net.sf.jasperreports.engine.design

Interface JRCompiler

All Known Implementing Classes:

JavaScriptClassCompiler, JavaScriptCompiler, JavaScriptCompilerBase, JRAbstractClassCompiler, JRAbstractCompiler, JRAbstractJavaCompiler, JRAbstractMultiClassCompiler, JRAbstractSingleClassCompiler, JRBshCompiler, JRGroovyCompiler, JRJavacCompiler, JRJdk13Compiler, JRJdtCompiler

public interface JRCompiler

This interface exposes methods to load expressions evaluators and compile report templates.

Source report templates, created either by using the API or by parsing JRXML files, are subject to the report compilation process before they are filled with data. This is necessary to make various consistency validations and to incorporate into these report templates data used to evaluate all report expressions at runtime.

The compilation process transforms JasperDesign objects into JasperReport objects. Both classes are implementations of the same basic JRReport interface. However, JasperReport objects cannot be modified once they are produced, while JasperDesign objects can. This is because some modifications made on the report template would probably require re-validation, or if a report expression is modified, the compiler-associated data stored inside the report template would have to be updated.

JasperDesign objects are produced when parsing JRXML files using the JRXmlLoader or created directly by the parent application if dynamic report templates are required. The GUI tools for editing JasperReports templates also work with this class to make in-memory modifications to the report templates before storing them on disk.

A JasperDesign object must be subject to the report compilation process to produce a JasperReport object.

Central to this process is this JRCompiler interface, which defines few methods, one being the following:

public JasperReport compileReport(JasperDesign design) throws JRException;

There are several implementations for this compiler interface depending on the language used for the report expressions or the mechanism used for their runtime evaluation.

Expressions Scripting Language

The default language for the report expressions is Java, but report expressions can be written in Groovy, JavaScript or any other scripting language as long as a report compiler implementation that can evaluate them at runtime is available.

JasperReports currently ships report compiler implementations for the Groovy scripting language (http://groovy.codehaus.org), JavaScript (http://www.mozilla.org/rhino), and the BeanShell scripting library (http://www.beanshell.org).

The related compiler implementation classes are:

• JRGroovyCompiler
• JavaScriptCompiler
• JRBshCompiler

Since the most common scenario is to use the Java language for writing report expressions, default implementations of the report compiler interface are shipped with the library and are ready to use. They generate a Java class from the report expressions and store bytecode in the generated JasperReport object for use at report-filling time.

Java Compilers

The Java report compilers come in different flavors depending on the Java compiler used to compile the class that is generated on the fly:

• JRJdtCompiler
• JRJdk13Compiler
• JRJavacCompiler

Author:

Teodor Danciu (teodord@users.sourceforge.net)

See Also:

JasperReport, JasperDesign, JRXmlLoader

Field Summary

Fields

Modifier and Type	Field and Description
static String	COMPILER_CLASS Deprecated. Replaced by COMPILER_PREFIX.
static String	COMPILER_CLASSPATH The classpath used by the report compiler.
static String	COMPILER_KEEP_JAVA_FILE Whether to keep the java file generated when the report is compiled.
static String	COMPILER_PREFIX Prefix for properties that map report compilers to expression languages.
static String	COMPILER_TEMP_DIR The temporary directory used by the report compiler.

Method Summary

Methods

Modifier and Type	Method and Description
JasperReport	compileReport(JasperDesign jasperDesign) Compiles a report design.
JREvaluator	loadEvaluator(JasperReport jasperReport) Loads the evaluator for a report's main dataset.
JREvaluator	loadEvaluator(JasperReport jasperReport, JRCrosstab crosstab) Loads a expression evaluator class for a crosstab of a report.
JREvaluator	loadEvaluator(JasperReport jasperReport, JRDataset dataset) Loads a expression evaluator class for a dataset of a report.

Field Detail

COMPILER_CLASS

static final String COMPILER_CLASS

Deprecated. Replaced by COMPILER_PREFIX.

The name of the class to be used for report compilation.

No default value.

See Also:

Constant Field Values

COMPILER_PREFIX

static final String COMPILER_PREFIX

Prefix for properties that map report compilers to expression languages.

Properties having this prefix are used to indicate the JRCompiler implementation to be used when compiling report designs that rely on the expression language specified as property suffix.

See Also:

Constant Field Values

COMPILER_KEEP_JAVA_FILE

static final String COMPILER_KEEP_JAVA_FILE

Whether to keep the java file generated when the report is compiled.

Defaults to false.

See Also:

Constant Field Values

COMPILER_TEMP_DIR

static final String COMPILER_TEMP_DIR

The temporary directory used by the report compiler.

Defaults to System.getProperty("user.dir").

See Also:

Constant Field Values

COMPILER_CLASSPATH

static final String COMPILER_CLASSPATH

The classpath used by the report compiler.

Defaults to System.getProperty("java.class.path").

See Also:

Constant Field Values

Method Detail

compileReport

JasperReport compileReport(JasperDesign jasperDesign)
                           throws JRException

Compiles a report design.

The compilation consists of verification of the design, generation of expression evaluators and construction of a serializable read-only version of the report.

A report compiler should usually extend JRAbstractCompiler.

Parameters:

jasperDesign - the report design

Returns:

the compiled report

Throws:

JRException

loadEvaluator

JREvaluator loadEvaluator(JasperReport jasperReport)
                          throws JRException

Loads the evaluator for a report's main dataset.

Parameters:

jasperReport - the report

Returns:

the evaluator for the report's main dataset

Throws:

JRException

loadEvaluator

JREvaluator loadEvaluator(JasperReport jasperReport,
                        JRDataset dataset)
                          throws JRException

Loads a expression evaluator class for a dataset of a report.

Parameters:

jasperReport - the report

dataset - the dataset

Returns:

an instance of the dataset evaluator class

Throws:

JRException

loadEvaluator

JREvaluator loadEvaluator(JasperReport jasperReport,
                        JRCrosstab crosstab)
                          throws JRException

Loads a expression evaluator class for a crosstab of a report.

Parameters:

jasperReport - the report

crosstab - the crosstab

Returns:

an instance of the dataset evaluator class

Throws:

JRException