课堂上讲课时写的一个简单的仿spring框架

框架部分

public abstract class ApplicationContext {
     public abstract Object getBean(String id);
}




public class BeanDefinetion {

    private String id;
    private String type;
    private List<PropertyDefinition>   propertyDefinitions=new ArrayList<PropertyDefinition>();

    public String getId() {
        return id;
    }

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

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public List<PropertyDefinition> getPropertyDefinitions() {
        return propertyDefinitions;
    }

    public void setPropertyDefinitions(List<PropertyDefinition> propertyDefinitions) {
        this.propertyDefinitions = propertyDefinitions;
    }

   
    public BeanDefinetion(String id, String type) {
        this.id = id;
        this.type = type;
    }

   
}


public class PropertyDefinition {

    private String name;
    private String ref;
    private String value;

    public String getValue() {
        return value;
    }

    public void setValue(String value) {
        this.value = value;
    }


   

    public String getName() {
        return name;
    }

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

    public String getRef() {
        return ref;
    }

    public void setRef(String ref) {
        this.ref = ref;
    }

    public PropertyDefinition(String name, String ref,String value) {
        this.name = name;
        this.ref = ref;
        this.value=value;
    }


}


属性或字段注入注解

@Target({ElementType.FIELD,ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface YmResource {

    public String name() default "";

}

对象注解
@Target({ElementType.TYPE, ElementType.FIELD, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface YmService {
    String value() default "";
}

容器实现
package spring;

import java.beans.IntrospectionException;
import java.beans.PropertyDescriptor;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.net.URL;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.XPath;
import org.dom4j.io.SAXReader;

/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
/**
*
* @author Administrator
*/
public class ClassPathXmlApplicationContext extends ApplicationContext {

    private Map<String, Object> singletons = new HashMap<String, Object>();
    private List<BeanDefinetion> beanDefinetions = new LinkedList<BeanDefinetion>();
    private List<String> beansFile = new LinkedList<String>();
    private InputStream input;
    private String basepcakage;

    public ClassPathXmlApplicationContext(String file) {
        try {
            input = getClass().getResourceAsStream(file);
            parseXML();//xml解析
            beanInstance();//基于xml的对象实例
            beanAnnotationInstance();//基于注解的对象实例
            injectObject();//基于xml的对象注入
            injectAnnotationObject();//基于注解的对象注入
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    private void beanAnnotationInstance() throws Exception {

        System.out.println(beanDefinetions);

        for (BeanDefinetion beanDefinetion : beanDefinetions) {
            Class z = Class.forName(beanDefinetion.getType());
            singletons.put(beanDefinetion.getId(), z.newInstance());
        }
        System.out.println(singletons);
    }

    public void list(File file) throws Exception {
        String id = null;
        if (file.isDirectory()) {
            File[] files = file.listFiles();
            for (File f : files) {
                list(f);
            }
        } else {
            if (file.getName().endsWith(".class")) {
                // System.out.println(file.getName().replace(".class", ""));
                String type = getType(file);
                Class z = Class.forName(type);
                if (z.isAnnotationPresent(YmService.class)) {
                    Annotation[] annotations = z.getAnnotations();
                    for (Annotation annotation : annotations) {
                        if (annotation.annotationType() == YmService.class) {
                            id = ((YmService) annotation).value();
                        }
                    }

                    BeanDefinetion beanDefinetion = new BeanDefinetion(id, type);
                    beanDefinetions.add(beanDefinetion);
                }
            }
        }


    }

    private String getType(File file) {
        String path = file.getPath();
        path = path.substring(path.indexOf("classes")).replace("classes" + File.separator, "");
        return path.replace(File.separator, ".").replace(".class", "");
    }

    private void injectAnnotationObject() throws Exception {


        for (BeanDefinetion beanDefinetion : beanDefinetions) {
            PropertyDescriptor[] propertyDescriptors = java.beans.Introspector.getBeanInfo(Class.forName(beanDefinetion.getType())).getPropertyDescriptors();
            for (PropertyDescriptor propertyDescriptor : propertyDescriptors) {
                Method setter = propertyDescriptor.getWriteMethod();
                if (setter != null && setter.isAnnotationPresent(YmResource.class)) {
                    YmResource ymResource = setter.getAnnotation(YmResource.class);
                    String ref = ymResource.name();
                    setter.setAccessible(true);
                    setter.invoke(singletons.get(beanDefinetion.getId()), singletons.get(ref));
                }
            }

            Field[] fields = Class.forName(beanDefinetion.getType()).getDeclaredFields();
            for (Field field : fields) {
                if (field != null && field.isAnnotationPresent(YmResource.class)) {
                    YmResource ymResource = field.getAnnotation(YmResource.class);
                    String ref = ymResource.name();
                    field.setAccessible(true);
                    field.set(singletons.get(beanDefinetion.getId()), singletons.get(ref));
                }
            }

        }



    }

    private void injectObject() throws Exception {
        for (BeanDefinetion beanDefinetion : beanDefinetions) {
            for (PropertyDefinition propertyDefinition : beanDefinetion.getPropertyDefinitions()) {
                PropertyDescriptor[] propertyDescriptors = java.beans.Introspector.getBeanInfo(Class.forName(beanDefinetion.getType())).getPropertyDescriptors();
                for (PropertyDescriptor propertyDescriptor : propertyDescriptors) {
                    if (propertyDescriptor.getName().equals(propertyDefinition.getName())) {
                        Method setter = propertyDescriptor.getWriteMethod();
                        setter.setAccessible(true);
                        if (propertyDefinition.getValue() == null) {
                            setter.invoke(singletons.get(beanDefinetion.getId()), singletons.get(propertyDefinition.getName()));
                        } else {
                            setter.invoke(singletons.get(beanDefinetion.getId()), propertyDefinition.getValue());
                        }

                    }
                }
            }

        }


    }

    private void parseXML() throws Exception {
        SAXReader reader = new SAXReader();
        Document doc = reader.read(input);
        Map<String, String> ns = new HashMap<String, String>();
        ns.put("ns", "http://www.springframework.org/schema/beans");
        XPath xpath = doc.createXPath("//ns:beans/ns:bean");
        xpath.setNamespaceURIs(ns);

        List<Element> elements = xpath.selectNodes(doc);
        for (Element element : elements) {
            String id = element.attributeValue("id");
            String type = element.attributeValue("class");
            BeanDefinetion beanDefinetion = new BeanDefinetion(id, type);
            beanDefinetions.add(beanDefinetion);
            List<Element> propertys = element.selectNodes("property");
            for (Element property : propertys) {
                String name = property.attributeValue("name");
                String ref = property.attributeValue("ref");
                String value = property.attributeValue("value");
                PropertyDefinition propertyDefinition = new PropertyDefinition(name, ref, value);
                beanDefinetion.getPropertyDefinitions().add(propertyDefinition);
            }
        }



     
        ns = new HashMap<String, String>();
        ns.put("context", "http://www.springframework.org/schema/context");
        xpath = doc.createXPath("//context:component-scan");
        xpath.setNamespaceURIs(ns);
        elements = xpath.selectNodes(doc);
        System.out.println(elements);
        Element element = elements.get(0);
        basepcakage = element.attributeValue("base-package");
        System.out.println(basepcakage);

        try {
            Enumeration enumer = ClassLoader.getSystemResources(basepcakage);
            while (enumer.hasMoreElements()) {
                URL path = (URL) enumer.nextElement();
                list(new File(path.getFile()));

            }
        } catch (IOException ex) {
            Logger.getLogger(ClassPathXmlApplicationContext.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    private void beanInstance() throws Exception {
        for (BeanDefinetion beanDefinetion : beanDefinetions) {
            Object o = Class.forName(beanDefinetion.getType()).newInstance();
            singletons.put(beanDefinetion.getId(), o);
        }
    }

    @Override
    public Object getBean(String id) {
        return singletons.get(id);
    }
}


测试的部分
<beans  xmlns="http://www.springframework.org/schema/beans"
        xmlns:context="http://www.springframework.org/schema/context">
<context:component-scan base-package="ym"/>
<bean id="test" class="ym.Test"/>
</beans>



public interface ProductDao {

    public void insert();
}

@YmService("productDao")
public class ProductDaoBean  implements ProductDao{

    public void insert() {
       System.out.println("svae............");
    }


}

public interface  ProductService {
    void  newProduct();
}


@YmService("productService")
public class ProductServiceBean  implements ProductService{

    public void newProduct() {
       productDao.insert();
       System.out.print(name);
    }

   @YmResource(name="productDao")  private ProductDao productDao;

    public ProductDao getProductDao() {
        return productDao;
    }

   // @YmResource(name="productDao")
    public void setProductDao(ProductDao productDao) {
        this.productDao = productDao;
    }




    private String name;

    public String getName() {
        return name;
    }

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

｝


public class Test {

    public static void main(String[] args) {
        //ProductService productService=new ProductServiceBean();
        ApplicationContext ctx = new ClassPathXmlApplicationContext("spring.xml");
        ProductService productService=(ProductService)ctx.getBean("productService");
        productService.newProduct();

    }
}