MongoDB Java 通用方法

package model.dao;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import org.apache.log4j.Logger;import org.bson.types.ObjectId;import com.mongodb.BasicDBObject;import com.mongodb.DB;import com.mongodb.DBCollection;import com.mongodb.DBCursor;import com.mongodb.DBObject;import com.mongodb.Mongo;import com.mongodb.MongoException;/*** MongoDB Manager* @author Ken Chau**/public class MongoDBManager {     private static Logger log = Logger.getLogger(MongoDBManager.class);         private static Mongo mg = null;     private static DB db = null;         private final static MongoDBManager instance = new MongoDBManager();         /**     * 实例化     * @return     * @throws Exception     */     public static MongoDBManager getInstance() throws Exception {            return instance;     }         static {          try {               mg = new Mongo(HOST, PORT);              db=mg.getDB(DB);          } catch (Exception e) {               log.error("Can't connect MongoDB!");              e.printStackTrace();          }     }                /**     * 获取集合（表）     * @param collection     */     public static DBCollection getCollection(String collection) {          return db.getCollection(collection);     }     /**     * ----------------------------------分割线--------------------------------------     */     /**     * 插入     * @param collection     * @param map     */     public void insert(String collection , Map<String, Object> map) {          try {               DBObject dbObject = map2Obj(map);               getCollection(collection).insert(dbObject);          } catch (MongoException e) {               log.error("MongoException:" + e.getMessage());          }     }     /**     * 批量插入     * @param collection     * @param list     */     public void insertBatch(String collection ,List<Map<String, Object>> list) {          if (list == null || list.isEmpty()) {               return;          }          try {               List<DBObject> listDB = new ArrayList<DBObject>();               for (int i = 0; i < list.size(); i++) {                    DBObject dbObject = map2Obj(list.get(i));                    listDB.add(dbObject);               }               getCollection(collection).insert(listDB);          } catch (MongoException e) {               log.error("MongoException:" + e.getMessage());          }     }     /**     * 删除     * @param collection     * @param map     */     public void delete(String collection ,Map<String, Object> map) {          DBObject obj = map2Obj(map);          getCollection(collection).remove(obj);     }     /**       * 删除全部       * @param collection       * @param map       */     public void deleteAll(String collection) {          List<DBObject> rs = findAll(collection);          if (rs != null && !rs.isEmpty()) {               for (int i = 0; i < rs.size(); i++) {                    getCollection(collection).remove(rs.get(i));               }          }     }     /**     * 批量删除     * @param collection     * @param list     */     public void deleteBatch(String collection,List<Map<String, Object>> list) {          if (list == null || list.isEmpty()) {               return;          }          for (int i = 0; i < list.size(); i++) {               getCollection(collection).remove(map2Obj(list.get(i)));          }     }     /**     * 计算满足条件条数     * @param collection     * @param map     */     public long getCount(String collection,Map<String, Object> map) {          return getCollection(collection).getCount(map2Obj(map));     }         /**     * 计算集合总条数     * @param collection     * @param map     */     public long getCount(String collection) {          return getCollection(collection).find().count();     }     /**     * 更新     * @param collection     * @param setFields     * @param whereFields     */     public void update(String collection,Map<String, Object> setFields,               Map<String, Object> whereFields) {          DBObject obj1 = map2Obj(setFields);          DBObject obj2 = map2Obj(whereFields);          getCollection(collection).updateMulti(obj1, obj2);     }     /**     * 查找对象（根据主键_id）     * @param collection     * @param _id     */     public DBObject findById(String collection,String _id) {          DBObject obj = new BasicDBObject();          obj.put("_id", ObjectId.massageToObjectId(_id));          return getCollection(collection).findOne(obj);     }     /**     * 查找集合所有对象     * @param collection     */     public List<DBObject> findAll(String collection) {          return getCollection(collection).find().toArray();     }     /**     * 查找（返回一个对象）     * @param map     * @param collection     */     public DBObject findOne(String collection,Map<String, Object> map) {          DBCollection coll = getCollection(collection);          return coll.findOne(map2Obj(map));     }     /**     * 查找（返回一个List<DBObject>）     * @param <DBObject>     * @param map     * @param collection     * @throws Exception     */     public List<DBObject> find(String collection,Map<String, Object> map) throws Exception {          DBCollection coll = getCollection(collection);          DBCursor c = coll.find(map2Obj(map));          if (c != null)               return c.toArray();          else               return null;     }