动态代理和静态代理的区别
动态代理是在运行时，将代理类加载到内存中
静态代理是提前把代理类写好，然后再启动项目的时候把代理类加载到内存中

动态代理

public class EncodingFilter implements Filter {public void destroy() {}public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException { //0 强转 final HttpServletRequest request = (HttpServletRequest) req; HttpServletResponse response = (HttpServletResponse) resp; //1 post乱码 request.setCharacterEncoding("UTF-8"); //2 使用动态代理增强request HttpServletRequest proxyRequest = (HttpServletRequest)Proxy.newProxyInstance( EncodingFilter.class.getClassLoader(), new Class[] { HttpServletRequest.class } , new InvocationHandler(){ @Override public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { //增强 String methodName = method.getName(); if("getParameter".equals(methodName)){ //args 所有参数 --> getParameter("username"); //1 从tomcat request获得原始数据（乱码） String value = request.getParameter((String)args[0]); //2 如果get请求处理乱码 if("GET".equals(request.getMethod())){ value = new String( value.getBytes("ISO-8859-1") , "UTF-8"); } //3 将结果返回 return value; } //不需要增强的直接执行目标类的方法 return method.invoke(request, args); } }); chain.doFilter(proxyRequest, response);}public void init(FilterConfig fConfig) throws ServletException {}}

静态代理（装饰者模式）

public class EncodingFilter implements Filter {public void destroy() {}public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException { //0 强转 HttpServletRequest request = (HttpServletRequest) req; HttpServletResponse response = (HttpServletResponse) resp; //1 post乱码 request.setCharacterEncoding("UTF-8"); //2 使用装饰者增强request MyRequest myRequest = new MyRequest(request); chain.doFilter(myRequest, response);}public void init(FilterConfig fConfig) throws ServletException {}}

/**

设计模式：固定的代码，用于解决固定问题装饰者：对方法进行增强
1.确定接口
2.提供成员变量
3.构造方法
4.增强需要的方法
*5.其他方法默认调用tomcat对应方法即可sun 提供 HttpServletRequest 接口使用装饰者编写默认类，及所有的方法都没有增强的。之后我们只需要继承即可

增强response对象，提供使用装饰者设计模式编写默认类：HttpServletResponseWrapper
*/

public class MyRequest extends HttpServletRequestWrapper {
private HttpServletRequest request; //tomcat request

public MyRequest(HttpServletRequest request){ super(request); this.request = request;}

//增强

@Override
public String getParameter(String name) {

//1 直接从tomcat的request获得数据String value = this.request.getParameter(name);//2 如果是get，处理// * 请求方式String method = this.request.getMethod();if("GET".equals(method)){ try { value = new String( value.getBytes("ISO-8859-1"), "UTF-8"); } catch (UnsupportedEncodingException e) { e.printStackTrace(); }} return value;}}