2018-03-04 Filter类(五):实现全站请求编码同一

笔记如下

• web.xml
  作用于全servlet请求

  
  4.png

• GenericEncodingFilter

public class GenericEncodingFilter implements Filter {

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        // TODO Auto-generated method stub

    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        
        HttpServletRequest req = (HttpServletRequest)request;
        HttpServletResponse resp= (HttpServletResponse) response;
        
        if ("post".equals(req.getMethod())) {
            
            req.setCharacterEncoding("UTF-8");
            
        }
        
        //包装类
        MyHttpServletRequestWrapper myrequest = new MyHttpServletRequestWrapper(req);
        
        
        chain.doFilter(myrequest, resp);//执行,放行

        
    }

    @Override
    public void destroy() {
        // TODO Auto-generated method stub

    }
    
}

class MyHttpServletRequestWrapper extends HttpServletRequestWrapper{
    
    private HttpServletRequest request;
    
    public MyHttpServletRequestWrapper(HttpServletRequest request) {
        super(request);
        this.request = request;
    }
    
    @Override
    public String getParameter(String name) {
        
        Map<String,String[]> map = getParameterMap();
        //获得对应  values 数组 
        String[] values = map.get(name);
        
        if(values!=null){
            
            //返回数组的第一个元素 
            return values[0];
        }
        return null;
    }
    
    @Override
    public String[] getParameterValues(String name) {
        Map<String,String[]> map = getParameterMap();
        //获得对应  values 数组 
        String[] values = map.get(name);
        return values;
    }
    
    //默认的是false, 表示没有 被 解码 过 
    private boolean hasBeenEncoded= false;
    
    
    @Override
    public Map<String, String[]> getParameterMap() {
        
        String method = request.getMethod();
        if ("post".equalsIgnoreCase(method)) {
            
            //进来说明是post请求方法
            
            try {
            
                request.setCharacterEncoding("UTF-8");
                
            } catch (Exception e) {
                // TODO: handle exception
                e.printStackTrace();
            }
            
        }else {
            
            //说明是get
            //拿到有乱码的map
            Map<String, String[]> map = request.getParameterMap();
            
            //遍历map
            Set<String> keys = map.keySet();
            
            if(!hasBeenEncoded){
                hasBeenEncoded = true;
                
                for (String key : keys) {
                    
                    //当前是乱码的
                    String[] values = map.get(key);
                    
                    for (int i = 0; i < values.length; i++) {
                        
                        try {
                            values[i] = new String(values[i].getBytes("iso8859-1"),"UTF-8");
                        } catch (UnsupportedEncodingException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
                        
                    }
                    
                }
            }
            
            
            return map;
            
        }
        
        return super.getParameterMap();
    }
    
}