On the way learning spring 5

 

Spring-24 Adding Support for Annotation-Based Wiring

Namespace-->check 'context'-->In 'context' Insert <context:annotation-config> element

 

<?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:p="http://www.springframework.org/schema/p"
    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-3.2.xsd">


    <bean id="logger" class="com.caveofprogramming.spring.test.Logger">
    </bean>

    <bean id="consoleWriter1" class="com.caveofprogramming.spring.test.ConsoleWriter">
    </bean>
    <bean id="fileWriter" class="com.caveofprogramming.spring.test.FileWriter">
    </bean>

    <context:annotation-config></context:annotation-config>
</beans>

 

Spring-25 The "Autowired" Annotation

@Autowired   

method,variables,constuctor

 

Spring-26 Optional Beans

Question : What happened if we use @Autowired(required=false)?

 

Spring-27 Using qualifiers

Right click 'consoleWriter'--> extend 'bean'--->Insert <qualifier> element --->setValue 'toConsole'

    
    @Autowired
    @Qualifier("toConsole")
    public void setConsoleWriter(ConsoleWriter writer) {
        this.consoleWriter = writer;
    }

还有一种用法

在method和class前分别添加@Qualifier？？？

 

Spring-28  The Resource Annotation(JSR-250)

@Resource

@Resource(name="banana")

这里的关于ambiguity有些问题？？？？？

 

Spring-29 Annotation-Based Init and Destroy Methods

import.javax.annotation.*

@PostConstruct

@PreDestroy

 

Spring-30 The Inject Annotation(JSR-330)

javax.inject-1.jar    (pom.xml)

public class Logger {

    private ConsoleWriter consoleWriter;
    private FileWriter fileWriter;

    /*
     * public Logger(ConsoleWriter consoleWriter, FileWriter fileWriter){
     * this.consoleWriter = consoleWriter; this.fileWriter = fileWriter;
     */
    
    @Inject
    @Named(value="consoleWriter")
    public void setConsoleWriter(ConsoleWriter writer) {
        this.consoleWriter = writer;
    }

    @Inject
    @Named(value="fileWriter")
    
    
    public void setFileWriter(FileWriter fileWriter) {
        this.fileWriter = fileWriter;
    }

    public void writeFile(String text) {
        fileWriter.write(text);
    }

    public void writeConsole(String text) {
        if (consoleWriter != null) {
            consoleWriter.write(text);
        }
    }
    
    @PostConstruct
    public void init(){
        System.out.println("init");
    }
    
    @PreDestroy
    public void destroy(){
        System.out.println("destroy");
    }

}

 

Spring-31 Automatic Bean Discovery

    <context:annotation-config></context:annotation-config>
    <context:component-scan
        base-package="com.caveofprogramming.spring.test">
    </context:component-scan>

加上 @Component

为了不存在 ambiguity

1.@Component("fileWriter")

2.@Inject

  @Named(value="fileWriter")

 

Spring-32 Setting Property Values via Annotations

@Value("")