已經(jīng)解決了，問題是出在我在JwtUser.java的時候，應(yīng)該是：

@JsonIgnore
@Override
public String getPassword() {
return password;
}

@Override
public String getUsername() {
return username;
}
可是我寫成了：
@JsonIgnore
@Override
public String getPassword() {
return null;
}

@Override
public String getUsername() {
return null;
}

我在官方demo中找到如下代碼：

// Perform the security
        final Authentication authentication = authenticationManager.authenticate(
                new UsernamePasswordAuthenticationToken(
                        authenticationRequest.getUsername(),
                        authenticationRequest.getPassword()
                )
        );
        SecurityContextHolder.getContext().setAuthentication(authentication);
         // Reload password post-security so we can generate token
        final UserDetails userDetails = userDetailsService.loadUserByUsername(authenticationRequest.getUsername());
        final String token = jwtTokenUtil.generateToken(userDetails, device);

不知道是否對你有所幫助