第三章 struts的应用举例                   在这一章里面我们要学习                     1)struts的开发步骤                     2)运用struts开发一个用户登录的例子，要求显示欢迎界面                     3)运用struts开发一个拥有员工增加，删除应用程序,在增加时检查工号不能重复，在                         删除时检查职工是否存在,操作后做出友情提示                     4)定义全局的Forward共多个Action共享                             struts的开发步骤                    1)进行需求分析,确定Web应用程序的功能                    2)设计数据库                    3)设计jsp页面(视图)                    4)设计ActionForm                    5)设计Action                    6)设计业务逻辑组件(模型)                   说明：                     1:在上述的开发步骤中并没有看到struts-config.xml配置文件，那是因为运用                               eclipse开发工具，struts-config.xml文件会自动产生，并自动更新                     2:一个struts一般会有多个Action,也就会有多个ActionForm.而ActionServlet由                             struts自动生成，用户无需管理                                                                                     用户登录的例子                       1)创建模型：                          A:数据层：         ===========================DbManager===================================                             public class dbManager                                {                           private static Connection conn=null;                           private static PreparedStatement ps=null;                           static                               {                                                                    Class.forName("oracle.jdbc.driver.OracleDriver");                                   conn=DriverManager.getConnection                                                                  ("jdbc:oracle:thin:@chen:1521:ht","scott","tiger");                                 //注意要把D:\oracle\ora90\jdbc\lib下的classes12.jar复制到                                     //应用程序的lib下面                             }                  public static void RunNoneResultSql(String sql)                     {          ps=conn.prepareStatement(sql);          ps.executeUpdate();                    }                  public static ResultSet RunHasResultSql(String sql)                  {       ps=conn.prepareStatement(sql);       ResultSet rs=ps.executeQuery();       return rs;                          }        ===========================DbManager============================================                                                   B:创建业务层：       ===============================LoginJavaBean======================================                          public static boolean CheckIsValid(String UserName,String PassWord)                             {                         String sql=String.format("select id from userinfo where                                           UserName='%s' and PassWord='%s'",UserName,PassWord);                         ResultSet rs=dbManager.RunHasResultSql(sql);                    if (rs.next())                   {                     return true;                   }                                return false;                            } ===============================LoginJavaBean======================================                    在Action的excute里面写上写上关键代码                loginForm loginform=(loginForm)form;  String uid=loginform.getUid();  String pwd=loginform.getPwd();  if (LoginJavaBean.CheckIsValid(uid, pwd))  {           request.setAttribute("uid", uid);//设置共享的uid到request里面,可以在                                                        //scuess.jsp中通过${uid}表达式语言来访问uid   return mapping.findForward("scuess");  }    return mapping.findForward("error");                           定义全局的Forward共多个Action共享          1)通常情况下，一个Action里面可以设置多个Forward，来决定Action处理之后要跳转的页面          2)有时需要多个Action共享多个Forward，比如：多个业务逻辑处理错误之后都要跳转到同一个页面            每一个业务逻辑相当于一个Action，同一个页面相当于一个共享的Forward.          3)可以在strtus-config.xml配置文件的<global-forwards>配置节下面进行配置。如下格式：                   <global-forwards>                        <forward name="msg" path="/msg.jsp"></forward>          <forward name="error" path="/error.jsp"></forward>               </global-forwards>                这样一个Web应用程序的所有Action都将共享msg.jsp与error.jsp页面。                             

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