new ServerAddress("localhost",27017);
List<ServerAddress> addrs = new ArrayList<ServerAddress>();
addrs.add(serverAddress);
//MongoCredential.createScramSha1Credential()三个参数分别为用户名数据库名称密码
MongoCredential credential = MongoCredential.createScramSha1Credential("userName", "databaseName", "password".toCharArray());
List<MongoCredential> credentials = new ArrayList<MongoCredential>();
credentials.add(credential);
//通过连接认证获取MongoDB连接
MongoClient mongoClient = new MongoClient(addrs,credentials);
//连接到数据库
MongoDatabase mongoDatabase = mongoClient.getDatabase("<span style="font-family: Arial, Helvetica, sans-serif;">databaseName</span><span style="font-family: Arial, Helvetica, sans-serif;">");</span>
System.out.println("Connect to database successfully");
//获取集合参数为“集合名称”
MongoCollection<Document> mongoCollection = mongoDatabase.getCollection("collectionName");
System.out.println("Collection mycol selected successfully");
//删除符合条件的第一个文档
mongoCollection.deleteOne(Filters.eq("likes", 200));
//删除所有符合条件的文档
mongoCollection.deleteMany (Filters.eq("likes", 200));
//检索查看结果
FindIterable<Document> findIterable = mongoCollection.find();
MongoCursor<Document> mongoCursor = findIterable.iterator();
while(mongoCursor.hasNext()){
System.out.println(mongoCursor.next());
}
} catch (Exception e) {
System.err.println( e.getClass().getName() + ": " + e.getMessage() );
}
}
}

要注意，上面的数据库连接我都没有手动调用关闭，为了防止意外发生建议加上如下代码：

finally{
mongoClient.close();
}

你还可以使用aggregate(),createIndex(),count()等方法来操作MongoDB数据库、集合。