java实现Spring在XML配置java类的方法

1. 创建自己的bean文件：beans.xml

<?xml version="1.0" encoding="UTF-8"?>
<busi-beans>
	<beans>
		<bean id="SysHelloImpl" type="com.cxm.test.SysHello">
			<desc>test</desc>
			<impl-class>com.cxm.test.SysHelloImpl</impl-class>
		</bean>
	</beans>
</busi-beans>

2. 提供解析xml类：XmlUtils

/**
 *
 */
package com.cxm.xmlutil;

import java.io.InputStream;
import java.util.Iterator;
import java.util.Map;

import org.jdom.Attribute;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.input.SAXBuilder;
import org.jdom.xpath.XPath;

import com.cxm.beaninfo.BeanInfo;

/**
 * @author admin
 *
 */
public class XmlUtils
{

	public static void parseXmlDef(InputStream in, Map<String,BeanInfo> beanDefMap,
			StringBuffer sb) throws Exception
	{
		SAXBuilder reader = new SAXBuilder(false);
		Document doc = null;
		try
		{
			doc = reader.build(in);
			Iterator beanIt = XPath.selectNodes(doc, "/busi-beans/beans/bean")
					.iterator();
			Element e;
			BeanInfo beanDef;
			while (beanIt.hasNext())
			{
				beanDef = new BeanInfo();
				e = (Element) beanIt.next();
				Attribute attrId = e.getAttribute("id");
				Attribute attrType = e.getAttribute("type");
				Attribute singleType = e.getAttribute("single");
				boolean isSingle = true;
				if(null != singleType&&"1".equals(singleType.getValue())){
					isSingle= false;
				}
				beanDef.setSingle(isSingle);
				beanDef.setBeanId(attrId.getValue());
				beanDef.setType(attrType.getValue());
				beanDef.setBeanDesc(getText(e, "desc"));
				beanDef.setImplClassName(getText(e, "impl-class"));
				//处理初始化参数
				beanDefMap.put(attrId.getValue(), beanDef);
			}
		}
		catch (Exception e)
		{
			e.printStackTrace();
		}
	}

	/**
	 * 根据指定的element, xPath获取XML文档内容
	 *
	 * @param p_element
	 * @param p_xPath
	 * @return
	 * @throws Exception
	 */
	public static String getText(Element p_element, String p_xPath)
			throws Exception {
		String text = null;
		Element e=(Element)XPath.selectSingleNode(p_element,p_xPath);
		if (e != null) {
			text = e.getText();
		} else {
		}
		return text;
	}
}

3.定义bean IO

/**
 *
 */
package com.cxm.beaninfo;

/**
 * @author admin
 *
 */
public class BeanInfo
{
	private String beanId;

	private String type;

	private String beanDesc;

	public String getBeanDesc()
	{
		return beanDesc;
	}

	public void setBeanDesc(String beanDesc)
	{
		this.beanDesc = beanDesc;
	}

	public String getType()
	{
		return type;
	}

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

	private String implClassName;

	public String getBeanId()
	{
		return beanId;
	}

	public void setBeanId(String beanId)
	{
		this.beanId = beanId;
	}

	public String getImplClassName()
	{
		return implClassName;
	}

	public void setImplClassName(String implClassName)
	{
		this.implClassName = implClassName;
	}

	public boolean isSingle()
	{
		return isSingle;
	}

	public void setSingle(boolean isSingle)
	{
		this.isSingle = isSingle;
	}

	private boolean isSingle = true;

}

4.bean的创建类：BeanUtil

/**
 *
 */
package com.cxm.bean;

/**
 * @author admin
 *
 */
public class BeanUtil
{
	private static XmlBeanFactory factory = new XmlBeanFactory();
	/**
	 * 获取定义好的Bean对象
	 * @param p_beanId
	 * @return
	 * @throws Exception
	 */
	public static Object createBean(String p_beanId)
			throws Exception {
		return factory.createBean(p_beanId);
	}
}

/**
 *
 */
package com.cxm.bean;

import java.io.FileNotFoundException;
import java.io.InputStream;
import java.lang.reflect.Constructor;
import java.util.HashMap;
import java.util.Map;

import com.cxm.beaninfo.BeanInfo;
import com.cxm.exception.NoSuchBeanDefinitionException;
import com.cxm.xmlutil.XmlUtils;

/**
 * @author admin
 *
 */
public class XmlBeanFactory
{
	private static String BEAN_XML = "/beans.xml";

	private static Map<String,BeanInfo> beanDefMap = new HashMap<String,BeanInfo>();

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

	static {
		InputStream in = XmlBeanFactory.class.getResourceAsStream(BEAN_XML);
		if(in ==null){
			try{
				throw new FileNotFoundException();
			}catch (FileNotFoundException e){
				e.printStackTrace();
			}
		}
		StringBuffer sb = new StringBuffer();
		try
		{
			XmlUtils.parseXmlDef(in, beanDefMap, sb);
		}
		catch (Exception e)
		{
			throw new RuntimeException();
		}
	}

	public Object createBean(String beanId) throws Exception{
		if(beanId==null || beanId.trim()==""){
			throw new Exception("BeanId can not NULL or '' ");
		}
		BeanInfo beanInfo = beanDefMap.get(beanId);
		if(null ==beanInfo ){
			throw new NoSuchBeanDefinitionException(" beanid is not define in xml");
		}
		Object instance;
		if(beanInfo.isSingle()){
			instance =instanceMap.get(beanId);
			if(null != instance){
				return instance;
			}
		}
		String implClass = beanInfo.getImplClassName();
		Constructor<?> constructor = Class.forName(implClass.trim()).getConstructor();
		instance = constructor.newInstance();
		if(beanInfo.isSingle()){
			instanceMap.put(beanId, instance);
		}
		return instance;
	}
}

5. 测试：

/**
 *
 */
package com.cxm.test;

/**
 * @author admin
 *
 */
public interface SysHello
{
	void sysHello();
}

/**
 *
 */
package com.cxm.test;

/**
 * @author admin
 *
 */
public class SysHelloImpl implements SysHello
{

	@Override
	public void sysHello()
	{
		System.out.println("hello world!");

	}

}

/**
 *
 */
package com.cxm.test;

import com.cxm.bean.BeanUtil;

/**
 * @author admin
 *
 */
public class Test
{

	/**
	 * @param args
	 * @throws Exception
	 */
	public static void main(String[] args) throws Exception
	{
		SysHello s = (SysHello)BeanUtil.createBean("SysHelloImpl");
		s.sysHello();
	}

}

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