这篇文章主要介绍了springboot跨域问题解决方案,文中通过示例代码介绍的非常详细，对大家的学习或者工作具有一定的参考学习价值,需要的朋友可以参考下

springboot中的跨域问题，如果不注意的话，容易造成错误，本次springboot版本为2.13

前端错误信息：

Access to XMLHttpRequest at 'http://localhost:8080/user/loginOn' from origin 'http://localhost:8082' has been blocked by CORS policy:
Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource.

第一种：是在每个Controller里，加上注解：@CrossOrigin

import javax.validation.Valid;
@CrossOrigin
@RestController
@RequestMapping("/user")
public class UserController{

也可以在方法上加上，比如这样，这样针对具体的方法

 @CrossOrigin
  @ApiOperation(value = "用户登录",notes = "")
  @PostMapping("/loginOn")
  public ResponseMessage loginOn(@RequestBody @Valid UserReq userReq){

每一个Controller这样写也是很麻烦。

第二种：是实现WebMvcConfigurer接口，在接口中进行跨域支持

以前可以继承WebMvcConfigurerAdapter，springboot2.x版本已经将其@Deprecated

我们直接实现接口：

@Configuration
public class WebConfig implements WebMvcConfigurer {

  /**
   * 跨域支持
   * @param registry
   */
  @Override
  public void addCorsMappings(CorsRegistry registry) {
    registry.addMapping("/**")
        .allowedOrigins("*")
        .allowCredentials(true)
        .allowedMethods("GET", "POST", "DELETE", "PUT")
        .maxAge(3600 * 24);
  }

但使用这种方法，我今天遇到一个坑，我准备在拦截器里面对用户的请求进行拦截

@Component
public class RequestInterceptor implements HandlerInterceptor {
  @Override
  public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
    Object loginUser = request.getSession().getAttribute("token");
    if(loginUser == null){
　　　　　　　　//自定义的异常类，这里抛出异常，交给全局异常捕捉类处理
      throw new ServiceException("没有权限，请先登录!");
    }else{
      return true;
    }
  }

  @Override
  public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

  }

  @Override
  public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

  }
}

全局异常捕捉类：

@RestControllerAdvice
public class GlobleExceptionHandler {
  @ExceptionHandler(value = ServiceException.class)
  public ResponseMessage caughtException(ServiceException e){

    return new ResponseMessage(e.getMsg());
  }
}

ResponseMessage 是自定义的统一的响应信息类：

ResponseMessage

@Data
public class ResponseMessage {
  private Integer Code;
  private String msg;
  private Integer count;
  private Object data;

  public ResponseMessage(Object data) {
    this.data = data;
  }

  public ResponseMessage(String msg) {
    this.msg = msg;
  }

  public ResponseMessage(Integer code, String msg) {
    Code = code;
    this.msg = msg;
  }

  public ResponseMessage(Integer code, String msg, Integer count) {
    Code = code;
    this.msg = msg;
    this.count = count;
  }

  public ResponseMessage(Integer code, String msg, Integer count, Object data) {
    Code = code;
    this.msg = msg;
    this.count = count;
    this.data = data;
  }

  public static ResponseMessage success(String msg){
    return new ResponseMessage(200,msg);
  }

  public static ResponseMessage fail(Integer code,String msg){
    return new ResponseMessage(code,msg);
  }
}