使用Java语言读取Spark中的二进制列 [英] Read a binary column in spark using java language
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问题描述
我有一个DataFrame，其中包含一个 Binary 列Type.
I have a DataFrame witch contains a Binary column Type.
DataFrame:
DataFrame :
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
|BinaryGeometry
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
|[00 00 00 00 01 03 00 00 00 01 00 00 00 11 00 00 00 04 00 F0 00 DC CC 1A C0 87 14 01 81 1E 1B 41 40 FC FF EF 00 68 AA 1A C0 BF EE 57 20 85 19 41 40 04 00 F0 00 8C 86 1A C0 CC DC 8B DC AE 1A 41 40 FF FF EF 00 44 74 1A C0 CA 9D 5D 61 10 1C 41 40 FF FF EF 00 64 63 1A C0 BF 1F 98 0B 3A 1D 41 40 FF FF EF 00 44 47 1A C0 E4 6B A0 DD CE 1D 41 40 FC FF EF 00 D8 2B 1A C0 54 E4 71 67 6D 1C 41 40 FF FF EF 00 44 1A 1A C0 BF 1F 98 0B 3A 1D 41 40 02 00 F0 00 80 0B 1A C0 0D 80 00 13 2F 23 41 40 02 00 F0 00 B0 35 1A C0 CC F6 23 F8 BD 26 41 40 04 00 F0 00 0C 43 1A C0 73 1A 44 AF 16 26 41 40 02 00 F0 00 40 5A 1A C0 FF 54 9C 7C 2D 27 41 40 02 00 F0 00 50 68 1A C0 87 6E B9 42 44 28 41 40 02 00 F0 00 00 7C 1A C0 78 2B 85 BA F5 26 41 40 FC FF EF 00 18 91 1A C0 49 96 6F 58 C6 28 41 40 02 00 F0 00 B0 BC 1A C0 91 FA 4B 0E 7F 20 41 40 04 00 F0 00 DC CC 1A C0 87 14 01 81 1E 1B 41 40] |
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
我正在努力阅读本专栏，以提取几何格式.
I'm triying to read this column to extract the geometry format.
从我的研究中，我发现geospark库中有一个函数是ST_GeomFromWKB，该函数需要一个长二进制文件作为参数.
from my research i found that there is a function from the geospark library which is ST_GeomFromWKB which takes a long binary as argument.
所以我正在执行以下代码:
SO I'm doing the following code :
df.withColumn("BinaryGeometry", hex(col("BinaryGeometry")))
.withColumn("BinaryGeometry",expr("ST_GeomFromWKB(BinaryGeometry)"))
我得到以下输出女巫不正确:
I get the following output witch is not correct :
POINT(0 0)
如何阅读此列以获得正确的几何值?
How can I read this column to get the correct geometry value ?
编辑
MySQL专栏的结构
The structute of column on MySQL
当我跟踪数据时，似乎是这样的:
And when I track the data it seems like that :
当我点击 [GEOMETRY-113 o] 文本文件下载.
When I click on [GEOMETRY - 113 o]
a text file downloads.
文本文件包含以下数据:
The text file contains this data :
ے FPہ>Pے{ح@@€àOہZDچ4ح@@ہ¨KہإضآTح@@àمJہî=Oƒح@@û ڑLہCBsn«ح@@ے FPہ>Pے{ح@@
EDIT2
我在MySQL数据库上有此表
I have this table on MySQL database
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|BinaryGeometry
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|'POLYGON((-6.70005799736828 34.2118684058451,-6.66641236748546 34.1993751935347,-6.63139344658703 34.208461349766,-6.6135406633839 34.2192498881446,-6.5970611711964 34.2283339016717,-6.5695953508839 34.2328755410488,-6.54281617607921 34.2220887476075,-6.5256500383839 34.2283339016717,-6.51123048271984 34.2748740913813,-6.55242921318859 34.3026724029165,-6.56547547783703 34.2975672800575,-6.58813477959484 34.3060756457653,-6.60186768975109 34.314583149474,-6.62109376396984 34.3043740415805,-6.64169312920421 34.318553022848,-6.68426515068859 34.2538774367323,-6.70005799736828 34.2118684058451))',0
+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
当我在Spark中加载此表时，我得到:
When I load this table in Spark I get :
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
|BinaryGeometry
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
|[00 00 00 00 01 03 00 00 00 01 00 00 00 11 00 00 00 04 00 F0 00 DC CC 1A C0 87 14 01 81 1E 1B 41 40 FC FF EF 00 68 AA 1A C0 BF EE 57 20 85 19 41 40 04 00 F0 00 8C 86 1A C0 CC DC 8B DC AE 1A 41 40 FF FF EF 00 44 74 1A C0 CA 9D 5D 61 10 1C 41 40 FF FF EF 00 64 63 1A C0 BF 1F 98 0B 3A 1D 41 40 FF FF EF 00 44 47 1A C0 E4 6B A0 DD CE 1D 41 40 FC FF EF 00 D8 2B 1A C0 54 E4 71 67 6D 1C 41 40 FF FF EF 00 44 1A 1A C0 BF 1F 98 0B 3A 1D 41 40 02 00 F0 00 80 0B 1A C0 0D 80 00 13 2F 23 41 40 02 00 F0 00 B0 35 1A C0 CC F6 23 F8 BD 26 41 40 04 00 F0 00 0C 43 1A C0 73 1A 44 AF 16 26 41 40 02 00 F0 00 40 5A 1A C0 FF 54 9C 7C 2D 27 41 40 02 00 F0 00 50 68 1A C0 87 6E B9 42 44 28 41 40 02 00 F0 00 00 7C 1A C0 78 2B 85 BA F5 26 41 40 FC FF EF 00 18 91 1A C0 49 96 6F 58 C6 28 41 40 02 00 F0 00 B0 BC 1A C0 91 FA 4B 0E 7F 20 41 40 04 00 F0 00 DC CC 1A C0 87 14 01 81 1E 1B 41 40] |
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
然后获取原始数据"Polygon ........."，我执行以下代码:
then to get the original data 'Polygon .........' I do the following code :
df.withColumn("geom",expr("ST_GeomFromWKB(BinaryGeometry)"));
但是出现以下错误:
20/08/10 22:28:50 ERROR Executor: Exception in task 87.0 in stage 39.0 (TID 929) java.lang.ClassCastException: [B cannot be cast to org.apache.spark.unsafe.types.UTF8String
at org.apache.spark.sql.geosparksql.expressions.ST_GeomFromWKB.eval(Constructors.scala:174)
at org.apache.spark.sql.catalyst.expressions.GeneratedClass$SpecificUnsafeProjection.writeFields_0_39$(Unknown Source)
at org.apache.spark.sql.catalyst.expressions.GeneratedClass$SpecificUnsafeProjection.apply(Unknown Source)
at org.apache.spark.sql.catalyst.expressions.GeneratedClass$SpecificUnsafeProjection.apply(Unknown Source)
EDIT3
推荐答案
MySQL几何类型不是真正存储为 WKB ，因此无法使用geospark的方法 ST_GeomFromWKB .
MySQL geometry types are not really stored as WKB and as such cannot be read using the geospark's method ST_GeomFromWKB.
https://dev.mysql.com/doc/refman/5.7/en/gis-data-formats.html
在内部，MySQL以与
WKT或WKB格式不同的格式存储几何值.(内部格式类似于WKB，但以开头的4个字节表示SRID.)
Internally, MySQL stores geometry values in a format that is not identical to either
WKTorWKBformat. (Internal format is likeWKBbut with an initial 4 bytes to indicate the SRID.)
一种解决方案是在加载数据帧时指定查询，该数据帧将使用内置函数 ST_AsWKT 将 geometry 类型解析为 WKT 格式:
Solution to that is to specify the query when loading dataframe that will parse the geometry types into WKT format using the builtin function ST_AsWKT:
df = spark
.read
.format("jdbc")
.options(
Map(
"driver" -> "com.mysql.cj.jdbc.Driver",
"url" -> "jdbc:mysql://host:3306/db",
"user" -> "user",
"password" -> "password",
"dbtable" -> "(select ST_AsWKT(BinaryGeometry) as BinaryGeometry from geo_table) as t")
)
.load
.withColumn("BinaryGeometry",expr("ST_GeomFromWKT(BinaryGeometry)"))
或者，可以使用
将列提取为WKB.
Alternatively, the column can be extracted as WKB using
select hex(ST_AsWKB(BinaryGeometry)) as BinaryGeometry from geo_table
并输入到 ST_GeomFromWKB 方法.
scala> df.printShema()
root
|-- BinaryGeometry: geometry (nullable = false)
scala> df.show()
+--------------------+
| BinaryGeometry|
+--------------------+
|POLYGON ((-7.5783...|
+--------------------+
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