javaWeb 字体替换过滤器

字体替换过滤器继承HttpServletRequestWrapper,重定义了: getParameter(),getParameterValues(),getParameterMap(),增强字节替换功能,满足更多的请求情况.

一: 字节替换过滤器:

package cc.openhome.controler;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebFilter("/*")
public class HtmlFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest sreq, ServletResponse sresp, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) sreq;
        HttpServletResponse resp = (HttpServletResponse) sresp;
        MyHtmlRequest mreq = new MyHtmlRequest(req);
        chain.doFilter(mreq,resp);
    }
    @Override
    public void destroy() {

    }
}

字节替换处理部分:

package cc.openhome.controler;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.util.*;

public class MyHtmlRequest extends HttpServletRequestWrapper {

    private HttpServletRequest req;
    public MyHtmlRequest(HttpServletRequest req){

        super(req);
        this.req = req;
    }

    public String getParameter(String name){
        String value = getRequest().getParameter(name);
        if(value == null){
            return null;
        }
        return filter(value);
    }

    public String [] getParameterValues(String name){
        String [] values = getRequest().getParameterValues(name);
        String [] res = new String[values.length];
        if(values == null){
            return null;
        }
        for(int i = 0;i < values.length;i++){
            res[i] = filter(values[i]);
        }
        return res;

    }

    public Map<String,String[]> getParameterMap(){
        Map<String,String[]> values = getRequest().getParameterMap();
        Map<String,String[]> res = new HashMap<String, String[]>();
        List <String> listv= new ArrayList<String>();
        String [] arrv;
        for(Iterator<String> it = values.keySet().iterator();it.hasNext();){
            String k = it.next();
            String [] v = values.get(k);
            if(v == null || v.length == 0){
                continue;
            }
            else {
                for (int i = 0;i < v.length;i++){
                    listv.add(filter(v[i]));
                }
                arrv = new String[listv.size()];
                arrv = listv.toArray(arrv);
            }
            res.put(k,arrv);
        }
        if(res == null){
            return null;
        }
        return res;
    }

    public String filter(String message){
        if(message == null){
            return null;
        }
        char content[] = new char[message.length()];
        message.getChars(0,message.length(),content,0);
        StringBuilder result = new StringBuilder(content.length + 50);
        for(int i = 0;i < content.length;i++){
            switch (content[i]){
                case '<':
                    result.append("&lt;");
                    break;
                case '>':
                    result.append("&gt;");
                    break;
                case '&':
                    result.append("&amp;");
                    break;
                case '"':
                    result.append("&quot");
                    break;
                default:
                    result.append(content[i]);
            }
        }
        return result.toString();
    }
}

对请求参数进行扩充,Filter方法处理请求到值.Filter方法可以扩充为功能更强大的方法.

二,总结:

(1).对getParameter(),getParameterValues(),getParameterMap(),方法有了更深入的理解.对于前端传入的复杂数据类型如checkbox数据,密码用户名等复杂数据类型处理

有了概念.

(2),首次使用List容器.