自定义IOC 简单实现

自定义IOC 简单实现

IOC概念:

IOC(inversion of control)的中文解释是“控制反转”，对象的使用者不是创建者. 作用是将对象的创建 反转给spring框架来创建和管理。说白了就是把对象交给spring创建和管理. 我们要用对象时直接从Spring的IOC容器【集合】中获取,使用spring最主要的目的是实现解耦, 到时候我们只需要修改配置文件, 不需要修改源码

简单实现流程

1.创建maven工程

2.导入依赖

 <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

    <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>1.2.0</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <!-- 指定jdk，防止update project -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <!-- 项目编码-->
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
        </plugins>
    </build>

3.代码实现

3.1 获取bean的工厂编写

package com.lyf.factory;

import com.lyf.util.Resources;
import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;

import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.List;
import java.util.Map;


public class MyBeanFactory {

    /**
     * 存放bean的容器
     */
    private static Map<String, Object> map;

    // 加载核心配置文件到流中
    static {
        InputStream is = null;
        try {
            map = new HashMap<>();
            is = Resources.getResourceAsStream("applicationContext.xml");
            //  用于解析xml文件的一个类, 第三方的
            SAXReader saxReader = new SAXReader();
            //  把inputStream读取到SAXReader类中
            Document document = saxReader.read(is);
            //  获取所有的节点对象 //bean
            List<Element> list = document.selectNodes("//bean");
            for (Element element : list) {
                String id = element.attributeValue("id");
                String className = element.attributeValue("class");
                Object obj = Class.forName(className).newInstance();
                map.put(id, obj);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (is != null) {
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    /**
     * 返回一个Object对象
     *
     * @return java.lang.Object
     */
    public static Object getBean(String id) {
        return map.get(id);
    }

}

3.2 service层

package com.lyf.service;

import com.lyf.bean.Account;

public interface AccountService {

    /**
     * 保存一个账户
     *
     * @param account 账户
     */
    void save(Account account);

3.3 service层接口实现类

package com.lyf.service.impl;

import com.lyf.bean.Account;
import com.lyf.service.AccountService;


public class AccountServiceImpl implements AccountService {

    /**
     * 保存一个账户
     *
     * @param account 账户
     */
    @Override
    public void save(Account account) {
        System.out.println("AccountServiceImpl 执行了保存一个账户方法..." + account);
    }
}

3.4 bean

package com.lyf.bean;

import java.io.Serializable;

public class Account implements Serializable {
    private Integer id;
    private String username;
    private Double money;

    public Integer getId() {
        return id;
    }

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

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public Double getMoney() {
        return money;
    }

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

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

3.5 工具类

package com.lyf.util;

import java.io.InputStream;

public class Resources {

    /**
     * 获取inputStream流的工具类
     *
     * @param classPath 配置文件所在地址
     * @return java.io.InputStream
     */
    public static InputStream getResourceAsStream(String classPath) {
        return Resources.class.getClassLoader().getResourceAsStream(classPath);
    }
}

3.6 测试类

package com.lyf.test;

import com.lyf.bean.Account;
import com.lyf.factory.MyBeanFactory;
import com.lyf.service.AccountService;
import org.junit.Test;

public class CustomIOCTest {

    @Test
    public void testCustomIOC() throws Exception {
        AccountService accountService = (AccountService) MyBeanFactory.getBean("accountService");
        Account account = new Account();
        account.setId(1);
        account.setUsername("张三");
        account.setMoney(1000.0);

        accountService.save(account);
    }
}

4.程序执行结果