java下一个简单的mongodb的helper类

类java下一个简单的mongodb的helper类，参考了下面地址的写法，做了一些修改，调整了全局变量定义，修改了init方法,增加了save方法。
http://blog.csdn.net/phinecos/article/details/8444515

package cls;

import java.net.UnknownHostException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import org.slf4j.LoggerFactory;
import org.slf4j.Logger;

import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.DBObject;
import com.mongodb.Mongo;
import com.mongodb.WriteResult;

public class MongoDbHelper {
    protected static Logger logger = LoggerFactory.getLogger("MongoDbHelper");
    private Mongo myMongo = null;
    private DB myDb = null;
    private static final String serverAddr="127.0.0.1";
    private static final int port=27017;
    private static final String myDbName="test";
    private static final String userName="admin";
    private static final String passWord="123456";
    private static Map<String, DBCollection> dbCollectionMap = new ConcurrentHashMap<String, DBCollection>();

    public MongoDbHelper(){
        this.init();
    }

     private void init() {
     if (this.myMongo == null) {
     try {
     this.myMongo = new Mongo( MongoDbHelper.serverAddr , MongoDbHelper.port);
     if (null != this.myMongo) {
     this.myDb = this.myMongo.getDB(MongoDbHelper.myDbName);
     //如果需要用户认证则先切换到admin数据库进行用户认证后，再切回用户数据库；
     if(userName!=""){
                            this.myDb=this.myMongo.getDB("admin");
                            this.myDb.authenticate(userName, passWord.toCharArray());
                            this.myDb=this.myMongo.getDB(MongoDbHelper.myDbName);
     }
     }
     } catch (UnknownHostException e) {
     logger.error("连接mongoDb失败, 服务器地址: " + MongoDbHelper.serverAddr + ", 端口: " + MongoDbHelper.port);
     throw new RuntimeException(e);
     }
     }
     }
     private DBCollection getDBCollection(String collectionName) {
            DBCollection collection = null;
     if (dbCollectionMap.containsKey(collectionName)) {
     collection = dbCollectionMap.get(collectionName);
     } else {
     collection = this.myDb.getCollection(collectionName);
     if (null != collection) {
                    dbCollectionMap.put(collectionName, collection);
     }
     }
     return collection;
     }

     public boolean isDocumentExsit(String collectionName, DBObject query) {
     boolean result = false;
            DBCursor dbCursor = null;
            DBCollection collection = this.getDBCollection(collectionName);
     if (null != collection) {
                dbCursor = collection.find(query);
     if (null != dbCursor && dbCursor.hasNext()) {
     result = true;
     }
     }
     return result;
     }

     public DBCursor selectDocument(String collectionName, DBObject query) {
            DBCursor result = null;
            DBCursor dbCursor = null;
            DBCollection collection = this.getDBCollection(collectionName);
     if (null != collection) {
                dbCursor = collection.find(query);
     if (null != dbCursor && dbCursor.hasNext()) {
     result = dbCursor;
     }
     }
     return result;
     }

     public void insertDocument(String collectionName, DBObject newDocument) {
            DBCollection collection = this.getDBCollection(collectionName);
     if (null != collection) {
     if (!this.isDocumentExsit(collectionName, newDocument)) {//insert only doc not exist
     collection.insert(newDocument);
     }
     }
     }

     public boolean updateDocument(String collectionName, DBObject query, DBObject updatedDocument) {
     boolean result = false;
            WriteResult writeResult = null;
            DBCollection collection = this.getDBCollection(collectionName);
     if (null != collection) {
                writeResult = collection.update(query, updatedDocument);
     if (null != writeResult) {
     if (writeResult.getN() > 0) {
     result = true;
     }
     }
     }
     return result;
     }
        //以下代码为测试mongodb的save功能
        /*
        DBObject upObject =new BasicDBObject("_id", new ObjectId("52fdbe36e97fee8601000000"));
        upObject.put("enterpriseName","cccc");
        myMongoDb.saveDoc("testColl", upObject);*/
        //============================================
     public boolean saveDoc(String collectionName,DBObject saveObject){
            boolean result=false;
            WriteResult writeResult = null;
            DBCollection collection = this.getDBCollection(collectionName);
     if (null != collection) {
                writeResult = collection.save(saveObject);
     if (null != writeResult) {
     if (writeResult.getN() > 0) {
     result = true;
     }
     }
     }
     return result;
     }

     public boolean deleteDocument(String collectionName, DBObject query) {
     boolean result = false;
            WriteResult writeResult = null;
            DBCollection collection = this.getDBCollection(collectionName);
     if (null != collection) {
                writeResult = collection.remove(query);
     if (null != writeResult) {
     if (writeResult.getN() > 0) {
     result = true;
     }
     }
     }
     return result;
     }


}