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接口
用于沟通的中介物的抽象化
实体把自己提供给外界的一种抽象化说明,用以由内部操作分离出外部沟通方法,使其能被修改内部而不影响外界其他实体与其交互的方式
对应Java接口即声明,声明了哪些方法是对外公开提供的
在Java8中,接口可以拥有方法体
面向接口编程
结构设计中,分清层次及调用关系,每层只向外(上层)提供一组功能接口,各层间依赖接口而非实现类
接口实现的变动不影响各层间的调用,这一点在公共服务中尤为重要
面向接口编程中的接口是用于隐藏具体实现和实现多态性的组件
实例:
1.OneInterface.java
package org.spring.ioc.interfaces; /** * 接口 * */ public interface OneInterface { String hello(String word); }
2.OneInterfaceImpl.java
package org.spring.ioc.interfaces.impl; import org.spring.ioc.interfaces.OneInterface; /** * 接口实现类 * */ public class OneInterfaceImpl implements OneInterface { public String hello(String word) { return "Word form interface "OneInterface":" + word; } }
3.Main.java
package org.spring.ioc.main; import org.spring.ioc.interfaces.OneInterface; import org.spring.ioc.interfaces.impl.OneInterfaceImpl; public class Main { public static void main(String[] args) { OneInterface oif = new OneInterfaceImpl();//手动获取依赖对象 System.out.println(oif.hello("word.")); } }
IOC
IOC:控制反转, 控制权的转移,应用程序本身不负责依赖对象的创建和维护,而是由外部容器负责创建和维护
DI(依赖注入)是IOC的一种实现方式
目的:创建对象并且组装对象之间的关系
实例:
1.OneInterface.java(与上面一样)
2.OneInterfaceImpl.java(与上面一样)
3.pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>org.spring</groupId> <artifactId>Spring</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>Spring</name> <url>http://maven.apache.org</url> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <spring.version>4.3.7.RELEASE</spring.version> </properties> <dependencies> <!-- junit依赖 --> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.12</version> <scope>test</scope> </dependency> <!-- spring依赖 --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-beans</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>${spring.version}</version> </dependency> </dependencies> </project>
4.spring-ioc.xml
<?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/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <bean id="oneInterface" class="org.spring.ioc.interfaces.impl.OneInterfaceImpl"/> </beans>
5.UnitTestBase.java
package org.spring.ioc.test; import org.junit.After; import org.junit.Before; import org.springframework.context.support.ClassPathXmlApplicationContext; import org.springframework.util.StringUtils; /** * 单元测试初始化类 * */ public class UnitTestBase { private ClassPathXmlApplicationContext context; private String springXmlPath; /** * 无参构造器 */ public UnitTestBase() { } /** * 含参构造器 * * @param springXmlPath * spring配置文件路径 */ public UnitTestBase(String springXmlPath) { this.springXmlPath = springXmlPath; } /** * 初始化spring配置文件 */ @Before//在@Test注解的方法执行前执行 public void before() { if(StringUtils.isEmpty(springXmlPath)) {//默认spring配置文件路径 springXmlPath = "classpath*:spring-*.xml"; } //加载配置文件 context = new ClassPathXmlApplicationContext(springXmlPath.split("[,\s]+")); //启动组件 context.start(); } /** * 销毁spring组件 */ @After//在@Test注解的方法执行后执行 public void after() { context.destroy();//销毁组件 } /** * 获取spring中定义的bean实例 * * @param beanId * * @return */ @SuppressWarnings("unchecked") protected <T extends Object> T getBean(String beanId) { return (T) context.getBean(beanId); } /** * 获取spring中定义的bean实例 * * @param clazz * * @return */ protected <T extends Object> T getBean(Class<T> clazz) { return (T) context.getBean(clazz); } }
6.TestOneInterface.java
package org.spring.ioc.test; import org.junit.Test; import org.junit.runner.RunWith; import org.junit.runners.BlockJUnit4ClassRunner; import org.spring.ioc.interfaces.OneInterface; @RunWith(BlockJUnit4ClassRunner.class)//指定JUnit默认执行类 public class TestOneInterface extends UnitTestBase { public TestOneInterface() {//通过构造方法传入spring配置文件路径 super("classpath*:spring-ioc.xml"); } @Test public void testHello() { OneInterface oneInterface = super.getBean("oneInterface");//从spring容器中获取依赖对象 System.out.println(oneInterface.hello("Word.")); } }
Bean容器初始化
文件
FileSystemXmlApplicationContext context = new FileSystemXmlApplicationContext("D:/properties/spring-ioc.xml");
ClassPath
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("classpath:spring-ioc.xml");
Web应用
<listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener>