Case study: Java 8 + Spring boot

I've made an internal application using newest technologies and aproaches.

Here is case study of what I achived and what I found interesting about new technology stack.

Slides contains examples of:
- Java 8 feautures
- Spring boot
- Thymeleaf
- Gradle
- front-end builds

Transcript

1. Case study
   Classic MVC with separated front-end
   Piotr Lewandowski
   @piotlr
   

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2. Back-end
   Java 8
   Spring 4 + Spring boot
   Apache POI
   Thymeleaf
   Gradle
   Front-end
   bootstrap
   require.js
   npm
   bower
   gulp
   

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3. Java 8
   

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4. Java 7 way
   Java 8 way
   List humans = ...
   Collections.sort(humans, new Comparator() {
   @Override
   public int compare(Human h1, Human h2)
   return h1.getName().compareTo(h2.getName());
   }
   }
   List humans = ...
   Collections.sort(humans, (Human h1, Human h2) ­> {
   h1.getName().compareTo(h2.getName())
   });
   

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5. Streams API
   List persons = ...;
   Stream tenPersonsOver18 = persons.stream()
   .filter(p ­> p.getAge() > 18)
   .limit(10);
   boolean isEmptyRow = csvRowEntries.stream()
   .allMatch(str ­> str.isEmpty());
   if (isEmptyRow) {
   return null;
   }
   

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6. Streams API
   // set id, location
   employees.stream()
   .filter(e ­> e.getId().equals(id))
   .findFirst()
   .ifPresent(e ­> {
   e.setLocation(location);
   });
   public List getErrors() {
   return parseErrors.stream()
   .map(pe ­> pe.getMessage())
   .collect(Collectors.toList());
   }
   

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7. Streams in tests
   // arrange
   // ...
   List divergenceReport;
   List missingEmployees;
   // act
   divergenceReport = service.getDivergenceReport();
   missingEmployees = divergenceReport.stream()
   .map(MissingEmployee::getId)
   .collect(Collectors.toList());
   // assert
   assertThat(missingEmployees.contains("Robert Smith"), is(true));
   

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8. Confusions
   Closure
   Custom lambdas
   

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9. Closures
   int i = 0;
   persons.forEach(person ­> {
   if ( person == null) {
   i++; // Error: Variable must be final or effective final
   }
   ...
   });
   

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10. Custom lamdas
    public class Main {
    public static void runCalc( ??? calc) {
    // ???
    }
    public static void main(String[] args) {
    BigDecimal a = new BigDecimal();
    runCalc(a ­> a.multiply(a));
    }
    }
    

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11. Custom lambdas
    Scala
    def runCalc(calc: (BigInt => BigInt)) {
    // ???
    }
    Java
    interface MyCalcLambda {
    BigInteger run(BigInteger input);
    }
    public static void runCalc(MyCalcLambda calc) {
    // ???
    }
    public static void main(String[] args) {
    runCalc(a ­> a.multiply(a));
    }
    

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12. Runing custom lambdas
    Scala
    def runCalc(calc: (BigInt => BigInt)) {
    System.out.println(calc(10))
    }
    Java
    public static void runCalc(MyCalcLambda calc) {
    System.out.println(calc(BigInteger.TEN));
    }
    

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13. Spring 4
    with Spring boot
    Long story short
    

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14. Configuration
    public class ServletInitializer extends SpringBootServletInitializer {
    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
    return application.sources(Application.class);
    }
    }
    @Configuration
    @ComponentScan
    @EnableAutoConfiguration
    public class Application extends WebMvcConfigurerAdapter {
    public static void main(String[] args) {
    SpringApplication.run(Application.class, args);
    }
    }
    

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15. start.spring.io
    

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16. Thymeleaf
    

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17. Primitive
    Maps
    Lists
    i18n config constans
    loops
    conditionals
    formats
    modules
    What can we put? What can we do?
    

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18. 
    
    
    
    Name
    Cost
    Hours
    
    
    
    
    Project ID
    
    1000.0
    
    
    353
    
    
    
    
    

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19. HTML5 way
    
    /*/­­>
    
    ...
    ...
    
    
    ...
    
    /*/­­>
    
    

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20. Gradle
    

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21. Worries
    Do I need to learn groovy?
    Can I still use my dependencies?
    If my IDE supports gradle?
    

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22. gradle hello world
    apply plugin: 'java'
    sourceCompatibility = 1.8
    jar {
    baseName = 'demo'
    version = '0.0.1­SNAPSHOT'
    }
    repositories {
    mavenCentral()
    }
    dependencies {
    compile("org.springframework.boot:spring­boot­starter­web")
    compile("org.springframework.boot:spring­boot­starter­thymeleaf")
    testCompile("org.springframework.boot:spring­boot­starter­test")
    }
    

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23. repositories {
    maven {
    credentials {
    username 'user'
    password 'password'
    }
    url "http://10.10.0.1/your­maven­repo"
    }
    }
    Custom repostiories
    

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24. So why gradle?
    Clean
    Efficient
    Easily expandable with plugins
    

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25. Front-end
    

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26. Building front-end
    Modularity
    Dependency managment
    Production-ready
    Tests
    

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27. Cons
    Many, many tools
    Frequent changes
    Pros
    Many, many tools
    Frequent changes
    

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28. Front-end structure
    src
    ├── css
    ├── js
    dist
    ├── lib
    ├── css
    ├── js
    gulpfile.js
    bower.json
    package.json
    

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29. Build tools demo
    

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30. Building process
    What are doing when we
    type `gradle build`
    

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31. gradle build
    1. Compille front-end
    1. Download tools with NPM
    2. Download dependencies with bower
    3. Build front-end with gulp
    4. Pack into JAR
    2. Compile the rest with front-end as a dependency
    

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32. Questions
    

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33. Thanks
    

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