ApplicationContextAware使用理解

接口的作用

當一個類實現了這個接口（ApplicationContextAware）之后，Aware接口的Bean在被初始之后，可以取得一些相對應的資源，這個類可以直接獲取spring 配置文件中 所有引用（注入）到的bean對象。

項目中的用法

@Component
public class WebUtil implements ApplicationContextAware {

    private static ApplicationContext applicationContext;
    
    public static final String COMPUTER   = "C"         ; //"Computer"
    public static final String MOBILE     = "M"         ; //"Mobile"
    public static final String UNKNOWN    = "Unknown"   ;
    public static final String USER_AGENT = "User-Agent";
    
    /**
     * 取得實際路徑
     */
    public static String getRealPath(String path) {
        return getHttpServletRequest().getServletContext().getRealPath(path);
    }
    
    /**
     * 從IOC中獲得對象: 根據類型
     */
    public static <T> T getBean(Class<T> requiredType){
        return applicationContext.getBean(requiredType);
    }
    
    /**
     * 從IOC中獲得對象: 根據id
     */
    public static Object getBean(String beanName){
        return applicationContext.getBean(beanName);
    }
    
    /**
     * 從IOC中獲得多個對象(實現接口或繼承的)
     */
    public static <T> Map<String, T> getBeansOfType(Class<T> requiredType){
        return applicationContext.getBeansOfType(requiredType);
    }
    
    /**
     * 獲得當前請求的Request對象
     */
    public static HttpServletRequest getHttpServletRequest() {
        return ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest();
    }

    /**
     * 取得設備類型
     */
    public static String getDeviceType() {
        String userAgent = getHttpServletRequest().getHeader(USER_AGENT);
        return getDeviceType(userAgent);
    }

    /**
     * 當前是否是電腦設備
     */
    public static boolean isComputer() {
        return COMPUTER.equals(getDeviceType());
    }
    /**
     * 獲得設備類型
     */
    public static String getDeviceType(String userAgentHeader) {
        if (userAgentHeader == null) return COMPUTER;
        if (userAgentHeader.contains("Andriod") || userAgentHeader.contains("iPhone") || userAgentHeader.contains("iPad"))
            return MOBILE;
        return COMPUTER;
    }
    
    /**
     * 取得瀏覽器
     */
    public static String getBrowser(String userAgentHeader) {
        UserAgent userAgent = UserAgent.parseUserAgentString(userAgentHeader);
        String brower = userAgent.getBrowser().getName();
        
        //考慮手機端的瀏覽器訪問,此處采用解析為Unknown時空格分隔取第一個
        if (Browser.UNKNOWN.getName().equals(brower) && userAgentHeader != null) {
            brower = userAgentHeader.split(" ")[0];
        }
        return brower;
    }    

    /**
     * 取得操作系統
     */
    public static String getOsName(String userAgentHeader) {
        UserAgent userAgent = UserAgent.parseUserAgentString(userAgentHeader);
        String osName = userAgent.getOperatingSystem().getName();
        return osName;
    }
    
    /**
     * 根據Request獲取IP地址
     * 
     * 使用Nginx等反向代理軟件， 則不能通過request.getRemoteAddr()獲取IP地址
     * 如果使用了多級反向代理的話，X-Forwarded-For的值並不止一個，
     * 而是一串IP地址，X-Forwarded-For中第一個非unknown的有效IP字符串，則為真實IP地址
     */
    public static String getIpAddr(HttpServletRequest request) {
        // 代理處理
        String ip = request.getHeader("x-forwarded-for");
        if (blankOrUnknown(ip)) ip = request.getHeader("Proxy-Client-IP");
        if (blankOrUnknown(ip)) ip = request.getHeader("WL-Proxy-Client-IP");
        if (blankOrUnknown(ip)) ip = request.getHeader("HTTP_CLIENT_IP");
        if (blankOrUnknown(ip)) ip = request.getHeader("HTTP_X_FORWARDED_FOR");
        
        // 多級代理
        if (StringUtils.isNotBlank(ip) && ip.contains(",")) ip = ip.split(",")[0];
        
        // 正常處理
        if (blankOrUnknown(ip)) ip = request.getRemoteAddr();

        // 特殊設置
        if("0:0:0:0:0:0:0:1".equals(ip) || "localhost".equals(ip)) ip = "127.0.0.1";
        
        //非空限定
        if(ip == null) ip = "unknown";
        
        return ip;
    }
    
    //IP地址為空(白)或為unknown
    private static boolean blankOrUnknown(String ip) {
        return StringUtils.isBlank(ip) || "unknown".equalsIgnoreCase(ip);
    }
    
    /**
     * 是否為ajax請求
     */
    public static boolean isAjax(HttpServletRequest request){
        //如果是ajax請求響應頭會有，x-requested-with
         if (request.getHeader("x-requested-with") != null 
                 && request.getHeader("x-requested-with").equalsIgnoreCase("XMLHttpRequest")) { 
             return true;
         }
         return false;
    }

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        WebUtil.applicationContext = applicationContext;
    }

    public static ApplicationContext getApplicationContext() {
        return applicationContext;
    }
    
    
}

用法：

LogQuartzService logQuartzService =WebUtil.getBean(LogQuartzService.class);