How to save a csv using hibernate and mysql [closed]

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How to save a csv using hibernate and mysql [closed]

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#1 by (2 votes)

0

I need to do the following routine:

Read some information from the database;

Generate a csv based on this data;

Save this csv to the database;

Start downloading this file to the user.

I was able to do items 1 and 2, generating the file as follows:

FileWriter writer = new FileWriter("c:\test.csv");
writer.append("user");
writer.flush();
writer.close();

Going to item 3. Define the field in the database as BLOB and in the entity as byte[]; How do I convert the object FileWriter to byte?

Regarding item 4, I intend to use p:fileDownload of Primefaces. However it expects a StreamedContent , that is. I'll have to do a new conversion!

I may be wrong in some of these notes. And I ask everyone's help to solve this problem!

java jsf hibernate jpa primefaces

asked by anonymous 12.07.2017 / 16:00

1 answer

Check for list records in the entity framework Do not add to the database when any value is null

score 2 · Accepted Answer

After several queries on the internet. I was able to find a solution ...

Generate csv using the StringBuilder. Example:

StringBuilder csv = new StringBuilder();
csv.append("USER");

Save the csv in your mapped entity (remembering that the entity field type must be byte [] and the database must be BLOB.)

ExportData exportData = new ExportData();
exportData.setFile(csv.toString().getBytes());

Retrieve the information in the database and convert to StreamedContent.

private StreamedContent file;

file = new DefaultStreamedContent(new ByteArrayInputStream(exportDataService.exportData()), "csv", "export.csv");

It generates the gets and sets of the file, to be able to get in xhtml.

Insert a commandButton with fileDownload, using actionListener . If you try to use the action the value will only be populated after the second iteration.

<p:commandButton value="Export Data" ajax="false"
                 actionListener="#{listaExportMB.exportData()}"                                       
                 styleClass="btn-info"
                 icon="fa fa-cloud-download">
    <p:fileDownload value="#{listaExportMB.file}"/>                         
</p:commandButton>