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Java：Cookie实现记住用户名、密码

2017-09-15 10:43 288 查看 
package
com.laizhi.util;
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003
import
java.io.IOException;
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005
import
java.io.PrintWriter;
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007
import
java.io.UnsupportedEncodingException;
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009
import
javax.servlet.FilterChain;
010
011
import
javax.servlet.ServletException;
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013
import
javax.servlet.http.Cookie;
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015
import
javax.servlet.http.HttpServletRequest;
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017
import
javax.servlet.http.HttpServletResponse;
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019
import
javax.servlet.http.HttpSession;
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021
import
java.security.MessageDigest;
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023
import
java.security.NoSuchAlgorithmException;
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025
import
com.laizhi.bean.User;
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027
import
com.laizhi.dao.UserDAO;
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029
import
com.laizhi.factory.DaoImplFactory;
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031
import
com.sun.org.apache.xerces.internal.impl.dv.util.Base64;
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033
/*
034
035
*2014.07.01
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037
**/
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public
class

CookieUtil {
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//保存cookie时的cookieName
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private

final
 
static
 
String cookieDomainName = “laizhi”;
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//加密cookie时的网站自定码
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044
private

final
 
static
 
String webKey = “
123456
”;
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//设置cookie有效期是两个星期，根据需要自定义
046
private

final
 
static
 
long
 
cookieMaxAge =
60

*
60
 
*

24
 
*
7

*
2
;
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//保存Cookie到客户端-------------------------------------------------------------------------
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//在CheckLogonServlet.java中被调用
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//传递进来的user对象中封装了在登陆时填写的用户名与密码
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051
public

static
 
void
 
saveCookie(User user,HttpServletResponse response) {
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//cookie的有效期
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long

validTime = System.currentTimeMillis() + (cookieMaxAge *

5000
);
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//MD5加密用户详细信息
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String cookieValueWithMd5 =getMD5(user.getUserName() +
":"
 
+ user.getPassword()
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057
+
":"
 
+ validTime +
":"

+ webKey);
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//将要被保存的完整的Cookie值
059
String cookieValue = user.getUserName() +
":"
 
+ validTime +
":"

+ cookieValueWithMd5;
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//再一次对Cookie的值进行BASE64编码
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String cookieValueBase64 =
new
 
String(Base64.encode(cookieValue.getBytes()));
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//开始保存Cookie
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Cookie cookie =
new
 
Cookie(cookieDomainName,cookieValueBase64);
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//存两年(这个值应该大于或等于validTime)
066
cookie.setMaxAge(
60

*
60
 
*

24
 
*
365

*
2
);
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//cookie有效路径是网站根目录
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cookie.setPath(
"/"
);
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//向客户端写入
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response.addCookie(cookie);
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}
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078
 
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//读取Cookie,自动完成登陆操作----------------------------------------------------------------
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//在Filter程序中调用该方法,见AutoLogonFilter.java
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public

static
 
void
 
readCookieAndLogon(HttpServletRequest request,HttpServletResponse response,
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086
FilterChain chain)
throws

IOException,ServletException,UnsupportedEncodingException{
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//根据cookieName取cookieValue
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Cookie cookies[] = request.getCookies();
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String cookieValue =
null
;
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if
(cookies!=
null
){
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for
(
int

i=
0
;i
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if

(cookieDomainName.equals(cookies[i].getName())) {
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cookieValue = cookies[i].getValue();
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break
;
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}
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}
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}
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//如果cookieValue为空,返回,
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if
(cookieValue==
null
){
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return
;
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}
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//如果cookieValue不为空,才执行下面的代码
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//先得到的CookieValue进行Base64解码
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String cookieValueAfterDecode =
new
 
String (Base64.decode(cookieValue),
"utf-8"
);
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//对解码后的值进行分拆,得到一个数组,如果数组长度不为3,就是非法登陆
108
String cookieValues[] = cookieValueAfterDecode.split(
":"
);
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if
(cookieValues.length!=
3
){
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response.setContentType(
"text/html;charset=utf-8"
);
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PrintWriter out = response.getWriter();
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out.println(
"你正在用非正常方式进入本站..."
);
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out.close();
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return
;
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}
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//判断是否在有效期内,过期就删除Cookie
117
long

validTimeInCookie =
new
 
Long(cookieValues[
1
]);
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if
(validTimeInCookie < System.currentTimeMillis()){
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//删除Cookie
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clearCookie(response);
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response.setContentType(
"text/html;charset=utf-8"
);
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PrintWriter out = response.getWriter();
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out.println(
""
);你的Cookie已经失效,请重新登陆
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out.close();
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return
;
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}
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//取出cookie中的用户名,并到数据库中检查这个用户名,
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String username = cookieValues[
0
];
129
 
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//根据用户名到数据库中检查用户是否存在
131
UserDAO ud = DaoImplFactory.getInstance();
132
User user = ud.selectUserByUsername(username);
133
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//如果user返回不为空,就取出密码,使用用户名+密码+有效时间+ webSiteKey进行MD5加密
135
if
(user!=
null
){
136
String md5ValueInCookie = cookieValues[
2
];
137
String md5ValueFromUser =getMD5(user.getUserName() +
":"
 
+ user.getPassword()
138
+
":"
 
+ validTimeInCookie +

":"
 
+ webKey);
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//将结果与Cookie中的MD5码相比较,如果相同,写入Session,自动登陆成功,并继续用户请求
140
if
(md5ValueFromUser.equals(md5ValueInCookie)){
141
HttpSession session = request.getSession(
true
);
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session.setAttribute(
"user"
,user);
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chain.doFilter(request,response);
144
}
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}
else
{
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//返回为空执行
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response.setContentType(
"text/html;charset=utf-8"
);
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PrintWriter out = response.getWriter();
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out.println(
"cookie验证错误！"
);
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out.close();
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return
;
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}
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}
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159
 
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//用户注销时,清除Cookie,在需要时可随时调用-----------------------------------------------------
162
public

static
 
void
 
clearCookie( HttpServletResponse response){
163
Cookie cookie =
new
 
Cookie(cookieDomainName,
null
);
164
cookie.setMaxAge(
0
);
165
cookie.setPath(
"/"
);
166
response.addCookie(cookie);
167
}
168
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//获取Cookie组合字符串的MD5码的字符串----------------------------------------------------------------
170
public

static
 
String getMD5(String value) {
171
String result =
null
;
172
try
{
173
byte
[] valueByte = value.getBytes();
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MessageDigest md = MessageDigest.getInstance(
"MD5"
);
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md.update(valueByte);
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result = toHex(md.digest());
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}
catch
 
(NoSuchAlgorithmException e2){
178
e1.printStackTrace();
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}
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return

result;
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}
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//将传递进来的字节数组转换成十六进制的字符串形式并返回
183
private

static
 
String toHex(
byte
[] buffer){
184
StringBuffer sb =
new
 
StringBuffer(buffer.length *
2
);
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for

(
int
 
i =
0
; i < buffer.length; i++){
186
sb.append(Character.forDigit((buffer[i] &
0xf0
) >>
4
,
16
));
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sb.append(Character.forDigit(buffer[i] &
0x0f
,
16
));
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}
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return

sb.toString();
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}
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}

                                            

                                        

                        
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