本文主要是介绍【Spring篇】三.springBean自动装配及Resources,希望对大家解决编程问题提供一定的参考价值,需要的开发者们随着小编来一起学习吧!
1. 自动装配(Autowiring)
类型
1.1 No : 不做任何操作
1.2 byName : 根据属性名自动装配。根据容器中bean名字查找与属性完全一致的bean,将其自动装配。bean中name重复会报错。
定义dao和service
public class TestDao {public void say(String word){System.out.println("word = [" + word + "]");}
}
public class TestService {private TestDao testDao;// 提供setter方法public void setTestDao(TestDao testDao) {this.testDao = testDao;}// 调用dao中的say()public void say(String word){this.testDao.say(word);}
}
创建spring-autowiring.xml 在beans中声明default-autowire=“byName”
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans.xsd"default-autowire="byName"><bean id="testDao" class="com.wpj.autowiring.dao.TestDao"></bean><bean id="testService" class="com.wpj.autowiring.service.TestService"></bean>
</beans>
定义测试类
@Test
public void testByName(){ApplicationContext ac = new ClassPathXmlApplicationContext("spring-autowiring.xml");TestService testService = ac.getBean("testService",TestService.class);testService.say("this is word");
}
1.3 byType : 根据class自动装配。bean中class重复会报错,并指出不能使用该方式进行自动装配。如果没有找到相匹配则什么都不发生。
dao和service不变,xml中bean中声明default-autowire=“byType” 声明dao的bean的name或id可以去掉
<?xml version="1.0" encoding="UTF-8"?>
<beans ...default-autowire="byType"><bean class="com.wpj.autowiring.dao.TestDao"></bean><bean id="testService" class="com.wpj.autowiring.service.TestService"></bean>
</beans>
1.4 Constructor : 与byType类似,不同于它应用于构造器参数。如果找不到相匹配的bean,则会报错。
在service中定义构造方法 注入dao,xml中bean中声明default-autowire=“constructor”
public class TestService {private TestDao testDao;public TestService(TestDao testDao) {System.out.println("TestService.TestService");this.testDao = testDao;}public void say(String word){this.testDao.say(word);}}
<beans ...default-autowire="constructor"><bean class="com.wpj.autowiring.dao.TestDao"></bean><bean id="testService" class="com.wpj.autowiring.service.TestService"></bean>
</beans>
2. Resources
针对于资源文件的统一接口
- UrlResource : URL对应的资源,根据一个URL地址即可构建
- ClassResource : 获取类路径下的资源文件
- FileSystemResource : 获取文件系统里的资源
- ServletContextResource : ServletContext封装的资源,用于访问ServletContext环境下的资源
- InputStreamResource : 针对于输入流封装的资源
- ByteArrayResource : 针对于字节数组封装的资源
ResourceLoader
对Resource加载的接口注入参数的前缀classpath : 从classpath中去加载file : 从文件系统中去加载http : 从URL去加载(none) : 依赖于ApplicationContext
例子
在resources(java项目的src目录下)中创建一个test.txt 随便输点内容
定义TestResources
public class TestResources implements ApplicationContextAware {private ApplicationContext applicationContext;@Overridepublic void setApplicationContext(ApplicationContext applicationContext) throws BeansException {this.applicationContext = applicationContext;}public void resource() throws IOException {Resource resource = applicationContext.getResource("classpath:config.txt");// Resource resource = applicationContext.getResource("file:F:\\JavaEE1911\\ideaDevelop3\\idea\\day46\\src\\main\\resources\\config.txt");// Resource resource = applicationContext.getResource("url:https://docs.spring.io/spring/docs/5.1.3.RELEASE/spring-framework-reference");// Resource resource = applicationContext.getResource("config.txt");System.out.println(resource.getFilename());System.out.println(resource.contentLength());}
}
在spring-resource.xml
<bean id="testResources" class="com.wpj.resources.TestResources"></bean>
Test
public class TestResource {@Testpublic void test(){ApplicationContext ac = new ClassPathXmlApplicationContext("spring-resource.xml");TestResources testResource = ac.getBean("testResources",TestResources.class);try {testResource.resource();} catch (IOException e) {e.printStackTrace();}}
}
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