src/com/javapandeng/filter/SystemContextFilter.java

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package com.javapandeng.filter;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;

import com.javapandeng.utils.SystemContext;

public class SystemContextFilter implements Filter {
    private Integer pageSize;

    public void destroy() {

    }

    public void doFilter(ServletRequest req, ServletResponse resp,
                         FilterChain chain) throws IOException, ServletException {
        Integer offset = 0;
        try {
            offset = Integer.parseInt(req.getParameter("pager.offset"));
        } catch (NumberFormatException e) {
        }
        try {
            SystemContext.setOrder(req.getParameter("order"));
            SystemContext.setSort(req.getParameter("sort"));
            SystemContext.setPageOffset(offset);
            SystemContext.setPageSize(pageSize);
            SystemContext.setRealPath(((HttpServletRequest) req).getSession().getServletContext().getRealPath("/"));
            chain.doFilter(req, resp);
        } finally {
            SystemContext.removeOrder();
            SystemContext.removeSort();
            SystemContext.removePageOffset();
            SystemContext.removePageSize();
            SystemContext.removeRealPath();
        }
    }

    public void init(FilterConfig cfg) throws ServletException {
        try {
            pageSize = Integer.parseInt(cfg.getInitParameter("pageSize"));
        } catch (NumberFormatException e) {
            pageSize = 15;
        }
    }

}