Java操作MongoDB数据库

1）、 建立MongoDBTest.java，完成简单的mongoDB数据库操作

Mongo mongo = new Mongo('127.0.0.1', 27017);

Mongo mongo = new Mongo();

这样就创建了一个MongoDB的数据库连接对象，它默认连接到当前机器的localhost地址，端口是27017。

2）、连接数据库test

DB db = mongo.getDB(“test”);

这样就获得了一个test的数据库，如果mongoDB中没有创建这个数据库，mongoDB会自动创建当前数据库。

得到了db，下一步我们要获取一个“聚集集合DBCollection”，通过db对象的getCollection方法来完成。

DBCollection users = db.getCollection(“users”);

这样就获得了一个DBCollection，它相当于我们数据库的“表”。

3）、接下来就可以进行增删改查操作

MongoURI uri = new MongoURI("mongodb://localhost:27017");      String databaseName ="myDatabase";      String collectionName = "mycollections";        Mongo mongo = null;      DB db = null;      DBCollection userCollection;      try {          定义Mongo服务          mongo =new Mongo("localhost", 27017);          mongo = new Mongo(uri);             mongo = new Mongo();         DBAddress addr = new DBAddress("localhost", 27017,databaseName);          mongo.connect(addr);            删除数据库          mongo.dropDatabase(databaseName);           获取databaseName对应的数据库，不存在则自动创建          db = mongo.getDB(databaseName);            添加用户          db.addUser("admin", new char []{'a','d','m','i','n'});            移除用户          db.removeUser("admin");            验证权限          boolean flag = db.authenticate("admin", new char []{'a','d','m','i','n'} );            if(flag == false){              return;          }            设置db为只读 ，只读就不能写入数据了   对save管用，对insert好像不管用         db.setReadOnly(true);                获取collectionName对应的集合，不存在则自动创建          db.createCollection("mycollection", new BasicDBObject());          userCollection = db.getCollection(collectionName);              查询所有的DataBase          for(String dbName : mongo.getDatabaseNames()){              System.out.println("databasename:" + dbName);          }              查询所有的聚集集合          for(String collection :db.getCollectionNames()){              System.out.println("collectionName:" + collection);          }              查询是否存在collectionName集合          if(db.collectionExists(collectionName)){            //去掉重复的数据             List dislist = userCollection.distinct("userId");             int len = dislist.size();           for(int i = 0 ; i< len ; i++){                 System.out.println(dislist.get(i));             }                查询              System.out.println(userCollection.find(new BasicDBObject("userId",1)).toArray());                返回前2个              System.out.println(userCollection.find({},{reviews:{slice:2}});                                  //System.out.println("分页："+userCollection.find(new BasicDBObject("",new BasicDBObject("slice", 2))).toArray());                查询所有的数据              DB游标              DBCursor cursor = userCollection.find();              while(cursor.hasNext()){                  DBObject userDbobj = cursor.next();             System.out.println("userId:"+userDbobj.get("userId")+";age:"+userDbobj.get("age")+";sex:"+userDbobj.get("sex")+";address:"+userDbobj.get("address"));              }                  条件查询              查询age 等于 24              System.out.println("find age = 24: " + userCollection.find(new BasicDBObject("age", 24)).toArray());                  查询age 大于等于 24              System.out.println("find age >= 24: " + userCollection.find(new BasicDBObject("age", new BasicDBObject("gte",24))).toArray());                               查询age小于等于24            System.out.println("findage<=24:"+userCollection.find(newBasicDBObject("age",newBasicDBObject("lte", 24))).toArray());                  查询age 不等于25              System.out.println("查询age!=25：" + userCollection.find(new BasicDBObject("age", new BasicDBObject("$ne", 25))).toArray());                查询某个范围的数据              System.out.println("查询age in 25/26/27：" + userCollection.find(new BasicDBObject("age", new BasicDBObject(QueryOperators.IN, new int[] { 25, 26, 27 }))).toArray());                查询不在某个范围数据              System.out.println("查询age not in 25/26/27：" + userCollection.find(new BasicDBObject("age", new BasicDBObject(QueryOperators.NIN, new int[] { 25, 26, 27 }))).toArray());                按age排序              System.out.println("查询age exists 排序：" + userCollection.find().sort(new BasicDBObject("age",new BasicDBObject(QueryOperators.ORDER_BY, 1))).limit(2).skip(1).toArray());   //(new BasicDBObject("age", new BasicDBObject(QueryOperators.ORDER_BY, 1))).toArray());                new BasicDBObject();                System.out.println("只查询age属性：" + userCollection.find(null, new BasicDBObject("age", true)).toArray());                System.out.println("只查属性：" + userCollection.find(null, new BasicDBObject("age", true), 0, 2).toArray());                System.out.println("只查属性：" + userCollection.find(null, new BasicDBObject("age", true), 0, 2, Bytes.QUERYOPTION_NOTIMEOUT).toArray());          }              添加数据          DBObject user = new BasicDBObject();          user.put("userId", 2);          user.put("userName", "tom");          user.put("age", 21);          user.put("sex", "male");          user.put("address", "北京海淀");            userCollection.save(user);            getN  对save和insert不管用         WriteResult saveResult = userCollection.save(user);         System.out.println(saveResult.getN());         System.out.println(saveResult.isLazy());        if(saveResult.getN() > 0){             System.out.println("添加成功");         }              添加List集合         List<DBObject> list = new ArrayList<DBObject>();         list.add(user);          DBObject user2 = new BasicDBObject();         user2.put("userId", 2);        user2.put("userName", "lily");         user2.put("age", 20);         user2.put("sex", "female");         user2.put("address", "新加坡");         list.add(user2);           userCollection.insert(list);          看是否插入成功          System.out.println("集合中数据量：" + userCollection.count());                删除数据         WriteResult wr = userCollection.remove(new BasicDBObject("userId",1));         System.out.println(wr.getN());         System.out.println(wr.isLazy());         if(wr.getN() > 0){             System.out.println("删除成功！");       }              删除整个集合          userCollection.drop();              修改          DBObject newUser =new  BasicDBObject();          newUser.put("userId", 3);          newUser.put("userName", "tomAndKitty");          newUser.put("age", 25);          user.put("sex", "male");          user.put("address", "北京朝阳");            WriteResult updateResult = userCollection.update(new BasicDBObject("userId",1),newUser);        WriteResult updateResult = userCollection.update(new BasicDBObject("userId",3),newUser,            关闭Mongo服务          if(mongo != null){              mongo.close();          }          db = null;          userCollection = null;      }  }