Struts2异常处理机制-优快云博客

本文介绍了Struts2框架中如何进行声明式异常处理。通过配置struts.xml文件中的异常映射，可以实现将特定类型的异常导向指定的错误页面。同时展示了具体的CategoryAction和UserService类代码示例。

1. 声明式异常

//struts.xml

<struts>
        <constant name="struts.devMode" value="true"></constant>

        <global-results>
               <result name="error">/error.jsp</result>
        </global-results>

        <global-exception-mappings>
              <exception-mapping result="error" exception="java.lang.Exception"></exception-mapping>
        </global-exception-mappings>


       <package name="admin" namespace="/admin" extends="struts-default" >

              <action name="userList" class="UserAction" method="list">

<result>/userAdd.jsp</result>
                                   
             </action>

    </package>

</struts>

//CategoryAction

public class CategoryAction extends ActionSupport {
private User user;

//Action接到user.list()抛来的异常,并把它抛出struts2,struts2根据struts.xml里的配置找到相应页面
public String list() throws Exception {

                   categories = user.list();
                   return SUCCESS;
         }

}

//UserService

public class UserService {

public List<User> list() throws SQLException {
        Connection conn = DB.createConn();
        String sql = "select * from t_user_";        //故意写错，产生java.sql.Exception,抛给了UserAction
        PreparedStatement ps = DB.prepare(conn, sql);
       List<User> users= new ArrayList<User>();
        try {
               ResultSet rs = ps.executeQuery();
               User u= null;
               while(rs.next()) {
                     u = new User();
                    u.setId(rs.getInt("id"));
                     u.setName(rs.getString("name"));
                     users.add(u);
               }
        } catch (SQLException e) {
                   e.printStackTrace();
                   throw(e);
        }
       DB.close(ps);
       DB.close(conn);
       return categories;
}