HttpClient Tutorial (第一章 HttpClient应用领域 1.1.3)

1.1.3 与消息头一起工作
HTTP消息能包含大量头，它们描述了消息的属性。例如内容长度，内容类型等等。HttpClient提供了获取，增加，去除和枚举头。

HttpResponse response = new BasicHttpResponse(HttpVersion.HTTP_1_1, HttpStatus.SC_OK, "OK");
response.addHeader("Set-Cookie", "c1=a; path=/; domain=localhost");
response.addHeader("Set-Cookie", "c2=b; path=\"/\", c3=c; domain=\"localhost\"");
		
Header h1 = response.getFirstHeader("Set-Cookie");
System.out.println(h1);
		
Header h2 = response.getLastHeader("Set-Cookie");
System.out.println(h2);
		
Header[] hs = response.getHeaders("Set-Cookie");
System.out.println(hs.length);

输出〉

Set-Cookie: c1=a; path=/; domain=localhost
Set-Cookie: c2=b; path="/", c3=c; domain="localhost"
2

取得所有给定类型的头最有效的方法是使用HeaderIterator接口。

HttpResponse response = new BasicHttpResponse(HttpVersion.HTTP_1_1, HttpStatus.SC_OK, "OK");
		response.addHeader("Set-Cookie", "c1=a; path=/; domain=localhost");
		response.addHeader("Set-Cookie", "c2=b; path=\"/\", c3=c; domain=\"localhost\"");
		
		HeaderElementIterator it = new BasicHeaderElementIterator(response.headerIterator("Set-Cookie"));
		
		while(it.hasNext()){
			System.out.println(it.next());
		}

它也提供了解析HTTP消息的便利方法，可以将消息解析为不同的头元素。

HttpResponse response = new BasicHttpResponse(HttpVersion.HTTP_1_1, HttpStatus.SC_OK, "OK");
		response.addHeader("Set-Cookie", "c1=a; path=/; domain=localhost");
		response.addHeader("Set-Cookie", "c2=b; path=\"/\", c3=c; domain=\"localhost\"");
		
		HeaderElementIterator it = new BasicHeaderElementIterator(response.headerIterator("Set-Cookie"));
		
		while(it.hasNext()){
			HeaderElement elem = it.nextElement();
			System.out.println(elem.getName() + " = " + elem.getValue());
			NameValuePair[] params = elem.getParameters();
			for (int i = 0; i < params.length; i++) {
				System.out.println(" " + params[i]);
			}
		}

输出>

c1 = a
 path=/
 domain=localhost
c2 = b
 path=/
c3 = c
 domain=localhost