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Spring provides several techniques that can help us reduce the number of XML configurations

Automated assembly: helps reduce or even eliminate configuration <property> elements and <construct-arg> elements, allowing spring to automatically identify how the bean's dependencies are assembled.

Automatic detection: More than automatic assembly, it allows spring to automatically identify which classes need to be configured for the spring bean, thus reducing the use of <bean> elements.

4 Types of automatic assembly

Byname,bytype,constructor,autodetect

1,byname Automatic Assembly

<BeanID= "One"class="......">< Propertyname= "Song"value= "Zhangsan"/>< Propertyname= "instrument"ref= "both"/></Bean>

<BeanID= "instrument"class="......"/>

<BeanID= "One"class="......"Autowire= "ByName">< Propertyname= "Song"value= "Zhangsan"/></Bean>

2,bytype Automatic Assembly

Autowire= "Bytype"

Identify a preferred bean for automatic assembly the primary property defaults to True

<id= "One"  class= "..."  primary= "false "/>

Exclude certain beans for automatic assembly setting the Autowire-candidate property to False

<id= "One"  class= "..."  autowire-candidate= " False "/>

3,constructor Automatic Assembly

Constructors

<id= "One"  class= "..."  autowire  = "constructor"/>

4,autodetect Automatic Assembly

First use constructor to assemble automatically, and if you do not find a bean that matches the constructor, spring will attempt to automatically assemble it using Bytype

<id= "One"  class= "..."  autowire= "AutoDetect"  />

can also be mixed with assembly and display assembly

<BeanID= "One"class="......"Autowire= "Bytype">< Propertyname= "Song"value= "Zhangsan"/>< Propertyname= "instrument"ref= "saxophone"/></Bean>

Assembling with annotations

<context:annotation-config/>

The SPRING3 supports several different annotations for automatic assembly:

@atutowired annotations of *spring;

@inject annotation of *jsp-330;

@resource annotation of *jsp-250;

1, using @autowired

Not only can you use it to label setter methods, but you can also annotate any method that requires automatic assembly of bean references

@Autowired (Required=false) @Qualifier ("...")

2, using @inject

Unlike @autowired, the dependency relationship that is marked by the @inject annotation must exist without the required attribute, and an exception is thrown if it does not exist.

@Inject @named ("...")

Automatically detect beans

Use the <context:component-scan> element instead of the <context:annotation-config> element

< Context:component-scan Base-package ="......" > </ Context:component-scan >

By default <context:component-scan> find classes annotated with stereotype annotations, these special annotations are as follows

@Component-generic stereotype annotation that identifies the type as a spring component

@Controller-Identity defines the class as Springmvc Controller

@Repository-Identifies the class defined as a data warehouse

@Service-Identifies the class defined as a service

Any custom annotations that use @component annotations

Filter Component Scan

We can configure <comtext:include-filter> and/or <context:exclude-filter> child elements for <context:component-scan>

<Context:component-scanBase-package="..."><Context:include-filtertype= "assignable"expression="..."/><Context:exclude-filtertype= "Annotation"expression="......"/></Context:component-scan>

Using spring Java-based configuration

Create a Java-based configuration

< Context:component-scan Base-package ="..." />

Defining a Configuration Class

@Configuration

Declaring a simple bean

@bean

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