Spring笔记之(一)初探

<?xml version="1.0" encoding="UTF-8"?>
<beans>
    <bean />
    </bean>
</beans>

public class myspring {
    public static void main(String[] args) throws Exception{ 
        Unit unit = (Unit)(BeanFactory.getBean("D:\……mytest\src\test\sprint.xml", "beanId"));
        System.out.print("unit is "+unit.toString()+",name:"+unit.getName()+",value:"+unit.getValue());
    }
}

public class Unit {
    private String name; // 注意这里的name与以上xml文件的name是对用关系（必须相同）
    private String value; // 同上
    public Unit(){
        System.out.print("create Unit object ");
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getValue() {
        return value;
    }
    public void setValue(String value) {
        this.value = value;
    }
}

package test;

import java.io.File;
import java.lang.reflect.InvocationTargetException;
import java.util.List;
import org.apache.commons.beanutils.BeanUtils;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;

public class BeanFactory {

    // 获取实例化后的对象
    static public Object getBean(String path,String nodeName) throws DocumentException, InstantiationException, IllegalAccessException, ClassNotFoundException, InvocationTargetException{
        Document document = loadXml(path);
        Element nodeElement = getNodeElement(document,nodeName);
        Object obj = reflectObject(nodeElement);
        setObjectAttr(obj,nodeElement);
        return obj;
    }

    // 加载xml文件
    static public Document loadXml(String path) throws DocumentException {
        SAXReader read = new SAXReader();
        return read.read(new File(path));
    }

    // 根据以上xml文件中配置的类全路径（pojo.Unit）使用反射得到实例
    static public Object reflectObject(Element node) throws InstantiationException, IllegalAccessException, ClassNotFoundException{
        return Class.forName(node.attributeValue("class")).newInstance();
    }

    
    static public Element getNodeElement(Document doc,String name){
        String nodeName = "//bean[@id='"+name+"']";
        return (Element)doc.selectSingleNode(nodeName);
    }

    // 根据spring.xml中的配置设置Unit对象的属性值即name和value的值
    static public void setObjectAttr(Object obj,Element element) throws IllegalAccessException, InvocationTargetException{
        List<Element> list = element.elements("property");
        for (Element node:list){
            String name = node.attributeValue("name");
            String value = node.attributeValue("value");

            // 这里关注下 BeanUtils工具类的使用
            BeanUtils.setProperty(obj, name, value);
        }
    }
}