从JDBC模板执行返回Map

Question

public List<Employee> getEmployeeDetails() {
    return jdbcTemplate.query(GET_EMPLOYEE_SQL, new RowMapper<Employee>() {
        @Override
        public Employee mapRow(ResultSet rs, int rowNum) throws SQLException {
            Employee employee = new Employee();
            employee.setCode(rs.getBigDecimal("cd"));
            employee.setAddress(rs.getString("address"));
            employee.setContactNo((rs.getString("contactNo")));

            return employee;
        }
    });
}

我需要从上面的方法做什么--它的返回列表--但是我需要返回

Map<BigDecimal, List<Employee>> employeeMap = new HashMap<>();

while doing that getting exception 

类型不匹配:无法从List>转换为Map

请查找以下代码

public Map<BigDecimal, Employee> getEmployeeDetails() {
Map<BigDecimal, Employee> employeeMap = new HashMap<>();

    return jdbcTemplate.query(GET_EMPLOYEE_SQL, new RowMapper<Map<String, Employee>>() {
        @Override
        public Map<BigDecimal, Employee> mapRow(ResultSet rs, int rowNum) throws SQLException {
            Employee employee = new Employee();
            employee.setCode(rs.getBigDecimal("cd"));
            employee.setAddress(rs.getString("address"));
            employee.setContactNo((rs.getString("contactNo")));

            employeeMap.put(rs.getBigDecimal("cd"), employee);

            return employeeMap;
        }
    });
}

Answer 1

你可以做两件事

1. 不返回查询语句，在getEmployeeDetails()方法中返回employeeMap。

1. 对于查询中的期望，您必须使用ResultSetExtractor而不是RowMapper对RowMapper进行操作，因此它总是返回list。

使用ResultSetExtractor，您可以做类似的事情

return template.query(GET_EMPLOYEE_SQL, new ResultSetExtractor<Map<BigDecimal, Employee>>() {
        @Override
        public Map<BigDecimal, Employee> extractData(ResultSet rs) throws SQLException, DataAccessException {
            Map<BigDecimal, Employee> employeeMap = new HashMap<>();
            while (rs.next()) {
                Employee employee = new Employee();
                employee.setCode(rs.getBigDecimal("cd"));
                employee.setAddress(rs.getString("address"));
                employee.setContactNo((rs.getString("contactNo")));
                employeeMap.put(rs.getBigDecimal("cd"), employee); 
            }
            return employeeMap;
        }
    });