spring
Configuration ApplicationContext

Remarques

Configuration Java

La configuration Java est généralement effectuée en appliquant l'annotation @Configuration à une classe pour suggérer qu'une classe contient des définitions de bean. Les définitions de bean sont spécifiées en appliquant l'annotation @Bean à une méthode qui renvoie un objet.

@Configuration // This annotation tells the ApplicationContext that this class
               // contains bean definitions.
class AppConfig {
    /**
     * An Author created with the default constructor
     * setting no properties
     */
    @Bean // This annotation marks a method that defines a bean 
    Author author1() {
        return new Author();
    }

    /**
     * An Author created with the constructor that initializes the 
     * name fields
     */
    @Bean
    Author author2() {
        return new Author("Steven", "King");
    }

    /**
     * An Author created with the default constructor, but  
     * then uses the property setters to specify name fields
     */
    @Bean
    Author author3() {
        Author author = new Author();
        author.setFirstName("George");
        author.setLastName("Martin");
        return author;
    }

    /**
     * A Book created referring to author2 (created above) via
     * a constructor argument.  The dependency is fulfilled by
     * invoking the method as plain Java.
     */
    @Bean
    Book book1() {
        return new Book(author2(), "It");
    }

    /**
     * A Book created referring to author3 (created above) via
     * a property setter.  The dependency is fulfilled by
     * invoking the method as plain Java.
     */
    @Bean
    Book book2() {
        Book book = new Book();
        book.setAuthor(author3());
        book.setTitle("A Game of Thrones");
        return book;
    }
}

// The classes that are being initialized and wired above...
class Book { // assume package org.springframework.example
    Author author;
    String title;
    
    Book() {} // default constructor
    Book(Author author, String title) {
        this.author = author;
        this.title= title;
    }

    Author getAuthor() { return author; }
    String getTitle() { return title; }

    void setAuthor(Author author) {
        this.author = author;
    }

    void setTitle(String title) {
        this.title= title;
    }
}

class Author { // assume package org.springframework.example
    String firstName;
    String lastName;

    Author() {} // default constructor
    Author(String firstName, String lastName) {
        this.firstName = firstName;
        this.lastName = lastName;
    }

    String getFirstName() { return firstName; }
    String getLastName() { return lastName; }

    void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    void setLastName(String lastName) {
        this.lastName = lastName;
    }
}

Configuration XML

La configuration XML est généralement effectuée en définissant des beans dans un fichier xml, en utilisant le schéma beans spécifique à Spring. Sous l'élément beans racines, la définition de haricot typique serait faite en utilisant le sous-élément bean .

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
                        http://www.springframework.org/schema/beans/spring-beans.xsd">
    <!-- An Author created with the default constructor
         setting no properties -->
    <bean id="author1" class="org.springframework.example.Author" />
    
    <!-- An Author created with the constructor that initializes the 
         name fields -->
    <bean id="author2" class="org.springframework.example.Author">
        <constructor-arg index="0" value="Steven" />
        <constructor-arg index="1" value="King" />
    </bean>

    <!-- An Author created with the default constructor, but  
         then uses the property setters to specify name fields -->
    <bean id="author3" class="org.springframework.example.Author">
        <property name="firstName" value="George" />
        <property name="lastName" value="Martin" />
    </bean>

    <!-- A Book created referring to author2 (created above) via
         a constructor argument -->
    <bean id="book1" class="org.springframework.example.Book">
        <constructor-arg index="0" ref="author2" />
        <constructor-arg index="1" value="It" />
    </bean>

    <!-- A Book created referring to author3 (created above) via
         a property setter -->
    <bean id="book1" class="org.springframework.example.Book">
        <property name="author" ref="author3" />
        <property name="title" value="A Game of Thrones" />
    </bean>
</beans>

// The classes that are being initialized and wired above...
class Book { // assume package org.springframework.example
    Author author;
    String title;
    
    Book() {} // default constructor
    Book(Author author, String title) {
        this.author = author;
        this.title= title;
    }

    Author getAuthor() { return author; }
    String getTitle() { return title; }

    void setAuthor(Author author) {
        this.author = author;
    }

    void setTitle(String title) {
        this.title= title;
    }
}

class Author { // assume package org.springframework.example
    String firstName;
    String lastName;

    Author() {} // default constructor
    Author(String firstName, String lastName) {
        this.firstName = firstName;
        this.lastName = lastName;
    }

    String getFirstName() { return firstName; }
    String getLastName() { return lastName; }

    void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    void setLastName(String lastName) {
        this.lastName = lastName;
    }
}

Autowiring

L'enregistrement automatique est effectué à l'aide d'une annotation de stéréotype pour spécifier les classes qui seront des beans dans ApplicationContext , et à l'aide des annotations Autowired et Value pour spécifier les dépendances du bean. La caractéristique unique de la création automatique est qu’il n’existe pas de définition externe d’ ApplicationContext , car elle se fait dans les classes qui sont les beans eux-mêmes.

@Component // The annotation that specifies to include this as a bean
           // in the ApplicationContext
class Book {
    
    @Autowired // The annotation that wires the below defined Author
               // instance into this bean
    Author author;

    String title = "It";

    Author getAuthor() { return author; }
    String getTitle() { return title; }
}

@Component // The annotation that specifies to include
           // this as a bean in the ApplicationContext
class Author {
    String firstName = "Steven";
    String lastName = "King";

    String getFirstName() { return firstName; }
    String getLastName() { return lastName; }
}

Amorcer l'applicationContext

Configuration Java

La classe de configuration doit uniquement être une classe figurant dans le chemin de classe de votre application et visible par la classe principale de vos applications.

class MyApp {
    public static void main(String[] args) throws Exception {
        AnnotationConfigApplicationContext appContext =
            new AnnotationConfigApplicationContext(MyConfig.class);
        
        // ready to retrieve beans from appContext, such as myObject.
    }
}

@Configuration
class MyConfig {
    @Bean
    MyObject myObject() {
        // ...configure myObject...
    }

    // ...define more beans...
}

Xml Config

Le fichier de configuration xml ne doit figurer que dans le classpath de votre application.

class MyApp {
    public static void main(String[] args) throws Exception {
        ClassPathXmlApplicationContext appContext =
            new ClassPathXmlApplicationContext("applicationContext.xml");
        
        // ready to retrieve beans from appContext, such as myObject.
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<!-- applicationContext.xml -->
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
                        http://www.springframework.org/schema/beans/spring-beans.xsd">
    <bean id="myObject" class="com.example.MyObject">
        <!-- ...configure myObject... -->
    </bean>

    <!-- ...define more beans... -->
</beans>

Autowiring

La création automatique doit savoir quels packages de base rechercher les beans annotés ( @Component ). Ceci est spécifié via la #scan(String...) .

class MyApp {
    public static void main(String[] args) throws Exception {
        AnnotationConfigApplicationContext appContext =
            new AnnotationConfigApplicationContext();
        appContext.scan("com.example");
        appContext.refresh();
        
        // ready to retrieve beans from appContext, such as myObject.
    }
}

// assume this class is in the com.example package.
@Component
class MyObject {
    // ...myObject definition...
}