无法使用 Jasper 报告库生成 Excel 工作表报告

Question

我尝试使用以下代码生成 Excel 报告。

import java.util.*;

import net.sf.jasperreports.engine.*;
import net.sf.jasperreports.engine.export.JRXlsExporter;
import net.sf.jasperreports.export.OutputStreamExporterOutput;
import net.sf.jasperreports.export.SimpleExporterInput;
import net.sf.jasperreports.export.SimpleOutputStreamExporterOutput;
import net.sf.jasperreports.export.SimpleXlsReportConfiguration;

public class FirstReport 
{
public static void main(String[] args) 
{
    try
    {

        JRXlsExporter exporter = new JRXlsExporter();
        exporter.setExporterInput(new         SimpleExporterInput("FirstReport.jrxml"));
        exporter.setExporterOutput(new SimpleOutputStreamExporterOutput("C://sample_report.xls"));

        SimpleXlsReportConfiguration configuration = new SimpleXlsReportConfiguration();
        configuration.setOnePagePerSheet(true);
        configuration.setDetectCellType(true);
        configuration.setCollapseRowSpan(false);
        exporter.setConfiguration(configuration);   
        exporter.exportReport();

    }
    catch (Exception e)
    {
        e.printStackTrace();
    }

}
}

此程序正在生成以下异常

net.sf.jasperreports.engine.JRRuntimeException：net.sf.jasperreports.engine.JRException：从文件加载对象时出错：FirstReport.jrxml 在 net.sf.jasperreports.export.SimpleExporterInput.(SimpleExporterInput.java:157) 在 FirstReport.main(FirstReport.java:33) 原因：net.sf.jasperreports.engine.JRException：从文件加载对象时出错：FirstReport.jrxml 在 net.sf.jasperreports.engine.util.JRLoader.loadObject(JRLoader.java:131) 在 net.sf.jasperreports.engine.util.JRLoader.loadObject(JRLoader.java:103) 在 net.sf.jasperreports.engine.util.JRLoader.loadObjectFromFile(JRLoader.java:94) 在 net.sf.jasperreports.export.SimpleExporterInput。 (SimpleExporterInput.java:153) ... 1 更多 引起：java.io.StreamCorruptedException：无效的流标头：3C3F786D 在 java.io.ObjectInputStream.readStreamHeader（未知来源） 在 java.io.ObjectInputStream.（未知来源） 在 net.sf.jasperreports.engine.util.ContextClassLoaderObjectInputStream。 (ContextClassLoaderObjectInputStream.java:57) 在 net.sf.jasperreports.engine.util.JRLoader.loadObject(JRLoader.java:126) ... 4 更多

Answer 1

exporter.setExporterInput() 的参数必须基于 JasperPrint 对象（不是 jrxml 文件）。

您可以在net.sf.jasperreports.export.SimpleExporterInput 课堂上看到它。这个类的一些代码：

/**
 * Creates an {@link ExporterInput} object with a single item wrapping the {@link JasperPrint} object that will be exported. 
 * If you already have a JasperPrint object, you can pass it to the exporter using this type of input.
 */
public SimpleExporterInput(JasperPrint jasperPrint)
{
    if (jasperPrint != null)
    {
        this.items = new ArrayList<ExporterInputItem>();
        items.add(new SimpleExporterInputItem(jasperPrint));
    }
}


/**
 * Creates an {@link ExporterInput} object with a single {@link JasperPrint} item read from the provided input stream. 
 * If you want to read the JasperPrint object from an input stream (like a web location), you can pass the stream to this constructor.
 */
public SimpleExporterInput(InputStream inputStream)
{
    if (inputStream != null)
    {
        JasperPrint jasperPrint = null;
        try
        {
            jasperPrint = (JasperPrint)JRLoader.loadObject(inputStream);
        }
        catch (JRException e)
        {
            throw new JRRuntimeException(e);
        }
        this.items = new ArrayList<ExporterInputItem>();
        items.add(new SimpleExporterInputItem(jasperPrint));
    }
}

JasperPrint 对象是执行方法fillReport 的结果。例如：

JasperPrint jasperPrint = JasperFillManager.fillReport(jasperReportFile, reportParameters, dataSource);

在此代码中，jasperReportFile 是与编译报告文件（不是 jrxml）相对应的对象。在你的情况下 FirstReport.jasper

来自net.sf.jasperreports.engine.JasperFillManager的一些代码：

/**
 * @see #fill(String, Map, JRDataSource)
 */
public static JasperPrint fillReport(
    String sourceFileName, 
    Map<String,Object> params,
    JRDataSource dataSource
    ) throws JRException
{
    return getDefaultInstance().fill(sourceFileName, params, dataSource);
}
....
    /**
 * Fills the compiled report design loaded from the specified file and returns
 * the generated report object.
 * 
 * @param sourceFileName source file containing the compile report design
 * @param params     report parameters map
 * @param dataSource     data source object
 * @return generated report object
 */
public JasperPrint fill(
    String sourceFileName, 
    Map<String,Object> params,
    JRDataSource dataSource
    ) throws JRException
{
    File sourceFile = new File(sourceFileName);

    JasperReport jasperReport = (JasperReport)JRLoader.loadObject(sourceFile);

    JasperReportsContext lcJrCtx = getLocalJasperReportsContext(sourceFile);

    return JRFiller.fill(lcJrCtx, jasperReport, params, dataSource);
}

HTH