java導出大量的excel

時間 2019-11-13

標籤 java 導出大量 excel 欄目 Java 简体版

原文原文鏈接

廢話少說，直入主題
html

基本思路爲建立一個臨時文件寫入數據導出數據刪除臨時文件
java

首先須要兩個jar包數據庫

antlr和stringtemplate緩存

建立數據庫中的類Row服務器

    private String name1;
    
    private String name2;
    
    private String name3;
    public String getName1() {
        return name1;
    }
    public void setName1(String name1) {
        this.name1 = name1;
    }
    public String getName2() {
        return name2;
    }
    public void setName2(String name2) {
        this.name2 = name2;
    }
    public String getName3() {
        return name3;
    }
    public void setName3(String name3) {
        this.name3 = name3;
    }

而後須要建立對應的Worksheet類app

private int columnNum;
    
    private int rowNum;
    
    private List<Row> rows;
    
    private List<SfOrder> orders;
    
    
    
    public List<SfOrder> getOrders() {
        return orders;
    }
    public void setOrders(List<SfOrder> orders) {
        this.orders = orders;
    }
    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;
    }

而後須要寫兩個文件分別爲this

head.st編碼

excel

<?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="宋體" x:CharSet="134" ss:Size="12"/>
   <Interior/>
   <NumberFormat/>
   <Protection/>
  </Style>
 </Styles>

和body.stcode

 $worksheet:{
 <Worksheet ss:Name="$it.sheet$">
  <Table ss:ExpandedColumnCount="$it.columnNum$" ss:ExpandedRowCount="$it.rowNum$" x:FullColumns="1"
   x:FullRows="1" ss:DefaultColumnWidth="54" ss:DefaultRowHeight="14.25">
 $it.rows:{
   <Row>
    <Cell><Data ss:Type="String">$it.name1$</Data></Cell>
   </Row>
 }$
  </Table>
 </Worksheet>
}$

下面就是程序代碼

首先你要從數據中查詢數據，假設你查詢的數據爲List數據

            //我這裏的list是從map中獲取的你能夠直接獲取
            List<Row> list=(List<Row>) result.get("list");
              list=(List<SfOrder>) result.get("list");
              if(list.size()==0){
                  return null;
              }
            long startTimne = System.currentTimeMillis();
            StringTemplateGroup stGroup = new StringTemplateGroup("stringTemplate");    
            stGroup.setFileCharEncoding("UTF-8");//設置編碼，不然有亂碼，導出excel格式不正確
            //寫入excel文件頭部信息
            StringTemplate head =  stGroup.getInstanceOf("/template/head");
            String path=request.getSession().getServletContext().getRealPath("/upload/excel/test1.xls");
            File file = new File(path);
            PrintWriter writer = new PrintWriter(new BufferedOutputStream(new FileOutputStream(file)));
            writer.print(head.toString());
            writer.flush();
            int sheets = 10;
            //excel單表最大行數是65535
            int maxRowNum = 3000;
            int maxRowNumLast=0;
            //計算要分幾個sheet
            sheets=(list.size()%maxRowNum==0) ? list.size()/maxRowNum:list.size()/maxRowNum+1;
            //計算最後一個sheet有多少行
            maxRowNumLast=list.size()-(sheets-1)*maxRowNum;

上面爲預備階段，下面則直接向文件寫數據

//寫入excel文件數據信息
            for(int i=0;i<sheets;i++){
                Integer nums=0;
                StringTemplate body =  stGroup.getInstanceOf("/template/body");
                Worksheet worksheet = new Worksheet();
                worksheet.setSheet(" "+(i+1)+" ");
                worksheet.setColumnNum(3);
                worksheet.setRowNum(maxRowNum);
                List<Row> orders = new ArrayList<Row>();
                if(i==(sheets-1)){
                    for(int j=0;j<maxRowNumLast;j++){
                        nums=i*maxRowNumLast+j;
                        SfOrder order=new SfOrder();
                        order.setOrderId(list.get(nums).getOrderId());
                        orders.add(order);
                    }
                }else{
                    for(int j=0;j<maxRowNum;j++){
                        nums=i*maxRowNum+j;
                        Row order=new Row();
                        order.setOrderId(list.get(nums).getOrderId());
                        orders.add(order);
                    }
                }
                worksheet.setOrders(orders);
                body.setAttribute("worksheet", worksheet);
                writer.print(body.toString());
                writer.flush();
                orders.clear();
                orders = null;
                worksheet = null;
                body = null;
                Runtime.getRuntime().gc();
                System.out.println("正在生成excel文件的 sheet"+(i+1));
            }

下面則寫入服務器磁盤

    //寫入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("用時="+((endTime-startTimne)/1000)+"秒");

下面要讀取文件,即正式的導出

 //建立file對象
            File upload=new File(path);
            //設置response的編碼方式
            response.setContentType("application/vnd.ms-excel");
            response.setHeader("Content-Disposition","attachment;filename=ceshi.xls");
            //讀出文件到i/o流
            FileInputStream fis=new FileInputStream(upload);
            BufferedInputStream buff=new BufferedInputStream(fis);
            byte [] b=new byte[1024];//至關於咱們的緩存
            long k=0;//該值用於計算當前實際下載了多少字節
            //從response對象中獲得輸出流,準備下載
            OutputStream myout=response.getOutputStream();
            //開始循環下載
            while(k<upload.length()){
                int j=buff.read(b,0,1024);
                k+=j;
                //將b中的數據寫到客戶端的內存
                myout.write(b,0,j);
            }
            //將寫入到客戶端的內存的數據,刷新到磁盤
            myout.flush();
            myout.close();

若是須要能夠，好比這個文件是動態的咱們能夠讓這個文件是動態的，就要將此文件刪除

               File fileDel = new File(path);  
                      // 若是文件路徑所對應的文件存在，而且是一個文件，則直接刪除  
                      if (fileDel.exists() && file.isFile()) {  
                       fileDel.delete()
                       }

這樣就大功告成啦，導出所用的時間大部分是花費在數據庫查詢中，固然這也是你數據庫功底的問題啦