Java spring-annotations for attribute injection

2017-11-06 21:19:43

One, spring annotation assembly bean
Spring2.5 introducing the use of annotations to define beans

• @Component describing beans in the spring framework

Three annotations equivalent to @component annotations are available in the spring framework

• @Repository for labeling DAO Implementation classes (DAO layer)
• @Service for labeling service implementation classes (service layer)
• @Controller used to label a Controller implementation class (Web layer)

Because there is only one property value, it can be written directly. Generally need value= "..." @Component ("User") public class User {public    void SayHello () {        System.out.println ("Hello World .");    }}

Configuration file:

<?xml version= "1.0" encoding= "UTF-8"? ><beans xmlns= "Http://www.springframework.org/schema/beans"    Xmlns:xsi= "Http://www.w3.org/2001/XMLSchema-instance"    xmlns:context= "Http://www.springframework.org/schema /context "xsi:schemalocation="        Http://www.springframework.org/schema/beans http://www.springframework.org/ Schema/beans/spring-beans.xsd        Http://www.springframework.org/schema/context http://www.springframework.org/ Schema/context/spring-context.xsd "> <!--bean definitions here--    <context:component-scan Base-package= "Spring5"/></beans>

Second, annotation for attribute injection

Normal Properties: @Value (value= "..."), this time can not write setter method

Object Properties: @Resource (name = "....")

Because there is only one property value, it can be written directly. Generally need value= "..." @Component ("User") public class User {    @Value (value= "Spring")    private String s;    public void SayHello () {        System.out.println ("Hello World");    @Override public    String toString () {        return "user{" +                "s= '" + S + ' \ ' +                '} ';}    }

Iii. mixed use of XML and annotations

Two ways to combine: generally using XML to register beans, using annotations for attribute injection

Let's start with some additional annotation configurations:

(1) Configure the Bean initialization method and destroy method:
* Init-method and Destroy-method.

• @PostConstruct Initialization
• @PreDestroy Destruction

@PostConstructpublic void Setup () {System.out.println ("Initialize ...");} @PreDestroypublic void Teardown () {System.out.println ("destroy ...");

(2) Scope of configuration Bean:@Scope

@Component ("User") @Scope (value= "prototype") public class User {    @Value (value= "Spring")    private String s;    public void SayHello () {        System.out.println ("Hello World");    @Override public    String toString () {        return "user{" +                "s= '" + S + ' \ ' +                '} ';}    }

(3) Use Java class to configure information, scan in XML can

@Configurationpublic class Beanconfig {    @Bean (name = "Car") public    Car Showcar () {        car car = new car ();        Car.setname ("Changan");        Car.setprice (40000d);        return car;    }    @Bean (name = "Product") Public    product initproduct () {        Product Product = new product ();        Product.setname ("Air Conditioning");        Product.setprice (3000d);        return product;}    }

Examples of mixed use:

public class Person {    @Autowired    @Qualifier ("car")    private car car;    @Autowired    @Qualifier (value = "plane")    private plane plane;    @Override public    String toString () {        return "person{" +                "car=" + car +                ", plane=" + Plane +                '} '; c26/>}}

Configuration file:

<?xml version= "1.0" encoding= "UTF-8"? ><beans xmlns= "Http://www.springframework.org/schema/beans"    Xmlns:xsi= "Http://www.w3.org/2001/XMLSchema-instance"    xmlns:context= "Http://www.springframework.org/schema /context "xsi:schemalocation="        Http://www.springframework.org/schema/beans http://www.springframework.org/ Schema/beans/spring-beans.xsd        Http://www.springframework.org/schema/context http://www.springframework.org/ Schema/context/spring-context.xsd "> <!--Bean Definitions---    <!--make attribute injection annotations Effective--    < context:annotation-config/>    <bean id= "car" class= "Spring6. Car "/>    <bean id=" plane "class=" Spring6. Plane "/>    <bean id=" person "class=" spring6. Person ">    </bean></beans>

Iv. Integration of JUnit testing

@RunWith (Springjunit4classrunner.class) @ContextConfiguration (locations = "Classpath:spring-config.xml") public Class Spring6 {    @Autowired    @Qualifier (' person ')    private person p;    @Test Public    Void Demo () {        System.out.println (p);    }}

Configuration file:

<?xml version= "1.0" encoding= "UTF-8"? ><beans xmlns= "Http://www.springframework.org/schema/beans"    Xmlns:xsi= "Http://www.w3.org/2001/XMLSchema-instance"    xmlns:context= "Http://www.springframework.org/schema /context "xsi:schemalocation="        Http://www.springframework.org/schema/beans http://www.springframework.org/ Schema/beans/spring-beans.xsd        Http://www.springframework.org/schema/context http://www.springframework.org/ Schema/context/spring-context.xsd "> <!--Bean Definitions---    <!--make attribute injection annotations Effective--    < context:annotation-config/>    <bean id= "car" class= "Spring6. Car "/>    <bean id=" plane "class=" Spring6. Plane "/>    <bean id=" person "class=" spring6. Person ">    </bean></beans>

Java spring-annotations for attribute injection