如何使用OAuth使用Facebook帐户登录Google App Engine的Java示例 [英] Java example of how to log in to Google App Engine with a Facebook account using OAuth
问题描述
我进行了很多搜索，阅读了许多博客，文章和教程，但是直到现在，仍没有使用Facebook帐户登录我的应用程序的有效示例.
我知道我必须使用OAuth，获取令牌，授权等...
任何人都可以分享一个例子吗?
这是我在App Engine上执行的操作:
第1步)在Facebook上注册应用"(请参见 https://developers.facebook.com/).您为Facebook指定该应用程序的名称和一个URL.您注册的url是您要处理登录的页面(jsp或servlet)的URL.从注册中，您将获得两个字符串，一个应用程序ID"和一个应用程序密码"(后者是您的密码，请不要透露此密码或将其写入html).
对于此示例，假设我注册的网址是" http://myappengineappid.appspot.com/signin_fb.do ".
2)从网页上说出一个按钮，您将用户重定向到Facebook上的以下URL，在以下示例中将您的应用程序ID替换为"myfacebookappid".您还必须选择要询问用户的权限(或范围")(参见
这是一个jsp代码段: 3)您的用户将被转发到Facebook，并被要求批准您要求的权限.然后，用户将被重定向回您已注册的网址.在此示例中，这是" http://myappengineappid.appspot.com/signin_fb.do 在我的web.xml中映射到以下servlet: 我删除了错误处理代码，因为您可能希望以与我不同的方式来处理它. (此外，性别"当然是我定义的类.)此时，您可以将数据用于所需的任何事情，例如注册新用户或寻找现有用户登录.请注意，""myfacebookappsecret"字符串当然应该是您来自Facebook的应用程序机密. 您将需要"org.json"包才能使用此代码，您可以在以下位置找到该代码: http://json.org/java/(只需获取.java文件，然后将其添加到org/json文件夹结构中的代码中即可). 我希望这会有所帮助.如果有任何不清楚的地方，请发表评论，我会更新答案. 前animo，-亚历山大. ****更新**** 我想补充一些信息，如果其中的某些内容看起来有些过分，我深表歉意. 要能够通过他/她的Facebook帐户登录用户，您需要知道我们正在谈论的数据存储中的哪个用户.如果是新用户，则轻松创建一个新的用户对象(具有一个名为"facebookId"的字段，或者您想调用它的任何对象，其值来自Facebook)，将其保留在数据存储区中并登录该用户./p>
如果用户存在，则需要使用带facebookId的字段.从Facebook重定向用户后，您可以获取facebookId，然后在数据存储区中查找要登录的用户. 如果您已经有用户，则需要让他们以通常的方式登录，这样您就知道他们是谁，然后将其发送到Facebook，取回facebookId并更新其用户对象.这样，他们可以下次使用Facebook登录. 另一个小注意事项:在Facebook上会向用户显示一个屏幕，要求您的应用访问您想要的任何范围，这是不可能的(您要求的范围越小，看上去越不那么侵入，尽管).但是，只有在第一次重定向用户时才会发生这种情况(除非您稍后再请求更多的作用域，然后它将再次询问). I searched a lot, read many blogs, articles, tutorials, but until now did not get a working example of using a Facebook account to log in to my application. I know that I have to use OAuth, get tokens, authorizations, etc... Can anyone share an example? Here is how I do it on App Engine: Step 1) Register an "app" on Facebook (cf. https://developers.facebook.com/ ). You give Facebook a name for the app and a url. The url you register is the url to the page (jsp or servlet) that you want to handle the login. From the registration you get two strings, an "app ID" and an "app secret" (the latter being your password, do not give this out or write it in html). For this example, let's say the url I register is "http://myappengineappid.appspot.com/signin_fb.do". 2) From a webpage, say with a button, you redirect the user to the following url on Facebook, substituting your app id for "myfacebookappid" in the below example. You also have to choose which permissions (or "scopes") you want the ask the user (cf. https://developers.facebook.com/docs/reference/api/permissions/ ). In the example I ask for access to the user's email only. (A useful thing to know is that you can also pass along an optional string that will be returned unchanged in the "state" parameter. For instance, I pass the user's datastore key, so I can retrieve the user when Facebook passes the key back to me. I do not do this in the example.) Here is a jsp snippet: 3) Your user will be forwarded to Facebook, and asked to approve the permissions you ask for. Then, the user will be redirected back to the url you have registered. In this example, this is "http://myappengineappid.appspot.com/signin_fb.do" which in my web.xml maps to the following servlet: I have removed error handling code, as you may want to handle it differently than I do. (Also, "Gender" is of course a class that I have defined.) At this point, you can use the data for whatever you want, like registering a new user or look for an existing user to log in. Note that the "myfacebookappsecret" string should of course be your app secret from Facebook. You will need the "org.json" package to use this code, which you can find at: http://json.org/java/ (just take the .java files and add them to your code in an org/json folder structure). I hope this helps. If anything is unclear, please do comment, and I will update the answer. Ex animo, - Alexander. ****UPDATE**** I want to add a few tidbits of information, my apologies if some of this seems a bit excessive. To be able to log in a user by his/her Facebook account, you need to know which user in the datastore we are talking about. If it's a new user, easy, create a new user object (with a field called "facebookId", or whatever you want to call it, whose value you get from Facebook), persist it in the datastore and log the user in. If the user exist, you need to have the field with the facebookId. When the user is redirected from Facebook, you can grab the facebookId, and look in the datastore to find the user you want to log in. If you already have users, you will need to let them log in the way you usually do, so you know who they are, then send them to Facebook, get the facebookId back and update their user object. This way, they can log in using Facebook the next time. Another small note: The user will be presented with a screen on Facebook asking to allow your app access to whatever scopes you ask for, there is no way around this (the less scopes you ask for, the less intrusive it seems, though). However, this only happens the first time a user is redirected (unless you ask for more scopes later, then it'll ask again). 这篇关于如何使用OAuth使用Facebook帐户登录Google App Engine的Java示例的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！<%@page import="java.net.URLEncoder" %>
<%
String fbURL = "http://www.facebook.com/dialog/oauth?client_id=myfacebookappid&redirect_uri=" + URLEncoder.encode("http://myappengineappid.appspot.com/signin_fb.do") + "&scope=email";
%>
<a href="<%= fbURL %>"><img src="/img/facebook.png" border="0" /></a>
import org.json.JSONObject;
import org.json.JSONException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLEncoder;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class SignInFB extends HttpServlet {
public void service(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
String code = req.getParameter("code");
if (code == null || code.equals("")) {
// an error occurred, handle this
}
String token = null;
try {
String g = "https://graph.facebook.com/oauth/access_token?client_id=myfacebookappid&redirect_uri=" + URLEncoder.encode("http://myappengineappid.appspot.com/signin_fb.do", "UTF-8") + "&client_secret=myfacebookappsecret&code=" + code;
URL u = new URL(g);
URLConnection c = u.openConnection();
BufferedReader in = new BufferedReader(new InputStreamReader(c.getInputStream()));
String inputLine;
StringBuffer b = new StringBuffer();
while ((inputLine = in.readLine()) != null)
b.append(inputLine + "\n");
in.close();
token = b.toString();
if (token.startsWith("{"))
throw new Exception("error on requesting token: " + token + " with code: " + code);
} catch (Exception e) {
// an error occurred, handle this
}
String graph = null;
try {
String g = "https://graph.facebook.com/me?" + token;
URL u = new URL(g);
URLConnection c = u.openConnection();
BufferedReader in = new BufferedReader(new InputStreamReader(c.getInputStream()));
String inputLine;
StringBuffer b = new StringBuffer();
while ((inputLine = in.readLine()) != null)
b.append(inputLine + "\n");
in.close();
graph = b.toString();
} catch (Exception e) {
// an error occurred, handle this
}
String facebookId;
String firstName;
String middleNames;
String lastName;
String email;
Gender gender;
try {
JSONObject json = new JSONObject(graph);
facebookId = json.getString("id");
firstName = json.getString("first_name");
if (json.has("middle_name"))
middleNames = json.getString("middle_name");
else
middleNames = null;
if (middleNames != null && middleNames.equals(""))
middleNames = null;
lastName = json.getString("last_name");
email = json.getString("email");
if (json.has("gender")) {
String g = json.getString("gender");
if (g.equalsIgnoreCase("female"))
gender = Gender.FEMALE;
else if (g.equalsIgnoreCase("male"))
gender = Gender.MALE;
else
gender = Gender.UNKNOWN;
} else {
gender = Gender.UNKNOWN;
}
} catch (JSONException e) {
// an error occurred, handle this
}
...
<%@page import="java.net.URLEncoder" %>
<%
String fbURL = "http://www.facebook.com/dialog/oauth?client_id=myfacebookappid&redirect_uri=" + URLEncoder.encode("http://myappengineappid.appspot.com/signin_fb.do") + "&scope=email";
%>
<a href="<%= fbURL %>"><img src="/img/facebook.png" border="0" /></a>
import org.json.JSONObject;
import org.json.JSONException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLEncoder;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class SignInFB extends HttpServlet {
public void service(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
String code = req.getParameter("code");
if (code == null || code.equals("")) {
// an error occurred, handle this
}
String token = null;
try {
String g = "https://graph.facebook.com/oauth/access_token?client_id=myfacebookappid&redirect_uri=" + URLEncoder.encode("http://myappengineappid.appspot.com/signin_fb.do", "UTF-8") + "&client_secret=myfacebookappsecret&code=" + code;
URL u = new URL(g);
URLConnection c = u.openConnection();
BufferedReader in = new BufferedReader(new InputStreamReader(c.getInputStream()));
String inputLine;
StringBuffer b = new StringBuffer();
while ((inputLine = in.readLine()) != null)
b.append(inputLine + "\n");
in.close();
token = b.toString();
if (token.startsWith("{"))
throw new Exception("error on requesting token: " + token + " with code: " + code);
} catch (Exception e) {
// an error occurred, handle this
}
String graph = null;
try {
String g = "https://graph.facebook.com/me?" + token;
URL u = new URL(g);
URLConnection c = u.openConnection();
BufferedReader in = new BufferedReader(new InputStreamReader(c.getInputStream()));
String inputLine;
StringBuffer b = new StringBuffer();
while ((inputLine = in.readLine()) != null)
b.append(inputLine + "\n");
in.close();
graph = b.toString();
} catch (Exception e) {
// an error occurred, handle this
}
String facebookId;
String firstName;
String middleNames;
String lastName;
String email;
Gender gender;
try {
JSONObject json = new JSONObject(graph);
facebookId = json.getString("id");
firstName = json.getString("first_name");
if (json.has("middle_name"))
middleNames = json.getString("middle_name");
else
middleNames = null;
if (middleNames != null && middleNames.equals(""))
middleNames = null;
lastName = json.getString("last_name");
email = json.getString("email");
if (json.has("gender")) {
String g = json.getString("gender");
if (g.equalsIgnoreCase("female"))
gender = Gender.FEMALE;
else if (g.equalsIgnoreCase("male"))
gender = Gender.MALE;
else
gender = Gender.UNKNOWN;
} else {
gender = Gender.UNKNOWN;
}
} catch (JSONException e) {
// an error occurred, handle this
}
...
