上一个讲了怎样用xml配置所有的Bean以及进行依赖注入，但是这样太麻烦了，对于每一个bean都要写一个xml，可以有几种方式进行自动装配。

• 　　四种装配方式
  • 　　byName(通过名字装配，这时属性的名字必须与bean名字一致)
  •       byType(通过类型，匹配与interface或class相同的类型)，这种是找到对应的方法，然后进行setter方法进行注入的
  •       constructor（也是通过类型匹配，但是是通过new的进行装配的）
  •       最佳自动装配（先用constructor装配，然后再用byType）

　　　　   但是自动装配有两个问题。要是有多个bean，就用这个。

　　　　　primary="false"   和    autowire-candicate='false'

public interface Food {    public String foodName();}public class BeefFood implements Food {    private String name;    public BeefFood() {    }    public BeefFood(String name) {        this.name = name;    }    public String foodName(){        return name;    }    public void setName(String name) {        this.name = name;    }}public interface Dinner {    public void foodList();}public class BigDinner implements Dinner{    private Food food;    private String position;    public BigDinner() {    }    public BigDinner(Food food) {        this.food = food;    }    public BigDinner(String position, Food food) {        this.position = position;        this.food = food;    }    public void setPosition(String position) {        this.position = position;    }    public void setFood(Food food) {        this.food = food;    }    public void foodList(){        System.out.println("今晚在" + position + "吃" + food.foodName());    }}

插入xml配置

其实只是少了一些<constractor-arg>和<property>配置

测试类为

public class TestBeanAutowire {    public static void main(String[] args) {        //传统依赖注入方式        Food beef = new BeefFood("黄牛肉");        System.out.println("传统依赖注入方式" + " =========>>>>>>>  yellowBeef " + "Test");        Dinner dinner = new BigDinner("家里",beef);        dinner.foodList();        //context        ApplicationContext context = new ClassPathXmlApplicationContext("spring-bean-autowire.xml");        //传统xml DI方式        Dinner dinnerTranditional = (Dinner) context.getBean("dinnerTranditional");        System.out.println("传统xml DI方式" + " =========>>>>>>>  yellowBeef " + "Test");        dinnerTranditional.foodList();        //autowire byName方式        Dinner dinnerByName = (Dinner) context.getBean("dinnerByName");        System.out.println("autowire byName方式" + " =========>>>>>>>  干煸大肠 " + "Test");        dinnerByName.foodList();        //autowire byType方式        Dinner dinnerByType = (Dinner) context.getBean("dinnerByType");        System.out.println("autowire byType方式" + " =========>>>>>>>  yellowBeef " + "Test");        dinnerByType.foodList();        //autowire constructor方式        Dinner dinnerConstructor = (Dinner) context.getBean("dinnerConstructor");        System.out.println("autowire constructor方式" + " =========>>>>>>>  yellowBeef " + "Test");        dinnerConstructor.foodList();//        //autowire autoDetect方式//        Dinner dinnerAutoDetect = (Dinner) context.getBean("dinnerAutoDetect");//        System.out.println("autowire autoDetect方式" + " =========>>>>>>>  yellowBeef " + "Test");//        dinnerAutoDetect.foodList();    }}

传统依赖注入方式 =========>>>>>>>  yellowBeef Test今晚在家里吃黄牛肉十一月 29, 2015 10:47:29 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@6f6827b5: startup date [Sun Nov 29 22:47:29 CST 2015]; root of context hierarchy十一月 29, 2015 10:47:29 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions信息: Loading XML bean definitions from class path resource [spring-bean-autowire.xml]传统xml DI方式 =========>>>>>>>  yellowBeef Test今晚在我和亲共同的家里吃黄牛肉autowire byName方式 =========>>>>>>>  干煸大肠 Test今晚在我和亲共同的家里吃干煸大肠autowire byType方式 =========>>>>>>>  yellowBeef Test今晚在我和亲共同的家里吃黄牛肉autowire constructor方式 =========>>>>>>>  yellowBeef Test今晚在我和亲共同的家里吃黄牛肉Process finished with exit code 0

这个是测试结果。

         　　　　　　　　　

• 　　然后这种不用注解的方式也必须要声明好多bean，只是之间的关系可以进行少一点，说白了就是少了点<constractor-arg>和<property>

　　        所以这种基于注解的方式就比较方便了。

　　　　  这样也存在问题，一是没有bean，解决方式@Autowired(required=false)

　　　　　　　　　　　　  二是有好几个bean，用这个@Qualifier("name")，这个名字小写就行，也可以自己定义一个限定器，见代码。

• • 　　　还有一个问题是扫描组件，@Component这样就自动扫描。

public interface Food {    public String foodName();}@Component@DefineRibpublic class RibFood implements Food{    private String name = "排骨";    public String foodName(){        return name;    }    public void setName(String name) {        this.name = name;    }}@Componentpublic class BeefFood implements Food {    private String name = "黄牛肉";    public String foodName(){        return name;    }    public void setName(String name) {        this.name = name;    }}public interface Dinner {    public void foodList();}@Componentpublic class BigDinner implements Dinner {    @Autowired//    @Qualifier("beefFood")//按class的小写名字    @DefineRib//按限定器来注解    private Food food ;    @Value("和亲的小屋里")    private String position;//    @Autowired//    public BigDinner(Food food, String position) {//        this.food = food;//        this.position = "和亲的家里";//    }    public void setPosition(String position) {        this.position = position;    }    public void setFood(Food food) {        this.food = food;    }    public void foodList(){        System.out.println("今晚在" + position + "吃" + food.foodName());    }}@Retention(RetentionPolicy.RUNTIME)@Target({ElementType.TYPE,ElementType.PARAMETER,ElementType.FIELD})@Qualifierpublic @interface DefineRib{}

public class TestBeanAnnotation {    public static void main(String[] args) {        ApplicationContext context = new ClassPathXmlApplicationContext("spring-bean-annotation.xml");        Dinner dinner = (Dinner)context.getBean("dinnerAuto");        dinner.foodList();    }}

这样xml就很小了