Java中HttpClient之Util简介说明

HttpClient简介

HttpClient:
    apache组织下面的一个用于处理HTTP请求和响应的开源工具

HTTP-REQUEST-GET

/**
     * HTTP-REQUEST-GET
     * @param url
     * @param dataMap
     * @return
     */
    public static String sendGetHttpRequest(String url, Map<String, String> dataMap){

        CloseableHttpClient httpClient = null;
        CloseableHttpResponse httpResponse = null;
        String param = "";
        String content = "";
        try {
            httpClient = HttpClients.createDefault();
            if(null != dataMap && !CollectionUtils.isEmpty(dataMap.keySet())){
                StringBuffer bufParam = new StringBuffer();
                for (String key : dataMap.keySet()) {
                    bufParam.append(key+"=").append(dataMap.get(key)).append("&");
                }
                param = bufParam.subSequence(0, bufParam.length()-1).toString();

                StringBuffer urlParam = new StringBuffer();

                urlParam.append(url).append("?").append(param);

                url = urlParam.toString();
            }

            HttpGet httpGet = new HttpGet(url);

            httpResponse = httpClient.execute(httpGet);

            HttpEntity httpEntity = httpResponse.getEntity();

            content = EntityUtils.toString(httpEntity, Charset.forName("UTF-8"));

        } catch (Exception e) {
            e.printStackTrace();
        } finally{
            try {
                httpResponse.close();
                httpClient.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

        return content;
    }

HTTP-REQUEST-POST

 /**
     * HTTP-REQUEST-POST
     * @param url
     * @param dataMap:传参
     * @return
     */
    public static String sendPostHttpRequest(String url, Map<String, String> dataMap){

        CloseableHttpClient httpClient = HttpClients.createDefault();

        HttpPost httpPost = new HttpPost(url);

        list<NameValuePair> formparams = new ArrayList<NameValuePair>();

        for (String key : dataMap.keySet()) {
            formparams.add(new BasicNameValuePair(key, dataMap.get(key)));
        }

        CloseableHttpResponse httpResponse = null;
        String content = "";
        try {
            UrlEncodedFormEntity entity = new UrlEncodedFormEntity(formparams, "UTF-8");

            httpPost.setEntity(entity);

            httpResponse = httpClient.execute(httpPost);

            HttpEntity httpEntity = httpResponse.getEntity();

            content = EntityUtils.toString(httpEntity, Charset.forName("UTF-8"));
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            try {
                httpResponse.close();
                httpClient.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return content;
    }

HTTP-REQUEST-UPLOAD(参数是个文件)

 /**
     * 上传文件
     * 
     */
    private static void upload(String url, File file, Map<String, Object> dataMap) {
        HttpPost httpPost = new HttpPost(url);
        httpPost.setHeader("Accept-Language", "zh-cn,zh;q=0.5");
        httpPost.setHeader("Accept-Charset", "GBK,utf-8;q=0.7,*;q=0.7");
        httpPost.setHeader("Connection", "keep-alive");

        FileBody fileBody = new FileBody(file);

        String data = JSON.toJSONString(dataMap);
        StringBody stringBody1 = new StringBody(data, ContentType.MULTIPART_FORM_DATA);

        try {
            HttpEntity entity = MultipartEntityBuilder.create().setMode(HttpMultipartMode.BROWSER_COMPATIBLE)
                    .addPart("filename", fileBody).addPart("data", stringBody1).setCharset(CharsetUtils.get("UTF-8"))
                    .build();

            httpPost.setEntity(entity);
            CloseableHttpClient httpClient = HttpClientBuilder.create().disableRedirectHandling().build();
            HttpResponse httpResponse;
            httpResponse = httpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();
            String content = EntityUtils.toString(httpEntity, Charset.forName("UTF-8"));
            JSONObject result = JSONObject.parseObject(content);
            if (result == null ) {
                throw new Exception("上传文件失败，返回数据为：" + content);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

注意事项：
   1.Accept-Language 是HTTP 请求里面的一个属性
      服务器支持的语言 
   2.请求头Accept-Charset客户端提交的表单使用的编码
     与服务器的响应内容编码无关
     而响应头Content-Type中charset则将告诉浏览器
     Connection:keep-alive长连接
      需要服务端支持
       同时Keep-Alive不会永久保持连接
       它有一个保持时间,可以在不同的服务器软件(如Apache)中设定这个时间

发送HTTP请求并携带Cookie

/**
     * HTTP-REQUEST-GET
     * @param url
     * @param dataMap
     * @param cookie 身份认证
     * @return
     */
    public static String sendGetHttpRequest(String url, Map<String, String> dataMap, String cookie) {

        CloseableHttpClient httpClient = null;
        CloseableHttpResponse httpResponse = null;
        String param = "";
        String content = "";
        try {
            httpClient = HttpClients.createDefault();
            if(null != dataMap && !CollectionUtils.isEmpty(dataMap.keySet())){
                StringBuffer bufParam = new StringBuffer();
                for (String key : dataMap.keySet()) {
                    bufParam.append(key+"=").append(dataMap.get(key)).append("&");
                }
                param = bufParam.subSequence(0, bufParam.length()-1).toString();

                StringBuffer urlParam = new StringBuffer();

                urlParam.append(url).append("?").append(param);

                url = urlParam.toString();
            }

            HttpGet httpGet = new HttpGet(url);

            httpGet.addHeader("Cookie", cookie);

            httpResponse = httpClient.execute(httpGet);

            HttpEntity httpEntity = httpResponse.getEntity();

            content = EntityUtils.toString(httpEntity, Charset.forName("UTF-8"));

        } catch (Exception e) {
            throw new BizException(null,"HTTP GET请求发生异常",e);
        } finally{
            try {
                httpResponse.close();
                httpClient.close();
            } catch (Exception e) {
                throw new BizException(null,"资源释放发生异常",e);
            }
        }
        return content;
    }

MAVEN依赖

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpcomponents-client</artifactId>
    <version>4.5.2</version>
</dependency>
<dependency>        
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpmime</artifactId>
    <version>4.5.2</version>
</dependency>