java 使用 JSF 下载 CSV 文件
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Downloading a CSV file using JSF
提问by yves.beutler
I don't know how to download a CSV file. The CSV will be generated at runtime. Do I need to save the file in the tomcat WEB-INF directory first? I'm using JSF 1.2.
我不知道如何下载 CSV 文件。CSV 将在运行时生成。需要先把文件保存在tomcat的WEB-INF目录下吗？我正在使用 JSF 1.2。
By the way, what's the favored JSF component for this kind of task?
顺便说一句，这种任务最喜欢的 JSF 组件是什么？
Edit (05.05.2012 - 15:53)
编辑 (05.05.2012 - 15:53)
I tried the solution BalusCstated in his first link, but if I click on my commandButton the content of the file is displayed on the webpage. Maybe there's a problem with the mimetype?
我尝试了BalusC他的第一个链接中所述的解决方案，但是如果我单击我的 commandButton，文件的内容将显示在网页上。也许有问题mimetype？
xhtml-file:
xhtml 文件：
<a4j:form>
<a4j:commandButton action="#{surveyEvaluationBean.doDataExport}" value="#{msg.srvExportButton}" />
</a4j:form>
main bean:
主豆：
public String doDataExport() {
try {
export.downloadFile();
} catch (SurveyException e) {
hasErrors = true;
}
return "";
}
export-bean:
出口豆：
public void downloadFile() throws SurveyException {
try {
String filename = "analysis.csv";
FacesContext fc = FacesContext.getCurrentInstance();
HttpServletResponse response = (HttpServletResponse) fc.getExternalContext().getResponse();
response.reset();
response.setContentType("text/comma-separated-values");
response.setHeader("Content-Disposition", "attachment; filename=\"" + filename + "\"");
OutputStream output = response.getOutputStream();
// writing just sample data
List<String> strings = new ArrayList<String>();
strings.add("filename" + ";" + "description" + "\n");
strings.add(filename + ";" + "this is just a test" + "\n");
for (String s : strings) {
output.write(s.getBytes());
}
output.flush();
output.close();
fc.responseComplete();
} catch (IOException e) {
throw new SurveyException("an error occurred");
}
}
Edit (05.05.2012 - 16:27)
编辑 (05.05.2012 - 16:27)
I solved my problem. I have to use <h:commandButton>instead of <a4j:commandButton>and now it works!
我解决了我的问题。我必须使用<h:commandButton>而不是，<a4j:commandButton>现在它可以工作了！
采纳答案by BalusC
Do I need to save the file in the tomcat WEB-INF directory first?
需要先把文件保存在tomcat的WEB-INF目录下吗？
No, just write it straight to the HTTP response body as you obtain by ExternalContext#getResponseOutputStream()after having set the proper response headers which tells the browser what it's going to retrieve.
不，只需将它直接写入 HTTP 响应正文，因为您ExternalContext#getResponseOutputStream()在设置了正确的响应标头后获得了它，该标头告诉浏览器它将要检索什么。
Do the math based on the concrete examples found in the following answers:
根据以下答案中的具体示例进行数学计算：
- How to provide a file download from a JSF backing bean?
- JSP generating Excel spreadsheet (XLS) to download
Basically:
基本上：
List<List<Object>> csv = createItSomehow();
writeCsv(csv, ';', ec.getResponseOutputStream());
By the way, what's the favorite jsf-component for this kind of task?
顺便说一句，这种任务最喜欢的 jsf 组件是什么？
This is subjective. But anyway, we're using <p:dataExporter>to full satisfaction.
这是主观的。但无论如何，我们使用<p:dataExporter>得非常满意。
回答by choop
If you are using JSF 2 you can use primefaces.
You can take a look at that link.
如果您使用的是 JSF 2，则可以使用 primefaces。
你可以看看那个链接。
If not you can do it like that:
如果没有，你可以这样做：
List<Object> report = new ArrayList<Object>(); // fill your arraylist with relevant data
String filename = "report.csv";
File file = new File(filename);
Writer output = new BufferedWriter(new FileWriter(file));
output.append("Column1");
output.append(",");
output.append("Column2");
output.append("\n");
//your data goes here, Replcae Object with your bean
for (Object row:report){
output.append(row.field1);
output.append(",");
output.append(row.field2);
output.append("\n");
}
output.flush();
output.close();
