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();
}
}
}