Primefaces fileDownload - 已为此响应调用 getOutputStream()
我正在使用 Primefaces 文件下载。当我第一次启动应用程序时，会下载文件，但每次按下下载按钮时，都会出现此错误：
java.lang.IllegalStateException: getOutputStream() has already been called for this response
我的 xhtml 代码：
<p:commandButton value="Download" ajax="true">
<p:fileDownload value="#{fileDownloadController.file}" />
</p:commandButton>
我的 java 代码：
private StreamedContent file;
public FileDownloadController() {
InputStream stream = null;
try {
stream = FacesContext.getCurrentInstance().getExternalContext().getResourceAsStream("/Enastr1.txt");
file = new DefaultStreamedContent(stream, "txt", "Downloaded_Enastr1");
} catch (Exception ex) {
Logger.getLogger(FileDownloadController.class.getName()).log(Level.SEVERE, null, ex);
} finally {
}
}
public StreamedContent getFile() {
return file;
}
public void setFile(StreamedContent file) {
this.file = file;
}
I'm using Primefaces fileDownload. When I first start the application the file is downloaded but then everytime I press the download button, this error appears:
java.lang.IllegalStateException: getOutputStream() has already been called for this response
My xhtml code:
<p:commandButton value="Download" ajax="true">
<p:fileDownload value="#{fileDownloadController.file}" />
</p:commandButton>
My java code:
private StreamedContent file;
public FileDownloadController() {
InputStream stream = null;
try {
stream = FacesContext.getCurrentInstance().getExternalContext().getResourceAsStream("/Enastr1.txt");
file = new DefaultStreamedContent(stream, "txt", "Downloaded_Enastr1");
} catch (Exception ex) {
Logger.getLogger(FileDownloadController.class.getName()).log(Level.SEVERE, null, ex);
} finally {
}
}
public StreamedContent getFile() {
return file;
}
public void setFile(StreamedContent file) {
this.file = file;
}
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评论（2）
您在 bean 的构造函数中创建流，而不是在与
您有 2 个选项：
将 bean 放入请求范围。
改为在操作方法中创建流并将其绑定到
You're creating the stream in the constructor of the bean instead of in the action method associated with the
<p:commandButton>. The symptoms indicate that the bean is placed in a broader scope than the request scope. The constructor is only called upon bean's construction, not on every HTTP request. If the bean is put in the request scope, then the constructor is called on every HTTP request.You have 2 options:
Put the bean in the request scope.
Create the stream in an action method instead and bind it to
<p:commandButton action>.您的页面中是否有多个
Are there multiple
<p:filedownload/>tags in your page (possibly with the same binding)? I had issues with Primefaces when attempting to use multiple ajax-enabled<p:filedownload/>tags (bound to different properties in the backing bean) in the same page with other ajax-y functionality. The main problem seemed to be that every<p:filedownload/>became bound to the same property. My project's requirements changed in a way that removed the need for ajax downloads, so I don't have a good solution for you, but this might help you on your way.