Java Apache POI

Question

我正在从excel文档中读取数据，该文档每两周更新一次，包含大约50,000行数据，在开始新的工作表之前可能会达到12万。我正在使用Apache来获取数据。我在下面得到了这个异常，但我认为最重要的一个异常是由: java.lang.OutOfMemoryError: Java堆空间引起的。我用较少的数据在另一个excel表上测试了我的代码，并且能够读取数据。

如果您对如何阅读大型excel文档有任何方法或建议，请分享。

org.apache.poi.POIXMLException: java.lang.reflect.InvocationTargetException
    at org.apache.poi.xssf.usermodel.XSSFFactory.createDocumentPart(XSSFFactory.java:62)
    at org.apache.poi.POIXMLDocumentPart.read(POIXMLDocumentPart.java:456)
    at org.apache.poi.POIXMLDocumentPart.read(POIXMLDocumentPart.java:461)
    at org.apache.poi.POIXMLDocumentPart.read(POIXMLDocumentPart.java:461)
    at org.apache.poi.POIXMLDocumentPart.read(POIXMLDocumentPart.java:461)
    at org.apache.poi.POIXMLDocument.load(POIXMLDocument.java:162)
    at org.apache.poi.xssf.usermodel.XSSFWorkbook.<init>(XSSFWorkbook.java:271)
    at excelreader.readExcelFile(excelreader.java:28)
    at excelreader.main(excelreader.java:18)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:140)
Caused by: java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:422)
    at org.apache.poi.xssf.usermodel.XSSFFactory.createDocumentPart(XSSFFactory.java:60)
    ... 13 more
Caused by: java.lang.OutOfMemoryError: Java heap space
    at org.apache.xmlbeans.impl.store.Cur.createElementXobj(Cur.java:260)
    at org.apache.xmlbeans.impl.store.Cur$CurLoadContext.startElement(Cur.java:2995)
    at org.apache.xmlbeans.impl.store.Locale$SaxHandler.startElement(Locale.java:3207)
    at org.apache.xmlbeans.impl.piccolo.xml.Piccolo.reportStartTag(Piccolo.java:1082)
    at org.apache.xmlbeans.impl.piccolo.xml.PiccoloLexer.parseAttributesNS(PiccoloLexer.java:1822)
    at org.apache.xmlbeans.impl.piccolo.xml.PiccoloLexer.parseOpenTagNS(PiccoloLexer.java:1521)
    at org.apache.xmlbeans.impl.piccolo.xml.PiccoloLexer.parseTagNS(PiccoloLexer.java:1362)
    at org.apache.xmlbeans.impl.piccolo.xml.PiccoloLexer.yylex(PiccoloLexer.java:4678)
    at org.apache.xmlbeans.impl.piccolo.xml.Piccolo.yylex(Piccolo.java:1290)
    at org.apache.xmlbeans.impl.piccolo.xml.Piccolo.yyparse(Piccolo.java:1400)
    at org.apache.xmlbeans.impl.piccolo.xml.Piccolo.parse(Piccolo.java:714)
    at org.apache.xmlbeans.impl.store.Locale$SaxLoader.load(Locale.java:3454)
    at org.apache.xmlbeans.impl.store.Locale.parseToXmlObject(Locale.java:1276)
    at org.apache.xmlbeans.impl.store.Locale.parseToXmlObject(Locale.java:1263)
    at org.apache.xmlbeans.impl.schema.SchemaTypeLoaderBase.parse(SchemaTypeLoaderBase.java:345)
    at org.openxmlformats.schemas.spreadsheetml.x2006.main.CTPivotCacheRecords$Factory.parse(Unknown Source)
    at org.apache.poi.xssf.usermodel.XSSFPivotCacheRecords.readFrom(XSSFPivotCacheRecords.java:62)
    at org.apache.poi.xssf.usermodel.XSSFPivotCacheRecords.<init>(XSSFPivotCacheRecords.java:53)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:422)
    at org.apache.poi.xssf.usermodel.XSSFFactory.createDocumentPart(XSSFFactory.java:60)
    at org.apache.poi.POIXMLDocumentPart.read(POIXMLDocumentPart.java:456)
    at org.apache.poi.POIXMLDocumentPart.read(POIXMLDocumentPart.java:461)
    at org.apache.poi.POIXMLDocumentPart.read(POIXMLDocumentPart.java:461)
    at org.apache.poi.POIXMLDocumentPart.read(POIXMLDocumentPart.java:461)
    at org.apache.poi.POIXMLDocument.load(POIXMLDocument.java:162)
    at org.apache.poi.xssf.usermodel.XSSFWorkbook.<init>(XSSFWorkbook.java:271)
    at excelreader.readExcelFile(excelreader.java:28)
    at excelreader.main(excelreader.java:18)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

Answer 1

它确实与堆大小有关。我把它设为2g，但仍然从记忆中消失。我正在使用的excel文档位于一个枢轴表中，Apache对该表有限制。这将导致第一个异常。

Answer 2

1 .Easy在java中解决OutOfMemoryError的方法是通过使用JVM选项"-Xmx512M"来增加最大堆大小，这将立即解决您的OutOfMemoryError。

Java虚拟机(JVM)运行时具有固定的上限内存，因此您可以修改它：

-Xms<size> - Set initial Java heap size
-Xmx<size> - Set maximum Java heap size

$ java -Xms512m -Xmx1024m JavaApp

2.在Java中解决OutOfMemoryError的第二种方法相当困难，当您没有太多内存时，即使在增加最大堆大小之后仍然得到java.lang.OutOfMemoryError，在这种情况下，您可能希望分析应用程序并查找任何内存泄漏。

因此，要检查内存leask，您可以使用一些非常困难的tools.Its没有它。其中一些受欢迎的有：

Jmap是JDK6附带的命令行实用工具，允许您在文件中获取堆的内存转储。它很容易用在下面的闪光上：

jmap -dump:format=b，file=heapdump 6054

日食内存分析器(MAT)

是eclipse基金会用于分析java堆转储的工具。它有助于查找类加载器泄漏和内存泄漏，并帮助最小化内存，consumption.you可以使用MAT来分析承载数百万个对象的堆转储，还可以帮助您提取内存泄漏的可疑信息。