Java Ninja Chronicles By Norris Shelton

Things I learned in the pursuit of code

How do you set the private member in another class? I was working on a Junit test for a class that isn’t usually wired into my Spring context. Since the class wasn’t being constructed by Spring for the test, I didn’t have the advantage of autowiring.

@Autowired
private CoreServiceBean coreServiceBean;

@Autowired
private EzMoneyServiceBean ezMoneyServiceBean;

Apache Commons BeanUtils didn’t work

I tried using Apache Commons BeanUtils to set the private property, but there is a silent return statement if it is truly private member.

try {
    descriptor =
        getPropertyUtils().getPropertyDescriptor(target, name);
    if (descriptor == null) {
        return; // Skip this property setter
    }
} catch (NoSuchMethodException e) {
    return; // Skip this property setter
}

Java Reflection

I next tried the Java Reflection API. It seems a little clunky, but it did the job without too much work. I performed the following steps:

  • I looked up the private field by name.
  • I set the field as accessible.
  • I set the new value of the field.

Here is what it looks like for one of the fields:

Field coreServiceBeanField = EzMoneyResourceBean.class.getDeclaredField("coreServiceBean");
coreServiceBeanField.setAccessible(true);
coreServiceBeanField.set(ezMoneyResourceBean, coreServiceBean);

November 14th, 2017

Posted In: Java, java ninja, Javaninja

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Generating Java classes from an XSD is a common use case. I am partial to the Highsource (e.g. jvnet) maven-jaxb2-plugin. This plugin is very easy to use. Add the following to your pom.xml.

<build>
    <plugins>
        <plugin>
            <groupId>org.jvnet.jaxb2.maven2</groupId>
            <artifactId>maven-jaxb2-plugin</artifactId>
            <version>0.13.2</version>
            <executions>
                <execution>
                    <id>generate</id>
                    <goals>
                        <goal>generate</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

By default, the plugin will compile any xsd files located in src/main/resources. They will be generated in target/generated-sources/xjc/generated.

Generated Classes

By default, the generated classes will be in the generated package. To customize this value, include an XJB file in the same directory as the target XSD. I prefer to do one XJB for each XSD like the following.

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<jaxb:bindings
        version="2.1"
        xmlns:jaxb="http://java.sun.com/xml/ns/jaxb"
        xmlns:xs="http://www.w3.org/2001/XMLSchema">

    <jaxb:bindings schemaLocation="a.xsd" node="//xs:schema">
        <jaxb:schemaBindings>
            <jaxb:package name="org.ab.a"/>
        </jaxb:schemaBindings>
    </jaxb:bindings>
</jaxb:bindings>

September 12th, 2017

Posted In: Javaninja

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In a previous blog entry, I wrote about hot to Get the active Springframework profiles. In this one, I had the need to set the profile for a test. Keep in mind, I am not setting which profile the test should be included in, but which profile should be activated when the test runs.

We had the dataSources defined in a local profile and a default profile. In this case, I needed the test to use the local profile. It turned out to be pretty easy. All I had to do was annotate the test class with @ActiveProfiles. The value inside the annotation can contain multiple profiles, separated by commas.

@RunWith(SpringRunner.class)
@SpringBootTest
@ActiveProfiles("local")
public class EventServiceTest {
   //...
}

August 23rd, 2017

Posted In: Spring

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In a previous blog, I talked about Testing Springframework MVC Rest controllers with MockMVC. What I didn’t know is that you can use the MockMVC framework to also interrogate the Request object.

In this case, we have an Interceptor that is modifying the request by modifying an object’s property and adding that object to the request as a request attribute. To test this, we had to be able to see the value of the request attribute object after the request is done. Luckily MockMVC provides us the ability to do just that.

To accomplish this, I had to utilize the RequestResultMatchers via MockMvcResultMatchers.request() method to get a reference to the request object. Once I had the request object, I was able to get the object being stored as a request attribute by calling the attribute() method . Once I had the object, I was able to access it’s properties by calling hasProperty on it. From there on, I was able to use matchers that I was used to using.

    @Test
    public void testExtractStateFromCookie() {

        try {
            mockMvc.perform(get("/legacy/tote/currentrace")
                                .param("param1", "value1")
                                .param("param2", "value2")
                                .param("param3", "value3")
                                .cookie(new Cookie("STATE", "kY")))
                   .andExpect(request().attribute("USER_INFO", hasProperty("state", equalToIgnoringCase("ky"))));
        } catch (Exception e) {
            fail(e.toString());
        }
    }

Along the way, I did use some new Matchers. They are:

  • org.hamcrest.text.IsEqualIgnoringCase.equalToIgnoringCase() – This provides functionality similar to is(), but ignores the case of the text.
  • org.hamcrest.core.IsNull.nullValue – This allows for easy comparison to null
  • IsEqualIgnoringWhiteSpace.equalToIgnoringWhiteSpace() – All leading and trailing whitespace is ignored. Any duplicate white spaces within the string are considered single spaces.
  • IsEmptyString.isEmptyOrNullString() – compares against empty string or null (e.g. StringUtils.isBlank()).

August 15th, 2017

Posted In: hamcrest, MockMVC

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We had a need to know who was calling various web services. That is fairly easy to do when you have a standard URL. One solution is to simply grep your code repository for the URL (e.g. /my/service/). This becomes much more difficult when there is a path variable involved. An example URL with path variables is

@RequestMapping(value = "/mvc/customer/getState/{account}/more/url", method = RequestMethod.GET)

Lots of times, the URL is composed of multiple calls. A common way that this code will be found is below:

String url = String.format("/mvc/customer/getState/%s/more/url", accountNumber);
return restTemplate.getForObject(url, String.class);

This works, but makes it very difficult to determine who uses this web service call. You can grep for /mvc/customer/getState/ and that will work just fine if there aren’t multiple calls that use that same part of the URL in them. If there are other similar URLs, then effort will have to be expended to determine which are true hits and which are false hits.

There is another way to solve this problem if you are using the Spring’s RestTemplate. The RestTemplate can use the exact same URL pattern that is used by the web service URL pattern. This is accomplished by supplying a Map of data containing the path variable name and it’s corresponding value. An example is below:

Map<String, Object> params = new HashMap<>();
params.put("account", accountNumber);
return restTemplate.getForObject("/mvc/customer/getState/{account}/more/url", String.class, params);

August 5th, 2017

Posted In: Spring, Spring MVC, Spring RestTemplate

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For the most part Java developers don’t need to be concerned with NewRelic. The server integration comes with the ability to handle Spring MVC services automatically. This is great, but what about other stuff?

I had a case where we had Spring Scheduler via Quartz firing off jobs based upon a cron schedule. These were not tracked by NewRelic, so we had to manually add them.

Maven Dependency

To add the NewRelic Java API to your project, include the following snippet.

 <dependency>
     <groupId>com.newrelic.agent.java</groupId>
     <artifactId>newrelic-api</artifactId>
     <version>3.36.0</version>
 </dependency>

Instrumenting methods

Instrumenting a call stack is very easy. Add the com.newrelic.api.agent.Trace annotation to the top of the method that you want to monitor and away you go.

@Trace(dispatcher = true)
@scheduled
public void doSomethingOnASchedule() {
    // ...
}

Error Flagging

NewRelic counts errors by counting exceptions that rise up through the instrumented methods. This works, unless your code handles the exceptions and continues on. For cases like this, you need to manually notify NewRelic that an error happened. This is handled by using the com.newrelic.api.agent.NewRelic class.

try {
    // ...
} catch (ConfigClientException ce) {
    logger.error("logging this error to the logs", e);
    NewRelic.noticeError(ce);
    // handle error without throwing
} 

The NewRelic.noticeError method has signatures that take the following data

  • Throwable
  • Throwable, Map
  • String
  • String, Map

Excluding from NewRelic instrumentation

We noticed for some applications that we had some very fast transactions that happened very regularly and the volume scaled perfectly with our servers. It turned out to be our health check system. We provide a URL to the monitoring servers that indicates if the target service is running. We did not want those to be instrumented and skew the results. This isn’t as simple as it could be, but here it goes. You need to make an annotation with a very specific name. The package doesn’t matter. I have no idea why they don’t provide this in the NewRelic API.

package com.javaninja.newrelic;


import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;


@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface NewRelicIgnoreTransaction {

}

Once you have created your NewRelicIgnoreTransaction annotation, you can use it to indicate that certain timings should be excluded. An example is below:

    @NewRelicIgnoreTransaction
    @RequestMapping("/healthcheck")
    public String getInternal() {
        return "true";
    }

July 14th, 2017

Posted In: NewRelic

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Spring Boot

Spring Boot is changing the world of Java development with Spring. It is taking away much of the pain that was involved with configuring applications. This is great when you are trying to create what they do by default. They create executable jars by default. What do you have to do if you need to create a WAR file to run on a Tomcat by someone else.

POM file

Let’s start with our project’s pom.xml file. Here we need to define the standard Spring Boot parent starter and also include include the Spring Boot Web starter. The Spring Boot Web starter also includes the Spring Boot Tomcat starter. In our case, we do not want it packaged inside our war because our war file will be deployed on a Tomcat server directly. We don’t have to roll our own. To change this behavior, we include the Spring Boot tomcat starter explicitly and set it’s scope to provided. We also must specify the packaging of our project to be a war.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.javaninja.springboot</groupId>
    <artifactId>springboot-web</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.4.RELEASE</version>
    </parent>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

</project>

Java Config

Normally the Java Configuration contains a main method because that is how the program will be launched. In this case, we do not need a main method and instead we need to provide a configure method to go along with the SpringBootServletInitializer that we extend.

package com.javaninja.springboot.web;


import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.web.support.SpringBootServletInitializer;


@SpringBootApplication
public class WebApplication extends SpringBootServletInitializer {

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(WebApplication.class);
    }
}

Example Controller

That is all of the configuration that we need to make this work as a normal Spring MVC controller. To test our functionality, we need a very simple controller, such as the following,.

package com.javaninja.springboot.web;


import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;


@RestController
public class ExampleController {

    private Logger log = LoggerFactory.getLogger(getClass());

    @GetMapping("/example/boolean")
    public Boolean exampleBoolean() {
        log.info("Eureka!");
        return true;
    }
}

Test the controller

Let’s create a very simple test using the Spring Boot Test starter. This brings in Junit and MockMvc among other useful APIs.

package com.javaninja.springboot.web;


import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
import org.springframework.http.MediaType;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.test.web.servlet.MockMvc;

import static org.assertj.core.api.Assertions.fail;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;


/**
 * @author norris.shelton
 */
@RunWith(SpringRunner.class)
@WebMvcTest(ExampleController.class)
public class TestExampleController {

    @Autowired
    private MockMvc mvc;

    @Test
    public void testExampleBoolean() {
        try {
            mvc.perform(get("/example/boolean")
                            .accept(MediaType.APPLICATION_JSON))
               .andExpect(status().isOk())
               .andExpect(content().string("true"));
        } catch (Exception e) {
            fail(e.toString());
        }
    }
}

The test run perfectly and produces the following logging and a nice pretty green bar.

2017-07-10 18:36:06.218  INFO 7499 --- [           main] c.j.springboot.web.ExampleController     : Eureka!

July 11th, 2017

Posted In: Maven, MockMVC, Spring, Spring Boot, Spring MVC, Test Driven Development, Unit Tests

Tags: , ,

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Working with Spring Data JPA repositories is easy if you use them the way they are intended to be used. One way that they don’t like to be used is with two different databases with the objects in the same directories. In a previous blog titled Spring Data JPA with multiple entity managers, I showed how to have multiple EntityManagers work with Spring Data JPA. As part of that, we had to annotate each method that used the repository with @Transactional. I didn’t like this and I was searching for a way to make it better.

I tried to filter the jpa:repositories with a regex, but that wouldn’t work.

I next tried filtering by annotation and it worked like a charm. Here is how I did it.

Create annotations

The annotations are very simple and there isn’t Spring specific about them. I created @ReadOnly and @ReadWrite annotations.

package com.javaninja.adw.spring;


import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;


/**
 * Annotation used to indicate that this should be picked up as a ReadOnly database operation, specifically for
 * Spring Data JPA repositories.
 * @author norrisshelton
 */
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface ReadOnly {

} 
package com.javaninja.adw.spring;


import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;


/**
 * Annotation used to indicate that this should be picked up as a ReadWrite database operation, specifically for
 * Spring Data JPA repositories.
 * @author norrisshelton
 */
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface ReadWrite {

} 

Annotate the repositories

I annotated the Read-only repository with @ReadOnly and annotated my Read-Write repository with @ReadWrite.

package com.javaninja.adw.example;


import com.javaninja.adw.spring.ReadOnly;

import org.springframework.data.jpa.repository.JpaRepository;


/**
 * Read-only Spring Data JPA Repository for Example objects.
 * @author norrisshelton
 */
@ReadOnly
public interface RoExampleRepository extends JpaRepository<ExampleEntity, Integer> {

    ExampleEntity findByAffiliateId(int affiliateId);
}
package com.javaninja.adw.example;


import com.javaninja.adw.spring.ReadWrite;

import org.springframework.data.jpa.repository.JpaRepository;


/**
 * Read-write Spring Data JPA Repository for Example objects.
 * @author norrisshelton
 */
@ReadWrite
public interface RwExampleRepository extends JpaRepository<ExampleEntity, Long> {

}

Repository declaration

Once I have that, I can move onto the Spring context configuration. I could then modify my jpa:repositories declaration to look like:

<jpa:repositories base-package="com.javaninja.adw"
                  entity-manager-factory-ref="roEntityManagerFactory"
                  transaction-manager-ref="roTransactionManager">
    <repository:include-filter type="annotation" expression="com.javaninja.adw.spring.ReadOnly"/>
</jpa:repositories>
<jpa:repositories base-package="com.javaninja.adw"
                  entity-manager-factory-ref="rwEntityManagerFactory"
                  transaction-manager-ref="rwTransactionManager">
    <repository:include-filter type="annotation" expression="com.javaninja.adw.spring.ReadWrite"/>
</jpa:repositories>

What does it look like when used

Once those changes are done, using it is as easy as any other usage. No more @Transactional annotations.

package com.javaninja.adw.example;


import com.javaninja.adw.ExampleModel;

import org.springframework.stereotype.Service;


/**
 * @author norris.shelton
 */
@Service
public class ExampleService {

    private final RoExampleRepository roExampleRepository;

    public ExampleService(RoExampleRepository roExampleRepository) {
        this.roExampleRepository = roExampleRepository;
    }

    /**
     * Gets an example model object.
     * @return populated example model
     */
    public ExampleModel getExampleModel(int affiliateId) {
        ExampleEntity exampleEntity = roExampleRepository.findByAffiliateId(affiliateId);
        ExampleModel exampleModel = new ExampleModel();
        exampleModel.setExampleProperty(exampleEntity.getName());
        return exampleModel;
    }
}

The rest of the Spring Context

The rest of the Spring Context configuration looks the same. There is two of anything. To prevent confusion, I pre-pended ro or rw to all of my objects.

<bean id="jpaVendorAdapter" class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"/>
<util:properties id="jpaProperties">
    <!--<prop key="hibernate.show_sql">false</prop>-->
    <prop key="hibernate.dialect">org.hibernate.dialect.MySQL5InnoDBDialect</prop>
</util:properties>
<bean id="rwEntityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"
      p:dataSource-ref="rwAdwDataSource"
      p:packagesToScan="com.javaninja.adw"
      p:persistenceUnitName="rwPersistenceUnit"
      p:jpaVendorAdapter-ref="jpaVendorAdapter"
      p:jpaProperties-ref="jpaProperties"/>
<bean id="roEntityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"
      p:dataSource-ref="roAdwDataSource"
      p:packagesToScan="com.javaninja.adw"
      p:persistenceUnitName="roPersistenceUnit"
      p:jpaVendorAdapter-ref="jpaVendorAdapter"
      p:jpaProperties-ref="jpaProperties"/>
<!--
    Transaction-related configuration
-->
<tx:annotation-driven/>
<bean id="rwTransactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
    <property name="entityManagerFactory" ref="rwEntityManagerFactory"/>
    <qualifier value="rw"/>
</bean>
<bean id="roTransactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
    <property name="entityManagerFactory" ref="roEntityManagerFactory"/>
    <qualifier value="ro"/>
</bean>

May 3rd, 2017

Posted In: Java, java ninja, Javaninja, Spring, Spring Data, Spring Data JPA

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We are using -D system parameters to define our connection pool values. They were defined in a Tomcat setenv file in the bin directory.

export CATALINA_OPTS="$CATALINA_OPTS -DPROXY-RO-JDBC=jdbc:mysql://192.168.0.1/javaninja?zeroDateTimeBehavior=convertToNull"
export CATALINA_OPTS="$CATALINA_OPTS -DPROXY-RO--- USER=javaninja"
export CATALINA_OPTS="$CATALINA_OPTS -DPROXY-RO-PASS=javaninja"
export CATALINA_OPTS="$CATALINA_OPTS -DPROXY-RO-INITIAL-SIZE=1"
export CATALINA_OPTS="$CATALINA_OPTS -DPROXY-RO-MIN-IDLE=1"
export CATALINA_OPTS="$CATALINA_OPTS -DPROXY-RO-MAX-IDLE=1"
export CATALINA_OPTS="$CATALINA_OPTS -DPROXY-RO-MAX-TOTAL=15"

The parameters appeared to be read correctly, as evidenced by the Tomcat log.

14-Dec-2016 09:23:41.499 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -DPROXY-RO-JDBC=jdbc:mysql://192.168.0.1/javaninja?zeroDateTimeBehavior=convertToNull
14-Dec-2016 09:23:41.499 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -DPROXY-RO--- USER=javaninja
14-Dec-2016 09:23:41.499 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -DPROXY-RO-PASS=javaninja
14-Dec-2016 09:23:41.499 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -DPROXY-RO-INITIAL-SIZE=1
14-Dec-2016 09:23:41.499 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -DPROXY-RO-MIN-IDLE=1
14-Dec-2016 09:23:41.499 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -DPROXY-RO-MAX-IDLE=1
14-Dec-2016 09:23:41.499 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -DPROXY-RO-MAX-TOTAL=15

This did not work. We would get weird messages about the value not being in range. This was due to one of the values having noAccessToProcedureBodies=true. The JDBC driver expected yes, no, true or false Unfortunately, what it was receiving was true\n. I have no idea where the newline was coming from. I deleted the end of the line and typed the characters myself, but they were still there.

The solution was to trim all of the values of control characters. Apache StringUtils is my preferred tool for that; however, it is a static class and Spring doesn’t like that. To get over that, I instantiated a copy of it.

<bean id="stringUtils" class="org.apache.commons.lang3.StringUtils"/>

Once I had a StringUtils bean, I used it to trim the values by

<bean id="dataSource" class="org.apache.commons.dbcp2.BasicDataSource" destroy-method="close"
      p:driverClassName="com.mysql.jdbc.Driver"
      p:url="#{stringUtils.trim(systemProperties['PROXY-RO-JDBC'])}"
      p:username="#{stringUtils.trim(systemProperties['PROXY-RO--- USER'])}"
      p:password="#{stringUtils.trim(systemProperties['PROXY-RO-PASS'])}"
      p:initialSize="#{stringUtils.trim(systemProperties['PROXY-RO-INITIAL-SIZE'])}"
      p:maxTotal="#{stringUtils.trim(systemProperties['PROXY-RO-MAX-TOTAL'])}"
      p:maxIdle="#{stringUtils.trim(systemProperties['PROXY-RO-MAX-IDLE'])}"
      p:minIdle="#{stringUtils.trim(systemProperties['PROXY-RO-MIN-IDLE'])}"
      p:testOnBorrow="false"
      p:timeBetweenEvictionRunsMillis="60000"
      p:testWhileIdle="true"/>

December 14th, 2016

Posted In: Java, java ninja, Javaninja, Spring

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In the previous blog entry titled Turning Spring MVC exceptions into status codes with messages, I mapped exceptions into HTTP status codes.

Test Controller

In this blog we will test those and verify that everything is working correctly. I started with a test controller that I would use to generate the exceptions and the message. I created controller methods that would generate consistent results:

  • ResourceException with an HTTP 400 and a message
  • ResourceException with an HTTP 404 and a message
  • RuntimeException without any developer customization
  • Exception with a message

I wanted to ensure that I had consistent behavior and I was able to pull information from the exception that would be relevant to the client/consumer, but I also wanted to ensure that I never returned a stacktrace to the outside world.

package com.javaninja.cam.spring;


import com.javaninja.cam.dto.Prospect;
import com.javaninja.cam.exception.ResourceException;

import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;


@RestController
public class TestController {

    @RequestMapping(value = "/test/resourceException400")
    public Prospect getResourceException400() {
        throw new ResourceException(HttpStatus.BAD_REQUEST, "Test Bad Request Exception message");
    }

    @RequestMapping(value = "/test/resourceException404")
    public Prospect getResourceException404() {
        throw new ResourceException(HttpStatus.NOT_FOUND, "Test Not Found Exception message");
    }

    @RequestMapping(value = "/test/runtimeException")
    public int getRuntimeException() {
        return Integer.parseInt("x");
    }

    @RequestMapping(value = "/test/exception")
    public int getException() throws Exception {
        throw new Exception("Test Exception message");
    }
}

Junit Test Class

Once that was written, it was fairly easy to test the results. I used MockMVC with Spring Test to implement my test class. As part of this test, I wanted to ensure that the custom ResourceException that I created was handled correctly. I also wanted to ensure that I could handle RuntimeExceptions that happened during regular program execution could be handled. The last thing I wanted to verify was that developer created and thrown exceptions could be handled and that the message that they were created with was outputted correctly. I checked the HTTP status and the content for each type of exception.

package com.javaninja.cam.spring;


import com.javaninja.cam.JunitTestUtility;

import org.junit.Before;
import org.junit.BeforeClass;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.test.context.web.WebAppConfiguration;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.test.web.servlet.setup.MockMvcBuilders;
import org.springframework.web.context.WebApplicationContext;

import static org.junit.Assert.fail;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultHandlers.print;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;


/**
 * @author norris.shelton
 */
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:applicationContext-test.xml")
@WebAppConfiguration
public class TestCamControllerAdvice {

    @Autowired
    private WebApplicationContext wac;

    private MockMvc mockMvc;

    /**
     * Needed because we have some legacy code that intereactes directly with the context.  This is NOT normal and 
     * will be removed as the project is modernized. 
     * @throws Exception
     */
    @BeforeClass
    public static void createMockContext() throws Exception {
        JunitTestUtility.setup();
    }

    @Before
    public void setup() {
        mockMvc = MockMvcBuilders.webAppContextSetup(wac).build();
    }

    /**
     * Tests the custom ResourceException and verifies that it returns a HTTP 400 with the expected message.
     */
    @Test
    public void testResourceException400() {
        try {
            mockMvc.perform(get("/test/resourceException400"))
                   .andExpect(status().isBadRequest())
                   .andExpect(content().string("Test Bad Request Exception message"))
                   .andDo(print());
        } catch (Exception e) {
            fail(e.toString());
        }
    }

    /**
     * Tests the custom ResourceException and verifies that it returns a HTTP 404 with the expected message.
     */
    @Test
    public void testResourceException404() {
        try {
            mockMvc.perform(get("/test/resourceException404"))
                   .andExpect(status().isNotFound())
                   .andExpect(content().string("Test Not Found Exception message"))
                   .andDo(print());
        } catch (Exception e) {
            fail(e.toString());
        }
    }

    /**
     * Tests that a RuntimeException is received and that it returns the expected message.
     */
    @Test
    public void testRuntimeException() {
        try {
            mockMvc.perform(get("/test/runtimeException"))
                   .andExpect(status().isInternalServerError())
                   .andExpect(content().string("java.lang.NumberFormatException: For input string: \"x\""))
                   .andDo(print());
        } catch (Exception e) {
            fail(e.toString());
        }
    }

    /**
     * Tests that an Exception is received and that it returns the expected message.
     */
    @Test
    public void testException() {
        try {
            mockMvc.perform(get("/test/exception"))
                   .andExpect(status().isInternalServerError())
                   .andExpect(content().string("Test Exception message"))
                   .andDo(print());
        } catch (Exception e) {
            fail(e.toString());
        }
    }
}

MockMVC Print Output

For readability, I also displayed the full MockMVC print output. The output makes it very clear that I received the anticipated information and nothing else. The example output is below:

com.javaninja.cam.spring.TestCamControllerAdvice

MockHttpServletRequest:
      HTTP Method = GET
      Request URI = /test/exception
       Parameters = {}
          Headers = {}

Handler:
             Type = com.javaninja.cam.spring.TestController
           Method = public int com.twinspires.cam.spring.TestController.getException() throws java.lang.Exception

Async:
    Async started = false
     Async result = null

Resolved Exception:
             Type = java.lang.Exception

ModelAndView:
        View name = null
             View = null
            Model = null

FlashMap:
       Attributes = null

MockHttpServletResponse:
           Status = 500
    Error message = null
          Headers = {Content-Type=, Content-Length=[22]}
     Content type = text/plain;charset=ISO-8859-1
             Body = Test Exception message
    Forwarded URL = null
   Redirected URL = null
          Cookies = []

MockHttpServletRequest:
      HTTP Method = GET
      Request URI = /test/resourceException400
       Parameters = {}
          Headers = {}

Handler:
             Type = com.javaninja.cam.spring.TestController
           Method = public com.javaninja.cam.dto.Prospect com.javaninja.cam.spring.TestController.getResourceException400()

Async:
    Async started = false
     Async result = null

Resolved Exception:
             Type = com.javaninja.cam.exception.ResourceException

ModelAndView:
        View name = null
             View = null
            Model = null

FlashMap:
       Attributes = null

MockHttpServletResponse:
           Status = 400
    Error message = null
          Headers = {Content-Type=, Content-Length=[34]}
     Content type = text/plain;charset=ISO-8859-1
             Body = Test Bad Request Exception message
    Forwarded URL = null
   Redirected URL = null
          Cookies = []

MockHttpServletRequest:
      HTTP Method = GET
      Request URI = /test/resourceException404
       Parameters = {}
          Headers = {}

Handler:
             Type = com.javaninja.cam.spring.TestController
           Method = public com.javaninja.cam.dto.Prospect com.javaninja.cam.spring.TestController.getResourceException404()

Async:
    Async started = false
     Async result = null

Resolved Exception:
             Type = com.javaninja.cam.exception.ResourceException

ModelAndView:
        View name = null
             View = null
            Model = null

FlashMap:
       Attributes = null

MockHttpServletResponse:
           Status = 404
    Error message = null
          Headers = {Content-Type=, Content-Length=[32]}
     Content type = text/plain;charset=ISO-8859-1
             Body = Test Not Found Exception message
    Forwarded URL = null
   Redirected URL = null
          Cookies = []

MockHttpServletRequest:
      HTTP Method = GET
      Request URI = /test/runtimeException
       Parameters = {}
          Headers = {}

Handler:
             Type = com.javaninja.cam.spring.TestController
           Method = public int com.javaninja.cam.spring.TestController.getRuntimeException()

Async:
    Async started = false
     Async result = null

Resolved Exception:
             Type = java.lang.NumberFormatException

ModelAndView:
        View name = null
             View = null
            Model = null

FlashMap:
       Attributes = null

MockHttpServletResponse:
           Status = 500
    Error message = null
          Headers = {Content-Type=, Content-Length=[54]}
     Content type = text/plain;charset=ISO-8859-1
             Body = java.lang.NumberFormatException: For input string: "x"
    Forwarded URL = null
   Redirected URL = null
          Cookies = []

Process finished with exit code 0

There you have it. A full Junit/MockMVC test harness that can be used to determine if a SpringMVC controller is returning the correct information when you are trying to map Exceptions into HTTP status codes, along with messages that can be returned with the client consumer.

November 16th, 2016

Posted In: Java, java ninja, Javaninja, JUnit, MockMVC, Spring, Spring MVC, Test Driven Development

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