Java 使用stringTemplate导出大批量数据excel(百万级)
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原文:http://blog.csdn.net/z69183787/article/details/50737709
参考资料:http://bbs.51cto.com/thread-1074293-1-1.html
目前Java框架中能够生成excel文件的的确不少,但是,能够生成大数据量的excel框架,我倒是没发现,一般数据量大了都会出现内存溢出,所以,生成大数据量的excel文件要返璞归真,用java的基础技术,IO流来实现。
如果想用IO流来生成excel文件,必须要知道excel的文件格式内容,相当于生成html文件一样,用字符串拼接html标签保存到文本文件就可以生成一个html文件了。同理,excel文件也是可以的。怎么知道excel的文件格式呢?其实很简单,随便新建一个excel文件,双击打开,然后点击“文件”-》“另存为”,保存的类型为“xml表格”,保存之后用文本格式打开,就可以看到excel的字符串格式一览无遗了。
把下面的xml字符串复制到文本文件,然后保存为xls格式,就是一个excel文件。
<?xml version="1.0"?> <?mso-application progid="Excel.Sheet"?> <Workbook xmlns="urn:schemas-microsoft-com:office:spreadsheet" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:x="urn:schemas-microsoft-com:office:excel" xmlns:ss="urn:schemas-microsoft-com:office:spreadsheet" xmlns:html="http://www.w3.org/TR/REC-html40"> <DocumentProperties xmlns="urn:schemas-microsoft-com:office:office"> <Created>1996-12-17T01:32:42Z</Created> <LastSaved>2000-11-18T06:53:49Z</LastSaved> <Version>11.9999</Version> </DocumentProperties> <OfficeDocumentSettings xmlns="urn:schemas-microsoft-com:office:office"> <RemovePersonalInformation/> </OfficeDocumentSettings> <ExcelWorkbook xmlns="urn:schemas-microsoft-com:office:excel"> <WindowHeight>4530</WindowHeight> <WindowWidth>8505</WindowWidth> <WindowTopX>480</WindowTopX> <WindowTopY>120</WindowTopY> <AcceptLabelsInFormulas/> <ProtectStructure>False</ProtectStructure> <ProtectWindows>False</ProtectWindows> </ExcelWorkbook> <Styles> <Style ss:ID="Default" ss:Name="Normal"> <Alignment ss:Vertical="Bottom"/> <Borders/> <Font ss:FontName="宋体" x:CharSet="134" ss:Size="12"/> <Interior/> <NumberFormat/> <Protection/> </Style> </Styles> <Worksheet ss:Name="Sheet1"> <Table ss:ExpandedColumnCount="2" ss:ExpandedRowCount="2" x:FullColumns="1" x:FullRows="1" ss:DefaultColumnWidth="54" ss:DefaultRowHeight="14.25"> <Column ss:AutoFitWidth="0" ss:Width="73.5"/> <Row> <Cell><Data ss:Type="String">zhangzehao</Data></Cell> <Cell><Data ss:Type="String">zhangzehao</Data></Cell> </Row> <Row> <Cell><Data ss:Type="String">zhangzehao</Data></Cell> </Row> </Table> <WorksheetOptions xmlns="urn:schemas-microsoft-com:office:excel"> <Selected/> <Panes> <Pane> <Number>3</Number> <ActiveRow>5</ActiveRow> <ActiveCol>3</ActiveCol> </Pane> </Panes> <ProtectObjects>False</ProtectObjects> <ProtectScenarios>False</ProtectScenarios> </WorksheetOptions> </Worksheet> <Worksheet ss:Name="Sheet2"> <Table ss:ExpandedColumnCount="0" ss:ExpandedRowCount="0" x:FullColumns="1" x:FullRows="1" ss:DefaultColumnWidth="54" ss:DefaultRowHeight="14.25"/> <WorksheetOptions xmlns="urn:schemas-microsoft-com:office:excel"> <ProtectObjects>False</ProtectObjects> <ProtectScenarios>False</ProtectScenarios> </WorksheetOptions> </Worksheet> <Worksheet ss:Name="Sheet3"> <Table ss:ExpandedColumnCount="0" ss:ExpandedRowCount="0" x:FullColumns="1" x:FullRows="1" ss:DefaultColumnWidth="54" ss:DefaultRowHeight="14.25"/> <WorksheetOptions xmlns="urn:schemas-microsoft-com:office:excel"> <ProtectObjects>False</ProtectObjects> <ProtectScenarios>False</ProtectScenarios> </WorksheetOptions> </Worksheet> </Workbook>
如果要生成千万级别以上的excel,除了这个关键点之外,还要控制IO流,如果有1000万记录,要迭代1000万次组装xml字符串,这样肯定占用相当大的内存,肯定内存溢出,所以,必须把组装的xml字符串分批用IO流刷新到硬盘里,如果是在web应用中,可以刷新到response中,web应用会自动把临时流保存到客户端的临时文件中,然后再一次性复制到你保存的路径。言归正传,分批刷新的话,可以迭代一批数据就flush进硬盘,同时把list,大对象赋值为空,显式调用垃圾回收器,表明要回收内存。这样的话,不管生成多大的数据量都不会出现内存溢出的,我曾经试过导出1亿的excel文件,都不会出现内存溢出,只是用了35分钟。
当然,如果要把实现做的优雅一些,在组装xml字符串的时候,可以结合模板技术来实现,我个人喜好stringtemplate这个轻量级的框架,我给出的DEMO也是采用了模板技术生成的,当然velocity和freemarker都是可以,stringbuilder也行,呵呵。
我为人比较懒,本意不是为了写个帖子的,只是想多赚点下载豆:lol1 ,这和赚钱一样谁不想?谁知道就写了那么多。同时鄙人知识寡陋,希望可以抛砖引玉。
综上:使用技术为 stringTemplate
pom.xml:
<dependency> <groupId>antlr</groupId> <artifactId>antlr</artifactId> <version>2.7.7</version> </dependency> <dependency> <groupId>org.antlr</groupId> <artifactId>stringtemplate</artifactId> <version>3.2.1</version> </dependency>
template对象:
class Row{ private List<String> result; public List<String> getResult() { return result; } public void setResult(List<String> result) { this.result = result; } } class Worksheet{ private String sheet; private int columnNum; private int rowNum; private List<String> title; private List<Row> rows; public String getSheet() { return sheet; } public void setSheet(String sheet) { this.sheet = sheet; } public List<Row> getRows() { return rows; } public void setRows(List<Row> rows) { this.rows = rows; } public int getColumnNum() { return columnNum; } public void setColumnNum(int columnNum) { this.columnNum = columnNum; } public int getRowNum() { return rowNum; } public void setRowNum(int rowNum) { this.rowNum = rowNum; } public List<String> getTitle() { return title; } public void setTitle(List<String> title) { this.title = title; } }
模版文件(通用):
excel 头模板
<?xml version="1.0"?> <?mso-application progid="Excel.Sheet"?> <Workbook xmlns="urn:schemas-microsoft-com:office:spreadsheet" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:x="urn:schemas-microsoft-com:office:excel" xmlns:ss="urn:schemas-microsoft-com:office:spreadsheet" xmlns:html="http://www.w3.org/TR/REC-html40"> <DocumentProperties xmlns="urn:schemas-microsoft-com:office:office"> <Created>1996-12-17T01:32:42Z</Created> <LastSaved>2013-08-02T09:21:24Z</LastSaved> <Version>11.9999</Version> </DocumentProperties> <OfficeDocumentSettings xmlns="urn:schemas-microsoft-com:office:office"> <RemovePersonalInformation/> </OfficeDocumentSettings> <ExcelWorkbook xmlns="urn:schemas-microsoft-com:office:excel"> <WindowHeight>4530</WindowHeight> <WindowWidth>8505</WindowWidth> <WindowTopX>480</WindowTopX> <WindowTopY>120</WindowTopY> <AcceptLabelsInFormulas/> <ProtectStructure>False</ProtectStructure> <ProtectWindows>False</ProtectWindows> </ExcelWorkbook> <Styles> <Style ss:ID="Default" ss:Name="Normal"> <Alignment ss:Vertical="Bottom"/> <Borders/> <Font ss:FontName="宋体" x:CharSet="134" ss:Size="12"/> <Interior/> <NumberFormat/> <Protection/> </Style> </Styles>
body模板:
$worksheet:{ <Worksheet ss:Name="$it.sheet$"> <Table ss:ExpandedColumnCount="$it.columnNum$" ss:ExpandedRowCount="$it.rowNum$" x:FullColumns="1" x:FullRows="1" ss:DefaultColumnWidth="54" ss:DefaultRowHeight="14.25"> <Row> $it.title:{ <Cell><Data ss:Type="String">$it$</Data></Cell> }$ </Row> $it.rows:{ <Row> $it.result:{ <Cell><Data ss:Type="String">$it$</Data></Cell> }$ </Row> }$ </Table> </Worksheet> }$
实际处理类:传入list对象,利用反射获取对象属性名及属性值
long startTimne = System.currentTimeMillis(); StringTemplateGroup stGroup = new StringTemplateGroup("stringTemplate"); //写入excel文件头部信息 StringTemplate head = stGroup.getInstanceOf("head"); File file = new File("D:/output2.xls"); PrintWriter writer = new PrintWriter(new BufferedOutputStream(new FileOutputStream(file))); writer.print(head.toString()); writer.flush(); int totalRowNum = listWinningRecordDTOList.size(); int maxRowNum = 60000; int sheets = totalRowNum % 60000 == 0 ? (totalRowNum/maxRowNum) : (totalRowNum/maxRowNum +1); //excel单表最大行数是65535 List record = listWinningRecordDTOList; List<String> title = new ArrayList<String>(); List<Method> getMethods = new ArrayList<Method>(); Class<?> clazz = record.get(0).getClass(); Field[] fields = clazz.getDeclaredFields(); if(fields != null && fields.length > 0){ for(Field field : fields){ if(!"serialVersionUID".equals(field.getName())) { title.add(field.getName()); getMethods.add(clazz.getDeclaredMethod("get" + field.getName().substring(0, 1).toUpperCase() + field.getName().substring(1))); } } } // BeanInfo beanInfo=Introspector.getBeanInfo(clazz,Object.class); // PropertyDescriptor[] proDescrtptors=beanInfo.getPropertyDescriptors(); // for(PropertyDescriptor propertyDescriptor : proDescrtptors){ // title.add(propertyDescriptor.getName()); // getMethods.add(propertyDescriptor.getReadMethod()); // } int columnLength = title.size(); SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); //写入excel文件数据信息 for(int i=0;i<sheets;i++){ StringTemplate body = stGroup.getInstanceOf("body"); Worksheet worksheet = new Worksheet(); worksheet.setTitle(title); worksheet.setSheet(" "+(i+1)+" "); worksheet.setColumnNum(columnLength); worksheet.setRowNum(maxRowNum+1); List<Row> rows = new ArrayList<Row>(); int startIndex = i*maxRowNum; int endIndex = Math.min((i+1)*maxRowNum -1,totalRowNum-1); for(int j=startIndex;j<=endIndex;j++){ Row row = new Row(); List<String> result = new ArrayList<String>(columnLength); for(int n=0;n<columnLength;n++){ Object value = getMethods.get(n).invoke(record.get(j)); if(value == null){ result.add(""); }else{ if(value instanceof Date){ result.add(sdf.format((Date)value)); }else{ result.add(value.toString()); } } } row.setResult(result); rows.add(row); } worksheet.setRows(rows); body.setAttribute("worksheet", worksheet); writer.print(body.toString()); writer.flush(); rows.clear(); rows = null; worksheet = null; body = null; Runtime.getRuntime().gc(); System.out.println("正在生成excel文件的 sheet"+(i+1)); } //写入excel文件尾部 writer.print("</Workbook>"); writer.flush(); writer.close(); System.out.println("生成excel文件完成"); long endTime = System.currentTimeMillis(); System.out.println("用时="+((endTime-startTimne)/1000)+"秒");
整理后的公用类:
import org.antlr.stringtemplate.StringTemplate; import org.antlr.stringtemplate.StringTemplateGroup; import java.io.*; import java.lang.reflect.Field; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.text.SimpleDateFormat; import java.util.ArrayList; import java.util.Date; import java.util.List; /** * Created by Administrator on 2016/2/25. */ public class ExcelStUtil { public static void export(OutputStream outputStream,List target) throws NoSuchMethodException, InvocationTargetException, IllegalAccessException { long startTime = System.currentTimeMillis(); StringTemplateGroup stGroup = new StringTemplateGroup("stringTemplate"); //解决可能发生的中文乱码 stGroup.setFileCharEncoding("UTF-8"); //写入excel文件头部信息 StringTemplate head = stGroup.getInstanceOf("st/head"); PrintWriter writer = new PrintWriter(new BufferedOutputStream(outputStream)); writer.print(head.toString()); writer.flush(); int totalRowNum = target.size(); int maxRowNum = 60000; int sheets = totalRowNum % 60000 == 0 ? (totalRowNum/maxRowNum) : (totalRowNum/maxRowNum +1); //excel单表最大行数是65535 List record = target; List<String> title = new ArrayList<String>(); List<Method> getMethods = new ArrayList<Method>(); Class<?> clazz = record.get(0).getClass(); Field[] fields = clazz.getDeclaredFields(); if(fields != null && fields.length > 0){ for(Field field : fields){ if(!"serialVersionUID".equals(field.getName())) { title.add(field.getName()); getMethods.add(clazz.getDeclaredMethod("get" + field.getName().substring(0, 1).toUpperCase() + field.getName().substring(1))); } } } // BeanInfo beanInfo=Introspector.getBeanInfo(clazz,Object.class); // PropertyDescriptor[] proDescrtptors=beanInfo.getPropertyDescriptors(); // for(PropertyDescriptor propertyDescriptor : proDescrtptors){ // title.add(propertyDescriptor.getName()); // getMethods.add(propertyDescriptor.getReadMethod()); // } int columnLength = title.size(); SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); //写入excel文件数据信息 for(int i=0;i<sheets;i++){ StringTemplate body = stGroup.getInstanceOf("st/body"); Worksheet worksheet = new Worksheet(); worksheet.setTitle(title); worksheet.setSheet(" "+(i+1)+" "); worksheet.setColumnNum(columnLength); worksheet.setRowNum(maxRowNum+1); List<Row> rows = new ArrayList<Row>(); int startIndex = i*maxRowNum; int endIndex = Math.min((i+1)*maxRowNum -1,totalRowNum-1); for(int j=startIndex;j<=endIndex;j++){ Row row = new Row(); List<String> result = new ArrayList<String>(columnLength); for(int n=0;n<columnLength;n++){ Object value = getMethods.get(n).invoke(record.get(j)); if(value == null){ result.add(""); }else{ if(value instanceof Date){ result.add(sdf.format((Date)value)); }else{ result.add(value.toString()); } } } row.setResult(result); rows.add(row); } worksheet.setRows(rows); body.setAttribute("worksheet", worksheet); writer.print(body.toString()); writer.flush(); rows.clear(); rows = null; worksheet = null; body = null; Runtime.getRuntime().gc(); System.out.println("正在生成excel文件的 sheet"+(i+1)); } //写入excel文件尾部 writer.print("</Workbook>"); writer.flush(); writer.close(); System.out.println("生成excel文件完成"); long endTime = System.currentTimeMillis(); System.out.println("用时="+((endTime-startTime)/1000)+"秒"); } public static void main(String[] args) throws IOException, NoSuchMethodException, IllegalAccessException, InvocationTargetException { System.out.println(Thread.currentThread().getContextClassLoader().getResource("").getPath()); System.out.println(ExcelStUtil.class.getResource("").getPath()); System.out.println(ExcelStUtil.class.getClassLoader().getResource("").getPath()); List<Sample> result = new ArrayList<Sample>(); for(int i=0;i<100;i++){ result.add(new Sample("放大双方的"+String.valueOf(i),String.valueOf(i))); } //OutputStream outputStream = new FileOutputStream("D:/output2.xls"); ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream(); ExcelStUtil.export(byteArrayOutputStream,result); //ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(byteArrayOutputStream.toByteArray()); //解决可能发生的中文乱码 ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(byteArrayOutputStream.toString().getBytes("UTF-8")); File file = new File("D:/output2.xls"); OutputStream output = new FileOutputStream(file); BufferedOutputStream bufferedOutput = new BufferedOutputStream(output); //bufferedOutput.write(byteArrayOutputStream.toByteArray()); bufferedOutput.write(byteArrayOutputStream.toString().getBytes("UTF-8")); bufferedOutput.flush(); bufferedOutput.close(); } }
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