自定义标签：在JSP页面中动态执行Spring Bean的方法

自定义标签：在JSP页面中动态执行Spring Bean的方法

     使用该自定义标签，可以在JSP页面中动态执行某个Spring Bean对象的一个方法，方法返回的结果存储在ValueStack中。该自定义标签在Spring2、Struts2、Hibernate3环境下测试通过。

一、java源代码

    1、ServiceTag源代码

Java代码

public class ServiceTag extends BaseBodyTagSupport {
	private String beanName;
	private String methodName;
	private String id;
	public List params = new ArrayList();
	
	public void setBeanName(String beanName) {
		this.beanName = beanName;
	}
	
	public void setMethodName(String methodName) {
		this.methodName = methodName;
	}

	public void setId(String id) {
		this.id = id;
	}
	
	public int doEndTag() throws JspException {		
		Object bean = null;
		Method method = null;
		
		//取得bean对象
		try{
			bean = SpringContextUtil.getBean(beanName);
		}catch(Exception ex){
			throw new JspException("get bean error: " + beanName);
		}
		
		//通过反射取得方法
		if(bean != null){
			try {
				method = bean.getClass().getMethod(methodName, TagUtil.getParameterTypes(params));
			}catch(Exception e) {
				throw new JspException("get method error: " + beanName + "." + methodName);
			}
		}else{
			throw new JspException("ServiceTag Error: bean [" + beanName + "] is null");
		}
		
		//通过反射执行方法，得到结果
		Object result = null;
		if(method != null){
			try {
				result = method.invoke(bean, TagUtil.getParameterValues(params));
			}catch(Exception e){
				throw new JspException("method invoke error");
			}
		}
		
		//将结果存储在ValueStack中
		ValueStack vs = TagUtils.getStack(pageContext);
		vs.getContext().put(id, result);
		
		return EVAL_PAGE;
	}
}

 

    2、ServiceParamTag源代码

Java代码

public class ServiceParamTag extends BaseBodyTagSupport {
	private String name;
	private Object value;
	private String type;
	
	public void setName(String name) {
		this.name = name;
	}

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

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

	public int doEndTag() throws JspException {
		Tag parent = getParent();
		if(parent instanceof ServiceTag){
			Map p = new HashMap();
			p.put("paramName", name);
			p.put("paramValue", value);
			p.put("paramType", type);
			((ServiceTag)parent).params.add(p);
		}
		
		return EVAL_PAGE;
	}
}

 

    3、公共方法源代码

Java代码

//参数类型数组
public static Class[] getParameterTypes(List params) throws Exception{
	Class[] c = new Class[params.size()];
	
	for(int i=0;i

 

* 一定要在spring.xml中加上:

* <bean id="SpringContextUtil " class="com.hmw.spring.SpringContextUtil" singleton="true" />

* 当对SpringContextUtil 实例时就自动设置applicationContext,以便后来可直接用applicationContext

*

package org.company.xxx;

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
    /**
     *
     * 获取spring容器，以访问容器中定义的其他bean
     * @author lyltiger
     * @since MOSTsView 3.0 2009-11-16
     */
public class SpringContextUtil implements ApplicationContextAware {

    // Spring应用上下文环境
    private static ApplicationContext applicationContext;

    /**
     * 实现ApplicationContextAware接口的回调方法，设置上下文环境
     *
     * @param applicationContext
     */
    public void setApplicationContext(ApplicationContext applicationContext) {
        SpringContextUtil.applicationContext = applicationContext;
    }

    /**
     * @return ApplicationContext
     */
    public static ApplicationContext getApplicationContext() {
        return applicationContext;
    }

    /**
     * 获取对象
     * 这里重写了bean方法，起主要作用
     * @param name
     * @return Object 一个以所给名字注册的bean的实例
     * @throws BeansException
     */
    public static Object getBean(String name) throws BeansException {
        return applicationContext.getBean(name);
    }

}

二、tld文件源代码

Xml代码

	serviceBean
	com.cjm.web.taglib.ServiceTag
	JSP
	
		beanName
		true
		true
	
	
		methodName
		true
		true
	
	
		id
		true
		true
	



	serviceParam
	com.cjm.web.taglib.ServiceParamTag
	JSP
	
		name
		true
		true
	
	
		value
		true
		true
	
	
		type
		true
		true
	

 

三、范例

    1、java源代码

Java代码

public class RoleService extends BaseService {
	private RoleDao roleDao;
	
	public RoleDao getRoleDao() {
		return roleDao;
	}

	public void setRoleDao(RoleDao roleDao) {
		this.roleDao = roleDao;
	}

	public Role getRole(String roleId){
		return (Role)get(Role.class, roleId);
	}
}

    2、JSP页面源代码

<cjm:serviceBean beanName="roleService" methodName="getRole" id="result">
    <cjm:serviceParam name="roleId" value="ADMIN" type="java.lang.String"/>
cjm:serviceBean>

<s:property value="#result.roleName"/>