这篇文章主要介绍Java拦截器和切面怎么用，文中介绍的非常详细，具有一定的参考价值，感兴趣的小伙伴们一定要看完！
拦截器的使用：每次接收到某个请求之前，都会调用此拦截器中的方法，其中preHandle方法如果return true,表示继续调用对应的controller,如果return false，
public class CheckLoginInterceptor implements HandlerInterceptor {
private Logger logger = Logger.getLogger(CheckLoginInterceptor.class);
private static String TOKEN_VALID_MSG ;
static
{
TOKEN_VALID_MSG=JsonUtil.writeObject2JSON(new AMSResultVO(CodeNum.TOKEN_VALID, CodeMessage.TOKEN_VALID));
}
public Boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
//request.getMethod获取请求是get,post等
if ("OPTIONS".equals(request.getMethod()))
{
// 指定允许其他域名访问
response.setHeader("Access-Control-Allow-Origin", "*");
// 响应类型
response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE");
// 响应头设置
response.setHeader("Access-Control-Allow-Headers", "Content-Type, x-requested-with, X-Custom-Header");
response.setStatus(204);
return true;
}
// 获取从header中得到的数据
String userName = request.getHeader(CommonConsts.PARAM_USER_NAME);
String userToken = request.getHeader(CommonConsts.PARAM_USER_TOKEN);
Boolean result = true;
String method = request.getRequestURI();
if(method.equals("/ams/fileUpload"))
{
return true;
}
if(StringUtil.isEmpty(userName) || StringUtil.isEmpty(userToken))
{
result = false;
} else
{
result = TokenUtil.validToken(userName, userToken);
}
// token校验失败
if(!result)
{
response.setContentType("text/html;charset=UTF-8");
response.getWriter().print(TOKEN_VALID_MSG);
response.getWriter().flush();
response.getWriter().close();
}
return result;
}
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
}
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
}
}切面的使用：
//坏绕通知：需要携带ProceedingJoinPoint类型的参数
//环绕通知类似于动态代理的全过程：ProceedingJoinPoint类型的参数可以决定是否执行目标方法
//且环绕通知必须有返回值，返回值即目标方法的返回值。
@Around("execution(* com.sowell.controller.*Controller.*(..))")
public Object aroundMethod(ProceedingJoinPoint pjd) {
Object result = null;
String methodName = pjd.getSignature().getName();
Object args = Arrays.asList(pjd.getArgs());
//执行目标方法
try {
logger.info("request channels begin, param{pageNum:" + methodName + ", pageSize:" + args);
//前置通知，表示在此之前的代码会在调用controller之前调用
result = pjd.proceed();
recordOprationLog(result, methodName, result);
//后置通知
logger.info("Arround:The method "+ methodName+" ends");
}
catch (Throwable e) {
e.printStackTrace();
//异常通知
logger.error("Arround:The method "+ methodName+"occurs exception:"+e);
//throw new RuntimeException(e);
//不抛出异常的话，异常就被上面抓住，执行下去，返回result，result值为null，转换为int
}
//返回通知
logger.info("Arround:The method "+ methodName+" ends with the Result "+ result);
return result;
}以上是“Java拦截器和切面怎么用”这篇文章的所有内容，感谢各位的阅读！希望分享的内容对大家有帮助，更多相关知识，欢迎关注创新互联行业资讯频道！
