SpringMVC中CharacterEncodingFilter为会在HiddenHttpMethodFilter之前

短命女 2023-05-21 07:27 26阅读 0赞

## 对于过滤器来说，就是在第一次请求前就要过滤条件，比如登录条件过滤，乱码过滤、HTTP请求过滤，但是对于这个只知道先过滤字符乱码然后其他，那么为什么要这么做呢！我们可以从源码中看到问题的实质 ##

*  CharacterEncodingFilter（通过构造方法来设置传入的字符集）

public class CharacterEncodingFilter extends OncePerRequestFilter { 
    
    	@Nullable
    	private String encoding;
    
    	private boolean forceRequestEncoding = false;
    
    	private boolean forceResponseEncoding = false;
    
    
    	/** * Create a default {@code CharacterEncodingFilter}, * with the encoding to be set via {@link #setEncoding}. * @see #setEncoding */
    	public CharacterEncodingFilter() { 
    	}
    
    	/** * Create a {@code CharacterEncodingFilter} for the given encoding. * @param encoding the encoding to apply * @since 4.2.3 * @see #setEncoding */
    	public CharacterEncodingFilter(String encoding) { 
    		this(encoding, false);
    	}
    	public void setEncoding(@Nullable String encoding) { 
    		this.encoding = encoding;
    	}
    @Override
    	protected void doFilterInternal(
    			HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
    			throws ServletException, IOException { 
    
    		String encoding = getEncoding();
    		if (encoding != null) { 
    			if (isForceRequestEncoding() || request.getCharacterEncoding() == null) { 
    				request.setCharacterEncoding(encoding);
    			}
    			if (isForceResponseEncoding()) { 
    				response.setCharacterEncoding(encoding);
    			}
    		}
    		filterChain.doFilter(request, response);
    	}

*  HiddenHttpMethodFilter，这个一上来就要了一个method并没有设置字符集什么的，如果这个在前，那么必定会发生乱码

@Override
    	protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
    			throws ServletException, IOException { 
    
    		HttpServletRequest requestToUse = request;
    
    		if ("POST".equals(request.getMethod()) && request.getAttribute(WebUtils.ERROR_EXCEPTION_ATTRIBUTE) == null) { 
    			String paramValue = request.getParameter(this.methodParam);
    			if (StringUtils.hasLength(paramValue)) { 
    				requestToUse = new HttpMethodRequestWrapper(request, paramValue);
    			}
    		}
    
    		filterChain.doFilter(requestToUse, response);
    	}

## 所以必须先写CharacterEncodingFilter再写HiddenHttpMethodFilter ##