1.实体类
注意点：别忘了autoResultMap = true
@Data
@TableName(value = "report", autoResultMap = true)
public class Report implements Serializable {
private static final long serialVersionUID = 1L;
@TableId(value = "id", type = IdType.AUTO)
private Integer id;
@TableField(typeHandler = ReportUserListTypeHandler.class)
private List<ReportUser> reportInfo;
}
2.公共的ListTypeHandler
提供一个 JSONArray 转换为 Java List集合的处理器
@MappedJdbcTypes指定jdbc的类型
@MappedTypes指定Java的类型
import cn.hutool.core.collection.CollUtil;
import cn.hutool.core.util.StrUtil;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.TypeReference;
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;
import java.util.ArrayList;
import java.util.List;
@MappedJdbcTypes(JdbcType.ARRAY)
@MappedTypes({List.class})
public abstract class ListTypeHandler<T> extends BaseTypeHandler<List<T>>
{
@Override
public void setNonNullParameter(PreparedStatement ps, int i, List<T> parameter, JdbcType jdbcType) throws SQLException {
String content = CollUtil.isEmpty(parameter) ? null : JSON.toJSONString(parameter);
ps.setString(i, content);
}
@Override
public List<T> getNullableResult(ResultSet rs, String columnName) throws SQLException {
return this.getListByJsonArrayString(rs.getString(columnName));
}
@Override
public List<T> getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
return this.getListByJsonArrayString(rs.getString(columnIndex));
}
@Override
public List<T> getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
return this.getListByJsonArrayString(cs.getString(columnIndex));
}
private List<T> getListByJsonArrayString(String content) {
return StrUtil.isBlank(content) ? new ArrayList<>() : JSON.parseObject(content, this.specificType());
}
/**
* 具体类型，由子类提供
*
* @return 具体类型
*/
protected abstract TypeReference<List<T>> specificType();
}
3.具体的ListTypeHandler
由具体的子类提供List集合泛型类型
import com.alibaba.fastjson.TypeReference;
import com.chandol.entity.po.ReportUser;
import java.util.List;
public class ReportUserListTypeHandler extends ListTypeHandler<ReportUser> {
@Override
protected TypeReference<List<ReportUser>> specificType() {
return new TypeReference<List<ReportUser>>() {
};
}
}
4.为什么不在公共类直接提供TypeReference<List>
如果在 ListTypeHandler 类中直接提供 TypeReference<List
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