struts2文件下载出现Can not find a java.io.InputStream with the name的错误
2014-01-02 11:30
706 查看
今天在用struts2就行文件下载时出现如下错误:
Servlet.service() for servlet default threw exception
java.lang.IllegalArgumentException: Can not find a java.io.InputStream with the name [imageStream] in the invocation stack. Check the <param name="inputName"> tag specified for this action.
at org.apache.struts2.dispatcher.StreamResult.doExecute(StreamResult.java:189)
at org.apache.struts2.dispatcher.StrutsResultSupport.execute(StrutsResultSupport.java:178)
at com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:348)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:253)
at com.best.top.validate.TopInterceptor.intercept(TopInterceptor.java:47)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:224)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:223)
at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:221)
at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:50)
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:504)
at org.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:419)
说实话这个提示真有误导人的嫌疑,刚开始还以为是名称不对,估计一般人看到这个提示都这样想。然后查看StreamResult的源代码才发现是因为InputStream为null的缘故,汗一个。看下源码:
if (inputStream == null) {
// Find the inputstream from the invocation variable stack
inputStream = (InputStream) invocation.getStack().findValue(conditionalParse(inputName, invocation));
}
if (inputStream == null) {
String msg = ("Can not find a java.io.InputStream with the name [" + inputName + "] in the invocation stack. " +
"Check the <param name=\"inputName\"> tag specified for this action.");
LOG.error(msg);
throw new IllegalArgumentException(msg);
}
大家如果也碰到此类问题,直接打印
InputStream in=ServletActionContext.getServletContext().getResourceAsStream(realPath);
System.out.println(in);
如果打印为NULL的话,恭喜您,问题得以解决,问题的原因是这个流的realPath路径错误,
还没明白的往下看
怪呀,我的配置应该没错呀
页面上:
<a href="fileDownload.action?fileName=<s:property value ="imageName" />">下载此图片</a>
struts.xml中
----------------------------------------------------------
<!-- 文件下载,支持中文附件名 -->
<action name="fileDownload"
class="com.test.action.filedown.FileDownloadAction">
<result name="success" type="stream">
<!-- 动态文件下载的,事先并不知道未来的文件类型,那么我们可以把它的值设置成为:application/octet-stream;charset=ISO8859-1 ,注意一定要加入charset,否则某些时候会导致下载的文件出错; -->
<param name="contentType">
application/octet-stream;charset=ISO8859-1
</param>
<param name="contentDisposition">
attachment;filename="${downloadFileName}"
</param>
<!-- 使用经过转码的文件名作为下载文件名,downloadFileName属性
对应action类中的方法 getDownloadFileName() 其中特殊的代码就是${downloadFileName},它的效果相当于运行的时候将action对象的属性的取值动态的填充在${}中间的部分,我们可以认为它等价于+action. getDownloadFileName()。 -->
<param name="inputName">inputStream</param>
<param name="bufferSize">4096</param>
</result>
</action>
----------------------------------------------------------
action中
----------------------------------------------------------
private String fileName;// 初始的通过param指定的文件名属性 set get
/** 文件名 转换编码 防止中文乱码*/
public String getDownloadFileName() {
String fileName=ServletActionContext.getRequest().getParameter("fileName");
String downFileName = fileName;
try {
downFileName = new String(downFileName.getBytes(), "ISO8859-1");
} catch (Exception e) {
e.printStackTrace();
}
return downFileName;
}
//下载的流
public InputStream getInputStream() {
String name=this.getDownloadFileName();
// String realPath=ServletActionContext.getServletContext().getRealPath("/uploadImages")+ "/"+name; 路径错误
String realPath="/uploadImages/"+name;
InputStream in=ServletActionContext.getServletContext().getResourceAsStream(realPath);
if(null==in){
System.out.println("Can not find a java.io.InputStream with the name [inputStream] in the invocation stack. Check the <param name=\"inputName\"> tag specified for this action.检查action中文件下载路径是否正确.");
}
return ServletActionContext.getServletContext().getResourceAsStream(realPath);
}
@Override
public String execute() throws Exception {
return SUCCESS;
}
具体异常是这句话:
Can not find a java.io.InputStream with the name [downloadFile] in the invocation stack. Check the <param name="inputName"> tag specified for this action.
1.文件路径不对,根本就没有取到文件。这种情况下,可以将获得InputStream的那条语句放在system.out.println()中输出一下,若为null,那就是路径不对了,或者说得准确些就根本没有找到文件。
2.在action中没有写配置文件中"<param name="inputName">"后面属性的那个get方法.
当以上两种情况都正确的情况下,问题就在这里了:
当采用 return ServletActionContext.getServletContext().getResourceAsStream("...") 这种方法获得输入流的时候,要保证文件位置在
ServletContext 当中,就是说要在当前的应用上下文中,
如果想要获得外部文件 譬如 D盘中的某个文件,那么就要自己创建输入流才可以,如:
[java] view
plaincopy
File file = new File("D://spring.doc");
InputStream is = new FileInputStream(file);
return is;
Servlet.service() for servlet default threw exception
java.lang.IllegalArgumentException: Can not find a java.io.InputStream with the name [imageStream] in the invocation stack. Check the <param name="inputName"> tag specified for this action.
at org.apache.struts2.dispatcher.StreamResult.doExecute(StreamResult.java:189)
at org.apache.struts2.dispatcher.StrutsResultSupport.execute(StrutsResultSupport.java:178)
at com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:348)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:253)
at com.best.top.validate.TopInterceptor.intercept(TopInterceptor.java:47)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:224)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:223)
at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:221)
at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:50)
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:504)
at org.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:419)
说实话这个提示真有误导人的嫌疑,刚开始还以为是名称不对,估计一般人看到这个提示都这样想。然后查看StreamResult的源代码才发现是因为InputStream为null的缘故,汗一个。看下源码:
if (inputStream == null) {
// Find the inputstream from the invocation variable stack
inputStream = (InputStream) invocation.getStack().findValue(conditionalParse(inputName, invocation));
}
if (inputStream == null) {
String msg = ("Can not find a java.io.InputStream with the name [" + inputName + "] in the invocation stack. " +
"Check the <param name=\"inputName\"> tag specified for this action.");
LOG.error(msg);
throw new IllegalArgumentException(msg);
}
大家如果也碰到此类问题,直接打印
InputStream in=ServletActionContext.getServletContext().getResourceAsStream(realPath);
System.out.println(in);
如果打印为NULL的话,恭喜您,问题得以解决,问题的原因是这个流的realPath路径错误,
还没明白的往下看
怪呀,我的配置应该没错呀
页面上:
<a href="fileDownload.action?fileName=<s:property value ="imageName" />">下载此图片</a>
struts.xml中
----------------------------------------------------------
<!-- 文件下载,支持中文附件名 -->
<action name="fileDownload"
class="com.test.action.filedown.FileDownloadAction">
<result name="success" type="stream">
<!-- 动态文件下载的,事先并不知道未来的文件类型,那么我们可以把它的值设置成为:application/octet-stream;charset=ISO8859-1 ,注意一定要加入charset,否则某些时候会导致下载的文件出错; -->
<param name="contentType">
application/octet-stream;charset=ISO8859-1
</param>
<param name="contentDisposition">
attachment;filename="${downloadFileName}"
</param>
<!-- 使用经过转码的文件名作为下载文件名,downloadFileName属性
对应action类中的方法 getDownloadFileName() 其中特殊的代码就是${downloadFileName},它的效果相当于运行的时候将action对象的属性的取值动态的填充在${}中间的部分,我们可以认为它等价于+action. getDownloadFileName()。 -->
<param name="inputName">inputStream</param>
<param name="bufferSize">4096</param>
</result>
</action>
----------------------------------------------------------
action中
----------------------------------------------------------
private String fileName;// 初始的通过param指定的文件名属性 set get
/** 文件名 转换编码 防止中文乱码*/
public String getDownloadFileName() {
String fileName=ServletActionContext.getRequest().getParameter("fileName");
String downFileName = fileName;
try {
downFileName = new String(downFileName.getBytes(), "ISO8859-1");
} catch (Exception e) {
e.printStackTrace();
}
return downFileName;
}
//下载的流
public InputStream getInputStream() {
String name=this.getDownloadFileName();
// String realPath=ServletActionContext.getServletContext().getRealPath("/uploadImages")+ "/"+name; 路径错误
String realPath="/uploadImages/"+name;
InputStream in=ServletActionContext.getServletContext().getResourceAsStream(realPath);
if(null==in){
System.out.println("Can not find a java.io.InputStream with the name [inputStream] in the invocation stack. Check the <param name=\"inputName\"> tag specified for this action.检查action中文件下载路径是否正确.");
}
return ServletActionContext.getServletContext().getResourceAsStream(realPath);
}
@Override
public String execute() throws Exception {
return SUCCESS;
}
具体异常是这句话:
Can not find a java.io.InputStream with the name [downloadFile] in the invocation stack. Check the <param name="inputName"> tag specified for this action.
1.文件路径不对,根本就没有取到文件。这种情况下,可以将获得InputStream的那条语句放在system.out.println()中输出一下,若为null,那就是路径不对了,或者说得准确些就根本没有找到文件。
2.在action中没有写配置文件中"<param name="inputName">"后面属性的那个get方法.
当以上两种情况都正确的情况下,问题就在这里了:
当采用 return ServletActionContext.getServletContext().getResourceAsStream("...") 这种方法获得输入流的时候,要保证文件位置在
ServletContext 当中,就是说要在当前的应用上下文中,
如果想要获得外部文件 譬如 D盘中的某个文件,那么就要自己创建输入流才可以,如:
[java] view
plaincopy
File file = new File("D://spring.doc");
InputStream is = new FileInputStream(file);
return is;
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