什么是 JWT -- JSON WEB TOKEN

看链接:http://www.jianshu.com/p/576dbf44b2ae

来个工具类:

import java.io.Serializable;
import java.util.Date;
import java.util.Map;
import org.springframework.stereotype.Component;

import io.jsonwebtoken.Claims;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.SignatureAlgorithm;

@Component
public class JwtTokenService implements Serializable {

    private static final long serialVersionUID = -3301605591108950415L;

    private static final String CLAIM_KEY_CREATED = "created";

    private String secret="absd";

    private Long expiration=7200L;


    /**
     * 获取创建token时间
     * @param token
     * @return
     */
    public Date getCreatedDateFromToken(String token) {
        Date created;
        try {
            final Claims claims = getClaimsFromToken(token);
            created = new Date((Long) claims.get(CLAIM_KEY_CREATED));
        } catch (Exception e) {
            created = null;
        }
        return created;
    }

    /**
     * 获取过期时间
     * @param token
     * @return
     */
    public Date getExpirationDateFromToken(String token) {
        Date expiration;
        try {
            final Claims claims = getClaimsFromToken(token);
            expiration = claims.getExpiration();
        } catch (Exception e) {
            expiration = null;
        }
        return expiration;
    }








    /**
     * 判断是否过期
     * @param token
     * @return
     */
    private Boolean isTokenExpired(String token) {
        final Date expiration = getExpirationDateFromToken(token);
        return expiration.before(new Date());
    }

    /**
     * 获取jwt中的body部分
     * @param token
     * @return
     */
    public Claims getClaimsFromToken(String token) {
        Claims claims;
        try {
            claims = Jwts.parser()
                    .setSigningKey(secret)
                    .parseClaimsJws(token)
                    .getBody();
        } catch (Exception e) {
            claims = null;
           // throw e;

        }
        return claims;
    }


    public String getSubject(String token){
        try {
            return   getClaimsFromToken(token).getSubject();
        }catch (Exception e){

        }
        return null;

    }

    /**
     * 生成过期时间
     * @return
     */
    private Date generateExpirationDate() {
        return new Date(System.currentTimeMillis() + expiration * 1000);
    }



    /**
     *  生成token
     * @param claims
     * @return
     */
    public String generateToken(Map<String, Object> claims, String subject) {
        return Jwts.builder()
                .setClaims(claims)
                .setSubject(subject)
                .setExpiration(generateExpirationDate())
                .signWith(SignatureAlgorithm.HS512, secret)
                .compact();
    }

    public String generateToken( String subject) {
        return Jwts.builder()
                .setSubject(subject)
                .setExpiration(generateExpirationDate())
                .signWith(SignatureAlgorithm.HS512, secret)
                .compact();
    }


    public String refreshToken(String token) {
        String refreshedToken;
        try {
            final Claims claims = getClaimsFromToken(token);
            claims.put(CLAIM_KEY_CREATED, new Date());
            refreshedToken = generateToken(claims,claims.getSubject());
        } catch (Exception e) {
            refreshedToken = null;
        }
        return refreshedToken;
    }

    /**
     * token是否过期
     * @param token
     * @return
     */
    public Boolean validateToken(String token) {
        Claims claims = getClaimsFromToken(token);
        if(claims==null) return false;
        return !isTokenExpired(token);
    }



}