parquet：查看parquet文件的schema信息

方法一、自己写代码

1.pom依赖

<dependency>
            <groupId>org.apache.parquet</groupId>
            <artifactId>parquet-hadoop</artifactId>
            <version>1.9.0</version>
        </dependency>

        <dependency>
            <groupId>com.github.jiayuhan-it</groupId>
            <artifactId>hadoop-common</artifactId>
            <version>2.7.3JYHTEST</version>
        </dependency>
           

2.代码实现

import org.apache.parquet.example.data.Group;
import org.apache.parquet.hadoop.ParquetReader;
import org.apache.parquet.hadoop.example.GroupReadSupport;
import org.apache.parquet.io.api.Binary;
import org.apache.parquet.schema.Type;

import java.io.IOException;
import java.math.BigDecimal;
import java.math.BigInteger;

import org.apache.hadoop.fs.Path;

import java.util.HashMap;
import java.util.Map;

public class ParquetTest {
    public static void main(String[] args) throws IOException {
        //1.创建GroupReadSupport
        GroupReadSupport readSupport = new GroupReadSupport();
        //2.使用ParquetReader.builder方法创建reader对象。
        ParquetReader.Builder<Group> reader = ParquetReader.builder(readSupport, new Path("D:\\part-00001-de10a7bd-e360-4c02-b4f4-1c30c6b91be3-c000.snappy.parquet"));
        ParquetReader<Group> build = reader.build();
        //3.读取一个数据，并输出group的schema列名
        Group group = null;
        if (((group = build.read()) != null)) {
            int fieldCount = group.getType().getFieldCount();
            for (int field = 0; field < fieldCount; field++) {
                Type fieldType = group.getType().getType(field);
                String fieldName = fieldType.getName();
                System.out.println(fieldName);
            }
        }
}
           

方法二、使用社区工具

1.下载社区工具

parquet-tools-1.6.0rc3-SNAPSHOT.jar

git project: https://github.com/apache/parquet-mr/tree/master/parquet-tools?spm=5176.doc52798.2.6.H3s2kL

2.查看schema信息

（我在windows下执行的，jar包和parquet文件都在D盘）

java -jar D:\parquet-tools-1.6.0rc3-SNAPSHOT.jar  schema -d D:\part-00001-de10a7bd-e360-4c02-b4f4-1c30c6b91be3-c000.snappy.parquet
           

结果：

D:\>java -jar D:\parquet-tools-1.6.0rc3-SNAPSHOT.jar  schema -d D:\part-00001-de10a7bd-e360-4c02-b4f4-1c30c6b91be3-c000.snappy.parquet
message spark_schema {
  required binary range_partition_date (UTF8);
  required int64 Id;
  required int64 UserId;
  optional binary dw_cre_date (UTF8);
  optional binary dw_upd_date (UTF8);
  optional int32 kudu_is_active (INT_8);
  optional binary FlowId (UTF8);
  optional binary Type (UTF8);
  optional binary Content (UTF8);
  optional binary InsertTime (UTF8);
  optional binary UpdateTime (UTF8);
  optional int32 IsActive;
  optional int64 listingId;
  optional int64 bizId;
  optional int64 dingId;
  optional int64 zuId;
}
。。。。。
           

3.查看数据

（n后指定数据条数，1表示只取一条）

D:\>java -jar D:\parquet-tools-1.6.0rc3-SNAPSHOT.jar head -n 1 D:\part-00001-de10a7bd-e360-4c02-b4f4-1c30c6b91be3-c000.snappy.parquet
           

结果：

D:\>java -jar D:\parquet-tools-1.6.0rc3-SNAPSHOT.jar head -n 1 D:\part-00001-de10a7bd-e360-4c02-b4f4-1c30c6b91be3-c000.snappy.parquet
range_partition_date = 2021-01-07
Id = 18716586
dw_cre_date = 2021-01-06 23:59:20
dw_upd_date = 2021-01-06 23:59:20
kudu_is_active = 1
FlowId = [email protected][email protected]@[email protected]@0
Type = 30001026_drools_input
Content = <batch-execution lookup="defaultStatelessKieSession">
  <insert entry-point="DEFAULT" out-identifier="LoyalCustomerAuditSimplified-output" return-object="true">
    <ppdaidrools.loyalcustomerauditsimplified.LoyalCustomerAudit>
      <blackListID>10</blackListID>
      <daeType>-1</daeType>
      <testVipList>0</testVipList>
      <daeDuedate>1900-01-01 00:00:00 +0800</daeDuedate>
      <xinkeEdu>-1</xinkeEdu>
      <xinkeGeieTime>1900-01-01 00:00:00 +0800</xinkeGeieTime>
      <bizid>11001</bizid>
      <zuid>12</zuid>
      <dingid>102</dingid>
      <listtype>21</listtype>
      <sublisttype>18</sublisttype>
      <repaymentSourceType>1</repaymentSourceType>
      <tongDunAll6mId>21</tongDunAll6mId>
      <tongDunAll3mId>7</tongDunAll3mId>
      <tongDunP2PNetLoan1mId>0</tongDunP2PNetLoan1mId>
      <tongDunSmallLoan1mId>1</tongDunSmallLoan1mId>
。。。。。。
           

方法二参考自：

参考：https://www.cnblogs.com/yako/p/7889341.html