Springboot Combat (Wang Yunfei) Learn-1-2

Java EE Developer Spring Boot combat with book learning-1

Next, learn Java configuration (or add new packages and code in the previous article):

Java configuration is the recommended configuration for spring4.x, which can completely replace the XML configuration and is the recommended configuration for Springboot. The Java configuration is implemented through @configuration and @bean.

@Configuration declares that the current class is a configuration class that automatically scans all classes under the specified package that use @service @Component @Repository and @controller through @componentscan annotations. Register them as spring's beans

@Bean annotations Using the method, declare that the return value of the current method is a Bean,bean name for the method name.

When do you use Java configuration? The main principle is that the global configuration uses Java configuration (such as database-related configuration, MVC-related configuration), and the configuration of business beans is configured using annotations (@Service @Component @Repository @Controller). The following shows the contents of one of the simplest Java configurations

1. Write the bean for the function class

1  PackageCom.wisely.highlight_spring4.ch1.javaconfig;2 3 /**4 * 1. The bean defining the function class no longer uses the @service annotation declaration the current Functionservice class is a bean managed by spring5  * @authorAdministrator6  */7  //And the difference in the previous example, hereThe Bean is not declared with @service8  Public classFunctionservice {9     Ten      Publicstring SayHello (string word) { One         return"Hello" + Word + "!"; A     } -  -}

2. Beans using the Feature class

1  PackageCom.wisely.highlight_spring4.ch1.javaconfig;2 3 /**4 * 2. Functionservice bean with function class5  * 6  * @authorAdministrator7  *8  */9 //no longer use @service to declare beansTen  Public classUsefunctionservice { One     //no longer use @autowired to automatically inject beans, instead set method settings Functionservice A     PrivateFunctionservice Functionservice; -      -     //Remove @service and @autowired annotations, add Set method the      Public voidSetfunctionservice (Functionservice functionservice) { -          This. Functionservice =Functionservice; -     } -  +      Publicstring SayHello (string word) { -         returnFunctionservice.sayhello (word); +     } A  at}

3.Java Configuration Class Authoring (emphasis)

1  PackageCom.wisely.highlight_spring4.ch1.javaconfig;2 3 ImportOrg.springframework.context.annotation.Bean;4 ImportOrg.springframework.context.annotation.ComponentScan;5 Importorg.springframework.context.annotation.Configuration;6 /**7 * 3.spring Configuration Class8 * Spring4.x recommends using Java Configuration instead of XML configuration, by @Configuration and @Bean two annotations to achieve9 * @Configuration declares that the current class is a configuration class, equivalent to a spring-configured XML fileTen * @Bean Annotations Use the method to declare that the return value of the current method is a Bean One * When to use Java configuration? : Global configuration using Java configuration (such as database-related configuration, MVC-related configuration), business bean configuration using A * Annotation configuration (@Service @Component @Repository @Controller) -  * @authorAdministrator -  * the  */ - @Configuration -  Public classJavaconfig { -  +     //The Bean annotation declares that the current method return value is a Bean,bean name that is the method name Functionservice - @Bean +      PublicFunctionservice Functionservice () { A         return NewFunctionservice (); at     } -      - @Bean -      PublicUsefunctionservice Usefunctionservice () { -Usefunctionservice Usefunctionservice =NewUsefunctionservice (); -         //call Functionservice () directly into the Functionservice bean inUsefunctionservice.setfunctionservice (Functionservice ());// -         returnUsefunctionservice; to     } +      - //@Bean the     //another way to inject: directly to the Functionservice as a parameter to UseFunctionService1 (). *     //In a spring container, as long as there is a bean in the container, it can be injected in the parameters of another bean's declaration Method!!!  $     /*Public usefunctionservice UseFunctionService1 (functionservice functionservice) {//cannot also be called hereUsefunctionservice, the error will be

Notoginsengusefunctionservice.setfunctionservice (functionservice)    +    * * * *

Description

(1) [email protected] The note indicates that the current class is a configuration class, which means that the class might have 0 or more @bean annotations immediately, and that the @componentscan annotation scan package is not used here because all beans are defined in this class
(2). Use @bean annotations to declare the current method, such as: Public Functionservice Functionservice () {return new Functionservice ();} The return value is a bean, The name of the Bean is the method name Functionservice

(4). Another way to inject the functionservice directly into the Usefunctionservice () as a parameter, which is a feature provided by the spring container. In a spring container, as long as there is a bean in the container, it can be injected into the parameters of another bean's declaration method.

4. Testing

1  PackageCom.wisely.highlight_spring4.ch1.javaconfig;2 3 ImportOrg.springframework.context.annotation.AnnotationConfigApplicationContext;4 /**5 * 4. Test6  * @authorAdministrator7  *8  */9  Public classMaintest {Ten      One      Public Static voidMain (string[] args) { A         //1. Accept a configuration class as a parameter using the Annotationconfigapplicationcontext most spring container -Annotationconfigapplicationcontext context =NewAnnotationconfigapplicationcontext (Javaconfig.class); -         //2. Get the Usefunctionservice bean for the declared configuration theUsefunctionservice Usefunctionservice = Context.getbean (usefunctionservice.class); -         //3. Methods for invoking Beans -System.out.println (Usefunctionservice.sayhello ("Java config")); - context.close (); +          -      +     } A  at}

Springboot Combat (Wang Yunfei) Learn-1-2