示例包含2个类文件, 1个操作枚举,1个帮助类.

Maven 引用

        <!-- https://mvnrepository.com/artifact/org.mongodb/mongo-java-driver -->
        <dependency>
            <groupId>org.mongodb</groupId>
            <artifactId>mongo-java-driver</artifactId>
            <version>3.4.2</version>
        </dependency>

枚举

/**
 * used for generating BasicDBObject for query
 */
public enum MongoOperationEnum {

    /*
     * =
     */
    EQ("$eq"),
    /*
     * !=
     */
    NE("$ne"),
    /*
     * <
     */
    LT("$lt"),
    /*
     * <=
     */
    LTE("$lte"),
    /*
     * >
     */
    GT("$gt"),
    /*
     * >=
     */
    GTE("$gte"),
    /*
     * and
     */
    AND("$and"),
    /*
     * or
     */
    OR("$or");

    private String value;

    public String getValue() {
        return value;
    }

    private MongoOperationEnum(String value) {
        this.value = value;
    }
}

帮助类

package yz20537.mongodb_test;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.ResourceBundle;

import org.bson.Document;

import com.mongodb.BasicDBObject;
import com.mongodb.MongoClient;
import com.mongodb.MongoClientOptions;
import com.mongodb.MongoClientOptions.Builder;
import com.mongodb.WriteConcern;
import com.mongodb.client.FindIterable;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoCursor;
import com.mongodb.client.MongoDatabase;
import com.mongodb.client.MongoIterable;
import com.mongodb.operation.OrderBy;

public class MongoHelper {

    public static MongoHelper INSTANCE;

    private static MongoClient mongoClient;
    private static String server = "localhost";
    private static int port = 27017;

    private MongoHelper() {
        // read properties
        try {
            ResourceBundle resource = ResourceBundle.getBundle("mongodb");//put the mongodb.properties under src
            server = resource.getString("server");
            port = Integer.parseInt(resource.getString("port"));
        } catch (Exception e) {
            e.printStackTrace();
        } 
        
        // boolean auth = mongoClient.authenticate(myUserName, myPassword);
        Builder builder = new MongoClientOptions.Builder();
        // options.autoConnectRetry(true);// 自动重连true
        // options.maxAutoConnectRetryTime(10); // the maximum auto connect
        // retry time
        builder.connectionsPerHost(300);// 连接池设置为300个连接,默认为100
        builder.connectTimeout(15000);// 连接超时，推荐>3000毫秒
        builder.maxWaitTime(5000); //
        builder.socketTimeout(0);// 套接字超时时间，0无限制
        builder.threadsAllowedToBlockForConnectionMultiplier(5000);// 线程队列数
        builder.writeConcern(WriteConcern.ACKNOWLEDGED);// 开启安全模式，如果写失败会获取到异常
        MongoClientOptions options =builder.build(); 
        
        mongoClient = new MongoClient(server+":"+port, options);
    }

    public MongoDatabase getDatabase(String dbName) {
        if (dbName == null || dbName.trim().length() == 0) {
            return null;
        }
        return mongoClient.getDatabase(dbName);
    }

    public List<String> getAllDatabaseNames() {
        return convert(mongoClient.listDatabaseNames());
    }

    public MongoCollection<Document> getCollection(String databaseName, String collectionName) {
        MongoDatabase database = getDatabase(databaseName);
        if (database == null) {
            return null;
        }
        return database.getCollection(collectionName);
    }

    public List<String> getAllCollectionNames(String dbName) {
        MongoDatabase database = getDatabase(dbName);
        if (database == null) {
            return null;
        }

        return convert(database.listCollectionNames());
    }

    public BasicDBObject condition(MongoOperationEnum con, String filedName, Object fieldValue) {
        if (con == MongoOperationEnum.AND || con == MongoOperationEnum.OR) {
            throw new IllegalArgumentException();
        }
        return new BasicDBObject(filedName, new BasicDBObject(con.getValue(), fieldValue));
    }

    public BasicDBObject condition(MongoOperationEnum con, BasicDBObject... objs) {
        if (con != MongoOperationEnum.AND && con != MongoOperationEnum.OR) {
            throw new IllegalArgumentException();
        }
        return new BasicDBObject(con.getValue(), Arrays.asList(objs));
    }

    public List<Document> find(String databaseName, String collectionName, BasicDBObject condition) {
        return find(databaseName, collectionName, condition, null, null, null, null);
    }

    public List<Document> find(String databaseName, String collectionName, BasicDBObject condition, String sortFieldName, OrderBy order, Integer pageNo, Integer pageSize) {
        int orderInt = order == null ? -1 : order.getIntRepresentation();
        FindIterable<Document> result = condition == null ? getCollection(databaseName, collectionName).find() : getCollection(databaseName, collectionName).find(condition);
        if (sortFieldName != null) {
            result.sort(new BasicDBObject(sortFieldName, orderInt));
        }
        if (pageNo != null && pageSize != null) {
            result.skip((pageNo.intValue() - 1) * pageSize.intValue()).limit(pageSize.intValue());
        }
        return convert(result);
    }

    public void insert(String databaseName, String collectionName, Map<String, Object> properties) {
        Document document = new Document(properties);
        getCollection(databaseName, collectionName).insertOne(document);
    }

    public long update(String databaseName, String collectionName, BasicDBObject condition, Map<String, Object> updateFields) {
        Document document = new Document("$set", updateFields);
        return getCollection(databaseName, collectionName).updateMany(condition, document).getModifiedCount();
    }

    public long delete(String databaseName, String collectionName, BasicDBObject condition) {
        return getCollection(databaseName, collectionName).deleteMany(condition).getDeletedCount();
    }

    public static MongoHelper getInstance() {
        synchronized (MongoHelper.class) {
            if (INSTANCE == null) {
                synchronized (MongoHelper.class) {
                    INSTANCE = new MongoHelper();
                }
            }
        }
        return INSTANCE;
    }

    public static <T> List<T> convert(MongoCursor<T> src) {
        if (src == null || !src.hasNext()) {
            return null;
        }
        List<T> result = new ArrayList<T>();
        while (src.hasNext()) {
            result.add(src.next());
        }
        return result;
    }

    public static <T> List<T> convert(MongoIterable<T> src) {
        if (src == null) {
            return null;
        }
        return convert(src.iterator());
    }

}

使用示例

import java.util.HashMap;
import java.util.Map;

import org.bson.Document;

import com.mongodb.client.MongoCollection;
import com.mongodb.operation.OrderBy;

/**
 * Hello world!
 *
 */
public class App {
    public static void main(String[] args) {
        MongoHelper helper = MongoHelper.getInstance();

        System.out.println(helper.getAllDatabaseNames());
        
        System.out.println(helper.getAllCollectionNames("test"));

        MongoCollection<Document> collection = helper.getCollection("test", "foods");

        System.out.println(helper.find("test", "foods", helper.condition(MongoOperationEnum.EQ, "name", "bread")));

        System.out.println(helper.find("test", "foods", helper.condition(MongoOperationEnum.GT, "price", 3)));

        System.out.println(helper.find("test", "foods", helper.condition(MongoOperationEnum.OR, helper.condition(MongoOperationEnum.EQ, "name", "bread"), helper.condition(MongoOperationEnum.GT, "price", 3)), "price", OrderBy.DESC, null, null));

        Map<String, Object> upda = new HashMap<>();
        upda.put("price", 55);
        System.out.println(helper.update("test", "foods", helper.condition(MongoOperationEnum.EQ, "price", 5.5), upda));

        System.out.println(helper.delete("test", "foods", helper.condition(MongoOperationEnum.EQ, "price", 55)));

        Map<String, Object> properties = new HashMap<>();
        properties.put("id", 4);
        properties.put("name", "milk2");
        properties.put("price", 5.5);
        helper.insert("test", "foods", properties);

        System.out.println(helper.find("test", "foods", null));
    }

}