我想制作java程序从网站下载文件，但我陷入了以下情况。当我运行以下代码时，页面记录已成功完成，但完成后，当我发送下一页的请求时，它显示响应代码 500。
public class Ss2mydb
{
private List<String> cookies;
private HttpURLConnection conn;
private final String USER_AGENT = "Mozilla/5.0";
public static void main(String[] args) throws Exception
{
String indexPage = "http://10.100.100.142/index.asp";
String validatePage = "http://10.100.100.142/validate.asp";
String ccmenuPage = "http://10.100.100.142/callcentre/ccmenu.asp";
String reportPage = "http://10.100.100.142/topmgmt/reports/PROJECTVIJAY/get_download_cafs.asp";
String reportPageDownload = "http://10.100.100.142/topmgmt/reports/PROJECTVIJAY/get_download_cafs.asp?view=N";
Ss2mydb http = new Ss2mydb();
// make sure cookies is turn on
CookieHandler.setDefault(new CookieManager());
// 1. Send a "GET" request, so that you can extract the form's data.
String page = http.GetPageContent(indexPage);
String postParams = http.getFormParams(page, "username", "password");
// 2. Construct above post's content and then send a POST request for
// authentication
http.sendPost(validatePage, postParams);
// System.exit(0);
// 3. success then go to gmail.
http.GetPageContent2(ccmenuPage);
String result = http.GetPageContent2(reportPage);
System.out.println(result);
}
private void sendPost(String url, String postParams) throws Exception {
URL obj = new URL(url);
conn = (HttpURLConnection) obj.openConnection();
// Acts like a browser
conn.setUseCaches(false);
conn.setRequestMethod("POST");
conn.setRequestProperty("Host", "10.100.100.142");
conn.setRequestProperty("User-Agent", USER_AGENT);
conn.setRequestProperty("Accept","text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8");
conn.setRequestProperty("Accept-Language", "en-US,en;q=0.5");
for (String cookie : this.cookies) {
System.out.println(" sendPost : "+cookie.split(";", 1)[0]);
conn.addRequestProperty("Cookie",cookie.split(";", 1)[0]);
}
conn.setRequestProperty("Connection", "keep-alive");
conn.setRequestProperty("Referer", "http://10.100.100.142/index.asp");
conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
conn.setRequestProperty("Content-Length", Integer.toString(postParams.length()));
conn.setDoOutput(true);
conn.setDoInput(true);
// Send post request
DataOutputStream wr = new DataOutputStream(conn.getOutputStream());
wr.writeBytes(postParams);
wr.flush();
wr.close();
int responseCode = conn.getResponseCode();
System.out.println("\nSending 'POST' request to URL : " + url);
System.out.println("Post parameters : " + postParams);
System.out.println("Response Code : " + responseCode);
// setCookies(conn.getHeaderFields().get("Set-Cookie"));
BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String inputLine;
StringBuffer response = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
in.close();
// System.out.println(response.toString());
}
private String GetPageContent2(String url) throws Exception {
URL obj = new URL(url);
conn = (HttpURLConnection) obj.openConnection();
// default is GET
conn.setRequestMethod("GET");
conn.setUseCaches(false);
// act like a browser
conn.setRequestProperty("User-Agent", USER_AGENT);
conn.setRequestProperty("Accept","text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8");
conn.setRequestProperty("Accept-Language", "en-US,en;q=0.5");
System.out.println(" L : "+cookies);
if (cookies != null) {
for (String cookie : this.cookies) {
System.out.println(" GetPageContent : "+cookie.split(";", 1)[0]);
conn.addRequestProperty("Cookie", cookie.split(";", 1)[0]);
}
}
int responseCode = conn.getResponseCode();
System.out.println("\nSending 'GET' request to URL : " + url);
System.out.println("Response Code : " + responseCode);
BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String inputLine;
StringBuffer response = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
in.close();
// Get the response cookies
// System.out.println(" Get : "+conn.getHeaderFields().get("Set-Cookie"));
// setCookies(conn.getHeaderFields().get("Set-Cookie"));
return response.toString();
}
private String GetPageContent(String url) throws Exception {
URL obj = new URL(url);
conn = (HttpURLConnection) obj.openConnection();
// default is GET
conn.setRequestMethod("GET");
conn.setUseCaches(false);
// act like a browser
conn.setRequestProperty("User-Agent", USER_AGENT);
conn.setRequestProperty("Accept","text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8");
conn.setRequestProperty("Accept-Language", "en-US,en;q=0.5");
System.out.println(" L : "+cookies);
if (cookies != null) {
for (String cookie : this.cookies) {
System.out.println(" GetPageContent : "+cookie.split(";", 1)[0]);
conn.addRequestProperty("Cookie", cookie.split(";", 1)[0]);
}
}
int responseCode = conn.getResponseCode();
System.out.println("\nSending 'GET' request to URL : " + url);
System.out.println("Response Code : " + responseCode);
BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String inputLine;
StringBuffer response = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
in.close();
// Get the response cookies
System.out.println(" Get : "+conn.getHeaderFields().get("Set-Cookie"));
setCookies(conn.getHeaderFields().get("Set-Cookie"));
return response.toString();
}
public String getFormParams(String html, String username, String password)
throws UnsupportedEncodingException {
System.out.println("Extracting form's data...");
Document doc = Jsoup.parse(html);
// Google form id
Element loginform = doc.getElementById("right");
Elements inputElements = loginform.getElementsByTag("input");
List<String> paramList = new ArrayList<String>();
for (Element inputElement : inputElements) {
String key = inputElement.attr("name");
String value = inputElement.attr("value");
if (key.equals("USERname"))
value = username;
else if (key.equals("password"))
value = password;
if(!key.equals(""))
paramList.add(key + "=" + URLEncoder.encode(value, "UTF-8"));
}
// build parameters list
StringBuilder result = new StringBuilder();
for (String param : paramList) {
if (result.length() == 0) {
result.append(param);
} else {
result.append("&" + param);
}
}
return result.toString();
}
public List<String> getCookies() {
return cookies;
}
public void setCookies(List<String> cookies) {
this.cookies = cookies;
}
}
最佳答案
500 表示“内部服务器错误”(请参阅 HTTP codes 及其含义)。
这确实意味着您发送的请求已被理解并且是有效的 HTTP，但要么存在内部、不相关的问题，要么您发送的请求缺少某些参数或发送一些不正确的值，并且该遗漏/错误会导致服务器逻辑崩溃(因为它无法验证请求内容，或者以更深层次、不受控制的方式)。
获取更具体信息的唯一方法是查看服务器日志(如果开发人员仔细检查参数和日志信息)。
您最好的选择是使用像wireshark这样的工具分析网络浏览器和服务器之间的流量，然后分析客户端和服务器之间的流量并尝试找出差异。
关于java - 使用java代码登录后向网站服务器发送响应代码500，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/35171509/