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key
private 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