2.7.0版本getContextPath方法：
```
protected String getContextPath(URL url) {
        String contextPath = url.getPath();
        return contextPath.endsWith("/") ? contextPath.substring(0,contextPath.length()-1) : contextPath;
    }
```
无法将方法置入web容器中，退回2.6.5版本的方法：
```
protected String getContextPath(URL url) {
        int pos = url.getPath().lastIndexOf("/");
        return pos > 0 ? url.getPath().substring(0, pos) : "";
    }
```
使用正常，两个方法应该不等价的。
map.putAll(parameters);
        return new URL(protocol, username, password, host, port, path, map);
    }
    public URL addParametersIfAbsent(Map<String, String> parameters) {
        if (CollectionUtils.isEmptyMap(parameters)) {
            return this;
        }
        Map<String, String> map = new HashMap<>(parameters);
        map.putAll(getParameters());
        return new URL(protocol, username, password, host, port, path, map);
    }
    public URL addParameters(String... pairs) {
        if (pairs == null || pairs.length == 0) {
            return this;
        }
        if (pairs.length % 2 != 0) {
            throw new IllegalArgumentException("Map pairs can not be odd number.");
        }
        Map<String, String> map = new HashMap<>();
        int len = pairs.length / 2;
        for (int i = 0; i < len; i++) {
            map.put(pairs[2 * i], pairs[2 * i + 1]);
        }
        return addParameters(map);
    }
    public URL addParameterString(String query) {
        if (StringUtils.isEmpty(query)) {
            return this;
        }
        return addParameters(StringUtils.parseQueryString(query));