jdbc utf8mb4

useUnicode=true&characterEncoding=utf-8

 https://www.jianshu.com/p/846f02d41c14

jdbc 在操作表情时，set names utf8mb4

Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(URL, USER, PASSWORD);
            st = conn.createStatement();

            PreparedStatement pstmtnames = conn.prepareStatement("set names utf8mb4;");
            pstmtnames.execute();

            // 点击横切位－wk申请好友30小时
            PreparedStatement pstmt = conn.prepareStatement(sql);
            pstmt.setObject(1, nickName);
            rs = pstmt.executeQuery();

            ResultSetMetaData md = rs.getMetaData(); //获得结果集结构信息,元数据
            int columnCount = md.getColumnCount();   //获得列数

            while (rs.next()) {
                Map<String,Object> rowData = new HashMap<String,Object>();
                for (int i = 1; i <= columnCount; i++) {
                    rowData.put(md.getColumnLabel(i), rs.getObject(i));
                }
                list.add(rowData);
            }
            return list;