public Result register(String username,String password){
    User u = userService.findByUserName(username);
    if (u==null){
        userService.register(username,password);
        return Result.success();
    }else{
        return Result.error("用戶名已被占用");
    }
}

@PostMapping("/register")
public Result register(String username, String password){
    if (username!=null && username.length()>=5 && username.length()<=16 &&
        password!=null && password.length()>=5 && password.length()<=16
    ){
       //查詢用戶
   User u = userService.findByUserName(username);
        if (u==null){
            //沒有占用
        //注冊(cè)
        userService.register(username,password);
            return Result.success();
        }else{
            //占用
            return Result.error("用戶名已被占用");
        }
    }else{
        return Result.error("參數(shù)不合法");
    }
}

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-validation</artifactId>
</dependency>

@Validated
public Result register(
@Pattern(regexp="^\\S{5,16}$") String username,@Pattern(regexp="^\\S{5,16}$")String password){
if (userService.findByUsername(username)!=null){
    return Result,error("該用戶名已被占用")：
}
userService.register(username,password);
return Result.success();

@RestControllerAdvice
public class GlobalExceptionHandler
    @ExceptionHandler(Exception.class)
    public Result handleException(Exception e){
        e.printstackTrace();
        return Result.error(StringUtils.hasLength(e.getMessage())?e.getMessage():"操作失敗")；

header+"."+payload+"."+singnature ---> 組成唯一的token

<dependency>
  <groupId>com.auth0</groupId>
  <artifactId>java-jwt</artifactId>
  <version>3.10.3</version>
</dependency>
 

void genToken() {
    Map<String, Object> user = new HashMap<>();
    user.put(“id”, “1”);
    user.put(“username”, “張三”);
    String token = JWT.create()
            .withClaim(“user”, user)
            .withExpiresAt(new Date(System.currentTimeMillis() + 1000*60*60))
            .sign(Algorithm.HMAC256(“秘鑰"));
    System.out.println(token);
}

void parseToken() {
    String token = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9…….";
    JWTVerifier jwtVerifier = JWT.require(Algorithm.HMAC256("itheima")).build();
   DecodedJWT decodedJWT = jwtVerifier.verify(token);
    Map<String, Claim> claims = decodedJWT.getClaims();
    System.out.println(claims.get("user"));
}

package com.liup.interceptor;
import com.auth0.jwt.exceptions.AlgorithmMismatchException;
import com.auth0.jwt.exceptions.SignatureVerificationException;
import com.auth0.jwt.exceptions.TokenExpiredException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.office.utils.JWTUtils;
import org.springframework.web.servlet.HandlerInterceptor;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.HashMap;
import java.util.Map;
/**
 * JWT驗(yàn)證攔截器
 */
public class JWTInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        Map<String,Object> map = new HashMap<>();
        //令牌建議是放在請(qǐng)求頭中，獲取請(qǐng)求頭中令牌
        String token = request.getHeader("token");
        try{
            JWTUtils.verify(token);//驗(yàn)證令牌
            return true;//放行請(qǐng)求
        } catch (SignatureVerificationException e) {
            e.printStackTrace();
            map.put("msg","無效簽名");
        } catch (TokenExpiredException e) {
            e.printStackTrace();
            map.put("msg","token過期");
        } catch (AlgorithmMismatchException e) {
            e.printStackTrace();
            map.put("msg","token算法不一致");
        } catch (Exception e) {
            e.printStackTrace();
            map.put("msg","token失效");
        }
        map.put("state",false);//設(shè)置狀態(tài)
        //將map轉(zhuǎn)化成json，response使用的是Jackson
        String json = new ObjectMapper().writeValueAsString(map);
        response.setContentType("application/json;charset=UTF-8");
        response.getWriter().print(json);
        return false;
    }
}

@Configuration
public class WebMvcConfiguration extends WebMvcConfigurationSupport {
    @Autowired
    private JwtTokenAdminInterceptor jwtTokenAdminInterceptor;
    /**
     * 注冊(cè)自定義攔截器
     *
     * @param registry
     */
    protected void addInterceptors(InterceptorRegistry registry) {
        log.info("開始注冊(cè)自定義攔截器...");
        registry.addInterceptor(jwtTokenAdminInterceptor)
                .addPathPatterns("/admin/**")
                .excludePathPatterns("/admin/employee/login");//除去那個(gè)路徑不驗(yàn)證
    }