完美解决Server returned HTTP response code:403 for URL报错问题

HttpURLConnection conn = (HttpURLConnection) url.openConnection()

httpUrlConn.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)");

conn.setRequestProperty("User-Agent", "Mozilla/4.76");

不要在java中使用URLConnection，不接受使用 urlConnection 的普通 java 。
访问互联网.要访问浏览器，它需要执行搜索，没有例外会导致 
HTTP response code : 403 for URL
但是我本身是使用的HttpURLConnection，并且，如果你使用HttpURLConnection，
应该按照我后面的添加setRequestProperty

        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpcore</artifactId>
            <version>4.4.10</version>
        </dependency>
        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
            <version>4.5.5</version>
        </dependency>

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
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 java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.URL;
public class PostClientUtil {
    public static String sendPost(String url,String param){
        OutputStreamWriter out =null;
        BufferedReader reader = null;
        String response = "";

        //创建连接
        try {
            URL httpUrl = null; //HTTP URL类 用这个类来创建连接
            //创建URL
            httpUrl = new URL(url);
            //建立连接
            HttpURLConnection conn = (HttpURLConnection) httpUrl.openConnection();
            conn.setRequestMethod("POST");
            conn.setRequestProperty("Content-Type", "application/json");
//            conn.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)");
            conn.setRequestProperty("connection", "keep-alive");
            conn.setRequestProperty("User-Agent", "Mozilla/4.76");
            conn.setUseCaches(false);//设置不要缓存
            conn.setInstanceFollowRedirects(true);
            conn.setDoOutput(true);
            conn.setDoInput(true);
            conn.connect();
            //POST请求
            out = new OutputStreamWriter(
                    conn.getOutputStream());
            out.write(param);
            out.flush();
            //读取响应
            reader = new BufferedReader(new InputStreamReader(
                    conn.getInputStream()));
            String lines;
            while ((lines = reader.readLine()) != null) {
                lines = new String(lines.getBytes(), "utf-8");
                response+=lines;
            }
            reader.close();
            // 断开连接
            conn.disconnect();

        } catch (Exception e) {
            System.out.println("发送 POST 请求出现异常！"+e);
            e.printStackTrace();
        }
        //使用finally块来关闭输出流、输入流
        finally{
            try{
                if(out!=null){
                    out.close();
                }
                if(reader!=null){
                    reader.close();
                }
            }
            catch(IOException ex){
                ex.printStackTrace();
            }
        }

        return response;
    }
}