已经解决了，是因为网站有反爬机制的。。。

弄成网站可以看一下，另外可以试着加密，因为我也是小白

package temp;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

import org.apache.http.HttpEntity;
import org.apache.http.ParseException;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.jsoup.nodes.Document;

public class Temp {

    public static void main(String[] args) {
        Document doc=null;
//      try {
//          doc = Jsoup.connect("http://www.baidu.com").get();
//      } catch (IOException e) {
//          // TODO Auto-generated catch block
//          e.printStackTrace();
//      }

         CloseableHttpClient httpclient = HttpClients.createDefault();
            try {
                HttpGet httpget = new HttpGet("http://www.baidu.com");
                CloseableHttpResponse response = httpclient.execute(httpget);
                try {
                    // 获取响应实体
                    HttpEntity entity = response.getEntity();
                    // 打印响应状态
                    if (entity != null) {
                        InputStream in = entity.getContent();
                        // byte[] b=new byte[in.available()];
                        // in.read(b);
                        BufferedReader br = new BufferedReader(new InputStreamReader(in, "utf-8"));
                        String temp = "";
                        String s = "";
                        while ((temp = br.readLine()) != null) {
                            s = s + temp;
                        }
                        System.out.println(s);
                    } 
                } finally {
                    response.close();
                }
            } catch (ClientProtocolException e) {
                e.printStackTrace();
            } catch (ParseException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                // 关闭连接,释放资源
                try {
                    httpclient.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

    }