Java连接MongoDB操作

作者：--    发布时间：2019-11-20

在本章中，我们将学习如何设置和使用mongodb jdbc驱动程序。

安装 mongodb jdbc驱动程序

要在java程序中使用mongodb之前，需要确保在机器上设置了mongodb jdbc驱动程序和java。 可以在机器上检查java环境可通过：java教程。 现在，我们来看一下如何设置mongodb jdbc驱动。

• 下载 mongo.jar(http://mongodb.github.io/mongo-java-driver/)，确保下载最新版本。
• 将 mongo.jar 包含到类路径中。

连接到数据库

要连接数据库，需要指定数据库名称，如果数据库不存在，那么mongodb会自动创建它。
使用 eclipse 创建一个 maven 工程 - mongodbjdbc ，其目录结果如下所示 -

有关 pom.xml 文件的内容如下 -

<project xmlns="http://maven.apache.org/pom/4.0.0" xmlns:xsi="http://www.w3.org/2001/xmlschema-instance"
    xsi:schemalocation="http://maven.apache.org/pom/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelversion>4.0.0</modelversion>

    <groupid>com.h3</groupid>
    <artifactid>mongodbjdbc</artifactid>
    <version>0.0.1-snapshot</version>
    <packaging>jar</packaging>

    <name>mongodbjdbc</name>
    <url>http://maven.apache.org</url>

    <properties>
        <project.build.sourceencoding>utf-8</project.build.sourceencoding>
    </properties>

    <dependencies>
        <dependency>
            <groupid>junit</groupid>
            <artifactid>junit</artifactid>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupid>org.mongodb</groupid>
            <artifactid>mongodb-driver</artifactid>
            <version>3.4.2</version>
        </dependency>
    </dependencies>
    <build>
        <defaultgoal>compile</defaultgoal>
    </build>
</project>

以下是连接到数据库的代码片段 -

package com.h3.mongodbjdbc;

/**
 * hello world!
 *
 */
import com.mongodb.mongoclient;
import com.mongodb.client.mongodatabase;

public class app {

    public static void main(string args[]) {

        try {

            // to connect to mongodb server
            mongoclient mongoclient = new mongoclient("localhost", 27017);

            // now connect to your databases
            mongodatabase mgdb = mongoclient.getdatabase("mycol");

            system.out.println("connect to database successfully!");
            system.out.println("mongodatabase inof is : "+mgdb.getname());
            // if mongodb in secure mode, authentication is required.
            // boolean auth = db.authenticate(myusername, mypassword);
            // system.out.println("authentication: "+auth);

        } catch (exception e) {
            system.err.println(e.getclass().getname() + ": " + e.getmessage());
        }
    }
}

默认认证机制

string user; // the user name
string database; // the name of the database in which the user is defined
char[] password; // the password as a character array
// ...
mongocredential credential = mongocredential.createcredential(user, database, password);
mongoclient mongoclient = new mongoclient(new serveraddress("host1", 27017),
                                         arrays.aslist(credential));

或者使用连接字符串而不明确指定认证机制：

mongoclienturi uri = new mongoclienturi("mongodb://user1:pwd1@host1/?authsource=db1");
mongoclient mongoclient = new mongoclient(uri);

执行上面代码，得到以下结果 -

com.mongodb.diagnostics.logging.jullogger log
信息: cluster created with settings {hosts=[localhost:27017], mode=single, requiredclustertype=unknown, serverselectiontimeout='30000 ms', maxwaitqueuesize=500}
connect to database successfully!
mongodatabase inof is : mycol

创建和列出集合

要创建集合，可使用 com.mongodb.db 类的 createcollection()方法。

以下是创建集合的代码片段 -

package com.h3.mongodbjdbc;

import org.bson.document;
import com.mongodb.dbcollection;
import com.mongodb.client.model.createcollectionoptions;
/**
 * hello world!
 *
 */
import com.mongodb.mongoclient;
import com.mongodb.client.mongocollection;
import com.mongodb.client.mongodatabase;

public class createcollection {

    public static void main(string args[]) {

        try {

            // to connect to mongodb server
            mongoclient mongoclient = new mongoclient("localhost", 27017);

            // now connect to your databases
            mongodatabase database = mongoclient.getdatabase("test");

            //database.createcollection("newcollection",new createcollectionoptions().capped(true).sizeinbytes(0x100000));

            mongocollection<document> coll = database.getcollection("mytestcollection");

            system.out.println("collection created successfully");

            system.out.println("当前数据库中的所有集合是：");

            for (string name : database.listcollectionnames()) {
                system.out.println(name);
            }

        } catch (exception e) {
            system.err.println(e.getclass().getname() + ": " + e.getmessage());
        }
    }
}

执行上面代码，得到以下结果 -

collection created successfully
当前数据库中的所有集合是：
mycol
inventory
post
mycollection
newcollection

插入文档

要将文档插入到mongodb中，使用com.mongodb.dbcollection类的insertone()方法。

以下是插入文档的代码片段 -

package com.h3.mongodbjdbc;

import java.util.arrays;

import org.bson.document;

import com.mongodb.basicdbobject;
import com.mongodb.block;
import com.mongodb.dbcollection;
import com.mongodb.dbcursor;
/**
 * hello world!
 *
 */
import com.mongodb.mongoclient;
import com.mongodb.client.mongocollection;
import com.mongodb.client.mongocursor;
import com.mongodb.client.mongodatabase;
import com.mongodb.client.model.createcollectionoptions;

public class insertdocument {

    public static void main(string args[]) {

        try {

            // to connect to mongodb server
            mongoclient mongoclient = new mongoclient("localhost", 27017);

            // now connect to your databases
            mongodatabase database = mongoclient.getdatabase("test");

            // database.createcollection("newcollection", new
            // createcollectionoptions().capped(true).sizeinbytes(0x100000));

            system.out.println("collection created successfully");

            system.out.println("当前数据库中的所有集合是：");

            for (string name : database.listcollectionnames()) {
                system.out.println(name);
            }

            mongocollection coll = database.getcollection("mycol");
            system.out.println("collection mycol selected successfully");
            mongocollection<document> collection = database.getcollection("mycol");

            document document = new document("_id", 1999).append("title", "mongodb insert demo")
                    .append("description","database")
                    .append("likes", 30)
                    .append("by", "h3 point")
                    .append("url", "http://www.h3.com/mongodb/");

            collection.insertone(document);

            collection.find().foreach(printblock);

            system.out.println("document inserted successfully");

        } catch (exception e) {
            system.err.println(e.getclass().getname() + ": " + e.getmessage());
        }
    }

    static block<document> printblock = new block<document>() {
        public void apply(final document document) {
            system.out.println(document.tojson());
        }
    };
}

执行上面代码，得到以下结果 -

newcollection
mycol
inventory
post
collection
mycollection
newcollection
collection mycol selected successfully
{ "_id" : 123.0, "title" : "mongodb overview", "description" : "mongodb is no sql database", "by" : "h3 tutorials", "url" : "http://www.h3.com", "tags" : ["mongodb", "database", "nosql"], "likes" : 100.0 }
{ "_id" : 100.0, "title" : "mongodb overview", "description" : "mongodb is no sql database", "by" : "h3 tutorials", "url" : "http://www.h3.com", "tags" : ["mongodb", "database", "nosql"], "likes" : 100.0 }
{ "_id" : 1999, "title" : "mongodb insert demo", "description" : "database", "likes" : 30, "by" : "h3 point", "url" : "http://www.h3.com/mongodb/" }
document inserted successfully

如何插入多行？

document doc1 = new document("name", "amarcord pizzeria")
               .append("contact", new document("phone", "264-555-0193")
                                       .append("email", "amarcord.pizzeria@example.net")
                                       .append("location",arrays.aslist(-73.88502, 40.749556)))
               .append("stars", 2)
               .append("categories", arrays.aslist("pizzeria", "italian", "pasta"));


document doc2 = new document("name", "blue coffee bar")
               .append("contact", new document("phone", "604-555-0102")
                                       .append("email", "bluecoffeebar@example.com")
                                       .append("location",arrays.aslist(-73.97902, 40.8479556)))
               .append("stars", 5)
               .append("categories", arrays.aslist("coffee", "pastries"));

list<document> documents = new arraylist<document>();
documents.add(doc1);
documents.add(doc2);

collection.insertmany(documents);

更新文档

要从集合更新文档，使用com.mongodb.dbcollection类的update()和updatemany()方法。以下是选择第一个文档的代码片段 -

package com.h3.mongodbjdbc;

import org.bson.document;

import com.mongodb.block;
/**
 * hello world!
 *
 */
import com.mongodb.mongoclient;
import com.mongodb.mongoclienturi;
import com.mongodb.serveraddress;

import com.mongodb.client.mongodatabase;
import com.mongodb.client.mongocollection;

import org.bson.document;

import com.mongodb.client.mongocursor;
import static com.mongodb.client.model.filters.*;
import com.mongodb.client.result.deleteresult;
import static com.mongodb.client.model.updates.*;
import com.mongodb.client.result.updateresult;
import java.util.arraylist;
import java.util.list;

public class app {

    public static void main(string args[]) {

        try {

            // to connect to mongodb server
            mongoclient mongoclient = new mongoclient("127.0.0.1", 27017);

            // now connect to your databases
            mongodatabase database = mongoclient.getdatabase("mycol");

            system.out.println("connect to database successfully!");
            system.out.println("mongodatabase inof is : "+database.getname());

            mongocollection<document> collection = database.getcollection("mycol");
            //collection.updateone(eq("_id", 1999),new document("$set", new document("title", "更新了标题2")));
            document document = new document("_id", 9999).append("title", "mongodb insert demo")
                    .append("description","database")
                    .append("likes", 30)
                    .append("by", "h3 point")
                    .append("url", "http://www.h3.com/mongodb/");

            collection.insertone(document);
            collection.find().foreach(printblock);
            collection.updateone(eq("_id", 9999),new document("$set", new document("title", "更新了标题2")));
            collection.find().foreach(printblock);

        } catch (exception e) {
            system.err.println(e.getclass().getname() + ": " + e.getmessage());
        }
    }

    static block<document> printblock = new block<document>() {
        public void apply(final document document) {
            system.out.println(document.tojson());
        }
    };
}

执行上面代码，得到以下结果 -

{ "_id" : 1999, "title" : "更新了标题2", "description" : "database", "likes" : 30, "by" : "h3 point", "url" : "http://www.h3.com/mongodb/" }
{ "_id" : 9999, "title" : "mongodb insert demo", "description" : "database", "likes" : 30, "by" : "h3 point", "url" : "http://www.h3.com/mongodb/" }
{ "_id" : 1999, "title" : "更新了标题2", "description" : "database", "likes" : 30, "by" : "h3 point", "url" : "http://www.h3.com/mongodb/" }
{ "_id" : 9999, "title" : "更新了标题2", "description" : "database", "likes" : 30, "by" : "h3 point", "url" : "http://www.h3.com/mongodb/" }

删除文档

要从集合中删除第一个文档，需要首先使用findone()方法选择文档，然后使用com.mongodb.dbcollection类的remove()方法。

以下是删除第一个文档的代码片段 -

package com.h3.mongodbjdbc;

import org.bson.document;

import com.mongodb.block;
/**
 * hello world!
 *
 */
import com.mongodb.mongoclient;
import com.mongodb.mongoclienturi;
import com.mongodb.serveraddress;

import com.mongodb.client.mongodatabase;
import com.mongodb.client.mongocollection;

import org.bson.document;

import com.mongodb.client.mongocursor;
import static com.mongodb.client.model.filters.*;
import com.mongodb.client.result.deleteresult;
import static com.mongodb.client.model.updates.*;
import com.mongodb.client.result.updateresult;
import java.util.arraylist;
import java.util.list;

public class app {

    public static void main(string args[]) {

        try {

            // to connect to mongodb server
            mongoclient mongoclient = new mongoclient("127.0.0.1", 27017);

            // now connect to your databases
            mongodatabase database = mongoclient.getdatabase("mycol");

            system.out.println("connect to database successfully!");
            system.out.println("mongodatabase inof is : "+database.getname());

            // 更新文档
            mongocollection<document> collection = database.getcollection("mycol");
            /**
            document document = new document("_id", 9999).append("title", "mongodb insert demo")
                    .append("description","database")
                    .append("likes", 30)
                    .append("by", "h3 point")
                    .append("url", "http://www.h3.com/mongodb/");

            collection.insertone(document);
            //collection.find().foreach(printblock);
            //collection.updateone(eq("_id", 9999),new document("$set", new document("title", "更新了标题2")));

            */
            collection.find().foreach(printblock);

            // 删除文档
            collection.deleteone(eq("_id", 9999));
            system.out.println("after delete document:");
            collection.find().foreach(printblock);

        } catch (exception e) {
            system.err.println(e.getclass().getname() + ": " + e.getmessage());
        }
    }

    static block<document> printblock = new block<document>() {
        public void apply(final document document) {
            system.out.println(document.tojson());
        }
    };
}

执行上面代码，得到以下结果 -

{ "_id" : 1999, "title" : "更新了标题2", "description" : "database", "likes" : 30, "by" : "h3 point", "url" : "http://www.h3.com/mongodb/" }
{ "_id" : 9999, "title" : "更新了标题2", "description" : "database", "likes" : 30, "by" : "h3 point", "url" : "http://www.h3.com/mongodb/" }
after delete document:
{ "_id" : 1999, "title" : "更新了标题2", "description" : "database", "likes" : 30, "by" : "h3 point", "url" : "http://www.h3.com/mongodb/" }