自定义 Filter 过滤器 和 HttpServletRequestWrapper 实现 request 参数 修改/验证

实现对request中参数去空格功能：
自定义过滤器：实现Filter

@Component
public class TestFilter implements Filter {

public TestFilter() {
}

@Override
public void init(FilterConfig filterConfig) throws ServletException {
}

@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws Exception {
HttpServletRequest req = (HttpServletRequest) request;
TestrequestWrapper testRequestWrapper = new TestRequestWrapper(req);
chain.doFilter(testRequestWrapper ,  response);
}

@Override
public void destroy() {
}

}

继承HttpServletRequestWrapper

public class TestWrapper extends HttpServletRequestWrapper {

private Map<String, String[]> params = new HashMap<>();

public TestWrapper(HttpServletRequest request) {
super(request);
this.params.putAll(request.getParameterMap());
this.modifyValues();
}

public void modifyValues() {//将parameter的值去除空格后重写回去
Set<String> set = params.keySet();
Iterator<String> iterator = set.iterator();
while (iterator .hasNext()) {
String ket = iterator .next();
String[] values = params.get(key);
for (int i = 0; i < values.length; i++) {
values[i] = values[i].trim();
}
params.put(key, values);
}
}

@Override
public Enumeration<String> getParameterNames() {
return new Vector<>(params.keySet()).elements();
}

@Override
public String getParameter(String name) {
String[] values = params.get(name);
if (values == null || values.length == 0) {
return null;
}
return values[0];
}

}

}