struts声明式异常二
上文如果资源文件改为：
error.login.usernull?= user must not null{0}
则输出user must not null null
即参数由null来代替。
我们可以看到ExceptionHandler的excute方法里面是这样处理的。
error = new ActionMessage(ae.getKey(), ex.getMessage()); property = error.getKey();
?
可以看到new ActionMessage(ae.getKey(), ex.getMessage());??
这里的ae.getKey()就是我们在配置文件的exception的key属性。
<action path="/logon" type="com.lwf.struts.action.LogonAction"name="logonForm" input="/logon.jsp" scope="session" validate="true" ><exception key="error.login.usernull" type="com.lwf.struts.util.UserNotFoundException" path="/index.jsp" ></exception></action>
?而第二个参数ex.getMessage()则是获取异常信息。
也就是说如果我们的异常处理类抛出一个带参数的异常如；
package com.lwf.struts.action.entity;import com.lwf.struts.exception.PasswordNotFoundException;import com.lwf.struts.exception.UserNotFoundException;public class UserManager {private static UserManager userManager = new UserManager();private UserManager(){}public static UserManager instance(){return userManager;}public boolean isValidaUser(String name, String pwd) throws Exception{boolean flagPwd = false;boolean flagUser = false;if(name!=null && name.equals("admin")){flagUser = true;}else{throw new UserNotFoundException(“user incorrect”);}if(pwd!=null && pwd.equals("super")){flagPwd = true;}else{throw new PasswordNotFoundException("pwd incorrect");}return flagPwd && flagUser;}}new UserNotFoundException(“user incorrect”);
?
注意黑体部分。那么异常会输出：
user must not null user incorrect null
即资源文件的key内容+异常抛出的文本+参数化
当然上面参数化也没有显示出来。需要我们写一个自己的ExceptionHandler来处理。
我们使用一个统一的异常类。如下：
package com.lwf.struts.exception;public class ErrorCodeException extends RuntimeException {private static final long serialVersionUID = 1L;private String errorCode;//错误码，对应资源文件的keyprivate Object[] args;//占位符，即参数public ErrorCodeException(){}public ErrorCodeException(String errorCode){this.errorCode = errorCode;}public ErrorCodeException(String errorCode, Object[] args){this.errorCode = errorCode;this.args = args;}public ErrorCodeException(String errorCode, Object args){this(errorCode,new Object[]{args});}public String getErrorCode() {return errorCode;}public void setErrorCode(String errorCode) {this.errorCode = errorCode;}public Object[] getArgs() {return args;}public void setArgs(Object[] args) {this.args = args;}}?
实际上我们是为构造ActionMessage做准备。
我们自己的handler类：
package com.lwf.struts.handler;import javax.servlet.ServletException;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.apache.struts.Globals;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.ExceptionHandler;import org.apache.struts.config.ExceptionConfig;import com.lwf.struts.exception.ErrorCodeException;public class LogonHandler extends ExceptionHandler {public ActionForward execute(Exception ex, ExceptionConfig ae,ActionMapping mapping, ActionForm formInstance,HttpServletRequest request, HttpServletResponse response)throws ServletException {if(!(ex instanceof ErrorCodeException)){ return super.execute(ex, ae, mapping, formInstance, request, response);} ActionForward forward; ActionMessage error; String property; if (ae.getPath() != null) { forward = new ActionForward(ae.getPath()); } else { forward = mapping.getInputForward(); } ErrorCodeException ece = (ErrorCodeException)ex; String errocode = ece.getErrorCode(); Object[] args = ece.getArgs(); error = new ActionMessage(errocode, args); property = error.getKey(); this.logException(ex); // Store the exception request.setAttribute(Globals.EXCEPTION_KEY, ex); this.storeException(request, property, error, forward, ae.getScope()); return forward;}}?
?error = new ActionMessage(errocode, args);
我们可以看到现在我们构造ActionMessage传入的第一个参数不再是ae.getKey()所以现在来说
配置文件exception的key属性在这里可以不需要与资源文件相对应，可随便取值。如下配置：
<action path="/login" type="com.lwf.struts.action.LoginAction"name="loginForm" input="/index.jsp" scope="session" validate="true" ><exception key="keyCode" type="com.lwf.struts.exception.ErrorCodeException" handler="com.lwf.struts.handler.LogonHandler"></exception></action>
?看上面key="keyCode"
下面action
package com.lwf.struts.action;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;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.ActionMessages;import com.lwf.struts.action.entity.UserManager;import com.lwf.struts.form.LoginForm;public class LoginAction extends Action {public ActionForward execute(ActionMapping mapping, ActionForm form,HttpServletRequest request, HttpServletResponse response)throws Exception {LoginForm loginForm = (LoginForm)form;String name = loginForm.getUsername();String pwd = loginForm.getPassword();ActionMessages errors = new ActionMessages();UserManager.instance().isValidaUser(name, pwd);return mapping.findForward("success");}}?下面是UserManager类。
package com.lwf.struts.action.entity;import com.lwf.struts.exception.ErrorCodeException;import com.lwf.struts.exception.PasswordNotFoundException;public class UserManager {private static UserManager userManager = new UserManager();private UserManager(){}public static UserManager instance(){return userManager;}public boolean isValidaUser(String name, String pwd) throws Exception{boolean flagPwd = false;boolean flagUser = false;if(name!=null && name.equals("admin")){flagUser = true;}else{throw new ErrorCodeException("user.name.incorrect",name);}if(pwd!=null && pwd.equals("super")){flagPwd = true;}else{throw new ErrorCodeException("user.pwd.incorrect",pwd);}return flagPwd && flagUser;}}?注意我们这里统一抛出的是ErrorCodeException异常，只是参数不同。第一个参数必须与资源文件的key对应，第二个参数则可以是对象或对象数组。对应于资源文件的点位符。如ApplicationResources.properties文件内容
user.name.incorrect= user incorrect {0}user.pwd.incorrect= pwd incorrect{0}?这里我们传入的是输入的用户名。
好测试一下。我们输入用户名为we
那么在页面上会看到：
user incorrect we
?
即实现了参数化