标签：simple output sig classes address col stat java schema
JasperReports is an open source reporting library that enables users to create pixel-perfect reports that can be printed or exported in many formats including PDF, HTML, and XLS.
In this article, we‘ll explore its key features and classes, and implement examples to showcase its capabilities.
First, we need to add the jasperreports dependency to our pom.xml:
<dependency>
<groupId>net.sf.jasperreports</groupId>
<artifactId>jasperreports</artifactId>
<version>6.4.0</version>
</dependency>
The latest version of this artifact can be found here.
Report designs are defined in JRXML files. These are ordinary XML files with a particular structure that JasperReports engine can interpret.
Let‘s now have a look at only the relevant structure of the JRXML files – to understand better the Java part of the report generation process, which is our primary focus.
Let‘s create a simple report to show employee information:
<jasperReport ... >
<field name="FIRST_NAME" class="java.lang.String"/>
<field name="LAST_NAME" class="java.lang.String"/>
<field name="SALARY" class="java.lang.Double"/>
<field name="ID" class="java.lang.Integer"/>
<detail>
<band height="51" splitType="Stretch">
<textField>
<reportElement x="0" y="0" width="100" height="20"/>
<textElement/>
<textFieldExpression class="java.lang.String">
<![CDATA[$F{FIRST_NAME}]]></textFieldExpression>
</textField>
<textField>
<reportElement x="100" y="0" width="100" height="20"/>
<textElement/>
<textFieldExpression class="java.lang.String">
<![CDATA[$F{LAST_NAME}]]></textFieldExpression>
</textField>
<textField>
<reportElement x="200" y="0" width="100" height="20"/>
<textElement/>
<textFieldExpression class="java.lang.String">
<![CDATA[$F{SALARY}]]></textFieldExpression>
</textField>
</band>
</detail>
</jasperReport>
JRXML files need to be compiled so the report engine can fill them with data.
Let‘s perform this operation with the help of the JasperCompilerManager class:
InputStream employeeReportStream
= getClass().getResourceAsStream("/employeeReport.jrxml");
JasperReport jasperReport
= JasperCompileManager.compileReport(employeeReportStream);
To avoid compiling it every time, we can save it to a file:
JRSaver.saveObject(jasperReport, "employeeReport.jasper");
The most common way to fill compiled reports is with records from a database. This requires the report to contain a SQL query the engine will execute to obtain the data.
First, let‘s modify our report to add a SQL query:
<jasperReport ... >
<queryString>
<![CDATA[SELECT * FROM EMPLOYEE]]>
</queryString>
...
</jasperReport>
Now, let‘s create a simple data source:
@Bean public DataSource dataSource() { return new EmbeddedDatabaseBuilder() .setType(EmbeddedDatabaseType.HSQL) .addScript("classpath:employee-schema.sql") .build(); }
Now, we can fill the report:
JasperPrint jasperPrint = JasperFillManager.fillReport( jasperReport, null, dataSource.getConnection());
Note that we are passing null to the second argument since our report doesn‘t receive any parameters yet.
Parameters are useful for passing data to the report engine that it can not find in its data source or when data changes depending on different runtime conditions.
We can also change portions or even the entire SQL query with parameters received in the report filling operation.
First, let‘s modify the report to receive three parameters:
<jasperReport ... > <parameter name="title"class="java.lang.String" /> <parameter name="minSalary"class="java.lang.Double" /> <parameter name="condition"class="java.lang.String"> <defaultValueExpression> <![CDATA["1 = 1"]]></defaultValueExpression> </parameter> // ... </jasperreport>
Now, let‘s add a title section to show the title parameter:
<jasperreport ... >
// ...
<title>
<band height="20" splitType="Stretch">
<textField>
<reportElement x="238" y="0" width="100" height="20"/>
<textElement/>
<textFieldExpression class="java.lang.String">
<![CDATA[$P{title}]]></textFieldExpression>
</textField>
</band>
</title>
...
</jasperreport/>
Next, let‘s alter the query to use the minSalary and condition parameters:
SELECT * FROM EMPLOYEE
WHERE SALARY >= $P{minSalary} AND $P!{condition}
Note the different syntax when using the condition parameter. This tells the engine that the parameter should not be used as a standard PreparedStatement parameter, but as if the value of that parameter would have been written originally in the SQL query.
Finally, let‘s prepare the parameters and fill the report:
Map<String, Object> parameters = new HashMap<>(); parameters.put("title", "Employee Report"); parameters.put("minSalary", 15000.0); parameters.put("condition", " LAST_NAME =‘Smith‘ ORDER BY FIRST_NAME"); JasperPrint jasperPrint = JasperFillManager.fillReport(..., parameters, ...);
Note that the keys of parameters correspond to parameter names in the report. If the engine detects a parameter is missing, it will obtain the value from defaultValueExpression of the parameter if any.
To export a report, first, we instantiate an object of an exporter class that matches the file format we need.
Then, we set our previous filled report as input and define where to output the resulting file.
Optionally, we can set corresponding report and export configuration objects to customize the exporting process.
JRPdfExporter exporter = new JRPdfExporter(); exporter.setExporterInput(new SimpleExporterInput(jasperPrint)); exporter.setExporterOutput( new SimpleOutputStreamExporterOutput("employeeReport.pdf")); SimplePdfReportConfiguration reportConfig = new SimplePdfReportConfiguration(); reportConfig.setSizePageToContent(true); reportConfig.setForceLineBreakPolicy(false); SimplePdfExporterConfiguration exportConfig = new SimplePdfExporterConfiguration(); exportConfig.setMetadataAuthor("baeldung"); exportConfig.setEncrypted(true); exportConfig.setAllowedPermissionsHint("PRINTING"); exporter.setConfiguration(reportConfig); exporter.setConfiguration(exportConfig); exporter.exportReport();
JRXlsxExporter exporter = new JRXlsxExporter(); // Set input and output ... SimpleXlsxReportConfiguration reportConfig = new SimpleXlsxReportConfiguration(); reportConfig.setSheetNames(new String[] { "Employee Data" }); exporter.setConfiguration(reportConfig); exporter.exportReport();
JRCsvExporter exporter = new JRCsvExporter(); // Set input ... exporter.setExporterOutput( new SimpleWriterExporterOutput("employeeReport.csv")); exporter.exportReport();
HtmlExporter exporter = new HtmlExporter(); // Set input ... exporter.setExporterOutput( new SimpleHtmlExporterOutput("employeeReport.html")); exporter.exportReport();
Subreports are nothing more than a standard report embedded in another report.
First, let‘s create a report to show the emails of an employee:
<jasperReport ... >
<parameter name="idEmployee" class="java.lang.Integer" />
<queryString>
<![CDATA[SELECT * FROM EMAIL WHERE ID_EMPLOYEE = $P{idEmployee}]]>
</queryString>
<field name="ADDRESS" class="java.lang.String"/>
<detail>
<band height="20" splitType="Stretch">
<textField>
<reportElement x="0" y="0" width="156" height="20"/>
<textElement/>
<textFieldExpression class="java.lang.String">
<![CDATA[$F{ADDRESS}]]></textFieldExpression>
</textField>
</band>
</detail>
</jasperReport>
Now, let‘s modify our employee report to include the previous one:
<detail>
<band ... >
<subreport>
<reportElement x="0" y="20" width="300" height="27"/>
<subreportParameter name="idEmployee">
<subreportParameterExpression>
<![CDATA[$F{ID}]]></subreportParameterExpression>
</subreportParameter>
<connectionExpression>
<![CDATA[$P{REPORT_CONNECTION}]]></connectionExpression>
<subreportExpression class="java.lang.String">
<![CDATA["employeeEmailReport.jasper"]]></subreportExpression>
</subreport>
</band>
</detail>
Note that we are referencing the subreport by the name of the compiled file and passing it the idEmployee and current report connection as parameters.
Next, let‘s compile both reports:
InputStream employeeReportStream = getClass().getResourceAsStream("/employeeReport.jrxml"); JasperReport jasperReport = JasperCompileManager.compileReport(employeeReportStream); JRSaver.saveObject(jasperReport, "employeeReport.jasper"); InputStream emailReportStream = getClass().getResourceAsStream("/employeeEmailReport.jrxml"); JRSaver.saveObject( JasperCompileManager.compileReport(emailReportStream), "employeeEmailReport.jasper");
Our code for filling and exporting the report doesn‘t require modifications.
In this article, we had a brief look at the core features of the JasperReports library.
We were able to compile and populate reports with records from a database; we passed parameters to change the data shown in the report according to different runtime conditions, embedded subreports and exported them to the most common formats.
Complete source code for this article can be found over on GitHub.
JasperPrint jasperPrint = JasperFillManager.fillReport( jasperReport, null, dataSource.getConnection());
标签：simple output sig classes address col stat java schema
原文地址：https://www.cnblogs.com/Jeely/p/14675726.html
