使用 Java 中的 HTTPClient 下载文件

Question

I'm trying to write a java program that logs into a website, types in a search engine, gets the result, and then downloads the excel file that is generated from the results. So far, I can log in ok. and send a search in and get the results. However, I'm having a lot of problems downloading the excel file.

Looking at the website's source code, I see Ajax and Javascript around the excel file, so I'm assuming it's ajax that helps produce it.

<input id="toexcel" type="image" src="/websmart/v9.4/XLGP/images/Excel-icon.png" alt="To Excel" title="To Excel: Max 20000 Records" onclick="" />

The JavaScript part:

$( document ).ready(function() {

        $('#toexcel').click(function(e) { 
            e.preventDefault();
            
            setTask('toexcel');
            
            var ajaxForm = $("#filter-form");
                        
            
            $(".spinner").show();

                var dataToSend = ajaxForm.serialize();
                $("#excelFrame").attr('src','V7BAE01R.pgm' + '?' + dataToSend);
            setTimeout(function() {
                            $(".spinner").hide();
                        }, 5000 );
                

Using TamperData, when I click the Excel File Export, it sends a post request (which I manage to send in the last part of the code) but I'm not sure where to Get it. I do see in tamperdata the Get that says Application/vnd.ms-excel

I'm not sure what to do to add in the code to get the excel file. Below, I tried to use BufferReader, but it doesn't get my file. Some of the code I simplified because of the Name Value pairs.

import java.util.List;
import java.util.ArrayList;
import org.apache.http.*;
import java.io.*;

import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.*;
import org.apache.http.impl.client.*;
import org.apache.http.message.*;
import org.apache.http.util.EntityUtils;
import org.apache.http.client.entity.*;
public class httpClientTest {
    
    
    
    public static void main (String[] args) throws ClientProtocolException, IOException {
            //Set up HttpClient
            CloseableHttpClient httpclient = HttpClients.createDefault();
            HttpGet httpGet = new HttpGet("http://website");
            CloseableHttpResponse response = httpclient.execute(httpGet);
            
            //Create Post request to log into the AS400 website
            HttpPost httpPost = new HttpPost("http://loginwebsite");
            
            List <NameValuePair> nvps = new ArrayList <NameValuePair>();
            
            nvps.add(new BasicNameValuePair("user","username"));
            nvps.add(new BasicNameValuePair("password","password"));
            nvps.add(new BasicNameValuePair("button", "Login"));
            nvps.add(new BasicNameValuePair("task", "extlogin"));
            httpPost.setEntity(new UrlEncodedFormEntity(nvps));
            response = httpclient.execute(httpPost);
            
            //Get Post response to ensure we logged in, which succeeds
            try{
                System.out.println(response.getStatusLine());   
                HttpEntity entity = response.getEntity();
                EntityUtils.consume(entity);
            } finally{
                response.close();
            }
            
            //Sent a Post request to filters out recoreds.
            httpPost = new HttpPost("http://searchresults");
            nvps.clear();
            nvps.add(new BasicNameValuePair("ActSts", "Edit"));
            nvps.add(new BasicNameValuePair("task", "filter"));
            nvps.add(new BasicNameValuePair("Field", "Plant"));
            response = httpclient.execute(httpPost);
            
            //Displays in printline the html/js of the page. This looks like it DOES display the search results
            //So it IS sending the Post request and receiving a response.
            BufferedReader rd = new BufferedReader(new InputStreamReader(response.getEntity().getContent())); 
            String line = "";
            while ((line = rd.readLine()) != null) {
                System.out.println(line);
            }

        //try to buffer to read in.
        String link = "http://website.com/uri?ActSts=Edit&task=filter&Field=Plant";
        HttpGet get = new HttpGet(link);
        response = httpclient.execute(get);
        
        InputStream is = response.getEntity().getContent();
        String filePath = "C:\\Users\\WindowsUserName\\Downloads\\WODETAIL_List.xls";
        FileOutputStream fos = new FileOutputStream(new File(filePath));
        int inByte;
        while((inByte = is.read()) != -1)
            fos.write(inByte);
        is.close();
        fos.close();

I'm pretty sure I'm Posting the data right, but I'm not sure about how to Get the excel file. Could anybody offer some help?

Edit I was able to download a file, but it wasn't the excel file. It was a webpage, and I think it's a little bit of an improvement. (Before, nothing downloaded, it just hanged there) The problem was, I think I need to send an authorization key or a cookie with this get request to download the file.

Edit 2 I've discovered if I just paste to http://website.com/uri?ActSts=Edit&task=filter&Field=Plant in a new tab while logged in, after waiting a little while, I get a link to the excel file. So originally I thought HTTPClient maintains the same cookies throughout as long as the same httpclient is used but apparently it doesn't(?) I guess I have to figure out a way to get a cookie and send it.

Answer 1

Oh my god I finally got something that worked. Ok. So apparently HTTPClient can only handle 2 responses before it starts to bug out, according to here: Why does me use HttpClients.createDefault() as HttpClient singleton instance execute third request always hang

So instead, I changed my code to just get a login response, then get the excel file as a response and then quit. I also added some timeout configurations and also changed order from Exporting the file first and then Consuming the entity. I used a separate 2nd response and 2nd entity. That seemed to have helped a bit too? I'm guessing.

import java.util.List;
import java.util.ArrayList;
import org.apache.http.*;
import java.io.*;

import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.CookieStore;
import org.apache.http.client.config.CookieSpecs;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.*;
import org.apache.http.client.protocol.HttpClientContext;
import org.apache.http.conn.ConnectionPoolTimeoutException;
import org.apache.http.cookie.Cookie;
import org.apache.http.impl.client.*;
import org.apache.http.message.*;
import org.apache.http.util.EntityUtils;
import org.apache.http.client.entity.*;

public class hcFeb {
    public static void main (String[] args) throws ClientProtocolException, IOException {
        //Set up Cookie settings and also Timeout settings
        CookieStore cookieStore = new BasicCookieStore();
        HttpClientContext context = HttpClientContext.create();
        context.setCookieStore(cookieStore);
        
        int CONNECTION_TIMEOUT = 80000;
        RequestConfig requestConfig = RequestConfig.custom().setCookieSpec(CookieSpecs.DEFAULT)
                .setConnectionRequestTimeout(CONNECTION_TIMEOUT)
                .setConnectTimeout(CONNECTION_TIMEOUT)
                .setSocketTimeout(CONNECTION_TIMEOUT)
                .build();
        
        //Set up HttpClient
        CloseableHttpClient httpclient = HttpClients.custom().setDefaultRequestConfig(requestConfig).setDefaultCookieStore(cookieStore).disableContentCompression().build();
        
        HttpGet httpGet = new HttpGet("http://website");
        CloseableHttpResponse response = httpclient.execute(httpGet);
        
        //Create Post request to log into the website
        HttpPost httpPost = new HttpPost("http://loginwebsite");
        
        //Login to website
         List <NameValuePair> nvps = new ArrayList <NameValuePair>();

            nvps.add(new BasicNameValuePair("user","username"));
            nvps.add(new BasicNameValuePair("password","password"));
            nvps.add(new BasicNameValuePair("button", "Login"));
            nvps.add(new BasicNameValuePair("task", "extlogin"));
            httpPost.setEntity(new UrlEncodedFormEntity(nvps));
            response = httpclient.execute(httpPost);

        
        try{
            System.out.println(response.getStatusLine());   
            HttpEntity entity = response.getEntity();
            EntityUtils.consume(entity);                
        } finally{
        }
        
        //Send request for Excel file and download it.
        String link = "http://website.com/uri?ActSts=Edit&task=filter&Field=Plant";
        HttpGet get = new HttpGet(link);
        
        //maybe create new response
        HttpResponse response2;

        try{
            response2 = httpclient.execute(get,context);
            System.out.println(response2.getStatusLine());  
            HttpEntity entity1 = response2.getEntity();


            if (entity1 != null) {
                System.out.println("Entity isn't null");
                
                InputStream is = entity1.getContent();
                String filePath = "C:\\Users\\windowsUserName\\Downloads\\WODETAIL_List.xls";
                FileOutputStream fos = new FileOutputStream(new File(filePath));
                
                byte[] buffer = new byte[5600];
                int inByte;
                while((inByte = is.read(buffer)) > 0)
                    fos.write(buffer,0,inByte);
                is.close();
                fos.close();
                
                System.out.println("Excel File recieved");                  
                
                
                EntityUtils.toString(response2.getEntity());
                EntityUtils.consume(entity1);
                
            }
            
        } catch (ConnectionPoolTimeoutException e){
            //response.close();
            System.out.println(e.getMessage());
        } catch (IOException e){
            System.out.println(e.getMessage());
        }
        
    }
}