java JDBC-使用List(map)和Map(map)来封装多条msql记录

布满荆棘的人生 2021-07-25 02:34 423阅读 0赞

**使用List(map)来封装多条记录**
    	public static void main(String[] args) { 
    		Connection conn=jdbcutil.getMysqlConn();
    		PreparedStatement ps=null;
    		ResultSet rs=null;
    		List<Map<String,Object>> list=new ArrayList<Map<String,Object>>();
    		
    		try { 
    			ps = conn.prepareStatement("select empname,salary,age from emp where id=?");
    			ps.setInt(1, 1);
    			rs=ps.executeQuery();
    
    			while(rs.next())
    			{ 
    				
    				Map<String,Object> map=new HashMap<String,Object>();
    				map.put("empname", rs.getObject(1));
    				map.put("salary", rs.getObject(2));
    				map.put("age", rs.getObject(3));
    				
    				list.add(map);
    				
    			}
    			for(Map<String,Object> map:list)
    			{ 
    				for(String key:map.keySet())
    				{ 
    					System.out.println(key+"--"+map.get(key));
    				}
    			}
    			
    			
    		} catch (SQLException e) { 
    			e.printStackTrace();
    		}finally
    		{ 
    			jdbcutil.close(rs, ps, conn);
    		}
    }
    
    **使用Map(Map)来封装多条记录**
    
    public static void main(String[] args) { 
    		Connection conn=jdbcutil.getMysqlConn();
    		PreparedStatement ps=null;
    		ResultSet rs=null;
    		Map<String,Map<String,Object>> maps=new HashMap<String,Map<String,Object>>();
    		
    		try { 
    			ps = conn.prepareStatement("select empname,salary,age from emp where id=?");
    			ps.setInt(1, 1);
    			rs=ps.executeQuery();
    
    			while(rs.next())
    			{ 
    				
    				Map<String,Object> map=new HashMap<String,Object>();
    				map.put("empname", rs.getObject(1));
    				map.put("salary", rs.getObject(2));
    				map.put("age", rs.getObject(3));
    				
    				maps.put(rs.getString(1), map);
    			}
    			for(String empname:maps.keySet())
    			{ 
    				Map<String,Object> map=maps.get(empname);
    				for(String key:map.keySet())
    				{ 
    					System.out.println(key+"--"+map.get(key));
    				}
    			}
    			
    			
    		} catch (SQLException e) { 
    			e.printStackTrace();
    		}finally
    		{ 
    			jdbcutil.close(rs, ps, conn);
    		}
    }