动态代理和静态代理的区别

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;}}