AbstractSetBinaryConverter.java

/**
 * 二进制数据与Set互转
 */
@MappedJdbcTypes({JdbcType.VARBINARY})
public abstract class AbstractSetBinaryConverter<T> implements TypeHandler<Set<T>> {
    /**
     * 暂用json序列化
     */
    private static final ObjectMapper OM = new ObjectMapper();

    @Override
    public void setParameter(
            PreparedStatement preparedStatement, int i, Set<T> objs, JdbcType jdbcType
    ) throws SQLException {
        try {
            var baos = new ByteArrayOutputStream();
            var oos = new ObjectOutputStream(baos);

            oos.write(OM.writeValueAsBytes(objs));
            oos.flush();

            preparedStatement.setBinaryStream(i, new ByteArrayInputStream(baos.toByteArray()));
        } catch (IOException e) {
            throw new SQLException(e.getCause());
        }
    }

    private Type getParameterizedType() {
        var superClazz = getClass().getGenericSuperclass();

        return ((ParameterizedType) superClazz).getActualTypeArguments()[0];
    }

    private Set<T> getObjectFromInputStream(InputStream is) throws IOException {
        var emptySet = new HashSet<T>();

        if (0 == is.available()) {
            return emptySet;
        }

        var buf = new byte[is.available()];
        var ois = new ObjectInputStream(is);
        ois.read(buf);
        var cType = OM.getTypeFactory().constructCollectionType(
                HashSet.class, (Class)getParameterizedType()
        );

        return OM.readValue(buf, cType);
    }

    @Override
    public Set<T> getResult(ResultSet rs, String c) throws SQLException {
        var is = rs.getBinaryStream(c);

        try {
            return getObjectFromInputStream(is);
        } catch (Exception e) {
            throw new SQLException(e.getCause());
        }
    }

    @Override
    public Set<T> getResult(ResultSet rs, int i) throws SQLException {
        var is = rs.getBinaryStream(i);

        try {
            return getObjectFromInputStream(is);
        } catch (Exception e) {
            throw new SQLException(e.getCause());
        }
    }

    @Override
    public Set<T> getResult(CallableStatement cs, int i) throws SQLException {
        var buf = cs.getBytes(i);

        try {
            var cType = OM.getTypeFactory().constructCollectionType(
                    HashSet.class, (Class)getParameterizedType()
            );
            return OM.readValue(buf, cType);
        } catch (IOException e) {
            throw new SQLException(e.getCause());
        }
    }
}