12.12.1 控制器组件UserSearchAction.java

package nm.admin.action;
import nm.Constants;
import nm.DB;
import nm.User;
import nm.admin.form.UserInfoForm;
import java.util.Vector;
import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import javax.sql.DataSource;
import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.action.ActionMessage;
import org.apache.struts.action.ActionMessages;
public final class UserSearchAction extends Action {
public ActionForward execute(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response)
throws Exception {
//获取来自UserInfoForm对象的数据
UserInfoForm searchUserForm = (UserInfoForm) form;
String username = (String) searchUserForm.getUsername();

            //使用struts-config.xml配置文件的数据源信息生成数据库操作类DB的对象
ServletContext context = servlet.getServletContext();
DataSource dataSource = (DataSource) context
.getAttribute(Constants.DATASOURCE_KEY);
DB db = new DB(dataSource);

            //新建需要用到的对象，并为其初始化。其中表示转发页面的pageForward
被初始化为ToErrorPage
HttpSession session = request.getSession();
ActionMessages errors = new ActionMessages();
String pageForward = "ToErrorPage";
try {
//使用User.search方法根据输入内容进行模糊查找，
//将查找到的结果包含到Vector中，并将这个Vector保存到session中。
//然后将请求转发到ToUserList所代表的路径
Vector users = new Vector();
users = User.search(db, username);
session.setAttribute(Constants.USER_LIST_KEY, users);
pageForward = "ToUserList";
} catch(Exception e) {
//如果User.search方法执行失败的话，
//则在ActionMessage对象中封装消息（由error.search.failed所代表）
//并保存到request范围内，此时表示转发页面的pageForward对象
仍然为初始值ToErrorPage
errors.add(ActionMessages.GLOBAL_MESSAGE, new ActionMessage(
"error.search.failed"));
if (!errors.isEmpty()) {
saveErrors(request, errors);
}
}

//关闭数据库连接，并根据pageForward值将请求转发到相应路径
db.close();
return (mapping.findForward(pageForward));
}
}