在开发中有时会遇到需要统一修改请求参数的需求，比如前端对某个请求参数进行了base64加密，后端需要统一进行解密。
这个时候只需要定义一个RequestParameterWrapper，再写一个Filter即可。
import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletRequestWrapper; import java.util.HashMap; import java.util.Map; /** * 请求参数修改 */ public class RequestParameterWrapper extends HttpServletRequestWrapper { private Map<String, String[]> params = new HashMap<>(); RequestParameterWrapper(HttpServletRequest request) { super(request); //将现有parameter传递给params this.params.putAll(request.getParameterMap()); } void addParameters(Map<String, Object> extraParams) { for (Map.Entry<String, Object> entry : extraParams.entrySet()) { addParameter(entry.getKey(), entry.getValue()); } } /** * 重写getParameter，代表参数从当前类中的map获取 * * @param name * @return */ @Override public String getParameter(String name) { String[] values = params.get(name); if (values == null || values.length == 0) { return null; } return values[0]; } /** * 同上 * * @param name * @return */ @Override public String[] getParameterValues(String name) { return params.get(name); } /** * 添加参数 * * @param name * @param value */ private void addParameter(String name, Object value) { if (value != null) { // System.out.println(value); if (value instanceof String[]) { params.put(name, (String[]) value); } else if (value instanceof String) { params.put(name, new String[]{(String) value}); } else { params.put(name, new String[]{String.valueOf(value)}); } } } }Filter
import lombok.extern.slf4j.Slf4j; import org.apache.commons.lang3.StringUtils; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Component; import org.springframework.web.filter.OncePerRequestFilter; import javax.servlet.FilterChain; import javax.servlet.ServletException; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; import java.net.URLDecoder; import java.util.HashMap; import java.util.Map; import java.util.Objects; /** * 请求设置 */ @Component @Slf4j public class ParamFilter extends OncePerRequestFilter { @Override protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain chain) throws IOException, ServletException { // 获取你需要的参数 String param = request.getParameter("key"); if (StringUtils.isBlank(param)) { chain.doFilter(request, response); } else { byte[] bytes = new BASE64Decoder().decodeBuffer(param); String decode = new String(bytes); Map<String, Object> map = new HashMap<>(); map.put("key", new String[]{decode}); RequestParameterWrapper wrapper = new RequestParameterWrapper(request); wrapper.addParameters(map); chain.doFilter(wrapper, response); } } }这个样在controller获取的key就是base64解密后的字符串了
