Posts Tagged ‘java’

Read a File as String with Java

Thursday, June 16th, 2011

Introduction

I’m always Googling for a way to do this. This seems to be the best “idiomatic” solution I’ve found. So without further ado…

Example

public String readFile(String path) throws IOException {
    FileInputStream stream = new FileInputStream(new File(path));
    try{
        FileChannel fc = stream.getChannel();
        MappedByteBuffer bb = fc.map(FileChannel.MapMode.READ_ONLY, 0, fc.size());
        return Charset.defaultCharset().decode(bb).toString();
    }
    finally {
        stream.close();
    }
}

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Posted in Development, How to's, quick tips | No Comments »

Unit Test Private Java Methods using Reflection

Thursday, May 5th, 2011

Introduction

I realise that the thought of Unit Testing private methods in Java classes can be like a red rag to a bull for some people and I understand the arguments.

Therefore, I present the following as a “how to”, not a moral argument for or against!

Example

The class under test

public class Product() {
    private String privateMethod(String id) {
    //Do something private
    return "product_" + id;
  }
}

The (Reflection Based) Unit Test

import java.lang.reflect.Method;

import static org.junit.Assert.*;
import org.junit.Test;

public class ProductTest {
    private Product product; // the class under test
    private Method m;
    private static String METHOD_NAME = "privateMethod";
    private Class[] parameterTypes;
    private Object[] parameters;

    @Before
    public void setUp() throws Exception {
        product = new Product();
        parameterTypes = new Class[1];
        parameterTypes[0] = java.lang.String.class;
        m = product.getClass().getDeclaredMethod(METHOD_NAME, parameterTypes);
        m.setAccessible(true);
        parameters = new Object[1];
    }

    @Test
    public void testPrivateMethod() throws Exception {
        parameters[0] = "someIdentifier";
        String result = (String) m.invoke(product, parameters); 
  
        //Do your assertions
        assertNotNull(result);
    }
}

Update

I’ve since been told that if dp4j.jar is in the classpath at compile-time, it will inject the necessary reflection to make this work. I haven’t had time to try this yet so YMMV.

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Posted in Development, How to's | No Comments »

Unit Testing Validation in Annotation Based Validating Spring Beans

Friday, April 22nd, 2011

Motivation

I added validation, via annotations, to a Spring “Model” bean. I needed someway to Unit Test this validation, without running the container and without initialising the Spring context.

The bean (simplified)

package foo.bar;

import javax.validation.constraints.NotNull;
import javax.validation.constraints.Pattern;
import javax.validation.constraints.Size;

public final class ProductModel {
        
    @NotNull
    @Size(max=100)
    @Pattern(regexp="[^\n^\t^\r]+", message="Long Name must not contain New Lines, Carriage Returns or Tabs")
    private String longName;

    @Size(max=20)
    private String shortName;

    // rest snipped for brevity
}

The Unit Test

package foo.bar;

import java.util.Set;

import javax.validation.ConstraintViolation;

import junit.framework.Assert;

import org.hibernate.validator.HibernateValidator;
import org.junit.Before;
import org.junit.Test;
import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;

public class Temp {
    private LocalValidatorFactoryBean localValidatorFactory;
	
    @Before
    public void setup() {
        localValidatorFactory = new LocalValidatorFactoryBean();
        localValidatorFactory.setProviderClass(HibernateValidator.class);
        localValidatorFactory.afterPropertiesSet();
    }
    @Test
    public void testLongNameWithInvalidCharCausesValidationError() {
        final ProductModel productModel = new ProductModel();
        productModel.setLongName("A long name with\t a Tab character");
    	Set<ConstraintViolation<ProductModel>> constraintViolations = localValidatorFactory.validate(productModel);
    	Assert.assertTrue("Expected validation error not found", constraintViolations.size() == 1);
    }
}

More

It actually took me a few hours to work the above test out (simple as it is). If I hadn’t stumbled upon these Spring Unit Tests, I might never have got it.

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Posted in Spring | 3 Comments »

Spring MVC URI Template Example

Monday, April 18th, 2011

Background

So, I’m working on an existing Spring 3.x web project. This project heavily favours the use of annotations over XML configuration. As I was trawling through the source code I noticed “some wierd” syntax: “/{xxxx}” (which of course I had to look up!).

Most of the following is based upon the excellent Spring Documentation. I’ve lifted and rewritten the parts I require to serve as a condensed “aide-mémoire”.

Description

A URI Template is a URI-like string, containing one or more variable names. When you substitute values for these variables, the template becomes a URI.
(more…)

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Posted in Spring | No Comments »

Spring MVC 3 @ModelAttribute Annotation Example

Monday, April 18th, 2011

Background

So, I’m working on an existing Spring 3.x web project. This project heavily favours the use of annotations over XML configuration files. As I was trawling through the source code I noticed the “@ModelAttribute” annotation (which of course I had to look up!).

If the above background seems familiar that’s because it’s the same as for a previous Spring Annotation post I made (ed: this is in danger of turning into a mini-series)

Description

Most of the following is based upon the excellent Spring Documentation. I’ve simply lifted and rewritten the parts I require to serve as an “aide-mémoire”.

The @ModelAttribute annotation serves two purposes depending on how it is used:

(more…)

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Posted in Spring | 12 Comments »