typeHandler="backStage.typehandler.ListTypeHandler"List类型转出工具

╰+攻爆jí腚メ 2022-05-13 11:24 154阅读 0赞

import com.fasterxml.jackson.core.JsonProcessingException;
    import com.fasterxml.jackson.databind.ObjectMapper;
    import backStage.exception.SystemException;
    import org.apache.commons.lang.StringUtils;
    import org.apache.ibatis.type.BaseTypeHandler;
    import org.apache.ibatis.type.JdbcType;
    import org.apache.ibatis.type.MappedTypes;
    
    import java.io.IOException;
    import java.sql.CallableStatement;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.util.ArrayList;
    import java.util.List;
    @MappedTypes({List.class})
    public class ListTypeHandler extends BaseTypeHandler<List> { 
    
        private final ObjectMapper mapper = new ObjectMapper();
    
        @Override
        public void setNonNullParameter(PreparedStatement preparedStatement, int i, List list, JdbcType jdbcType) throws SQLException {
            try {
                if (list != null && list.size() > 0) {
                    String value = this.mapper.writeValueAsString(list);
                    preparedStatement.setString(i, value);
                }
            } catch (JsonProcessingException e) {
                throw new SystemException(e);
            }
        }
    
        @Override
        public List getNullableResult(ResultSet resultSet, String s) throws SQLException {
            List list = new ArrayList();
            String value = resultSet.getString(s);
    
            try {
                if (!StringUtils.isBlank(value)) {
                    list = this.mapper.readValue(value, List.class);
                }
            } catch (IOException e) {
                throw new SystemException(e);
            }
            return list;
        }
    
        @Override
        public List getNullableResult(ResultSet resultSet, int i) {
            return null;
        }
    
        @Override
        public List getNullableResult(CallableStatement callableStatement, int i) {
            return null;
        }
    }

注意：如要先数据库存储map格式的数据应该对前台传回的String字符串做如下处理

new ObjectMapper().writeValueAsString(string)