Mybatis通过TypeHandler对于数据库存储字段查询进行自定义转换

使用：

自定义Handler继承BaseTypeHandler

代码如下：

@MappedJdbcTypes(JdbcType.VARCHAR)
@MappedTypes({List.class})
public class ListTypeHandler extends BaseTypeHandler<List<Integer>> {
@Override
public void setNonNullParameter(PreparedStatement preparedStatement, int i, List<Integer> integers, JdbcType jdbcType) throws SQLException {
    StringBuffer sb = new StringBuffer();
    for (int j = 0; j < integers.size(); j++) {
        sb.append(integers.get(j)).append(",");
    }
    preparedStatement.setString(i, sb.toString().substring(0, sb.toString().length() - 1));
}

@Override
public List<Integer> getNullableResult(ResultSet resultSet, String s) throws SQLException {
    return getResult(resultSet.getString(s));
}

@Override
public List<Integer> getNullableResult(ResultSet resultSet, int i) throws SQLException {
    return getResult(resultSet.getString(i));
}

@Override
public List<Integer> getNullableResult(CallableStatement callableStatement, int i) throws SQLException {
    return null;
}

private List<Integer> getResult(String str) {
    List<Integer> result = new ArrayList<>();
    if (StringUtils.isNotBlank(str)) {
        String[] array = str.split(",");
        for (int i = 0; i < array.length; i++) {
            result.add(Integer.valueOf(array[i]));
        }
    }
    return result;
}

}

测试：

@RunWith(SpringRunner.class)
@SpringBootTest
public class MyBatisTest {

@Autowired
private MerchantMapper merchantMapper;


@Test
public void testInsertHandler() {
    Merchant merchant = new Merchant();
    merchant.setId(1);
    merchant.setSname("test数据");
    List<Integer> list = new ArrayList<>();
    list.add(1);
    list.add(2);
    list.add(3);
    merchant.setSrange(list);
    merchantMapper.insert(merchant);
}

@Test
public void testSelectHandler() {
    Merchant merchant = merchantMapper.selectOne(1);
    System.out.println(merchant);
}

}

setNonNullParameter可以对于传入的参数转换成用逗号连接
getNullableResult可以将数据库中逗号连接的值转换成List类型