全站统一字符编码的几种方式

向右看齐 2022-06-10 23:55 157阅读 0赞

# 统一字符编码 #

## 装饰设计模式 ##

import javax.servlet.*;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletRequestWrapper;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    import java.io.UnsupportedEncodingException;
    import java.util.Map;
    
    
    public class EncodingFilter implements Filter { 
        public void destroy() {
        }
    
        public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
            //强转
            HttpServletRequest request = (HttpServletRequest) req;
            HttpServletResponse response = (HttpServletResponse) resp;
            //放行
            chain.doFilter(new MyRequest(request), response);
        }
    
        public void init(FilterConfig config) throws ServletException {
    
        }
    
    }
    
    class MyRequest extends HttpServletRequestWrapper {
        private HttpServletRequest request;
        //同一个对象只进行一次编码处理
        private boolean flag = true;
    
        public MyRequest(HttpServletRequest request) {
            super(request);
            this.request = request;
    
        }
    
        @Override
        public String getParameter(String name) {
            if (name == null || name.trim().length() == 0) {
                return null;
            }
            String[] values = getParameterValues(name);
            if (values == null || values.length == 0) {
                return null;
            }
            return values[0];
        }
    
        @Override
        public String[] getParameterValues(String name) {
            if (name == null || name.trim().length() == 0) {
                return null;
            }
            Map<String, String[]> map = getParameterMap();
            if (map == null || map.size() == 0) {
                return null;
            }
            return map.get(name);
        }
    
        @Override
        public Map<String, String[]> getParameterMap() {
            //截获表单访问方式
            String method = request.getMethod();
            Map<String, String[]> map = null;
            if (method.equalsIgnoreCase("POST")) {
                try {
                    request.setCharacterEncoding("UTF-8");
                    map = request.getParameterMap();
                    return map;
                } catch (UnsupportedEncodingException e) {
                    e.printStackTrace();
                }
    
            } else if (method.equalsIgnoreCase("GET")) {
                map = request.getParameterMap();
                if (flag) {
                    for (String key : map.keySet()) {
                        String[] values = map.get(key);
                        for (int i = 0; i < values.length; i++) {
                            try {
                                String value = new String(values[i].getBytes("ISO8859-1"), "UTF-8");
                                values[i] = value;
                            } catch (UnsupportedEncodingException e) {
                                e.printStackTrace();
                            }
                        }
                        map.replace(key, values);
                        return map;
                    }
                    flag = false;
                }
            }
            return super.getParameterMap();
        }
    }

## 使用代理 ##

import java.io.IOException;
    import java.lang.reflect.InvocationHandler;
    import java.lang.reflect.Method;
    import java.lang.reflect.Proxy;
    
    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.annotation.WebFilter;
    import javax.servlet.http.HttpServletRequest;
    
    @WebFilter(urlPatterns="/*")
    public class GenericCharacterEncodingFilter implements Filter{ 
    
        @Override
        public void init(FilterConfig filterConfig) throws ServletException {
    
        }
    
        @Override
        public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
                throws IOException, ServletException {
            final HttpServletRequest req = (HttpServletRequest) request;
    
            // 对req产生代理对象:
            HttpServletRequest myReq = (HttpServletRequest) Proxy.newProxyInstance(req.getClass().getClassLoader(),req.getClass().getInterfaces(), new InvocationHandler() {
    
                @Override
                public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                    // 增强getParameter:
                    if("getParameter".equals(method.getName())){
                        // 增强.
                        // 根据请求方式:
                        String type = req.getMethod();
                        if("get".equalsIgnoreCase(type)){
                            // 调用原有的getParameter：
                            String value = (String)method.invoke(req, args);
                            String s = new String(value.getBytes("ISO-8859-1"),"UTF-8");
                            return s;
    
                        }else if("post".equalsIgnoreCase(type)){
                            req.setCharacterEncoding("UTF-8");
                            return method.invoke(req, args);
                        }
    
                    }
                    // 不增强:
                    return method.invoke(req, args);    
                }
            });
    
            chain.doFilter(myReq, response);
        }
    
        @Override
        public void destroy() {
    
        }
    
    }