In IDE Jaspersoft Studio (JSS) or the older version iReport Designer it is sufficient to press Preview.

The JasperReports design file .jrxml will automatically be compiled to .jasper in same folder as .jrxml if no errors are present.

Another way is to press "Compile Report" button in JSS

or use the context menu "Compile Report" called from Report Inspector in iReport

<target name="compile" description="Compiles report designs specified using the 'srcdir' in the &lt;jrc&gt; tag." depends="prepare-compile-classpath"> 
  <mkdir dir="./build/reports"/> 
    <taskdef name="jrc" classname="net.sf.jasperreports.ant.JRAntCompileTask"> 
        <classpath refid="project-classpath"/>
    </taskdef>
    <jrc 
            srcdir="./reports"
            destdir="./build/reports"
            tempdir="./build/reports"
            keepjava="true"
            xmlvalidation="true">
        <classpath refid="sample-classpath"/>
        <include name="**/*.jrxml"/>
    </jrc>
</target>

Apache Ant build tool needs to be correctly installed on your system

While it is possible to compile .jrxml files into .jasper files using Java code, this incurs a performance hit that is best avoided by pre-compiling .jrxml files using the IDE. With that in mind, compiling .jrxml files can be accomplished using the JasperCompileManager as follows:

JasperCompileManager.compileReportToFile(
            "designFile.jrxml", //Relative or absoulte path to the .jrxml file to compile
            "compiled.jasper"); //Relative or absolute path to the compiled file .jasper

The JasperReports-plugin by Alex Nederlof is a good alternative of abandoned org.codehaus.mojo:jasperreports-maven-plugin plugin.

The adding of plugin is a typical, simple procedure:

<build>
    <plugins>
        <plugin>
            <groupId>com.alexnederlof</groupId>
            <artifactId>jasperreports-plugin</artifactId>
            <version>2.3</version>
            <executions>
                <execution>
                    <phase>process-sources</phase>
                    <goals>
                        <goal>jasper</goal>
                    </goals>
                </execution>
            </executions>
            <configuration>
                <sourceDirectory>src/main/resources/jrxml</sourceDirectory>
                <outputDirectory>${project.build.directory}/jasper</outputDirectory>
            </configuration>
        </plugin>
    </plugins>
</build>

The command for compilation with Maven:

mvn jasperreports:jasper

The jasper files will be created in ${project.build.directory}/jasper folder (for example, in /target/jasper)