1. 创建maven项目，maven相关配置如下：
<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>com.chzhao</groupId>
<artifactId>springtest</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>springtest</name>
<url>http://maven.apache.org</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>4.0.1.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>4.0.1.RELEASE</version>
</dependency>
</dependencies>
</project>
2. Java的基本代码
package com.chzhao.springtest;
public class Person {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
package com.chzhao.springtest;
public interface IPersonBll {
void addPerson(Person p);
}
package com.chzhao.springtest;
public class PersonBll implements IPersonBll {
public void addPerson(Person p) {
System.out.println("add person: " + p.getName());
}
}
3. 添加Spring配置文件applicationContext.xml
内容如下，配置了一个bean
<?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 name="PersonBll" class="com.chzhao.springtest.PersonBll"/>
</beans>
4. 主函数
package com.chzhao.springtest;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class App {
public static void main(String[] args) {
IPersonBll pbll = new PersonBll();
Person p = new Person();
p.setName("chzhao");
pbll.addPerson(p);
ApplicationContext act = new ClassPathXmlApplicationContext(
"applicationContext.xml");
IPersonBll pbll1 = (IPersonBll) act.getBean("PersonBll");
pbll1.addPerson(p);
}
}
可以看到，我通过两种方法实例化了PersonBll：一种是常见的方法；一种是通过spring。
5. 输出
add person: chzhao
十二月 27, 2014 10:56:24 下午 org.springframework.context.support.AbstractApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@1cbfa42: startup date [Sat Dec 27 22:56:24 CST 2014]; root of context hierarchy
十二月 27, 2014 10:56:24 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [applicationContext.xml]
add person: chzhao
两张方法的输出是一样的。
6. 什么是IOC
上图是Spring官方文档中队IOC的介绍，Spring有一个container，你把pojo和配置拿过来，直接输出对象。减少了对象实例化的过程，降低了系统的耦合度。