Sunday, 14 June 2020

FreeMarker: Raw String Literals

In Raw string literals ${, backslash do not have any specific meaning.

 

How to define raw literal?

Just put an r directly before the opening quotation mark or apostrophe-quote.

 

Example:

${r"C:\foo\bar\tab\n"}

 

Step 1: Define rawLiteral.ftl file under src/main/resources/templates folder.

 

rawLiteral.ftl

${r"C:\foo\bar\tab\n"}

 

Step 2: Define ‘FreeMarkerUtil’ class that takes model class and template file as input and merge them.

 

FreeMarkerUtil.java

package com.sample.app.util;

import java.io.StringWriter;
import java.util.Locale;

import freemarker.template.Configuration;
import freemarker.template.Template;
import freemarker.template.TemplateExceptionHandler;

public class FreeMarkerUtil {

	private static final Configuration FREE_MARKER_CONFIGURATION = new Configuration(Configuration.VERSION_2_3_30);

	static {
		FREE_MARKER_CONFIGURATION.setClassForTemplateLoading(FreeMarkerUtil.class, "/templates/");
		FREE_MARKER_CONFIGURATION.setDefaultEncoding("UTF-8");
		FREE_MARKER_CONFIGURATION.setLocale(Locale.US);
		FREE_MARKER_CONFIGURATION.setTemplateExceptionHandler(TemplateExceptionHandler.RETHROW_HANDLER);
		FREE_MARKER_CONFIGURATION.setFallbackOnNullLoopVariable(false);
	}

	public static StringWriter mergeModelAndTemplate(Object modelObject, String ftlFile) throws Exception {
		StringWriter stringWriter = new StringWriter();

		Template template = FREE_MARKER_CONFIGURATION.getTemplate(ftlFile);

		template.process(modelObject, stringWriter);

		return stringWriter;
	}

}

Step 3: Define RawLiteralPopulator.

 

RawLiteralPopulator.java

package com.sample.app;

import java.io.StringWriter;
import java.util.HashMap;
import java.util.Map;

import com.sample.app.util.FreeMarkerUtil;

public class RawLiteralPopulator {
	public static void main(String args[]) throws Exception {

		Map<String, Object> modelObject = new HashMap<String, Object>();
		
		StringWriter stringWriter = FreeMarkerUtil.mergeModelAndTemplate(modelObject, "rawLiteral.ftl");
		System.out.println(stringWriter.toString().trim());

	}
}

Run the application, you will see below messages in the console.

 

C:\foo\bar\tab\n



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