使用javassist高级反射调用任意参数的方法-模拟Struts2的实现

注：转自王健老师QQ空间。。。。很接地气的代码。。。。 URL：http://user.qzone.qq.com/549051701/blog/1466088405
使用javassist高级反射调用任意参数的方法-模拟Struts2的实现

1：核心过虑器

package cn.mystruts;

import java.io.IOException;

import java.lang.reflect.Method;

import java.net.URL;

import javax.servlet.Filter;

import javax.servlet.FilterChain;

import javax.servlet.FilterConfig;

import javax.servlet.ServletException;

import javax.servlet.ServletRequest;

import javax.servlet.ServletResponse;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.HttpSession;

import org.apache.commons.beanutils.BeanUtils;

import org.dom4j.Document;

import org.dom4j.Element;

import org.dom4j.io.SAXReader;

import javassist.ClassClassPath;

import javassist.ClassPool;

import javassist.CtClass;

import javassist.CtMember;

import javassist.CtMethod;

/**

 * 使用javassist高级反射动态调用任意方法的过虑器实现

 * @author wangjian

 */

public class CoreFilter implements Filter {

private Document dom;

 

@Override

public void init(FilterConfig filterConfig) throws ServletException {

try {

SAXReader reader = new SAXReader();

String pa = CoreFilter.class.getClassLoader().getResource("mystruts.xml").getPath();

System.err.println("p2 is:" + pa);

dom = reader.read(pa);

} catch (Exception e) {

throw new RuntimeException(e);

}

}

 

// url-pattern=/*

// http://ip:port/project/one

@Override

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)

throws IOException, ServletException {

HttpServletRequest req = (HttpServletRequest) request;

String uri = req.getRequestURI();

uri = uri.replace(req.getContextPath() + "/", "");

 

String action = "";

String methodName = "execute";//默认的方法名为execute

if (uri.contains("!")) {//如果在uri中包含 !即：one!say则解析出方法名为say

action = uri.substring(0, uri.indexOf("!"));

methodName = uri.substring(uri.indexOf("!") + 1);

} else {

action = uri;//默认action名称即为uri

}

 

// 取出one从dom中查询

String xpath = "//controller[@name='" + action + "']";

Element ele = (Element) dom.selectSingleNode(xpath);

try {

if (ele != null) {

// 如果配置过

// 解析且通过反射来执行它

String clsName = ele.attributeValue("class");

Class cls = Class.forName(clsName);

Object obj = cls.newInstance();

 

// 判断是否是Model的子类，设置参数

if (obj instanceof Model) {

Object bean = ((Model) obj).getBean();

BeanUtils.populate(bean, req.getParameterMap());

}

 

// 设置参数

BeanUtils.populate(obj, req.getParameterMap());

 

// 反射出方法的参数 - 通过高级反射javassist反射出方法

ClassPool cp = ClassPool.getDefault();

//设置从当前类目录下加载Class类

cp.insertClassPath(new ClassClassPath(this.getClass()));

CtClass ctClass = cp.get(cls.getName());

 

CtMethod ctMethod = ctClass.getDeclaredMethod(methodName);

int paramSize = ctMethod.getParameterTypes().length;

Class[] clses = new Class[paramSize];

 

for (int i = 0; i < paramSize; i++) {

clses[i] = Class.forName(ctMethod.getParameterTypes()[i].getName());

}

 

// 反射来执行它

Method method = cls.getMethod(methodName, clses);

//判断参数，并设置参数类型和参数值

Object[] paramObjs = new Object[paramSize];

for (int i = 0; i < paramSize; i++) {

for (int j = 0; j < 4; j++) {

if (clses[i] == HttpSession.class) {

paramObjs[i] = req.getSession();

}else if(clses[i] == HttpServletRequest.class){

paramObjs[i] = req;

}else{

Object ooBean = clses[i].newInstance();

paramObjs[i] = ooBean;

BeanUtils.populate(ooBean, req.getParameterMap());

}

}

 

}

 

String res = (String) method.invoke(obj,paramObjs);

// 执行完成了

 

if (obj instanceof Model) {

Object bean = ((Model) obj).getBean();

// user

req.setAttribute(bean.getClass().getSimpleName().toLowerCase(), bean);

}

req.setAttribute(obj.getClass().getSimpleName().toLowerCase(), obj);

 

if (res != null) {

// 找到page页面转 发

xpath += "/page[@name='" + res + "']";

Element page = (Element) dom.selectSingleNode(xpath);

if (page != null) {

String jsp = page.getText();

req.getRequestDispatcher(jsp).forward(request, response);

}

}

// 返回的这字符串表示的是

} else {// 如果没有找到则直接放行

// HttpServletResponse resp = (HttpServletResponse) response;

// resp.sendError(407, "没有配置【" + uri + "】这个action。。");

chain.doFilter(request, response);

}

} catch (Exception e) {

throw new RuntimeException(e);

}

}

 

@Override

public void destroy() {

}

}

 

2：配置

<filter>

<filter-name>m2</filter-name>

<filter-class>cn.mystruts.CoreFilter</filter-class>

</filter>

<filter-mapping>

<filter-name>m2</filter-name>

<url-pattern>/*</url-pattern>

</filter-mapping>

3：配置action

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

<mystruts>

<controller name="one" class="cn.mystruts.OneAction">

<page name="success">/jsps/show.jsp</page>

</controller>

</mystruts>

4：开发Action任意类

package cn.mystruts;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpSession;

import cn.mystruts.domain.User;

/**

 * 任意类，可以包含任意方法

 * @author wangjian

 */

public class OneAction implements Model<User> {

private String name;

private User user = new User();

 

@Override

public User getBean() {

return user;

}

 

public String getName() {

return name;

}

 

public void setName(String name) {

this.name = name;

}

 

public String execute() {

System.err.println("user is:" + user);

user.setName("Alext新名称");

System.err.println("接收到的值是:" + name);

name = "修改以后的名称";

return "success";

}

 

// one!hi

public String hi() {

System.err.println("Hi....");

return "success";

}

 

public String say(HttpSession s) {

System.err.println("say is ...." + s);

return "success";

}

 

public String good(HttpSession s, HttpServletRequest req) {

System.err.println("good is ...." + s + ",req is:" + req);

return "success";

}

 

public String hello(HttpSession s, HttpServletRequest req, User u) {

System.err.println("hello is ...." + s + ",req is:" + req + ",user is:" + u);

return "success";

}

 

public String ok(User user){

System.err.println("in ok user is:"+user);

return "success";

}

 

}

5：测试

<a href="one!hi">调用OneActon.hi()</a>

<br>

<a href="one!say">调用OneAction.say(HttpSession)</a>

<br>

<a href="one!good">调用OneAction.good(HttpSessoin,HttpServletRequest)</a>

<br>

<a href="one!hello?name=Jack">调用OneAction.hello(HttpSession,HttpServletRequest,User)同时封装参数</a>

6：运行结果
   say is ....org.apache.catalina.session.StandardSessionFacade@6747f5 //正确接收到Session

good is ....org.apache.catalina.session.StandardSessionFacade@6747f5,req is:org.apache.catalina.connector.RequestFacade@1bd42e8 //正确接收到Session,Request

 

hello is ....org.apache.catalina.session.StandardSessionFacade@6747f5,req is:org.apache.catalina.connector.RequestFacade@1bd42e8,user is:User [name=Jack, age=null]//正确接收到Session,Req,Bean

小结：
   ClassPool高级反射
   ClassPool反射出方法的所有参数。
   必须要设置ClassPool加载的类路径即classPool.insertClassPath(...);