public abstract class Handler {
   
    /**
     * 持有后繼的責(zé)任對(duì)象
     */
    protected Handler successor;
    /**
     * 示意處理請(qǐng)求的方法，雖然這個(gè)示意方法是沒(méi)有傳入?yún)?shù)的
     * 但實(shí)際是可以傳入?yún)?shù)的，根據(jù)具體需要來(lái)選擇是否傳遞參數(shù)
     */
    public abstract void handleRequest();
    /**
     * 取值方法
     */
    public Handler getSuccessor() {
        return successor;
    }
    /**
     * 賦值方法，設(shè)置后繼的責(zé)任對(duì)象
     */
    public void setSuccessor(Handler successor) {
        this.successor = successor;
    }
   
}

public class ConcreteHandler extends Handler {
    /**
     * 處理方法，調(diào)用此方法處理請(qǐng)求
     */
    @Override
    public void handleRequest() {
        /**
         * 判斷是否有后繼的責(zé)任對(duì)象
         * 如果有，就轉(zhuǎn)發(fā)請(qǐng)求給后繼的責(zé)任對(duì)象
         * 如果沒(méi)有，則處理請(qǐng)求
         */
        if(getSuccessor() != null)
        {           
            System.out.println("放過(guò)請(qǐng)求");
            getSuccessor().handleRequest();           
        }else
        {           
            System.out.println("處理請(qǐng)求");
        }
    }

}

public class Client {

    public static void main(String[] args) {
        //組裝責(zé)任鏈
        Handler handler1 = new ConcreteHandler();
        Handler handler2 = new ConcreteHandler();
        handler1.setSuccessor(handler2);
        //提交請(qǐng)求
        handler1.handleRequest();
    }

}

public abstract class Handler {
    /**
     * 持有下一個(gè)處理請(qǐng)求的對(duì)象
     */
    protected Handler successor = null;
    /**
     * 取值方法
     */
    public Handler getSuccessor() {
        return successor;
    }
    /**
     * 設(shè)置下一個(gè)處理請(qǐng)求的對(duì)象
     */
    public void setSuccessor(Handler successor) {
        this.successor = successor;
    }
    /**
     * 處理聚餐費(fèi)用的申請(qǐng)
     * @param user    申請(qǐng)人
     * @param fee    申請(qǐng)的錢(qián)數(shù)
     * @return        成功或失敗的具體通知
     */
    public abstract String handleFeeRequest(String user , double fee);
}

public class ProjectManager extends Handler {

    @Override
    public String handleFeeRequest(String user, double fee) {
       
        String str = "";
        //項(xiàng)目經(jīng)理權(quán)限比較小，只能在500以?xún)?nèi)
        if(fee < 500)
        {
            //為了測(cè)試，簡(jiǎn)單點(diǎn)，只同意張三的請(qǐng)求
            if("張三".equals(user))
            {
                str = "成功：項(xiàng)目經(jīng)理同意【" + user + "】的聚餐費(fèi)用，金額為" + fee + "元";   
            }else
            {
                //其他人一律不同意
                str = "失敗：項(xiàng)目經(jīng)理不同意【" + user + "】的聚餐費(fèi)用，金額為" + fee + "元";
            }
        }else
        {
            //超過(guò)500，繼續(xù)傳遞給級(jí)別更高的人處理
            if(getSuccessor() != null)
            {
                return getSuccessor().handleFeeRequest(user, fee);
            }
        }
        return str;
    }

}

public class DeptManager extends Handler {

    @Override
    public String handleFeeRequest(String user, double fee) {
       
        String str = "";
        //部門(mén)經(jīng)理的權(quán)限只能在1000以?xún)?nèi)
        if(fee < 1000)
        {
            //為了測(cè)試，簡(jiǎn)單點(diǎn)，只同意張三的請(qǐng)求
            if("張三".equals(user))
            {
                str = "成功：部門(mén)經(jīng)理同意【" + user + "】的聚餐費(fèi)用，金額為" + fee + "元";   
            }else
            {
                //其他人一律不同意
                str = "失敗：部門(mén)經(jīng)理不同意【" + user + "】的聚餐費(fèi)用，金額為" + fee + "元";
            }
        }else
        {
            //超過(guò)1000，繼續(xù)傳遞給級(jí)別更高的人處理
            if(getSuccessor() != null)
            {
                return getSuccessor().handleFeeRequest(user, fee);
            }
        }
        return str;
    }

}

public class GeneralManager extends Handler {

    @Override
    public String handleFeeRequest(String user, double fee) {
       
        String str = "";
        //總經(jīng)理的權(quán)限很大，只要請(qǐng)求到了這里，他都可以處理
        if(fee >= 1000)
        {
            //為了測(cè)試，簡(jiǎn)單點(diǎn)，只同意張三的請(qǐng)求
            if("張三".equals(user))
            {
                str = "成功：總經(jīng)理同意【" + user + "】的聚餐費(fèi)用，金額為" + fee + "元";   
            }else
            {
                //其他人一律不同意
                str = "失敗：總經(jīng)理不同意【" + user + "】的聚餐費(fèi)用，金額為" + fee + "元";
            }
        }else
        {
            //如果還有后繼的處理對(duì)象，繼續(xù)傳遞
            if(getSuccessor() != null)
            {
                return getSuccessor().handleFeeRequest(user, fee);
            }
        }
        return str;
    }

}

public class Client {

    public static void main(String[] args) {
        //先要組裝責(zé)任鏈
        Handler h1 = new GeneralManager();
        Handler h2 = new DeptManager();
        Handler h3 = new ProjectManager();
        h3.setSuccessor(h2);
        h2.setSuccessor(h1);
       
        //開(kāi)始測(cè)試
        String test1 = h3.handleFeeRequest("張三", 300);
        System.out.println("test1 = " + test1);
        String test2 = h3.handleFeeRequest("李四", 300);
        System.out.println("test2 = " + test2);
        System.out.println("---------------------------------------");
       
        String test3 = h3.handleFeeRequest("張三", 700);
        System.out.println("test3 = " + test3);
        String test4 = h3.handleFeeRequest("李四", 700);
        System.out.println("test4 = " + test4);
        System.out.println("---------------------------------------");
       
        String test5 = h3.handleFeeRequest("張三", 1500);
        System.out.println("test5 = " + test5);
        String test6 = h3.handleFeeRequest("李四", 1500);
        System.out.println("test6 = " + test6);
    }

}

public class TestFilter implements Filter{

    public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {
       
        chain.doFilter(request, response);
    }

    public void destroy() {
    }

    public void init(FilterConfig filterConfig) throws ServletException {
    }

}

/**
     * Filters.
     */
    private ApplicationFilterConfig[] filters =
        new ApplicationFilterConfig[0];

/**
 * Implementation of a <code>javax.servlet.FilterConfig</code> useful in
 * managing the filter instances instantiated when a web application
 * is first started.
 *
 * @author Craig R. McClanahan
 * @version $Id: ApplicationFilterConfig.java 1201569 2011-11-14 01:36:07Z kkolinko $
 */

private ApplicationFilterConfig[] filters =
        new ApplicationFilterConfig[0];

  /**
     * The int which gives the current number of filters in the chain.
     */
    private int n = 0;
 public static final int INCREMENT = 10;

void addFilter(ApplicationFilterConfig filterConfig) {

        // Prevent the same filter being added multiple times
        for(ApplicationFilterConfig filter:filters)
            if(filter==filterConfig)
                return;

        if (n == filters.length) {
            ApplicationFilterConfig[] newFilters =
                new ApplicationFilterConfig[n + INCREMENT];
            System.arraycopy(filters, 0, newFilters, 0, n);
            filters = newFilters;
        }
        filters[n++] = filterConfig;

    }

public ApplicationFilterChain createFilterChain
        (ServletRequest request, Wrapper wrapper, Servlet servlet) {

        // get the dispatcher type
        DispatcherType dispatcher = null;
        if (request.getAttribute(DISPATCHER_TYPE_ATTR) != null) {
            dispatcher = (DispatcherType) request.getAttribute(DISPATCHER_TYPE_ATTR);
        }
        String requestPath = null;
        Object attribute = request.getAttribute(DISPATCHER_REQUEST_PATH_ATTR);
       
        if (attribute != null){
            requestPath = attribute.toString();
        }
       
        // If there is no servlet to execute, return null
        if (servlet == null)
            return (null);

        boolean comet = false;
       
        // Create and initialize a filter chain object
        ApplicationFilterChain filterChain = null;
        if (request instanceof Request) {
            Request req = (Request) request;
            comet = req.isComet();
            if (Globals.IS_SECURITY_ENABLED) {
                // Security: Do not recycle
                filterChain = new ApplicationFilterChain();
                if (comet) {
                    req.setFilterChain(filterChain);
                }
            } else {
                filterChain = (ApplicationFilterChain) req.getFilterChain();
                if (filterChain == null) {
                    filterChain = new ApplicationFilterChain();
                    req.setFilterChain(filterChain);
                }
            }
        } else {
            // Request dispatcher in use
            filterChain = new ApplicationFilterChain();
        }

        filterChain.setServlet(servlet);

        filterChain.setSupport
            (((StandardWrapper)wrapper).getInstanceSupport());

        // Acquire the filter mappings for this Context
        StandardContext context = (StandardContext) wrapper.getParent();
        FilterMap filterMaps[] = context.findFilterMaps();

        // If there are no filter mappings, we are done
        if ((filterMaps == null) || (filterMaps.length == 0))
            return (filterChain);

        // Acquire the information we will need to match filter mappings
        String servletName = wrapper.getName();

        // Add the relevant path-mapped filters to this filter chain
        for (int i = 0; i < filterMaps.length; i++) {
            if (!matchDispatcher(filterMaps[i] ,dispatcher)) {
                continue;
            }
            if (!matchFiltersURL(filterMaps[i], requestPath))
                continue;
            ApplicationFilterConfig filterConfig = (ApplicationFilterConfig)
                context.findFilterConfig(filterMaps[i].getFilterName());
            if (filterConfig == null) {
                // FIXME - log configuration problem
                continue;
            }
            boolean isCometFilter = false;
            if (comet) {
                try {
                    isCometFilter = filterConfig.getFilter() instanceof CometFilter;
                } catch (Exception e) {
                    // Note: The try catch is there because getFilter has a lot of
                    // declared exceptions. However, the filter is allocated much
                    // earlier
                    Throwable t = ExceptionUtils.unwrapInvocationTargetException(e);
                    ExceptionUtils.handleThrowable(t);
                }
                if (isCometFilter) {
                    filterChain.addFilter(filterConfig);
                }
            } else {
                filterChain.addFilter(filterConfig);
            }
        }

        // Add filters that match on servlet name second
        for (int i = 0; i < filterMaps.length; i++) {
            if (!matchDispatcher(filterMaps[i] ,dispatcher)) {
                continue;
            }
            if (!matchFiltersServlet(filterMaps[i], servletName))
                continue;
            ApplicationFilterConfig filterConfig = (ApplicationFilterConfig)
                context.findFilterConfig(filterMaps[i].getFilterName());
            if (filterConfig == null) {
                // FIXME - log configuration problem
                continue;
            }
            boolean isCometFilter = false;
            if (comet) {
                try {
                    isCometFilter = filterConfig.getFilter() instanceof CometFilter;
                } catch (Exception e) {
                    // Note: The try catch is there because getFilter has a lot of
                    // declared exceptions. However, the filter is allocated much
                    // earlier
                }
                if (isCometFilter) {
                    filterChain.addFilter(filterConfig);
                }
            } else {
                filterChain.addFilter(filterConfig);
            }
        }

        // Return the completed filter chain
        return (filterChain);

    }

public final void invoke(Request request, Response response)
        throws IOException, ServletException {
   ...省略中間代碼
　　　　 // Create the filter chain for this request
        ApplicationFilterFactory factory =
            ApplicationFilterFactory.getInstance();
        ApplicationFilterChain filterChain =
            factory.createFilterChain(request, wrapper, servlet);
　　...省略中間代碼
         filterChain.doFilter(request.getRequest(), response.getResponse());
　　...省略中間代碼
    }

// Call the next filter if there is one
        if (pos < n) {
　　　　　　　//拿到下一個(gè)Filter，將指針向下移動(dòng)一位
            //pos它來(lái)標(biāo)識(shí)當(dāng)前ApplicationFilterChain（當(dāng)前過(guò)濾器鏈）執(zhí)行到哪個(gè)過(guò)濾器
            ApplicationFilterConfig filterConfig = filters[pos++];
            Filter filter = null;
            try {
　　　　　　　　　 //獲取當(dāng)前指向的Filter的實(shí)例
                filter = filterConfig.getFilter();
                support.fireInstanceEvent(InstanceEvent.BEFORE_FILTER_EVENT,
                                          filter, request, response);
               
                if (request.isAsyncSupported() && "false".equalsIgnoreCase(
                        filterConfig.getFilterDef().getAsyncSupported())) {
                    request.setAttribute(Globals.ASYNC_SUPPORTED_ATTR,
                            Boolean.FALSE);
                }
                if( Globals.IS_SECURITY_ENABLED ) {
                    final ServletRequest req = request;
                    final ServletResponse res = response;
                    Principal principal =
                        ((HttpServletRequest) req).getUserPrincipal();

                    Object[] args = new Object[]{req, res, this};
                    SecurityUtil.doAsPrivilege
                        ("doFilter", filter, classType, args, principal);
                   
                } else {
　　　　　　　　　　　　//調(diào)用Filter的doFilter()方法 
                    filter.doFilter(request, response, this);
                }