数据库存的内容
mapper注解typeHander,class在下面代码块.可复制. 对象嵌套
/** * mapper里json型字段到类的映射。 * 用法一: * 入库：#{jsonDataField, typeHandler=com.adu.spring_test.mybatis.typehandler.JsonTypeHandler} * 出库： * <resultMap> * <result property="jsonDataField" column="json_data_field" javaType="com.xxx.MyClass" typeHandler="com.adu.spring_test.mybatis.typehandler.JsonTypeHandler"/> * </resultMap> * * 用法二： * 1）在mybatis-config.xml中指定handler: * <typeHandlers> * <typeHandler handler="com.adu.spring_test.mybatis.typehandler.JsonTypeHandler" javaType="com.xxx.MyClass"/> * </typeHandlers> * 2)在MyClassMapper.xml里直接select/update/insert。 * * * @author yunjie.du * @date 2016/5/31 19:33 */ public class JsonTypeHandler<T extends Object> extends BaseTypeHandler<T> { private static final ObjectMapper mapper = new ObjectMapper(); private Class<T> clazz; public JsonTypeHandler(Class<T> clazz) { if (clazz == null) throw new IllegalArgumentException("Type argument cannot be null"); this.clazz = clazz; } @Override public void setNonNullParameter(PreparedStatement ps, int i, T parameter, JdbcType jdbcType) throws SQLException { ps.setString(i, this.toJson(parameter)); } @Override public T getNullableResult(ResultSet rs, String columnName) throws SQLException { return this.toObject(rs.getString(columnName), clazz); } @Override public T getNullableResult(ResultSet rs, int columnIndex) throws SQLException { return this.toObject(rs.getString(columnIndex), clazz); } @Override public T getNullableResult(CallableStatement cs, int columnIndex) throws SQLException { return this.toObject(cs.getString(columnIndex), clazz); } private String toJson(T object) { try { return mapper.writeValueAsString(object); } catch (Exception e) { throw new RuntimeException(e); } } private T toObject(String content, Class<?> clazz) { if (content != null && !content.isEmpty()) { try { return (T) mapper.readValue(content, clazz); } catch (Exception e) { throw new RuntimeException(e); } } else { return null; } } static { mapper.configure(Feature.WRITE_NULL_MAP_VALUES, false); mapper.setSerializationInclusion(Inclusion.NON_NULL); } }查询结果如下.不指定typeHandler会失败.如此证明tpyeHandler有效
