Mybatis Blob和String互转，实现文件上传等。

 1 @MappedJdbcTypes(JdbcType.BLOB) 2 public class BlobAndStringTypeHandler extends BaseTypeHandler<String> { 3 ?4 ????private static final String DEFAULT_CHARSET = "UTF-8"; //感觉没屌用 5 ?6 ????@Override 7 ????public void setNonNullParameter(PreparedStatement ps, int i, String parameter, JdbcType jdbcType) throws SQLException { 8 ????????ByteArrayInputStream bis = null; 9 ????????bis = new ByteArrayInputStream(parameter.getBytes());10 ????????ps.setBinaryStream(i, bis, parameter.getBytes().length); //网上都是直接paramter.length() 这样是不对的。 11 12 ????}13 14 ????@Override15 ????public String getNullableResult(ResultSet rs, String columnName) throws SQLException {16 ????????Blob blob = rs.getBlob(columnName);17 ????????byte[] returnValue = null;18 ????????String result = null;19 ????????if (null != blob) {20 ????????????returnValue = blob.getBytes(1, (int) blob.length());21 ????????}22 ????????//将取出的流对象转为utf-8的字符串对象23 ????????if (null != returnValue) {24 ????????????result = new String(returnValue);25 ????????}26 ????????return result;27 ????}28 29 ????@Override30 ????public String getNullableResult(ResultSet rs, int columnIndex) throws SQLException {31 ????????Blob blob = rs.getBlob(columnIndex);32 ????????byte[] returnValue = null;33 ????????String result = null;34 ????????if (null != blob) {35 ????????????returnValue = blob.getBytes(1, (int) blob.length());36 ????????}37 ????????//将取出的流对象转为utf-8的字符串对象38 ????????if (null != returnValue) {39 ????????????result = new String(returnValue);40 ????????}41 ????????return result;42 ????}43 44 ????@Override45 ????public String getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {46 ????????Blob blob = cs.getBlob(columnIndex);47 ????????byte[] returnValue = null;48 ????????String result = null;49 ????????if (null != blob) {50 ????????????returnValue = blob.getBytes(1, (int) blob.length());51 ????????}52 ????????//将取出的流对象转为utf-8的字符串对象53 ????????if (null != returnValue) {54 ????????????result = new String(returnValue);55 ????????}56 ????????return result;57 ????}58 }