第3章 装配Bean---高级装配--笔记1

概述：

Sring 一些新特性：

• Spring profile ： 让bean活起来
• 条件化的bean声明：过滤bean 
• 自动装配与歧义性： 请给我一个精准的bean
• bean的作用域：  正确行使的权利
• SpringEL表达式： Spring自己的语言

1.spring profile

profile 简单解释就是根据需求创建bean

package learn.chapter3;import javax.sql.DataSource;import org.apache.commons.dbcp.BasicDataSource;import org.springframework.context.annotation.Bean;import org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseBuilder;import org.springframework.jndi.JndiObjectFactoryBean;public class ThirdDatabase {/** * 测试环境获取数据库 * @return */@Bean(destroyMethod="shutdown")public DataSource dataSourceE(){return new EmbeddedDatabaseBuilder().addScript("classpath:schema.sql").addScript("classpath:test-data.sql").build();}/** * 生产环境的数据库 * @return */public DataSource dataSourceJOF(){JndiObjectFactoryBean jndiObjectFactoryBean = new JndiObjectFactoryBean();jndiObjectFactoryBean.setJndiName("jdbc/myDS");jndiObjectFactoryBean.setResourceRef(true);jndiObjectFactoryBean.setProxyInterface(javax.sql.DataSource.class);return (DataSource) jndiObjectFactoryBean.getObject();}/** * QA环境的数据库对象 * @return */public DataSource dataSourceQA(){BasicDataSource dataSource = new BasicDataSource();dataSource.setUrl("jdbc:h2:top://dbserver/~/test");dataSource.setDriverClassName("org.h2.Driver");dataSource.setUsername("sa");dataSource.setPassword("password");dataSource.setInitialSize(20);dataSource.setMaxActive(30);return dataSource;}}

有三种数据库对象分别应用不同的场景，开发，生产，测试，多个环境，如果保证在三个环境进行切换，也就是根据需要创建不同datasource？

接下来以一个简单的例子：定义一个Fruit接口，创建三个实现类，Apple.java Peach.java Banana.java，每个人喜欢不同的水果，合理创建不同的水果

package learn.chapter3;public interface Fruit {void favorFruit();}

package learn.chapter3;public class Peach implements Fruit{public void favorFruit() {System.out.println("我喜欢吃桃子");}}

package learn.chapter3;public class Apple implements Fruit{public void favorFruit() {System.out.println("我喜欢吃苹果");}}

package learn.chapter3;public class Banana implements Fruit {public void favorFruit() {System.out.println("我喜欢吃香蕉");}}

然后采用两种注入方式

方式一：javaConfig

package learn.chapter3.javaConfig;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.context.annotation.Profile;import learn.chapter3.Apple;import learn.chapter3.Banana;import learn.chapter3.Fruit;import learn.chapter3.Peach;@Configurationpublic class FruitConfig {@Bean("fruit")@Profile("apple")public Fruit getApple(){return new Apple();}@Bean("fruit")@Profile("peach")public Fruit getPeach(){return new Peach();}@Bean("fruit")@Profile("banana")public Fruit getBanana(){return new Banana();}}

总结：注意看所有的bean的名称都是fruit的，增加一个@Profile注解用来区分不同的名称

方式二：采用xml配置方式

<?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"xmlns:c="http://www.springframework.org/schema/c" xmlns:p="http://www.springframework.org/schema/p"xmlns:util="http://www.springframework.org/schema/util"xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/contexthttp://www.springframework.org/schema/context/spring-context.xsdhttp://www.springframework.org/schema/utilhttp://www.springframework.org/schema/util/spring-util.xsd">    <beans profile="apple">    <bean id="fruit" class="learn.chapter3.Apple"></bean>    </beans>    <beans profile="peach">    <bean id="fruit" class="learn.chapter3.Peach"></bean>    </beans>    <beans profile="banana">    <bean id="fruit" class="learn.chapter3.Banana"></bean>    </beans></beans>

测试类：

package learn.chapter2;import org.junit.Test;import org.junit.runner.RunWith;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.test.context.ActiveProfiles;import org.springframework.test.context.ContextConfiguration;import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;import learn.chapter3.Fruit;import learn.chapter3.javaConfig.FruitConfig;@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(classes={FruitConfig.class})@ActiveProfiles("peach")public class ProfileTest {@Autowiredprivate Fruit fruit;@Testpublic void favor(){fruit.favorFruit();}}

总结：增加注解@ActiveProfiles("peach")激活对应profile，就创建不同的bean

结果：
我喜欢吃桃子

这只是测试profiles,可以通过很多方式就行激活对应的profile当工程中

1. 作为DispatcherServlet的初始化参数：
2. 作为Web应用的上下文参数
3. 作为环境变量
4. 作为JVM的系统属性
5. 集成测试直接用注解@ActiveProfiles设置

主要有两个属性： spring.profiles.active 和 spring.profiles.default

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
version="3.0">
<display-name>Archetype Created Web Application</display-name>
<!-- Spring和mybatis的配置文件 -->
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:spring-mybatis.xml</param-value>
</context-param>
<context-param>
<param-name>spring.profiles.default</param-name>
<param-value>apple</param-value>
</context-param>
<!-- 编码过滤器 -->
<filter>
<filter-name>encodingFilter</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
<async-supported>true</async-supported>
<init-param>
<param-name>encoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>encodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<!-- Spring监听器 -->
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<!-- 防止Spring内存溢出监听器 -->
<listener>
<listener-class>org.springframework.web.util.IntrospectorCleanupListener</listener-class>
</listener>


<!-- Spring MVC servlet -->
<servlet>
<servlet-name>SpringMVC</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:spring-mvc.xml</param-value>
</init-param>
<init-param>
<param-name>spring.profiles.default</param-name>
<param-value>peach</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
<async-supported>true</async-supported>
</servlet>
<servlet-mapping>
<servlet-name>SpringMVC</servlet-name>
<!-- 此处可以可以配置成*.do，对应struts的后缀习惯 -->
<url-pattern>/</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>/index.jsp</welcome-file>
</welcome-file-list>

</web-app>

总结：第一个是基于web，第二个基于servlet，多个不同profile可用逗号隔开，例如 peach,apple（同类不过没有必要）

2.条件化的Bean

@Conditional(实现condition接口的实现类)，不同于profile，这个更加宽泛，自由

利用Conditional注解实现成年人才能创建网吧对象，模拟成年人大于等于18才能进入网吧

package learn.chapter3;public  class Person {public int age;public String name;public Person(int age, String name) {this.age = age;this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public String getName() {return name;}public void setName(String name) {this.name = name;}}

package learn.chapter3;import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;import org.springframework.context.annotation.Condition;import org.springframework.context.annotation.ConditionContext;import org.springframework.core.type.AnnotatedTypeMetadata;public class IsAdult implements Condition {public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {ConfigurableListableBeanFactory ss = context.getBeanFactory();//判断是否有Person的beanPerson p = (Person) ss.getBean("person");if(null != p && p.getAge()>=18) {return true;}return false;}}

这个类实现Condition接口

package learn.chapter3.javaConfig;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Conditional;import org.springframework.context.annotation.Configuration;import learn.chapter3.InternetBar;import learn.chapter3.IsAdult;import learn.chapter3.Person;@Configurationpublic class InternetBarConfig {@Bean public Person person(){return new Person(19, "小明");}@Bean@Conditional( IsAdult.class)public InternetBar internetBar(){return new InternetBar();}}

在注入InternetBar增加了条件类（IsAdult.class） 返回true 才创建这个bean

测试类：

package learn.chapter2;import static org.junit.Assert.*;import org.junit.Test;import org.junit.runner.RunWith;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.test.context.ContextConfiguration;import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;import learn.chapter3.InternetBar;import learn.chapter3.javaConfig.InternetBarConfig;@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(classes={InternetBarConfig.class})public class ConditionTest2 {@Autowiredprivate InternetBar internetBar;@Testpublic void isNullInternetBar(){assertNotNull(internetBar);}}

总结：当前Person未实例化，或者age<18都会报错。