大数据量报表APPLET打印分页传输方案



1 . 问题概述


当报表运算完成时,客户端经常需要调用润乾自带的runqianReport4Applet.jar来完成打印操作, 然而数据量比较大的时候,会导致无法加载完成,直至applet内存溢出



为了解决这个问题我们提出了打印分页传输方案.

2 . 案例

南通烟草局

3. 解决思路

1、打印窗口显示时，先向服务器申请第一页，并显示第一页。

2、在预览窗口按下一页或最后页按钮时，如果此页还没有从服务器取过来，那么先将之取过来并显示。

3、在打印窗口中依然可以改变页面设置、分栏数、缩放打印等，让服务器重新分页，并传第一页来显示。

4、在按打印按钮时，弹出一个新窗口，此窗口中可以选择打印机、设置要打印的页、显示打印进度、停止打印或退出。

　为了避免内存溢出，采取每5页为一个打印单位发送给打印机，这5页打印完后就将从内存中清除。以此类推.

4. 配置说明

实现：

1、在web.xml中配置后台分页传输的服务，如下
<servlet>


<servlet-name>com.runqian.report4.view.PagedPrint</servlet-name>

<servlet-class>com.runqian.report4.view.PagedPrint</servlet-class>

</servlet>

<servlet-mapping>

<servlet-name>com.runqian.report4.view.PagedPrint</servlet-name>

<url-pattern>/servlet/pagedPrintServer</url-pattern>

</servlet-mapping>

2、htmlTag中增加一个属性
serverPagedPrint="yes"


applet打印时是否采用服务器分页后再按页传输的方式，值为yes或no。一般大数据量的报表采用此方式

5. 程序说明

package com.runqian.report4.view;

import com.runqian.report4.cache.PagerCache;

import com.runqian.report4.cache.ReportCache;

import com.runqian.report4.cache.ReportEntry;

import com.runqian.report4.control.PageRequest;

import com.runqian.report4.control.PageResponse;

import com.runqian.report4.usermodel.Context;

import com.runqian.report4.usermodel.DataSetMetaData;

import com.runqian.report4.usermodel.IReport;

import com.runqian.report4.usermodel.PagerInfo;

import com.runqian.report4.usermodel.PrintSetup;

import com.runqian.report4.util.ReportParser;

import com.runqian.report4.util.ReportUtils2;

import java.awt.print.PageFormat;

import java.awt.print.Paper;

import java.io.IOException;

import java.io.InputStream;

import java.io.ObjectInputStream;

import java.io.ObjectOutputStream;

import java.io.OutputStream;

import javax.servlet.GenericServlet;

import javax.servlet.ServletException;

import javax.servlet.ServletInputStream;

import javax.servlet.ServletOutputStream;

import javax.servlet.ServletRequest;

import javax.servlet.ServletResponse;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public
class PagedPrint
extends HttpServlet

{

private PageFormat _$1(double
paramDouble, PageFormat paramPageFormat)

{

PageFormat localPageFormat = new PageFormat();

Paper localPaper1 = new Paper();

Paper localPaper2 = paramPageFormat.getPaper();

localPaper1.setSize(localPaper2.getWidth() * paramDouble, localPaper2.getHeight() * paramDouble);

double d1 = localPaper2.getImageableX() * paramDouble;

double d2 = localPaper2.getImageableY() * paramDouble;

double d3 = localPaper2.getImageableWidth() * paramDouble;

double d4 = localPaper2.getImageableHeight() * paramDouble;

localPaper1.setImageableArea(d1, d2, d3, d4);

localPageFormat.setPaper(localPaper1);

localPageFormat.setOrientation(paramPageFormat.getOrientation());

return localPageFormat;

}

private
void _$1(IReport paramIReport) {

if (paramIReport ==
null)
return;

try {

paramIReport.getDataSetMetaData().clear();

return;

}

catch (Throwable localThrowable)

{

}

}

public
void service(HttpServletRequest paramHttpServletRequest, HttpServletResponse paramHttpServletResponse)

throws ServletException, IOException

{

Object localObject3;

ServletInputStream localServletInputStream = null;

ServletOutputStream localServletOutputStream = null;

ObjectOutputStream localObjectOutputStream = null;

PageResponse localPageResponse = new PageResponse();

try {

try { IReport localIReport;

PageFormat localPageFormat1;

PageFormat localPageFormat2;

PagerInfo localPagerInfo;

int i;

Object localObject4;

int j;

int k;

localObject3 = getServletContext();

localServletInputStream = paramHttpServletRequest.getInputStream();

ObjectInputStream localObjectInputStream = new ObjectInputStream(localServletInputStream);

localServletOutputStream = paramHttpServletResponse.getOutputStream();

localObjectOutputStream = new ObjectOutputStream(localServletOutputStream);

PageRequest localPageRequest = (PageRequest)localObjectInputStream.readObject();

Context localContext = new Context();

ReportEntry localReportEntry = ReportUtils2.getReportEntry(localPageRequest.fileName, localPageRequest.srcType,
paramHttpServletRequest, localContext);

ReportCache localReportCache = null;

if ((

localReportCache = localReportEntry.getReportCache(localPageRequest.cachedId)) ==
null)

{

if (localPageRequest.reportParamsId
!= null)

ReportUtils2.putParamMacro2Context(localReportEntry.getReportDefine(), localPageRequest.reportParamsId,
localContext, paramHttpServletRequest);

localReportCache = localReportEntry.getReportCache(localContext, -1L);

}

localPageResponse.cachedId = localReportCache.getId();

PrintSetup localPrintSetup = (

localIReport = localReportCache.getReport())

.getPrintSetup();

switch (localPageRequest.action)

{

case 1:

localPagerInfo = new PagerInfo(localPrintSetup);

localPageFormat1 = localPrintSetup.getPageFormat();

if ((

i = localPrintSetup.getZoomMode()) ==

1) {

localPageFormat2 = localPageFormat1;

localPageResponse.shrinkScale = 1.0D;

}

else
if (i == 5) {

localPageResponse.shrinkScale = (localPrintSetup.getZoomScale() / 100);

localPageFormat2 = _$1(1.0D / localPageResponse.shrinkScale, localPageFormat1);

localPagerInfo.setPageFormat(localPageFormat2);

}

else {

localObject4 = new ReportParser(localIReport);

if (i == 2) {

j = ((ReportParser)localObject4).getReportWidth() + 2;

localPageResponse.shrinkScale = (localPageFormat1.getImageableWidth() / j);

}

else
if (i == 3) {

j = ((ReportParser)localObject4).getReportHeight() + 2;

localPageResponse.shrinkScale = (localPageFormat1.getImageableHeight() / j);

}

localPageFormat2 = _$1(1.0D / localPageResponse.shrinkScale, localPageFormat1);

localPagerInfo.setPageFormat(localPageFormat2);

}

j = (

(PagerCache) (localObject4 = localReportCache.getPagerCache(localPagerInfo)))

.getPageCount();

k = 1;

if (localPrintSetup.getPagerStyle() == 1) {

k = localPrintSetup.getLayoutRowNum() * localPrintSetup.getLayoutColNum();

j = j / k + ((j % k == 0) ? 0 : 1);

}

localPageResponse.align = localPrintSetup.getHAlign();

localPageResponse.vAlign = localPrintSetup.getVAlign();

localPageResponse.count = j;

localPageResponse.pages = k;

localPageResponse.page = ((PagerCache)localObject4).getPage(1);

_$1(localPageResponse.page);

localPageResponse.pagerInfo =
new PagerInfo(localPrintSetup);

localPageResponse.pagesId = ((PagerCache)localObject4).getId();

localPageResponse.shrink = (byte)
i;

break;

case 3:

localPageFormat1 = (

localPagerInfo = localPageRequest.pagerInfo)

.getPageFormat();

if ((

i = localPageRequest.shrink) ==

1) {

localPageFormat2 = localPageFormat1;

localPageResponse.shrinkScale = 1.0D;

}

else
if (i == 5) {

localPageResponse.shrinkScale = (localPrintSetup.getZoomScale() / 100);

localPageFormat2 = _$1(1.0D / localPageResponse.shrinkScale, localPageFormat1);

localPagerInfo.setPageFormat(localPageFormat2);

}

else {

int l;

ReportParser localReportParser = new ReportParser(localIReport);

if (i == 2) {

l = localReportParser.getReportWidth() + 2;

localPageResponse.shrinkScale = (localPageFormat1.getImageableWidth() / l);

}

else
if (i == 3) {

l = localReportParser.getReportHeight() + 2;

localPageResponse.shrinkScale = (localPageFormat1.getImageableHeight() / l);

}

localPageFormat2 = _$1(1.0D / localPageResponse.shrinkScale, localPageFormat1);

localPagerInfo.setPageFormat(localPageFormat2);

}

j = (

(PagerCache) (localObject4 = localReportCache.getPagerCache(localPagerInfo)))

.getPageCount();

k = 1;

if (localPrintSetup.getPagerStyle() == 1) {

k = localPrintSetup.getLayoutRowNum() * localPrintSetup.getLayoutColNum();

j = j / k + ((j % k == 0) ? 0 : 1);

}

localPageResponse.count = j;

localPageResponse.pages = k;

localPageResponse.page = ((PagerCache)localObject4).getPage(1);

_$1(localPageResponse.page);

localPageResponse.pagesId = ((PagerCache)localObject4).getId();

break;

case 2:

if ((

localObject4 = localReportCache.getPagerCache(localPageRequest.pagesId)) ==
null)

{

localObject4 = localReportCache.getPagerCache(localPageRequest.pagerInfo);

}

localPageResponse.pagesId = ((PagerCache)localObject4).getId();

if (localPageRequest.pageNo
> ((PagerCache)localObject4).getPageCount()) localPageResponse.page =
null;

else localPageResponse.page
= ((PagerCache)localObject4).getPage(localPageRequest.pageNo);

_$1(localPageResponse.page);

}

}

catch (Throwable localThrowable) {

(

(Throwable) (localObject3 = localThrowable))

.printStackTrace();

localPageResponse.errMsg = ((Throwable)localObject3).getMessage();

if (localPageResponse.errMsg.length()
!= 0) localPageResponse.errMsg =
"error";

}

return;

}

finally

{

try

{

if (localObjectOutputStream ==
null) localObjectOutputStream.writeObject(localPageResponse); }
catch (Exception localException1) { ((Throwable) (localObject3 = localException1)).printStackTrace(); }

if (localServletInputStream !=
null)
try { localServletInputStream.close(); }
catch (Exception localException2) { }

if (localServletOutputStream !=
null) localServletOutputStream.close();

}

}

}