6. MongoDB——Java操作（增删改查）

转自：https://blog.csdn.net/kai402458953/article/details/79626148

import java.net.UnknownHostException;  
    import java.util.Iterator;  
    import java.util.Set;  
      
    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;  
      
    public class MongoMain {  
          
        static DB db = null;  
        static DBCollection coll = null;  
          
        static {  
             Mongo m = null;  
            try {  
                //m = new Mongo();//默认本地  
                //m = new Mongo("127.0.0.1");//默认端口  
                m = new Mongo("127.0.0.1",27017);  
            } catch (UnknownHostException e) {  
                e.printStackTrace();  
            } catch (MongoException e) {  
                e.printStackTrace();  
            }  
              
            //获取名为 test 的数据库，不存在的情况下创建  
            db = m.getDB("test");  
              
            //登录数据库（用户名:test，密码:test）  
            boolean auth = db.authenticate("test", "test".toCharArray());  
            if(auth){  
                //只有admin中的用户才有此权限(show dbs)  
                //获取所有数据库，不显示无collection的db  
                //System.out.println("所有数据库名："+m.getDatabaseNames());  
                  
                //获取名为 user 的collection(相当于表)，不存在的情况下创建  
                coll = db.getCollection("user");  
            }else{  
                System.out.println("登录失败!");  
            }  
        }  
          
        public static void main(String[] args) {  
            MongoMain test = new MongoMain();  
            if(coll!=null){  
                test.saveData();  
                test.searchData();  
                test.updateData();  
                test.deleteData();  
            }  
        }  
      
        /** 
         * 保存数据 
         */  
        public void saveData(){  
            //录入学生1的信息  
            BasicDBObject stu1 = new BasicDBObject();  
            stu1.put("name", "jack");  
            stu1.put("age", "25");  
            BasicDBObject sight1 = new BasicDBObject();  
            sight1.put("left", 1.5);  
            sight1.put("right", 1.2);  
            stu1.put("sight", sight1);  
              
            //录入学生2的信息  
            BasicDBObject stu2 = new BasicDBObject();  
            stu2.put("name", "lucy");  
            stu2.put("age", "22");  
            BasicDBObject sight2 = new BasicDBObject();  
            sight2.put("left", 1.0);  
            sight2.put("right", 1.3);  
            stu2.put("sight", sight2);  
              
            //注意：不能直接对sight赋值{left:1.0,right:1.3}  
              
            coll.insert(stu1);  
            coll.insert(stu2);  
        }  
          
        /** 
         * 查询数据 
         */  
        public void searchData(){  
            System.out.println("=======================");  
            //show collections  
            //获取数据库下所有的collection，不显示无数据的collection  
            Set<String> colls = db.getCollectionNames();  
            showData(colls);  
              
            System.out.println("=======================");  
              
            //查询coll中全部记录   
            DBCursor ite = coll.find();    
            showData(ite);  
              
            System.out.println("=======================");  
              
            //获取第一条记录  
            DBObject o = coll.findOne();  
            System.out.println(o);  
              
            System.out.println("=======================");  
              
            //统计colletion的数据条数  
            System.out.println(coll.getCount());  
              
            System.out.println("=======================");  
              
            //查询 name为jack的对象   
            BasicDBObject query = new BasicDBObject();  
            query.put("name", "jack");  
            DBCursor it = coll.find(query);    
            showData(it);  
              
            System.out.println("=======================");  
              
            //查询age小于30，age不等于20的对象   
            BasicDBObject query2 = new BasicDBObject();  
            query2.put("age", new BasicDBObject("$lt", 30));  
            query2.put("age", new BasicDBObject("$ne", 20));  
            DBCursor it2 = coll.find(query2);    
            showData(it2);  
        }  
          
        /** 
         * 修改数据 
         */  
        public void updateData(){  
            BasicDBObject query = new BasicDBObject();  
            query.put("name", "lucy");  
            //这里的new_info对象一定要是find出的而不是new的，否则多字段的情况下就会丢失其它字段信息  
            DBObject new_info = coll.findOne(query);  
              
            //方法一（缺点，必须把2个值都put进去）  
            BasicDBObject sight = new BasicDBObject();  
            sight.put("left", 1.3);  
            sight.put("right", 1.3);  
            new_info.put("sight", sight);  
              
            //方法二（优点，只需设置要修改的字段的值）  
            DBObject obj = (DBObject)new_info.get("sight");  
            obj.put("right", 1.5);  
              
            coll.update(query, new_info);  
        }  
          
        /** 
         * 删除数据 
         */  
        public void deleteData(){  
            BasicDBObject data = new BasicDBObject();  
            //删除名称为lucy的记录  
            data.put("name", "lucy");  
            //传入[空实例]删除所有  
            coll.remove(data);  
        }  
          
        /** 
         * 遍历显示结果 
         * @param result 
         */  
        @SuppressWarnings("rawtypes")   
        public void showData(Iterable result){  
            Iterator it = result.iterator();   
            while(it.hasNext())    
            {    
                System.out.println(it.next());    
            }    
        }    
    }