ua.com.manometer.jasperreports.AbstractJasperReportsSingleFormatView.java Source code

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Here is the source code for ua.com.manometer.jasperreports.AbstractJasperReportsSingleFormatView.java

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/*
 * Copyright 2002-2008 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 ua.com.manometer.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 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();

}