deleteservlet.java

java结合ajax编写的简易留言本

package anni.gbook.ajax;

import java.io.IOException;
import java.io.PrintWriter;

import java.util.logging.Logger;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import anni.gbook.BoardInfo;
import anni.gbook.FileDAO;
import anni.gbook.IBoardDAO;


/**
 * 删除留言.
 * @author Lingo
 * @version 1.0
 * @since 2006-01-19
 */
public class DeleteServlet extends HttpServlet {
    /**
     * 日志.
     */
    private Logger log = Logger.getLogger(DeleteServlet.class.getName());

    /**
     * dao接口.
     */
    private IBoardDAO dao;

    /**
     * 初始化dao.
     * @param config 配置
     * @throws ServletException servlet异常
     */
    public final void init(final ServletConfig config)
        throws ServletException {
        super.init(config);
        dao = FileDAO.getInstance();
    }

    /**
     * 销毁servlet.
     */
    public final void destroy() {
        super.destroy();
        dao = null;
    }

    /**
     * 处理post请求.
     * @param request 请求
     * @param response 响应
     * @throws ServletException servlet异常
     * @throws IOException io异常
     */
    protected final void doPost(final HttpServletRequest request,
        final HttpServletResponse response)
        throws ServletException, IOException {
        log.info("start");

        /* ===================获取验证数据================================================ */
        StringBuffer buff = new StringBuffer();
        response.setContentType("text/xml");
        response.setCharacterEncoding("GBK");

        PrintWriter out = response.getWriter();
        buff.append("<?xml version=\"1.0\" encoding=\"GBK\"?>")
            .append("<constants>");

        //先从form中取出各个字段的值
        //
        String id0 = request.getParameter("id");
        String pass = request.getParameter("pass");

        int id = 0;

        try {
            id = Integer.parseInt(id0);
        } catch (NumberFormatException ex) {
            System.out.println("输入的id不是一个数字：" + ex.getMessage());
            buff.append("<err>").append("ID错误").append("</err>")
                .append("</constants>");
            out.print(buff.toString());

            return;
        }

        if ((pass == null) || !pass.equals(Constants.PASSWORD)) {
            System.out.println("输入的密码不正确：" + pass);
            buff.append("<err>").append("密码错误").append("</err>")
                .append("</constants>");
            out.print(buff.toString());

            return;
        }

        //删除记录
        //
        BoardInfo info = dao.findById(id);

        if (info == null) {
            System.out.println("找不到指定id的留言：" + id);
            buff.append("<err>").append("找不到指定id的留言").append("</err>")
                .append("</constants>");
            out.print(buff.toString());

            return;
        }

        dao.delete(id);

        buff.append("<id>").append(id).append("</id>")
            .append("</constants>");
        out.print(buff.toString());

        log.info("end");
    }
}