手写一个简单的IOC

ゝ一纸荒年。 2023-10-03 09:11 72阅读 0赞

<dependency>
                <groupId>dom4j</groupId>
                <artifactId>dom4j</artifactId>
                <version>1.6.1</version>
            </dependency>

public class SimpleIOC {
        
    
    
        /*
        *
        *Map<id,Object>
         */
        private Map<String,Object> beans = new HashMap<>();
        public SimpleIOC(String path) throws Throwable{
        
                loadBeans(path);      
        }
        public <T>T getBean(String id){
        
            Object bean = beans.get(id);
            if(bean== null)
                throw new RuntimeException(id+":xml中没有注册该id");
            return (T)bean;
        }
    
        public <T>T getBean(Class beanClass){
        
           Collection<Object> values = beans.values();
           for (Object value : values) {
        
                if(value.getClass().equals(beanClass))return (T)value;
            }
            throw new NullPointerException(beanClass.getName()+":这个类型没有在xml中注册");
    	}
    
    
        /**
         * 使用DOM4j来解析xml
         *
         *
         * @param path
         * @throws Throwable
         */
        private void loadBeans(String path)  throws Throwable{
        
            //加载xml
            SAXReader reader = new SAXReader();
            Document dom = reader.read(path);
            Element root = dom.getRootElement();
            List<Element> elements = root.elements();
            //String,Map<String,String> ->className,Map<fieldName,ref>
            Map<String,Map<String,String>> refs = new HashMap<>();
    
            for (Element element : elements) {
        
                String id = element.attributeValue("id");
                String className = element.attributeValue("class");    
                Map<String,String> propertyValue= new HashMap<>();
                List<Element> property = element.elements();
                Map<String,String> ref = new HashMap<>();
                for (Element pro : property) {
        //获取bean配置的属性值               
                    if(existAttribute(pro,"value"))
                        propertyValue.put(pro.attributeValue("name"),pro.attributeValue("value"));
                    else
                        ref.put(pro.attributeValue("name"),pro.attributeValue("ref"));
                }
                Class cl  = Class.forName(className);
                Object bean = cl.newInstance();//无参构造创建bean
                if(!ref.isEmpty())
                    refs.put(className,ref);
                if(!propertyValue.isEmpty())//属性值不为空，将属性值装配到bean中
                    assembleBean(cl,bean,propertyValue);
                beans.put(id,bean);
              
              }
            refreshBean(refs);
        }
    
    
        /**
         *遍历完xml，将所有bean加载到容器中，再给bean中属性值为ref的属性赋值；
         *String,Map<String,String> ->className,Map<fieldName,ref>
         * @param refs
         * @throws NoSuchFieldException
         * @throws IllegalAccessException
         */
        public void refreshBean(Map<String,Map<String,String>> refs) throws NoSuchFieldException, IllegalAccessException {
        
            if(refs.isEmpty())return;
            Iterator<String> iter = refs.keySet().iterator();
            while(iter.hasNext()){
        
                String className = iter.next();
                Object object = getBean(Class.forName(className));
                Map<String, String> refValue = refs.get(className);
                Iterator<String> fieldValue = refValue.keySet().iterator();
                while(fieldValue.hasNext()){
        
                    String fieldName = fieldValue.next();
                    String id = refValue.get(fieldName);
                    Object refObject = getBean(id);
                    Field field = object.getClass().getDeclaredField(fieldName);              
                    field.setAccessible(true);
                    field.set(object,refObject);
                }
            }
        }
    
        private boolean existAttribute(Element pro,String attributeName){
        
            return pro.attribute(attributeName) ==null ?false:true;
        }
    
        /*
        转换类型
         */
        private Object ConvertValueType(String type,String value) throws IllegalAccessException {
        
            switch (type){
        
                case "String":
                    return value;
                case "Integer":
                    return Integer.valueOf(value);
                case "int":
                    return Integer.parseInt(value);
                case "Boolean":
                    return Boolean.valueOf(value);
                case "boolean":
                    return Boolean.parseBoolean(value);
                case "Short":
                    return Short.valueOf(value);
                case "short":
                    return Short.parseShort(value);
                case "Long":
                    return Long.valueOf(value);
                case "long":
                    return Long.parseLong(value);
                case "Byte":
                    return Byte.valueOf(value);
                case "byte":
                    return Byte.parseByte(value);
                case "Character":
                    return Character.valueOf(value.charAt(0));
                case "char":
                    return value.charAt(0);
                case "Double":
                    return Double.valueOf(value);
                case "double":
                    return Double.parseDouble(value);
                case "Float":
                    return Float.valueOf(value);
                case "float":
                    return Float.parseFloat(value);
                default:
                    throw  new  RuntimeException("不支持");
            }
        }
    
    
    
    
        /**
         *
         * 8个基础属性 + 8个包装类+String：用value
         * 
         * 将配置的属性装配到bean中
         *
         * @param bean
         * @param propertyValue 配置的属性值
         * @return
         */
         private Object assembleBean(Class cl,Object bean,Map<String,String> propertyValue) throws IllegalAccessException {
        
             Field[] fields = cl.getDeclaredFields();
             for (Field field : fields) {
        
                 field.setAccessible(true);
                 String fieldName = field.getName();
                 if(propertyValue.containsKey(fieldName)) {
        
                     Object valueObject = ConvertValueType(field.getType().getSimpleName(),propertyValue.get(fieldName));
                     field.set(bean,valueObject);
                 }
             }
             return bean;
         }
    
    
    
    }

xml配置

测试类

public class Test {
        
    
        public static void main(String[] args)throws Throwable {
        
            SimpleIOC ioc = new SimpleIOC("src/main/resources/ioc.xml");
            ConTest conTest = ioc.getBean(ConTest.class);
            System.out.println(conTest.toString());
            System.out.println(conTest.people.toString());
            System.out.println("====================================");
            People people = ioc.getBean("pp");
            System.out.println(people);
        }
    
    }
    
    
    结果：
    ConTest{
        name='null', sex='man', age=123, ID='QEWQWE'}
    People{
        name='people-number1', age=123, ID='qwer23234'}
    ====================================
    People{
        name='people-number1', age=123, ID='qwer23234'}

===============================================================  
更新：最近重新写了ioc容器，可以在xml中定义一个ComponentScan标签用来扫描注解@Component，使用了@Component的class可以将该class注入到ioc容器中，另外还实现了@Autowried，实现类型自动注入；

Gitee地址：[地址][Link 1]

[Link 1]: https://gitee.com/myd123/aop-ioc/tree/main/iocContainer/src/main/java/com/myd