6. MongoDB——Java操作（增刪改查）

轉自：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();//默認本地  
                //m = new Mongo("127.0.0.1");//默認端口  
                m = new Mongo("127.0.0.1",27017);  
            } catch (UnknownHostException e) {  
                e.printStackTrace();  
            } catch (MongoException e) {  
                e.printStackTrace();  
            }  
              
            //獲取名為 test 的數據庫，不存在的情況下創建  
            db = m.getDB("test");  
              
            //登錄數據庫（用戶名:test，密碼:test）  
            boolean auth = db.authenticate("test", "test".toCharArray());  
            if(auth){  
                //只有admin中的用戶才有此權限(show dbs)  
                //獲取所有數據庫，不顯示無collection的db  
                //System.out.println("所有數據庫名："+m.getDatabaseNames());  
                  
                //獲取名為 user 的collection(相當於表)，不存在的情況下創建  
                coll = db.getCollection("user");  
            }else{  
                System.out.println("登錄失敗!");  
            }  
        }  
          
        public static void main(String[] args) {  
            MongoMain test = new MongoMain();  
            if(coll!=null){  
                test.saveData();  
                test.searchData();  
                test.updateData();  
                test.deleteData();  
            }  
        }  
      
        /** 
         * 保存數據 
         */  
        public void saveData(){  
            //錄入學生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);  
              
            //錄入學生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：不能直接對sight賦值{left:1.0,right:1.3}  
              
            coll.insert(stu1);  
            coll.insert(stu2);  
        }  
          
        /** 
         * 查詢數據 
         */  
        public void searchData(){  
            System.out.println("=======================");  
            //show collections  
            //獲取數據庫下所有的collection，不顯示無數據的collection  
            Set<String> colls = db.getCollectionNames();  
            showData(colls);  
              
            System.out.println("=======================");  
              
            //查詢coll中全部記錄   
            DBCursor ite = coll.find();    
            showData(ite);  
              
            System.out.println("=======================");  
              
            //獲取第一條記錄  
            DBObject o = coll.findOne();  
            System.out.println(o);  
              
            System.out.println("=======================");  
              
            //統計colletion的數據條數  
            System.out.println(coll.getCount());  
              
            System.out.println("=======================");  
              
            //查詢 name為jack的對象   
            BasicDBObject query = new BasicDBObject();  
            query.put("name", "jack");  
            DBCursor it = coll.find(query);    
            showData(it);  
              
            System.out.println("=======================");  
              
            //查詢age小於30，age不等於20的對象   
            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);  
        }  
          
        /** 
         * 修改數據 
         */  
        public void updateData(){  
            BasicDBObject query = new BasicDBObject();  
            query.put("name", "lucy");  
            //這里的new_info對象一定要是find出的而不是new的，否則多字段的情況下就會丟失其它字段信息  
            DBObject new_info = coll.findOne(query);  
              
            //方法一（缺點，必須把2個值都put進去）  
            BasicDBObject sight = new BasicDBObject();  
            sight.put("left", 1.3);  
            sight.put("right", 1.3);  
            new_info.put("sight", sight);  
              
            //方法二（優點，只需設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);  
        }  
          
        /** 
         * 刪除數據 
         */  
        public void deleteData(){  
            BasicDBObject data = new BasicDBObject();  
            //刪除名稱為lucy的記錄  
            data.put("name", "lucy");  
            //傳入[空實例]刪除所有  
            coll.remove(data);  
        }  
          
        /** 
         * 遍歷顯示結果 
         * @param result 
         */  
        @SuppressWarnings("rawtypes")   
        public void showData(Iterable result){  
            Iterator it = result.iterator();   
            while(it.hasNext())    
            {    
                System.out.println(it.next());    
            }    
        }    
    }