HttpClient四中跨域获取数据的方式

1.HttpClient 是Apache Jakarta Common 下的子项目，可以用来提供高效的，最新的，功能丰富的支持http协议的客户端编程工具包，并且他支持http协议最新的版本和协议

2.导入依赖

<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.3.5</version>
</dependency>

3.DoGet方法（无参）

 DoGet(有参)

 DoPost(无参)

 带有参数的post的请求

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

        // 创建Httpclient对象
        CloseableHttpClient httpclient = HttpClients.createDefault();

        // 创建http POST请求
        HttpPost httpPost = new HttpPost("http://www.oschina.net/search");
        
     // 伪装成浏览器
        httpPost.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/50.0.2661.94 Safari/537.36");

        // 设置2个post参数，一个是scope、一个是q
        List<NameValuePair> parameters = new ArrayList<NameValuePair>(0);
        parameters.add(new BasicNameValuePair("scope", "project"));
        parameters.add(new BasicNameValuePair("q", "java"));
        parameters.add(new BasicNameValuePair("fromerr", "7nXH76r7"));
        // 构造一个form表单式的实体
        UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(parameters);
        // 将请求实体设置到httpPost对象中
        httpPost.setEntity(formEntity);    

        CloseableHttpResponse response = null;
        try {
            // 执行请求
            response = httpclient.execute(httpPost);
            // 判断返回状态是否为200
            if (response.getStatusLine().getStatusCode() == 200) {
                String content = EntityUtils.toString(response.getEntity(), "UTF-8");
                System.out.println(content);
            }
        } finally {
            if (response != null) {
                response.close();
            }
            httpclient.close();
        }

    }