AbstractFilter.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package com.hwlcn.security.web.servlet;

import com.hwlcn.security.util.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.servlet.Filter;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;


public abstract class AbstractFilter extends ServletContextSupport implements Filter {

    private static transient final Logger log = LoggerFactory.getLogger(AbstractFilter.class);

    protected FilterConfig filterConfig;

    public FilterConfig getFilterConfig() {
        return filterConfig;
    }

    public void setFilterConfig(FilterConfig filterConfig) {
        this.filterConfig = filterConfig;
        setServletContext(filterConfig.getServletContext());
    }

    /**
     * @param paramName
     * @return
     */
    protected String getInitParam(String paramName) {
        FilterConfig config = getFilterConfig();
        if (config != null) {
            return StringUtils.clean(config.getInitParameter(paramName));
        }
        return null;
    }


    public final void init(FilterConfig filterConfig) throws ServletException {
        setFilterConfig(filterConfig);
        try {
            onFilterConfigSet();
        } catch (Exception e) {
            if (e instanceof ServletException) {
                throw (ServletException) e;
            } else {
                if (log.isErrorEnabled()) {
                    log.error("Unable to start Filter: [" + e.getMessage() + "].", e);
                }
                throw new ServletException(e);
            }
        }
    }

    /**
     * 配置初始化函数
     *
     * @throws Exception
     */
    protected void onFilterConfigSet() throws Exception {
    }

    /**
     * servlet 停止时的操作
     */
    public void destroy() {
    }


}