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Spring注解(赋值相关)

上面是与生命周期有关的内容，下面是属性赋值相关的：

@Configurationpublic class ProperTyValueConfig {@Beanpublic Person person() {retu new Person();}}

测试：

public class test {private void printBeans(AnnotationConfigApplicationContext applicationContext) {String[] beanDefinitionNames = applicationContext.getBeanDefinitionNames();for(String name : beanDefinitionNames) {System.out.println(name);}Object p = applicationContext.getBean("person");System.out.println(p);}@Test public void test01(){  AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(ProperTyValueConfig.class);System.out.println("容器创建完成");printBeans(applicationContext);//关闭容器applicationContext.close();}}

看看容器有哪些Bean

除了容器自带的，还有就是我们配置的person，还没有赋值哦

xml：

</bean>

注解：

@Value() boolean

Spel 基本数值都可以写 #{}

${} 取出配置文件中的值在运行环境中的变量值

Bean类及其赋值：

package com.toov5.Bean;import org.springframework.beans.factory.annotation.Value;public class Person {@Value("#{20-1}")  int age; @Value("MaYun")  String name; public Person() {// TODO Auto-generated constructor stub}public Person(int age, String name) {super();this.age = age;this.name = name;}@Overridepublic String toString() {retu "Person [age=" + age + ", name=" + name + "]";}  }

注意赋值 @Value 类型要匹配

下面介绍使用properties文件的：

如果用xml形式的读取：

xml中需要有命名空间： <context: property-placeholder location=“xxxxxx/xxx” /> 用其导入外部的配置文件

如果用注解的方式读取：

config:

@Configuration@PropertySource(value= {"classpath"/person.properties"})public class ProperTyValueConfig { @Beanpublic Person person() {retu new Person();}}

Bean类：

public class Person {@Value("#{20-1}")  int age; @Value("MaYun")  String name;  @Value("${person.addr}")  String addr; public Person() {// TODO Auto-generated constructor stub}public Person(int age, String name) {super();this.age = age;this.name = name;}public int getAge() {retu age;}public void setAge(int age) {this.age = age;}public String getName() {retu name;}public void setName(String name) {this.name = name;}public String getAddr() {retu addr;}public void setAddr(String addr) {this.addr = addr;}@Overridepublic String toString() {retu "Person [age=" + age + ", name=" + name + ", addr=" + addr + "]";}  }

properties：

person.addr=beijing

测试：

public class test {private void printBeans(AnnotationConfigApplicationContext applicationContext) {String[] beanDefinitionNames = applicationContext.getBeanDefinitionNames();for(String name : beanDefinitionNames) {System.out.println(name);}Object p = applicationContext.getBean("person");System.out.println(p);}@Test public void test01(){  AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(ProperTyValueConfig.class);System.out.println("容器创建完成");printBeans(applicationContext);//关闭容器applicationContext.close();}}

一旦properties文件被加载，还可以使用如下方式获取：

public class test {private void printBeans(AnnotationConfigApplicationContext applicationContext) {String[] beanDefinitionNames = applicationContext.getBeanDefinitionNames();for(String name : beanDefinitionNames) {System.out.println(name);}Object p = applicationContext.getBean("person");System.out.println(p);//运行时环境变量ConfigurableEnvironment environment = applicationContext.getEnvironment();String property = environment.getProperty("person.addr");System.out.println(property);}@Test public void test01(){  AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(ProperTyValueConfig.class);System.out.println("容器创建完成");printBeans(applicationContext);//关闭容器applicationContext.close();}}

自动装配：

Spring 利用依赖注入（DI）,完成IOC容器中格个组件的依赖关系赋值

Service

@Servicepublic class BookService {@Autowiredprivate BookDao bookDao;public void print() {System.out.println(bookDao);}@Overridepublic String toString() {retu "BookService"+bookDao;}}

config：

@Configuration@ComponentScan({"com.toov5.dao","com.toov5.service","com.toov5.controller"})public class ProperTyValueConfig {}

test:

public class test {@Test public void test01(){  AnnotationConfigApplicationContext applicationContext  =new AnnotationConfigApplicationContext(ProperTyValueConfig.class);BookService bookService =(BookService) applicationContext.getBean(BookService.class); //按照类型去拿System.out.println(bookService);applicationContext.close();}}

有了dao哦

其实就是容器中的到哦：

@Autowired 自动注入

默认优先按照类型去容器找对应的组件： applicationContext.getBean(BookService.class);

找到则赋值

如果这个类型的组件在IOC中有多个，怎么处理？

容器中有两个类型相同名字不同的bean

如果找到多个相同类型的组件，再将属性名作为组件的id 去容器中查找。applicationContext.getBean("bookDao")

在装配时候：

名字是bookDao2

@Servicepublic class BookService {@Autowiredprivate BookDao bookDao2;public void print() {System.out.println(bookDao2);}@Overridepublic String toString() {retu "BookService"+bookDao2.getFlag();}}

config注入的是 bookDao2

@Configuration@ComponentScan({"com.toov5.dao","com.toov5.service","com.toov5.controller"})public class ProperTyValueConfig {@Bean(name="bookDao2")public BookDao bookDao() { BookDao bookDao = new BookDao(); bookDao.setFlag("2"); retu bookDao;}}

测试：

public class test {@Test public void test01(){  AnnotationConfigApplicationContext applicationContext  =new AnnotationConfigApplicationContext(ProperTyValueConfig.class);BookService bookService =(BookService) applicationContext.getBean(BookService.class); //按照类型去拿System.out.println(bookService);BookDao bookDao = applicationContext.getBean(BookDao.class);System.out.println(bookDao.getFlag());applicationContext.close();}  }

可以在装配时候这么玩儿

@Qualifier("bookDao") 指定需要抓给你配的组件的id 而不是属性名

@Servicepublic class BookService {@Qualifier("bookDao")@Autowiredprivate BookDao bookDao2;public void print() {System.out.println(bookDao2);}@Overridepublic String toString() {retu "BookService"+bookDao2.getFlag();}}

打印：

自动装配默认一定要将属性赋值好，没有就会报错

如果：

@Servicepublic class BookService {@Qualifier("bookDao")@Autowired(required=false)private BookDao bookDao2;public void print() {System.out.println(bookDao2);}@Overridepublic String toString() {retu "BookService"+bookDao2.getFlag();}}

如果没有的情况下，不报错：

@Servicepublic class BookService {@Qualifier("bookDao666")@Autowired(required=false)private BookDao bookDao2;public void print() {System.out.println(bookDao2);}}

测试：

public class test {@Test public void test01(){  AnnotationConfigApplicationContext applicationContext  =new AnnotationConfigApplicationContext(ProperTyValueConfig.class);BookService bookService =(BookService) applicationContext.getBean(BookService.class); //按照类型去拿bookService.print();applicationContext.close();}  }

打印：

容器中没有的情况会null

还有一个spring的牛逼的注解 @Primary 让spring自动装配的时候默认使用首选bean

@Configuration@ComponentScan({"com.toov5.dao","com.toov5.service","com.toov5.controller"})public class ProperTyValueConfig {@Primary@Bean(name="bookDao2")public BookDao bookDao() { BookDao bookDao = new BookDao(); bookDao.setFlag("2"); retu bookDao;}}

每次首选装配的是加了 @Primary的

既然已经在容器中声明了在装配时候 @Qualifier 就不需要了

使用首选来装配

如果加了@Qualifier 那就是明确指定的了

service：

@Servicepublic class BookService {@Autowired(required=false)private BookDao bookDao;public void print() {System.out.println(bookDao.getFlag());}}

config 明确了优先装配的bean

@Configuration@ComponentScan({"com.toov5.dao","com.toov5.service","com.toov5.controller"})public class ProperTyValueConfig {@Primary@Bean(name="bookDao2")public BookDao bookDao() { BookDao bookDao = new BookDao(); bookDao.setFlag("2"); retu bookDao;}}

测试：

public class test {@Test public void test01(){  AnnotationConfigApplicationContext applicationContext  =new AnnotationConfigApplicationContext(ProperTyValueConfig.class);BookService bookService =(BookService) applicationContext.getBean(BookService.class); //按照类型去拿bookService.print();applicationContext.close();}  }

Spring还支持使用 @Resource(JSR250) java 规范的注释 @Qualifier+ @Autowired = @Resource 或者 @Resource(name="bookDao2") 否则就默认当前的属性名字

和 @Inject（JSP330）需要额外导入依赖（maven仓库搜索inject） Autowried可以设置required属性

@Autowried构造器参数方法属性都可以标注使用

CarBean:

@Componentpublic class Car {  public Car() {System.out.println("无参构造初始化");}  public void init() {System.out.println("CarBean---init");}public void destory() {System.out.println("CarBean---destory");  }}

BossBean: 默认加载IOC容器中的组件，容器会调用无参构造器创建对象，在进行初始化赋值等操作。

@Componentpublic class Boss {private Car car;public Car getCar() {retu car;}@Autowired //标注在方法上 spring容器创建对象时候 调用方法 完成赋值。方法使用的参数，自定义类型的值 从IOC获取值public void setCar(Car car) {this.car = car;}}

config:

@Configuration@ComponentScan({"com.toov5.Bean"})public class ProperTyValueConfig {@Primary@Bean(name="bookDao2")public BookDao bookDao() { BookDao bookDao = new BookDao(); bookDao.setFlag("2"); retu bookDao;}}

测试：

public class test {@Test public void test01(){  AnnotationConfigApplicationContext applicationContext  =new AnnotationConfigApplicationContext(ProperTyValueConfig.class);Boss boss =(Boss) applicationContext.getBean(Boss.class); //按照类型去拿System.out.println(boss.getCar());  //再从容器中获取car  进行比对Car carBean =applicationContext.getBean(Car.class);System.out.println(carBean);applicationContext.close();}  }

打印：

来个有参构造器：标注在有参构造器上面： Spring启动时候调用有参构造器

@Componentpublic class Boss {private Car car;@Autowired public Boss(Car car) {this.car=car;System.out.println("Boss 有参构造器  ");}public Car getCar() {retu car;} //@Autowired //标注在方法上 spring容器创建对象时候 调用方法 完成赋值。方法使用的参数，自定义类型的值 从IOC获取值public void setCar(Car car) {this.car = car;}}

当然也可以放在参数位置：

public Boss(@Autowired  Car car) {this.car=car;System.out.println("Boss 有参构造器  ");}

如果只有一个有参构造器，注解可以省略。建议平时大家开发时候还是不要省略了吧

也可以在config里面这么玩儿

@Configuration@ComponentScan({"com.toov5.Bean"})public class ProperTyValueConfig {@Primary@Bean(name="boss")public Boss boss(Car car) {Boss boss =new Boss();boss.setCar(car);retu boss;}}

Bean标注的方法创建对象的时候，方法参数的值从容器中获取！

原理可以看Aware接口

可以看下这个：

启动容器后，创建对象，需要的其他组件都会以接口方法回调的方式引入进来

bean：

@Componentpublic class Animal implements ApplicationContextAware,BeanNameAware,EmbeddedValueResolverAware {  private ApplicationContext applicationContext;  String  color ;  String  name;  public Animal() {// TODO Auto-generated constructor stub}public Animal(String color, String name) {super();this.color = color;this.name = name;}//第一个接口public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {System.out.println("传入IOC:"+applicationContext);this.applicationContext=applicationContext;}//第二个接口public void setBeanName(String name) {  //传入bean名字 通过名字去容器查找beanSystem.out.println("当前bean的名字"+name);}//第三个接口 //容器启动时候  创建对象 然后把resolver对象传递进来  public void setEmbeddedValueResolver(StringValueResolver resolver) { //解析字符串 # {}  等等// TODO Auto-generated method stubString resolveStringValue = resolver.resolveStringValue("你好${os.name} 我是#{30*1}");System.out.println("解析的字符串"+resolveStringValue);}}

config:

@Configuration@ComponentScan({"com.toov5.Bean"})public class ProperTyValueConfig {@Primary@Bean(name="boss")public Boss boss(Car car) {Boss boss =new Boss();boss.setCar(car);retu boss;  }}

测试：

public class test {@Test public void test01(){  AnnotationConfigApplicationContext applicationContext  =new AnnotationConfigApplicationContext(ProperTyValueConfig.class);Boss boss =(Boss) applicationContext.getBean(Boss.class); //按照类型去拿System.out.println(boss.getCar());  //再从容器中获取car  进行比对Car carBean =applicationContext.getBean(Car.class);System.out.println(carBean);applicationContext.close();}  }