相信大家对拦截器和切面的概念已经不陌生了,本文我们就看一些在应用市场中,拦截器和切面的使用是怎样的。
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,
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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 {
}
}
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切面的使用:
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//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;
}
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总结
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原文链接:http://blog.csdn.net/qq_28893679/article/details/72841958