如何调用别人的接口或网络上的接口

import java.io.IOException;
import java.util.Map;

import org.apache.http.HttpEntity;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

import com.google.gson.Gson;

public class HttpClientUtil {
    
    private final static String CONTENT_TYPE_TEXT_JSON = "text/json";
    
    public static String postRequest(String url, Map<String, Object> param) throws ClientProtocolException, IOException{
        
        CloseableHttpClient client = HttpClients.createDefault();

        HttpPost httpPost = new HttpPost(url);
        httpPost.setHeader("Content-Type", "application/json;charset=UTF-8");
        
        Gson gson = new Gson();
        String parameter = gson.toJson(param);
        StringEntity se = new StringEntity(parameter,"UTF-8");
        se.setContentType(CONTENT_TYPE_TEXT_JSON);
        httpPost.setEntity(se);

        CloseableHttpResponse response = client.execute(httpPost);
        HttpEntity entity = response.getEntity();
        String result = EntityUtils.toString(entity, "UTF-8");
        
        return result;
    }

}

@RequestMapping(value="buy",produces = "text/plain;charset=utf-8")
@ResponseBody
public String buy(String name) throws Exception{
String url = "https://suggest.taobao.com/sug?code=utf-8&q="+name+"&callback=cb";
String result=HttpClientUtil.postRequest(url, new HashMap<String,Object>());
return result;
}

<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient-cache</artifactId>
<version>4.5.3</version>
</dependency>
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpmime</artifactId>
<version>4.5.3</version>
</dependency>

<!-- https://mvnrepository.com/artifact/com.google.code.gson/gson -->
<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
<version>2.2.4</version>
</dependency>