Struts 声明式异常处理和个性化异常处理(转)
首先我们的国际化资源文件中有
- user.not.found = 用户不能找到,用户名称=[{0}]
- user.password.error = user.password.error
第一种 声明式异常处理
为国际化配置文件中的每个key,设计一个异常。
用户登录验证,用户名错误抛出UserNotFoundException,密码错误抛出PasswordErrorException
![](https://images.cnblogs.com/OutliningIndicators/ExpandedBlockStart.gif)
public void login(String username, String password) {
if (!"admin".equals()) {
throw new UserNotFoundException();
}
if (!"admin".equals(password)) {
throw new PasswordErrorException();
}
}
if (!"admin".equals()) {
throw new UserNotFoundException();
}
if (!"admin".equals(password)) {
throw new PasswordErrorException();
}
}
struts-config.xml文件中,<exception/>的key对应国际化配置文件中key,type是对应的异常处理类
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<global-exceptions>
<!-- 为所有Action使用的,全局异常 -->
<exception key="user.not.found" type="demo.struts.UserNotFoundException"/>
<exception key="user.password.error" type="demo.struts.PasswordErrorException"/>
</global-exceptions>
<action-mappings>
<action path="/login"
type="demo.struts.LoginAction"
name="loginForm"
scope="request"
validate="false"
input="/login.jsp"
>
<!-- path 错误时候 跳转的页面,优先级高于 action中的input -->
<!-- 为每一个action配置
<exception key="user.not.found" type="demo.struts.UserNotFoundException" path="/login_error.jsp"/>
<exception key="user.password.error" type="demo.struts.PasswordErrorException" path="/login_error.jsp"/>
-->
<forward name="success" path="/login_success.jsp"/>
<forward name="error" path="/login.jsp"/>
</action>
<action path="/changelang"
type="demo.struts.ChangeLanguageAction"
>
<forward name="index" path="/index.jsp"/>
</action>
</action-mappings>
<!-- 为所有Action使用的,全局异常 -->
<exception key="user.not.found" type="demo.struts.UserNotFoundException"/>
<exception key="user.password.error" type="demo.struts.PasswordErrorException"/>
</global-exceptions>
<action-mappings>
<action path="/login"
type="demo.struts.LoginAction"
name="loginForm"
scope="request"
validate="false"
input="/login.jsp"
>
<!-- path 错误时候 跳转的页面,优先级高于 action中的input -->
<!-- 为每一个action配置
<exception key="user.not.found" type="demo.struts.UserNotFoundException" path="/login_error.jsp"/>
<exception key="user.password.error" type="demo.struts.PasswordErrorException" path="/login_error.jsp"/>
-->
<forward name="success" path="/login_success.jsp"/>
<forward name="error" path="/login.jsp"/>
</action>
<action path="/changelang"
type="demo.struts.ChangeLanguageAction"
>
<forward name="index" path="/index.jsp"/>
</action>
</action-mappings>
Struts的RequestProcessor类
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protected ActionForward processException(HttpServletRequest request,
HttpServletResponse response,
Exception exception,
ActionForm form,
ActionMapping mapping)
throws IOException, ServletException {
// 是否在配置了Exception
ExceptionConfig config = mapping.findException(exception.getClass());
// 找到的config就是下面这条信息
// <exception key="user.not.found" type="demo.struts.UserNotFoundException" path="/login_error.jsp"/>
if (config == null) {
// 没有配置,struts不管了,往web容器里抛,看在web.xml文件中是否配置,
// 如果仍没有配置,则把异常显示到页面上
log.warn(getInternal().getMessage("unhandledException",
exception.getClass()));
if (exception instanceof IOException) {
throw (IOException) exception;
} else if (exception instanceof ServletException) {
throw (ServletException) exception;
} else {
throw new ServletException(exception);
}
}
// struts异常默认处理类
try {
ExceptionHandler handler = (ExceptionHandler)
RequestUtils.applicationInstance(config.getHandler());
return (handler.execute(exception, config, mapping, form,
request, response));
} catch (Exception e) {
throw new ServletException(e);
}
}
HttpServletResponse response,
Exception exception,
ActionForm form,
ActionMapping mapping)
throws IOException, ServletException {
// 是否在配置了Exception
ExceptionConfig config = mapping.findException(exception.getClass());
// 找到的config就是下面这条信息
// <exception key="user.not.found" type="demo.struts.UserNotFoundException" path="/login_error.jsp"/>
if (config == null) {
// 没有配置,struts不管了,往web容器里抛,看在web.xml文件中是否配置,
// 如果仍没有配置,则把异常显示到页面上
log.warn(getInternal().getMessage("unhandledException",
exception.getClass()));
if (exception instanceof IOException) {
throw (IOException) exception;
} else if (exception instanceof ServletException) {
throw (ServletException) exception;
} else {
throw new ServletException(exception);
}
}
// struts异常默认处理类
try {
ExceptionHandler handler = (ExceptionHandler)
RequestUtils.applicationInstance(config.getHandler());
return (handler.execute(exception, config, mapping, form,
request, response));
} catch (Exception e) {
throw new ServletException(e);
}
}
struts默认的exceptionHandler
![](https://images.cnblogs.com/OutliningIndicators/ExpandedBlockStart.gif)
public ActionForward execute(
Exception ex,
ExceptionConfig ae,
ActionMapping mapping,
ActionForm formInstance,
HttpServletRequest request,
HttpServletResponse response)
throws ServletException {
ActionForward forward = null;
ActionMessage error = null;
String property = null;
// 在<exception>中配置了path,返回actionForward就是path中的配置
if (ae.getPath() != null) {
forward = new ActionForward(ae.getPath());
} else {
// 没有配置的话,返回actionForward就是<action>中的input
forward = mapping.getInputForward();
}
// Figure out the error
if (ex instanceof ModuleException) {
error = ((ModuleException) ex).getActionMessage();
property = ((ModuleException) ex).getProperty();
} else {
// 我们写的程序抛出的异常都是这种情况
// 从国际化文件中,根据key取
// ae.getKey() -- 拿到<exception>中key值 user.not.found
error = new ActionMessage(ae.getKey(), ex.getMessage());
// 集合ActionMessages中的key,和国际化资源文件中的key一样
property = error.getKey();
}
this.logException(ex);
// Store the exception
request.setAttribute(Globals.EXCEPTION_KEY, ex);
// 放到ActionMessages集合中 getScope()默认request
this.storeException(request, property, error, forward, ae.getScope());
return forward;
Exception ex,
ExceptionConfig ae,
ActionMapping mapping,
ActionForm formInstance,
HttpServletRequest request,
HttpServletResponse response)
throws ServletException {
ActionForward forward = null;
ActionMessage error = null;
String property = null;
// 在<exception>中配置了path,返回actionForward就是path中的配置
if (ae.getPath() != null) {
forward = new ActionForward(ae.getPath());
} else {
// 没有配置的话,返回actionForward就是<action>中的input
forward = mapping.getInputForward();
}
// Figure out the error
if (ex instanceof ModuleException) {
error = ((ModuleException) ex).getActionMessage();
property = ((ModuleException) ex).getProperty();
} else {
// 我们写的程序抛出的异常都是这种情况
// 从国际化文件中,根据key取
// ae.getKey() -- 拿到<exception>中key值 user.not.found
error = new ActionMessage(ae.getKey(), ex.getMessage());
// 集合ActionMessages中的key,和国际化资源文件中的key一样
property = error.getKey();
}
this.logException(ex);
// Store the exception
request.setAttribute(Globals.EXCEPTION_KEY, ex);
// 放到ActionMessages集合中 getScope()默认request
this.storeException(request, property, error, forward, ae.getScope());
return forward;
第二种 个性化异常处理
![](https://images.cnblogs.com/OutliningIndicators/ExpandedBlockStart.gif)
public void login(String username, String password) {
if (!"admin".equals(username)) {
//user.not.found资源文件中的key, username 占位符
throw new ErrorCodeException("user.not.found", username);
}
if (!"admin".equals(password)) {
throw new ErrorCodeException("user.password.error");
}
if (!"admin".equals(username)) {
//user.not.found资源文件中的key, username 占位符
throw new ErrorCodeException("user.not.found", username);
}
if (!"admin".equals(password)) {
throw new ErrorCodeException("user.password.error");
}
![](https://images.cnblogs.com/OutliningIndicators/ExpandedBlockStart.gif)
<global-exceptions>
<!-- key值随便配一个 具体的是在程序中控制-->
<!-- type异常类 handler异常处理类 都是由我们来写和控制 -->
<exception key="error.exception" type="demo.struts.ErrorCodeException" handler="demo.struts.ErrorCodeExceptionHandler"/>
</global-exceptions>
<!-- key值随便配一个 具体的是在程序中控制-->
<!-- type异常类 handler异常处理类 都是由我们来写和控制 -->
<exception key="error.exception" type="demo.struts.ErrorCodeException" handler="demo.struts.ErrorCodeExceptionHandler"/>
</global-exceptions>
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public class ErrorCodeException extends RuntimeException {
// 错误码就是国际化资源文件的key
private String errorCode;
// 占位符
private Object[] args;
public ErrorCodeException(String errorCode) {
this(errorCode, null);
}
public ErrorCodeException(String errorCode, Object arg) {
this(errorCode, new Object[]{arg});
}
public ErrorCodeException(String errorCode, Object[] args){
this.errorCode = errorCode;
this.args = args;
}
// 只提供get方法
public String getErrorCode() {
return errorCode;
}
public Object[] getArgs() {
return args;
}
// 错误码就是国际化资源文件的key
private String errorCode;
// 占位符
private Object[] args;
public ErrorCodeException(String errorCode) {
this(errorCode, null);
}
public ErrorCodeException(String errorCode, Object arg) {
this(errorCode, new Object[]{arg});
}
public ErrorCodeException(String errorCode, Object[] args){
this.errorCode = errorCode;
this.args = args;
}
// 只提供get方法
public String getErrorCode() {
return errorCode;
}
public Object[] getArgs() {
return args;
}
![](https://images.cnblogs.com/OutliningIndicators/ExpandedBlockStart.gif)
public class ErrorCodeExceptionHandler extends ExceptionHandler {
public ActionForward execute(Exception ex, ExceptionConfig ae,
ActionMapping mapping, ActionForm formInstance,
HttpServletRequest request, HttpServletResponse response)
throws ServletException {
// 不是ErrorCodeException,我们不处理
if (!(ex instanceof ErrorCodeException)) {
return super.execute(ex, ae, mapping, formInstance, request, response);
}
ActionForward forward = null;
ActionMessage error = null;
String property = null;
// Build the forward from the exception mapping if it exists
// or from the form input
if (ae.getPath() != null) {
forward = new ActionForward(ae.getPath());
} else {
forward = mapping.getInputForward();
}
// Figure out the error
if (ex instanceof ModuleException) {
error = ((ModuleException) ex).getActionMessage();
property = ((ModuleException) ex).getProperty();
} else {
// 原来的代码 error = new ActionMessage(ae.getKey(), ex.getMessage());
// ae.getKey() 拿出的key是配置文件中<exception>写的,因为所有异常都用同一个key
// 无法找到国际化资源文件中的key,好在我们在抛异常时,把key写进异常的errorCode中
ErrorCodeException ece = (ErrorCodeException) ex;
// 拿到errorCode
String errorCode = ece.getErrorCode();
// 拿到占位符
Object[] args = ece.getArgs();
error = new ActionMessage(errorCode, 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;
}
public ActionForward execute(Exception ex, ExceptionConfig ae,
ActionMapping mapping, ActionForm formInstance,
HttpServletRequest request, HttpServletResponse response)
throws ServletException {
// 不是ErrorCodeException,我们不处理
if (!(ex instanceof ErrorCodeException)) {
return super.execute(ex, ae, mapping, formInstance, request, response);
}
ActionForward forward = null;
ActionMessage error = null;
String property = null;
// Build the forward from the exception mapping if it exists
// or from the form input
if (ae.getPath() != null) {
forward = new ActionForward(ae.getPath());
} else {
forward = mapping.getInputForward();
}
// Figure out the error
if (ex instanceof ModuleException) {
error = ((ModuleException) ex).getActionMessage();
property = ((ModuleException) ex).getProperty();
} else {
// 原来的代码 error = new ActionMessage(ae.getKey(), ex.getMessage());
// ae.getKey() 拿出的key是配置文件中<exception>写的,因为所有异常都用同一个key
// 无法找到国际化资源文件中的key,好在我们在抛异常时,把key写进异常的errorCode中
ErrorCodeException ece = (ErrorCodeException) ex;
// 拿到errorCode
String errorCode = ece.getErrorCode();
// 拿到占位符
Object[] args = ece.getArgs();
error = new ActionMessage(errorCode, 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;
}
如果我们不想写国际化配置文件,在程序中之际页面提示内容
<!-- 用默认的handler也能能执行 -->
<exception key="error.exception" type="demo.struts.AppException" handler="demo.struts.AppExceptionHandler"/>
<exception key="error.exception" type="demo.struts.AppException" handler="demo.struts.AppExceptionHandler"/>
国际化资源文件:
- # 只有一个占位符
- error.exception={0}
代码
public void login(String username, String password) {
if (!"admin".equals(username)) {
// 直接写内容
throw new AppException("用户不能找到【" + username + "】");
}
if (!"admin".equals(password)) {
throw new ErrorCodeException("密码错误");
}
}
public class AppException extends RuntimeException {
public AppException(String msg){
super(msg);
}
}
public AppException(String msg){
super(msg);
}
}
![](https://images.cnblogs.com/OutliningIndicators/ExpandedBlockStart.gif)
public class AppExceptionHandler extends ExceptionHandler {
public ActionForward execute(Exception ex, ExceptionConfig ae,
ActionMapping mapping, ActionForm formInstance,
HttpServletRequest request, HttpServletResponse response)
throws ServletException {
if(!(ex instanceof AppException)){
return super.execute(ex, ae, mapping, formInstance, request, response);
}
ActionForward forward = null;
ActionMessage error = null;
String property = null;
// Build the forward from the exception mapping if it exists
// or from the form input
if (ae.getPath() != null) {
forward = new ActionForward(ae.getPath());
} else {
forward = mapping.getInputForward();
}
// Figure out the error
if (ex instanceof ModuleException) {
error = ((ModuleException) ex).getActionMessage();
property = ((ModuleException) ex).getProperty();
} else {
AppException appe = (AppException) ex;
// ae.getKey() 没用
// appe.getMessage() ("用户不能找到【" + username + "】
error = new ActionMessage(ae.getKey(), appe.getMessage());
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;
}
public ActionForward execute(Exception ex, ExceptionConfig ae,
ActionMapping mapping, ActionForm formInstance,
HttpServletRequest request, HttpServletResponse response)
throws ServletException {
if(!(ex instanceof AppException)){
return super.execute(ex, ae, mapping, formInstance, request, response);
}
ActionForward forward = null;
ActionMessage error = null;
String property = null;
// Build the forward from the exception mapping if it exists
// or from the form input
if (ae.getPath() != null) {
forward = new ActionForward(ae.getPath());
} else {
forward = mapping.getInputForward();
}
// Figure out the error
if (ex instanceof ModuleException) {
error = ((ModuleException) ex).getActionMessage();
property = ((ModuleException) ex).getProperty();
} else {
AppException appe = (AppException) ex;
// ae.getKey() 没用
// appe.getMessage() ("用户不能找到【" + username + "】
error = new ActionMessage(ae.getKey(), appe.getMessage());
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;
}