mybatis 返回null 转 空字符串

package com.neusoft.mid.msf.issaweb.config;

import org.apache.ibatis.executor.result.ResultMapException;
import org.apache.ibatis.type.BaseTypeHandler;
import org.apache.ibatis.type.JdbcType;
import org.apache.ibatis.type.MappedJdbcTypes;
import org.apache.ibatis.type.MappedTypes;

import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

/**

• @Name: CustomStringTypeHandler

• @Desc: 自定义mybatis处理类，将null返回为空串（‘’）

• @Author: zhou.wang

• @Date: 2021-05-20 13:41
  */
  @MappedTypes({String.class})
  @MappedJdbcTypes(JdbcType.VARCHAR)
  public class CustomStringTypeHandler extends BaseTypeHandler {

  @Override
  public String getResult(ResultSet rs, String columnName) {
  String result;
  try {
  result = getNullableResult(rs, columnName);
  } catch (Exception e) {
  throw new ResultMapException("Error attempting to get column '" + columnName + "' from result set. Cause: " + e, e);
  }
  return result;
  }

  @Override
  public void setNonNullParameter(PreparedStatement ps, int i, String parameter, JdbcType jdbcType)
  throws SQLException {
  ps.setString(i, parameter);
  }

  @Override
  public String getNullableResult(ResultSet rs, String columnName)
  throws SQLException {
  return rs.getString(columnName) == null? "" : rs.getString(columnName);
  }

  @Override
  public String getNullableResult(ResultSet rs, int columnIndex)
  throws SQLException {
  return rs.getString(columnIndex) == null? "" : rs.getString(columnIndex);
  }

  @Override
  public String getNullableResult(CallableStatement cs, int columnIndex)
  throws SQLException {
  return cs.getString(columnIndex) == null? "" : cs.getString(columnIndex);
  }
  }