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; } }
