自定义IOC

引入依赖

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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.company</groupId>
    <artifactId>Spring01</artifactId>
    <version>1.0-SNAPSHOT</version>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <encoding></encoding>
                </configuration>
            </plugin>
        </plugins>
    </build>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <dependency>
            <groupId>dom4j</groupId>
            <artifactId>dom4j</artifactId>
            <version>1.6.1</version>
        </dependency>
        <dependency>
            <groupId>jaxen</groupId>
            <artifactId>jaxen</artifactId>
            <version>1.1.6</version>
        </dependency>
    </dependencies>
</project>

在Resources目录下Beans.xml

<?xml version="1.0" encoding="UTF-8" ?>
<beans>
    <bean id="accountDao" class="com.company.dao.AccountDaoImpl"></bean>
    <bean id="accountService" class="com.company.service.AccountServiceImpl"></bean>
</beans>

在POJO目录下定义Account类

public class Account {
    private int id;
    private String name;
    private double money;

    @Override
    public String toString() {
        return "Account{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", money=" + money +
                '}';
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public double getMoney() {
        return money;
    }

    public void setMoney(double money) {
        this.money = money;
    }
}

dao层

接口AccountDao.java

public interface AccountDao {
    void  addAccount(Account account);
}

实现类AccountDaoImpl.java

public class AccountDaoImpl implements AccountDao {
    @Override
    public void addAccount(Account account) {
        System.out.println("创建一个新账户");
    }
}

service层

接口AccountService.java

public interface AccountService {
    void addAccount(Account account);
}

实现类AccountServiceImpl.java

public class AccountServiceImpl implements AccountService{
    private AccountDao accountDao=new AccountDaoImpl();
    @Override
    public void addAccount(Account account) {
          accountDao.addAccount(account);
    }
}

解析Beans.xml

public class BeanFactory {

    private static Map<String, Object> map = new HashMap<>();

    static {
        try {
            SAXReader saxReader = new SAXReader();
            InputStream inputStream = BeanFactory.class.getClassLoader().getResourceAsStream("beans.xml");
            Document document = saxReader.read(inputStream);
            inputStream.close();
            Element rootElement = document.getRootElement();
            List<Element> listElement = rootElement.selectNodes("//bean");
            for (Element element : listElement) {
                String id = element.attributeValue("id");
                String aClass = element.attributeValue("class");
                Class<?> clazz = Class.forName(aClass);
                Object o = clazz.newInstance();
                map.put(id, o);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static Object getBean(String id) throws Exception {
        return map.get(id);
    }
}

测试

public class MyIOCTest {
    @Test
    public void test() throws Exception {
        AccountDao accountDao = (AccountDaoImpl)BeanFactory.getBean("accountDao");
        AccountService accountService =(AccountServiceImpl) BeanFactory.getBean("accountService");
        System.out.println(accountDao);
        System.out.println(accountService);
    }
}

文件目录如下：