java - 传递一个类，实例化它，然后使用正确的方法

我有一个发送Get请求的包装方法：

public CloseableHttpResponse sendGetWithHeaders(String url, Map<String, String> headers) {

    HttpGet httpget = new HttpGet(url);

    // loop over entrySet() and httpget.setHeader(key, value);

    return client.execute(httpget); // client instantiated elsewhere
}

有用。

但是我不想为Head，Put，Options等创建另外5种几乎相同的方法。

我可以通过传递类来泛化这种方法吗？含义

sendRequestWithHeaders(HttpGet.class, "url", someMap)

以下尝试失败：

CloseableHttpResponse sendRequestWithHeaders(Class<?> clazz, String url, Map<String, String> headers) {

    Object request = clazz.newInstance();
    // request.setHeader(key, value); doesn't compile because it's of type Object
}

要么

<T> CloseableHttpResponse sendRequestWithHeaders(Class<T> clazz, String url, Map<String, String> headers) {

    Object request = clazz.newInstance();
    T t = clazz.cast(request);

    // setHeader(key, value); doesn't compile either because T is generic
}

附言无论如何，我有一个使用Apache的RequestBuilder的替代解决方案，我只是想知道是否有上述解决方案。

最佳答案

Get，Post ...的请求类扩展了HttpRequestBase，因此您可以相应地限制T：

public <T extends HttpRequestBase> CloseableHttpResponse sendRequestWithHeaders(Class<T> clazz, String url, Map<String, String> headers) throws IOException {
    CloseableHttpResponse response = null;
    try {
        HttpRequestBase request = clazz.getConstructor(String.class).newInstance(url);
        if (headers != null) {
            for (Map.Entry<String, String> header : headers.entrySet()) {
                request.setHeader(header.getKey(), header.getValue());
            }
        }
        response = client.execute(request);
    } catch (Exception ex) {
        // handle exception
    }
    return response;
}

关于java - 传递一个类，实例化它，然后使用正确的方法，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/47371567/