HttpClient总结

旧城等待， 2022-06-16 05:52 123阅读 0赞

HttpClient不是浏览器，但可以模拟浏览器发送请求，主要作用：

1.  爬取网页（Http,Https）内容
2.  使用get/post方式发送请求，post可以是表单提交或json提交

依赖的jar包

<dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpclient</artifactId>
        <version>4.5.7</version>
    </dependency>
    <dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpcore</artifactId>
        <version>4.4.7</version>
    </dependency>

使用httpClient的步骤为:

创建httpClient对象-->创建httpGet-->执行get/post请求-->返回HTTPEntity-->通过EntityUtil取出响应内容。

1、get方式

//get方式请求
    public static String get(String url) throws IOException {
    //        CloseableHttpClient httpClient = HttpClients.createDefault();
        //建造者模式
        CloseableHttpClient httpClient = HttpClientBuilder.create().build();
        HttpGet httpGet = new HttpGet(url);
        CloseableHttpResponse response = null;
        response = httpClient.execute(httpGet);
        HttpEntity entity = response.getEntity();
        String html = EntityUtils.toString(entity);
        response.close();
        httpClient.close();
        return html;
    }
    //请求方式
    get("http://www.chery.cn/vehicles/tiggo8#page-1");

2、表单提交

/**
     * 表单提交
     *
     * @param url
     * @return
     */
    public static String post(String url) throws Exception {
        //和上面一样，也可以通过build创建
        CloseableHttpClient httpClient = HttpClients.createDefault();
        HttpPost httpPost = new HttpPost(url);
        CloseableHttpResponse response = null;
        List<NameValuePair> list = Lists.newArrayList();
        list.add(new BasicNameValuePair("name", "张三"));
        list.add(new BasicNameValuePair("pwd", "123321"));
        log.info(JSONObject.toJSONString(list));
        //需要把表单包装到entity中
        StringEntity formEntity = new UrlEncodedFormEntity(list, "UTF-8");
        httpPost.setEntity(formEntity);
    
        //设置请求和传输超时时间
        RequestConfig requestConfig = RequestConfig.custom().setSocketTimeout(3000).setConnectTimeout(3000).build();
        httpPost.setConfig(requestConfig);
    
        response = httpClient.execute(httpPost);
        HttpEntity entity = response.getEntity();
    
        String result = EntityUtils.toString(entity, "UTF-8");
        response.close();
        httpClient.close();
        return result;
    }

3、json方式发送post请求

/**
     * json参数提交
     *
     * @param url
     * @return
     * @throws Exception
     */
    public static String httpPostWithJSON(String url) throws Exception {
    
        CloseableHttpClient client = HttpClients.createDefault();
        HttpPost httpPost = new HttpPost(url);
        String respContent = null;
    
        //封装json参数
        //{"endpoint":"abd.cn-beijing.abc.com","reportData":{"metricName":"test","groupId":"101","values":{"value":10.5},"dimensions":{"sampleName1":"value1","sampleName2":"value2"}},"acckey":"something","secret":"something"}
        JSONObject jsonParam = new JSONObject();
        jsonParam.put("endpoint", "abd.cn-beijing.abc.com");
        jsonParam.put("acckey", "something");
        jsonParam.put("secret", "something");
    
        JSONObject paramVar = new JSONObject();
        paramVar.put("groupId", "101");
        paramVar.put("metricName", "test");
        paramVar.put("groupId", "101");
    
        JSONObject dimensions = new JSONObject();
        dimensions.put("sampleName1", "value1");
        dimensions.put("sampleName2", "value2");
        paramVar.put("dimensions", dimensions);
    
        JSONObject values = new JSONObject();
        values.put("value", 10.5);
        paramVar.put("values", values);
    
        jsonParam.put("reportData", paramVar);
        //解决中文乱码问题
        StringEntity entity = new StringEntity(jsonParam.toString(), "UTF-8");
        entity.setContentType("application/json");
        httpPost.setEntity(entity);
        log.info(JSONObject.toJSONString(jsonParam));
    
        HttpResponse resp = client.execute(httpPost);
        if (resp.getStatusLine().getStatusCode() == 200) {
            HttpEntity he = resp.getEntity();
            respContent = EntityUtils.toString(he, "UTF-8");
        }
        return respContent;
    }