Httpclient的使用

4.4.1 什么是httpclient
HttpClient 是 Apache Jakarta Common 下的子项目，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，并且它支持 HTTP 协议最新的版本和建议。
下载地址：
http://hc.apache.org/

4.4.2 添加依赖

需要把httpclient的jar包添加到工程中。只需要在工程中添加httpclient的依赖。

4.4.3 使用方法
4.4.3.1 使用httpclient执行get请求

@Test
    public void doGet() throws Exception {
        //创建一个httpclient对象
        CloseableHttpClient httpClient = HttpClients.createDefault();
        //创建一个GET对象
        HttpGet get = new HttpGet("http://www.sogou.com");
        //执行请求
        CloseableHttpResponse response = httpClient.execute(get);
        //取响应的结果
        int statusCode = response.getStatusLine().getStatusCode();
        System.out.println(statusCode);
        HttpEntity entity = response.getEntity();
        String string = EntityUtils.toString(entity, "utf-8");
        System.out.println(string);
        //关闭httpclient
        response.close();
        httpClient.close();
    }

4.4.3.2 执行get请求带参数

@Test
    public void doGetWithParam() throws Exception{
        //创建一个httpclient对象
        CloseableHttpClient httpClient = HttpClients.createDefault();
        //创建一个uri对象
        URIBuilder uriBuilder = new URIBuilder("http://www.sogou.com/web");
        uriBuilder.addParameter("query", "花千骨");
        HttpGet get = new HttpGet(uriBuilder.build());
        //执行请求
        CloseableHttpResponse response = httpClient.execute(get);
        //取响应的结果
        int statusCode = response.getStatusLine().getStatusCode();
        System.out.println(statusCode);
        HttpEntity entity = response.getEntity();
        String string = EntityUtils.toString(entity, "utf-8");
        System.out.println(string);
        //关闭httpclient
        response.close();
        httpClient.close();
    }

4.4.3.3 使用httpclient执行post请求

@Test
    public void doPost() throws Exception {
        CloseableHttpClient httpClient = HttpClients.createDefault();

        //创建一个post对象
        HttpPost post = new HttpPost("http://localhost:8082/httpclient/post.html");
        //执行post请求
        CloseableHttpResponse response = httpClient.execute(post);
        String string = EntityUtils.toString(response.getEntity());
        System.out.println(string);
        response.close();
        httpClient.close();

    }

4.4.3.4 带参数post请求

@Test
    public void doPostWithParam() throws Exception{
        CloseableHttpClient httpClient = HttpClients.createDefault();

        //创建一个post对象
        HttpPost post = new HttpPost("http://localhost:8082/httpclient/post.html");
        //创建一个Entity。模拟一个表单
        List<NameValuePair> kvList = new ArrayList<>();
        kvList.add(new BasicNameValuePair("username", "zhangsan"));
        kvList.add(new BasicNameValuePair("password", "123"));

        //包装成一个Entity对象
        StringEntity entity = new UrlEncodedFormEntity(kvList, "utf-8");
        //设置请求的内容
        post.setEntity(entity);

        //执行post请求
        CloseableHttpResponse response = httpClient.execute(post);
        String string = EntityUtils.toString(response.getEntity());
        System.out.println(string);
        response.close();
        httpClient.close();
    }

4.4.4 Httpclient封装成工具类
其他项目也可能会用到httpclient，所以把工具类放到taotao-common中。