HttpClient模拟http请求详解

清疚 2024-04-17 05:59 59阅读 0赞

## 一、HttpClient简介 ##

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。HttpClient最新版本是HttpClient 4.5.9。

以下是官方网站上httpClient支持的功能Examples（部分）。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoYW84MjE_size_16_color_FFFFFF_t_70][]

## 二、HttpClient如何引入到Spring项目中 ##

pom文件增加如下信息即可:

<dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpclient</artifactId>
        <version>4.5.9</version>
    </dependency>

## 三、HttpClient使用示例 ##

1）get请求

/**
     *普通的GET请求
     */
    public class DoGET {
        public static void main(String[] args) throws Exception {
            // 创建Httpclient对象
            CloseableHttpClient httpclient = HttpClients.createDefault();
            // 创建http GET请求
            HttpGet httpGet = new HttpGet("http://www.baidu.com");
            CloseableHttpResponse response = null;
            try {
                // 执行请求
                response = httpclient.execute(httpGet);
                // 判断返回状态是否为200
                if (response.getStatusLine().getStatusCode() == 200) {
                    //请求体内容
                    String content = EntityUtils.toString(response.getEntity(), "UTF-8");
                    //内容写入文件
                    FileUtils.writeStringToFile(new File("E:\\devtest\\baidu.html"), content, "UTF-8");
                    System.out.println("内容长度："+content.length());
                }
            } finally {
                if (response != null) {
                    response.close();
                }
                //相当于关闭浏览器
                httpclient.close();
            }
        }
    }

2）post+form

/**
     * 常规post请求
     *    可以设置Header来伪装浏览器请求
     */
    public class DoPOSTForm {
        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/");
            //伪装浏览器请求
            httpPost.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36");
            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");
                    //内容写入文件
                    FileUtils.writeStringToFile(new File("E:\\devtest\\oschina.html"), content, "UTF-8");
                    System.out.println("内容长度："+content.length());
                }
            } finally {
                if (response != null) {
                    response.close();
                }
                httpclient.close();
            }
        }
    }

3）post+json

/**
     * 常规post请求
     *    可以设置Header来伪装浏览器请求
     */
    public class DoPOSTJson {
        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://localhost:8080/testJson");
            JSONObject params=new JSONObject();
            params.put("aa",11);
            httpPost.setHeader("Content-type", "application/json");
            httpPost.setEntity(new StringEntity(params.toJSONString(),"UTF-8"));
            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");
                }
            } finally {
                if (response != null) {
                    response.close();
                }
                httpclient.close();
            }
        }
    }

另外，HttpClient还支持PUT/DELETE传参以及https请求等功能，此处不赘述了。

参考文档：

官方说明：[http://hc.apache.org/downloads.cgi][http_hc.apache.org_downloads.cgi]

Github下载：[https://github.com/apache/httpcomponents-client/tree/4.5.9][https_github.com_apache_httpcomponents-client_tree_4.5.9]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoYW84MjE_size_16_color_FFFFFF_t_70]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/15/004ae5d3127e48b382a162c86d45ee2c.png
[http_hc.apache.org_downloads.cgi]: https://link.jianshu.com/?t=http://hc.apache.org/downloads.cgi
[https_github.com_apache_httpcomponents-client_tree_4.5.9]: https://github.com/apache/httpcomponents-client/tree/4.5.9