java发送http get 和 post 请求

原生的纯java发送书写起来很麻烦，所以推荐apache的HttpClient和HttpCore包，里面已经封装好了一系列的接口。

1.get

<pre name="code" class="java">public class HttpGetTest {

public static void main(String[] args) throws IOException{

<span style="white-space:pre"></span>//直接将参数写在网址中并请求这个网址

<span style="white-space:pre"></span>String url = "https://www.baidu.com/s?ie=UTF-8&wd=%E7%99%BE%E5%BA%A6";

<span style="white-space:pre"></span>//旧的方法如HttpClient client = new DefaultHttpClient();已经被弃用，现在用该静态方法来创建clientCloseableHttpClient httpClient = HttpClients.createDefault();HttpGet httpget = new HttpGet(url);CloseableHttpResponse response = httpClient.execute(httpget);if(response.getStatusLine().getStatusCode() == 200){

<span style="white-space:pre"></span>//获取返回的值String result = EntityUtils.toString(response.getEntity());System.out.println(result);}}}

2.post

public class HttpPostTest {public static void main(String[] args) throws IOException{

<span style="white-space:pre"></span>String url = "https://www.baidu.com";CloseableHttpClient httpClient = HttpClients.createDefault();

<span style="white-space:pre"></span>//使用包装好的类来设置post的参数List<NameValuePair> formparams = new ArrayList<NameValuePair>();formparams.add(new BasicNameValuePair("q", "www.douban.com/note site:www.douban.com"));UrlEncodedFormEntity entity = new UrlEncodedFormEntity(formparams, Consts.UTF_8);HttpPost httppost = new HttpPost(url);

<span style="white-space:pre"></span>httppost.setEntity(entity);

CloseableHttpResponse response = httpClient.execute(httppost);System.out.println(response.getStatusLine().getStatusCode());if(response.getStatusLine().getStatusCode() == 200){String result = EntityUtils.toString(response.getEntity());System.out.println(result);}

<span style="white-space:pre"></span>//关闭资源

<span style="font-family: Arial, Helvetica, sans-serif;"></span>EntityUtils.consume(entity);<span style="font-family: Arial, Helvetica, sans-serif;"></span>

}}

3.总结

可以看出post仅仅比get多出了一些添加参数的工作，其他的方面都大致差不多。

在官网上还给出了更简洁的例子，但是我没有进行测试，放上来仅供大家参考。

The same requests can be executed using a simpler, albeit less flexible, fluent API.

// The fluent API relieves the user from having to deal with manual deallocation of system// resources at the cost of having to buffer response content in memory in some cases.Request.Get("http://targethost/homepage")    .execute().returnContent();Request.Post("http://targethost/login")    .bodyForm(Form.form().add("username",  "vip").add("password",  "secret").build())    .execute().returnContent();

（在正常的请求过程中，需要使用try-catch-finally来关闭掉response以释放资源，在这里我为了代码更加简单就没有进行相应的操作，但是强烈建议关闭不必要的链接。）

在程序运行的过程中需要注意的是，可能会报java.lang.NoClassDefFoundError: org/apache/commons/logging/LogFactory的错误，主要是因为缺少commons-logging jar包，导入commons-logging.jar即可。

最后附上下载地址：

HttpClient及HttpCore：http://hc.apache.org/downloads.cgi

commons-logging.jar：点击打开链接