如何从标头获取上次修改日期到字符串

Question

我已经在标头对象中获得了标头值。但我需要将“Last-Modified”放入字符串对象中进行比较。请您告诉我如何将最后一个标头放入字符串中。

HttpClient client = new DefaultHttpClient();
//HttpGet get = new HttpGet(url);
HttpHead method = new HttpHead(url);
HttpResponse response = client.execute(method);
Header[] s = response.getAllHeaders();

String sh = String.valueOf(s);
System.out.println("The value of sh:"+sh);

System.out.println("The header from the httpclient:");

for (int i = 0; i < s.length; i++) {
  Header hd = s[i];
  System.out.println("Header Name: "+hd.getName() + "       " + " Header Value: " +  hd.getValue());
}

String last-modified =   // here I need to convert this header(last-modified);

Answer 1

在许多情况下，您只获得一个 Last-Modified 标头，因此您可以简单地使用：

String lastModified = response.getHeader("last-modified");
if (lastModified != null) {    // in case the header isn't set
  // do something
}

对于多个值，JavaDoc 表示：如果具有给定名称的响应标头存在并且包含多个值，则使用第一个添加的值将被退回。

Answer 2

尝试这样的事情：

Header[] s = response.getHeaders("last-modified");
String lastModified = s[0].getValue();   // ! There might be more than 1 header
                                         // ! or none at all

Answer 3

private String getLastModifiedDate(HttpResponse response) {
    Header header = response.getFirstHeader("Date");
    if (header != null) {
        return header.getValue();
    }

    return "";
}