构造函数UrlEncodedFormEntity（List <NameValuePair> ，String）是构建帖子请求时的未定义错误

Question

I am trying to make a post request in java using Apache HTTP components , when I set my entity on this line

httppost.setEntity(new UrlEncodedFormEntity(params, "UTF-8"));

It says

"The constructor UrlEncodedFormEntity(List, String) is undefined" and I am not sure why.

Here is my entire code

@Component
public class ScheduledTasks {

@Scheduled(cron="0 9 1-7 * 1 *")    //first monday of each month, at 9am
public void dataLoaderTask() throws Exception   {
    HttpClient httpclient = HttpClients.createDefault();
    HttpPost httppost = new HttpPost("https://erudite-master-api-awsmaui.lab.expts.net/erudite/search");
        List<NameValuePair> params = new ArrayList<NameValuePair>(3);
            params.add(new NameValuePair("action", "count"));
            params.add(new NameValuePair("fields", "Status"));
            params.add(new NameValuePair("filters", ""));
        httppost.setEntity(new UrlEncodedFormEntity(params, "UTF-8"));

            //Execute and get the response.
            HttpResponse response = httpclient.execute(httppost);
            HttpEntity entity = response.getEntity();
            if (entity != null) {
                InputStream instream = entity.getContent();
                try {
                    // do something useful
                } finally {
                    instream.close();
                }
            }
    }

Every resource that I have searched shows this is the proper way of doing so, so I am not sure why it is returning undefined.

Answer 1

Maybe there could be conflicting Apache HTTP Components JAR files. I tried the below code and there was no compilation error: These are the two JAR files used in the classpath: http-client-4.5.3.jar, http-core-4.4.6.jar. Using spring-boot will ensure the latest version of open source JAR files in your repository.

@Scheduled(cron = "0 9 1-7 * 1 *") // first monday of each month, at 9am
public void dataLoaderTask() throws Exception {
    CloseableHttpClient httpclient = HttpClients.createDefault();
    HttpPost httppost = new HttpPost("https://erudite-master-api-awsmaui.lab.expts.net/erudite/search");
    List<NameValuePair> params = new ArrayList<NameValuePair>(3);
    params.add(new BasicNameValuePair("action", "count"));
    params.add(new BasicNameValuePair("fields", "Status"));
    params.add(new BasicNameValuePair("filters", ""));
    httppost.setEntity(new UrlEncodedFormEntity(params, "UTF-8"));
    // Execute and get the response.
    CloseableHttpResponse response = httpclient.execute(httppost);
    HttpEntity entity = response.getEntity();
    if (entity != null) {
        InputStream instream = entity.getContent();
        try {
            // do something useful
        } finally {
            instream.close();
        }
    }
}