Java單例模式下的MongoDB數據庫操作工具類

<!-- MongoDB驅動 -->
<dependency>
  <groupId>org.mongodb</groupId>
  <artifactId>mongo-java-driver</artifactId>
  <version>3.0.2</version>
</dependency>

package utils;
import java.util.ArrayList;
import java.util.List;
import org.apache.commons.configuration.CompositeConfiguration;
import org.apache.commons.configuration.ConfigurationException;
import org.apache.commons.configuration.PropertiesConfiguration;
import org.bson.Document;
import org.bson.conversions.Bson;
import org.bson.types.ObjectId;
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.MongoCollection;
import com.mongodb.client.MongoCursor;
import com.mongodb.client.MongoDatabase;
import com.mongodb.client.MongoIterable;
import com.mongodb.client.model.Filters;
import com.mongodb.client.result.DeleteResult;
/**
 * MongoDB工具類 Mongo實例代表了一個數據庫連接池，即使在多線程的環境中，一個Mongo實例對我們來說已經足夠了<br>
 * 注意Mongo已經實現了連接池，并且是線程安全的。 <br>
 * 設計為單例模式， 因 MongoDB的Java驅動是線程安全的，對于一般的應用，只要一個Mongo實例即可，<br>
 * Mongo有個內置的連接池（默認為10個） 對于有大量寫和讀的環境中，為了確保在一個Session中使用同一個DB時，<br>
 * DB和DBCollection是絕對線程安全的<br>
 *
 * @author zhoulingfei
 * @date 2015-5-29 上午11:49:49
 * @version 0.0.0
 * @Copyright (c)1997-2015 NavInfo Co.Ltd. All Rights Reserved.
 */
public enum MongoDBUtil {
  /**
   * 定義一個枚舉的元素，它代表此類的一個實例
   */
  instance;
  private MongoClient mongoClient;
  static {
    System.out.println("===============MongoDBUtil初始化========================");
    CompositeConfiguration config = new CompositeConfiguration();
    try {
      config.addConfiguration(new PropertiesConfiguration("mongodb.properties"));
    } catch (ConfigurationException e) {
      e.printStackTrace();
    }
    // 從配置文件中獲取屬性值
    String ip = config.getString("host");
    int port = config.getInt("port");
    instance.mongoClient = new MongoClient(ip, port);
    // or, to connect to a replica set, with auto-discovery of the primary, supply a seed list of members
    // List<ServerAddress> listHost = Arrays.asList(new ServerAddress("localhost", 27017),new ServerAddress("localhost", 27018));
    // instance.mongoClient = new MongoClient(listHost);
    // 大部分用戶使用mongodb都在安全內網下，但如果將mongodb設為安全驗證模式，就需要在客戶端提供用戶名和密碼：
    // boolean auth = db.authenticate(myUserName, myPassword);
    Builder options = new MongoClientOptions.Builder();
    // options.autoConnectRetry(true);// 自動重連true
    // options.maxAutoConnectRetryTime(10); // the maximum auto connect retry time
    options.connectionsPerHost(300);// 連接池設置為300個連接,默認為100
    options.connectTimeout(15000);// 連接超時，推薦>3000毫秒
    options.maxWaitTime(5000); //
    options.socketTimeout(0);// 套接字超時時間，0無限制
    options.threadsAllowedToBlockForConnectionMultiplier(5000);// 線程隊列數，如果連接線程排滿了隊列就會拋出“Out of semaphores to get db”錯誤。
    options.writeConcern(WriteConcern.SAFE);//
    options.build();
  }
  // ------------------------------------共用方法---------------------------------------------------
  /**
   * 獲取DB實例 - 指定DB
   *
   * @param dbName
   * @return
   */
  public MongoDatabase getDB(String dbName) {
    if (dbName != null && !"".equals(dbName)) {
      MongoDatabase database = mongoClient.getDatabase(dbName);
      return database;
    }
    return null;
  }
  /**
   * 獲取collection對象 - 指定Collection
   *
   * @param collName
   * @return
   */
  public MongoCollection<Document> getCollection(String dbName, String collName) {
    if (null == collName || "".equals(collName)) {
      return null;
    }
    if (null == dbName || "".equals(dbName)) {
      return null;
    }
    MongoCollection<Document> collection = mongoClient.getDatabase(dbName).getCollection(collName);
    return collection;
  }
  /**
   * 查詢DB下的所有表名
   */
  public List<String> getAllCollections(String dbName) {
    MongoIterable<String> colls = getDB(dbName).listCollectionNames();
    List<String> _list = new ArrayList<String>();
    for (String s : colls) {
      _list.add(s);
    }
    return _list;
  }
  /**
   * 獲取所有數據庫名稱列表
   *
   * @return
   */
  public MongoIterable<String> getAllDBNames() {
    MongoIterable<String> s = mongoClient.listDatabaseNames();
    return s;
  }
  /**
   * 刪除一個數據庫
   */
  public void dropDB(String dbName) {
    getDB(dbName).drop();
  }
  /**
   * 查找對象 - 根據主鍵_id
   *
   * @param collection
   * @param id
   * @return
   */
  public Document findById(MongoCollection<Document> coll, String id) {
    ObjectId _idobj = null;
    try {
      _idobj = new ObjectId(id);
    } catch (Exception e) {
      return null;
    }
    Document myDoc = coll.find(Filters.eq("_id", _idobj)).first();
    return myDoc;
  }
  /** 統計數 */
  public int getCount(MongoCollection<Document> coll) {
    int count = (int) coll.count();
    return count;
  }
  /** 條件查詢 */
  public MongoCursor<Document> find(MongoCollection<Document> coll, Bson filter) {
    return coll.find(filter).iterator();
  }
  /** 分頁查詢 */
  public MongoCursor<Document> findByPage(MongoCollection<Document> coll, Bson filter, int pageNo, int pageSize) {
    Bson orderBy = new BasicDBObject("_id", 1);
    return coll.find(filter).sort(orderBy).skip((pageNo - 1) * pageSize).limit(pageSize).iterator();
  }
  /**
   * 通過ID刪除
   *
   * @param coll
   * @param id
   * @return
   */
  public int deleteById(MongoCollection<Document> coll, String id) {
    int count = 0;
    ObjectId _id = null;
    try {
      _id = new ObjectId(id);
    } catch (Exception e) {
      return 0;
    }
    Bson filter = Filters.eq("_id", _id);
    DeleteResult deleteResult = coll.deleteOne(filter);
    count = (int) deleteResult.getDeletedCount();
    return count;
  }
  /**
   * FIXME
   *
   * @param coll
   * @param id
   * @param newdoc
   * @return
   */
  public Document updateById(MongoCollection<Document> coll, String id, Document newdoc) {
    ObjectId _idobj = null;
    try {
      _idobj = new ObjectId(id);
    } catch (Exception e) {
      return null;
    }
    Bson filter = Filters.eq("_id", _idobj);
    // coll.replaceOne(filter, newdoc); // 完全替代
    coll.updateOne(filter, new Document("$set", newdoc));
    return newdoc;
  }
  public void dropCollection(String dbName, String collName) {
    getDB(dbName).getCollection(collName).drop();
  }
  /**
   * 關閉Mongodb
   */
  public void close() {
    if (mongoClient != null) {
      mongoClient.close();
      mongoClient = null;
    }
  }
  /**
   * 測試入口
   *
   * @param args
   */
  public static void main(String[] args) {
    String dbName = "GC_MAP_DISPLAY_DB";
    String collName = "COMMUNITY_BJ";
    MongoCollection<Document> coll = MongoDBUtil.instance.getCollection(dbName, collName);
    // 插入多條
    // for (int i = 1; i <= 4; i++) {
    // Document doc = new Document();
    // doc.put("name", "zhoulf");
    // doc.put("school", "NEFU" + i);
    // Document interests = new Document();
    // interests.put("game", "game" + i);
    // interests.put("ball", "ball" + i);
    // doc.put("interests", interests);
    // coll.insertOne(doc);
    // }
    // // 根據ID查詢
    // String id = "556925f34711371df0ddfd4b";
    // Document doc = MongoDBUtil2.instance.findById(coll, id);
    // System.out.println(doc);
    // 查詢多個
    // MongoCursor<Document> cursor1 = coll.find(Filters.eq("name", "zhoulf")).iterator();
    // while (cursor1.hasNext()) {
    // org.bson.Document _doc = (Document) cursor1.next();
    // System.out.println(_doc.toString());
    // }
    // cursor1.close();
    // 查詢多個
    // MongoCursor<Person> cursor2 = coll.find(Person.class).iterator();
    // 刪除數據庫
    // MongoDBUtil2.instance.dropDB("testdb");
    // 刪除表
    // MongoDBUtil2.instance.dropCollection(dbName, collName);
    // 修改數據
    // String id = "556949504711371c60601b5a";
    // Document newdoc = new Document();
    // newdoc.put("name", "時候");
    // MongoDBUtil.instance.updateById(coll, id, newdoc);
    // 統計表
    // System.out.println(MongoDBUtil.instance.getCount(coll));
    // 查詢所有
    Bson filter = Filters.eq("count", 0);
    MongoDBUtil.instance.find(coll, filter);
  }
}