Question

使用HttpClient获取URL状态的最快方法是什么？我不想下载页面/文件，我只是想知道页面/文件是否存在？（如果它是重定向，我希望它遵循重定向）

Answer 1

以下是我从HttpClient获取状态代码的方法，我非常喜欢：

public boolean exists(){
    CloseableHttpResponse response = null;
    try {
        CloseableHttpClient client = HttpClients.createDefault();
        HttpHead headReq = new HttpHead(this.uri);                      
        response = client.execute(headReq);         
        StatusLine sl = response.getStatusLine();           
        switch (sl.getStatusCode()) {
            case 404:  return false;                     
            default: return true;                     
        }           

    } catch (Exception e) {
        log.error("Error in HttpGroovySourse : "+e.getMessage(), e );
    } finally {

        try {
            response.close();
        } catch (Exception e) {
            log.error("Error in HttpGroovySourse : "+e.getMessage(), e );
        }
    }       

    return false;
}

Answer 2

使用HEAD来电。它基本上是一个GET调用，服务器不返回正文。他们的文档示例：

HeadMethod head = new HeadMethod("http://jakarta.apache.org");
// execute the method and handle any error responses.
...
// Retrieve all the headers.
Header[] headers = head.getResponseHeaders();

// Retrieve just the last modified header value.
String lastModified = head.getResponseHeader("last-modified").getValue();

Answer 3

您可以使用：

HeadMethod head = new HeadMethod("http://www.myfootestsite.com");
head.setFollowRedirects(true);

// Header stuff
Header[] headers = head.getResponseHeaders();

确保您的Web服务器支持HEAD命令。

参见HTTP 1.1 Spec

中的第9.4节

Answer 4

您可以使用java.net.HttpURLConnection获取此信息：

URL url = new URL("http://stackoverflow.com/");
URLConnection urlConnection = url.openConnection();
if (urlConnection instanceof HttpURLConnection) {
    int responseCode = ((HttpURLConnection) urlConnection).getResponseCode();
    switch (responseCode) {
    case HttpURLConnection.HTTP_OK:
        // HTTP Status-Code 302: Temporary Redirect.
        break;
    case HttpURLConnection.HTTP_MOVED_TEMP:
        // HTTP Status-Code 302: Temporary Redirect.
        break;
    case HttpURLConnection.HTTP_NOT_FOUND:
        // HTTP Status-Code 404: Not Found.
        break;
    }
}

使用HttpClient获取URL状态代码的最快方法是什么

4 个答案: