使用HttpServletRequestWrapper重写Request请求参数

使用HttpServletRequestWrapper重写Request请求参数

前言

改变请求参数的值,满足项目需求（通过过滤器过滤请求，增加用户信息进入到请求头）

public class HeaderHttpServletRequestWrapper extends HttpServletRequestWrapper {

    private final Map<String, String> customHeaders;

    public HeaderHttpServletRequestWrapper(HttpServletRequest request) {
        super(request);
        this.customHeaders = new HashMap<>();
    }

    public void setHeader(String name, String value) {
        this.customHeaders.put(name, value);
    }

    @Override
    public String getHeader(String name) {
        String headerValue = customHeaders.get(name);

        if (null != headerValue) {
            return headerValue;
        }
        return ((HttpServletRequest) getRequest()).getHeader(name);
    }

    @Override
    public Enumeration<String> getHeaderNames() {
        Set<String> set = new HashSet<>(customHeaders.keySet());

        Enumeration<String> e = ((HttpServletRequest) getRequest()).getHeaderNames();
        while (e.hasMoreElements()) {
            String n = e.nextElement();
            set.add(n);
        }

        return Collections.enumeration(set);
    }

    @Override
    public Enumeration<String> getHeaders(String name) {
        List<String> values = Collections.list(super.getHeaders(name));

        if (customHeaders.containsKey(name)) {
            values = Collections.singletonList(customHeaders.get(name));
        }

        return Collections.enumeration(values);
    }
}