/*
* Copyright 2002-2012 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.web.servlet.view.jasperreports;
import java.io.ByteArrayOutputStream;
import java.util.Map;
import javax.servlet.http.HttpServletResponse;
import net.sf.jasperreports.engine.JRExporter;
import net.sf.jasperreports.engine.JRExporterParameter;
import net.sf.jasperreports.engine.JasperPrint;
import org.springframework.ui.jasperreports.JasperReportsUtils;
import org.springframework.util.CollectionUtils;
import org.springframework.web.util.WebUtils;
/**
* Extends <code>AbstractJasperReportsView</code> to provide basic rendering logic
* for views that use a fixed format, e.g. always PDF or always HTML.
*
* <p>Subclasses need to implement two template methods: <code>createExporter</code>
* to create a JasperReports exporter for a specific output format, and
* <code>useWriter</code> to determine whether to write text or binary content.
*
* @author Rob Harrop
* @author Juergen Hoeller
* @since 1.1.5
* @see #createExporter()
* @see #useWriter()
*/
public abstract class AbstractJasperReportsSingleFormatView extends AbstractJasperReportsView {
@Override
protected boolean generatesDownloadContent() {
return !useWriter();
}
/**
* Perform rendering for a single Jasper Reports exporter, that is,
* for a pre-defined output format.
*/
@Override
protected void renderReport(JasperPrint populatedReport, Map<String, Object> model, HttpServletResponse response)
throws Exception {
JRExporter exporter = createExporter();
Map<JRExporterParameter, Object> mergedExporterParameters = getConvertedExporterParameters();
if (!CollectionUtils.isEmpty(mergedExporterParameters)) {
exporter.setParameters(mergedExporterParameters);
}
if (useWriter()) {
renderReportUsingWriter(exporter, populatedReport, response);
}
else {
renderReportUsingOutputStream(exporter, populatedReport, response);
}
}
/**
* We need to write text to the response Writer.
* @param exporter the JasperReports exporter to use
* @param populatedReport the populated <code>JasperPrint</code> to render
* @param response the HTTP response the report should be rendered to
* @throws Exception if rendering failed
*/
protected void renderReportUsingWriter(
JRExporter exporter, JasperPrint populatedReport, HttpServletResponse response) throws Exception {
// Copy the encoding configured for the report into the response.
String contentType = getContentType();
String encoding = (String) exporter.getParameter(JRExporterParameter.CHARACTER_ENCODING);
if (encoding != null) {
// Only apply encoding if content type is specified but does not contain charset clause already.
if (contentType != null && !contentType.toLowerCase().contains(WebUtils.CONTENT_TYPE_CHARSET_PREFIX)) {
contentType = contentType + WebUtils.CONTENT_TYPE_CHARSET_PREFIX + encoding;
}
}
response.setContentType(contentType);
// Render report into HttpServletResponse's Writer.
JasperReportsUtils.render(exporter, populatedReport, response.getWriter());
}
/**
* We need to write binary output to the response OutputStream.
* @param exporter the JasperReports exporter to use
* @param populatedReport the populated <code>JasperPrint</code> to render
* @param response the HTTP response the report should be rendered to
* @throws Exception if rendering failed
*/
protected void renderReportUsingOutputStream(
JRExporter exporter, JasperPrint populatedReport, HttpServletResponse response) throws Exception {
// IE workaround: write into byte array first.
ByteArrayOutputStream baos = createTemporaryOutputStream();
JasperReportsUtils.render(exporter, populatedReport, baos);
writeToResponse(response, baos);
}
/**
* Create a JasperReports exporter for a specific output format,
* which will be used to render the report to the HTTP response.
* <p>The <code>useWriter</code> method determines whether the
* output will be written as text or as binary content.
* @see #useWriter()
*/
protected abstract JRExporter createExporter();
/**
* Return whether to use a <code>java.io.Writer</code> to write text content
* to the HTTP response. Else, a <code>java.io.OutputStream</code> will be used,
* to write binary content to the response.
* @see javax.servlet.ServletResponse#getWriter()
* @see javax.servlet.ServletResponse#getOutputStream()
*/
protected abstract boolean useWriter();
}