使用Struts2上传一个文件(我使用的web服务器是Tomcat7)

Question

当我使用Struts2上传文件时，我在jsp中点击了提交，但tomcat给我显示了错误的消息，我在互联网上搜索过，但找不到答案，所以我希望有人能帮助我，谢谢！

错误消息如下：

HTTP Status 500 - 
type Exception report
message 
description The server encountered an internal error () that prevented it from fulfilling this request.
exception 
java.lang.NullPointerException
java.io.FileInputStream.<init>(FileInputStream.java:134)
lanxiaoxing.upload.upLoadAction.execute(upLoadAction.java:58)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
java.lang.reflect.Method.invoke(Method.java:601)
com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:441)
com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:280)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:243)
com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:165)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:252)
org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:122)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:179)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:75)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:94)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:306)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:89)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:130)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:267)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:126)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:138)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:165)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:179)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:176)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:52)
org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:488)
org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91)

注意：Apache Tomcat/7.0.26日志中提供了根本原因的完整堆栈跟踪。Apache Tomcat/7.0.26

struts.xml是：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.1//EN"
   "http://struts.apache.org/dtds/struts-2.1.dtd">
<struts>
<package name="lanxiaoxing.user" extends="struts-default">
<action name="loginUser" class="lanxiaoxing.user.userAction">
  <result name="success">success.jsp</result>
  <result name="error">error.jsp</result>
</action>
</package>
<package name="lanxiaoxing.upload" extends="struts-default">
<action name="upLoad" class="lanxiaoxing.upload.upLoadAction">
  <result name="SUCCESS">upload_success.jsp</result>
</action>
</package>
</struts>

upLoadAction.java是：

package lanxiaoxing.upload;
import java.io.*;
import javax.servlet.http.*;
import org.apache.struts2.*;
import com.opensymphony.xwork2.*;
public class upLoadAction extends ActionSupport{
/**
 * 
 */
private static final long serialVersionUID = 1L;
private File lanxiaoxingfile;
private String lanxiaoxingfileContentType;
private String lanxiaoxingfileName;
private String savePath;

private String getSavePath(){
    HttpServletRequest request = ServletActionContext.getRequest();
    return request.getSession().getServletContext().getRealPath(savePath);
}

public File getlanxiaoxingfile(){
    return lanxiaoxingfile;
}
public void setlanxiaoxingfile(File lanxiaoxingfile){
    this.lanxiaoxingfile=lanxiaoxingfile;
}
public String getlanxiaoxingfileContentType(){
    return lanxiaoxingfileContentType;
}
public void setlanxiaoxingfileContenType(String lanxiaoxingfileContentType){
    this.lanxiaoxingfileContentType=lanxiaoxingfileContentType;
}
public String getlanxiaoxingfileName(){
    return lanxiaoxingfileName;
}
public void setlanxiaoxingfileName(String lanxiaoxingfileName){
    this.lanxiaoxingfileName=lanxiaoxingfileName;
}
public void setsavePath(String savePath){
    this.savePath=savePath;
}
public String execute() throws Exception{
    setsavePath("");
    FileOutputStream fos = new FileOutputStream(getSavePath()+"\"+getlanxiaoxingfileName());
    FileInputStream fis = new FileInputStream(getlanxiaoxingfile());
    byte[]buffer = new byte[1024];
    int len=0;
    while((len=fis.read(buffer))>0){
        fos.write(buffer, 0, len);
    }
    return SUCCESS;
}

}

Answer 1

您的getter和setter名称都不正确；它们应该遵循正常的Java命名约定，以及文件上传拦截器所期望的约定，例如：

public void setLanxiaoxingfile(File lanxiaoxingfile) { // Note capital "L"

这假定了一个名为"lanxiaoxifile"的文件输入字段。

IMO变量名的"file"部分是多余的

有关详细信息，请参阅文件上传文档。

此外，正如tusar所说，结果名称应该是小写"success"，或者留空，因为这是默认值。不过，默认堆栈已经包含"fileUpload"拦截器，因此为该操作重新配置它将是多余的，并且会产生误导。

考虑通过实用程序方法进行文件复制，或者只使用Commons IO文件复制实用程序之一。

Answer 2

FileUpload使用Struts2并且缺少fileUpload和defaultStack拦截器似乎导致了错误。尝试更改您的行动声明，如：

<action name="upLoad" class="lanxiaoxing.upload.upLoadAction">
    <interceptor-ref name="fileUpload">
        <param name="maximumSize">999999999999</param>
        <param name="allowedTypes">
            image/png,image/gif,image/jpeg,image/pjpeg
        </param>
    </interceptor-ref>
    <interceptor-ref name="defaultStack"></interceptor-ref>
    <result name="success">upload_success.jsp</result>
</action>

此外，SUCCESS实际上是一个字符串"success"，这就是我将结果名称修改为小写字母的原因。在学习的同时，遵循教程总是很好的。