I have to download a Zip file, from rest call and extract its contents (some PDF files and a PNG file).
I'm using Java Spring.
How can do it?
You can use Spring's RestTemplate to download the file
RestTemplate templ = new RestTemplate();
byte[] downloadedBytes = templ.getForObject(url, byte[].class);
Extract the contents with standard java or a third party library.
Example utility, adapted from here: http://www.codejava.net/java-se/file-io/programmatically-extract-a-zip-file-using-java
package com.test;
import java.io.BufferedOutputStream;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;
public class ZipHelper {
private static final int BUFFER_SIZE = 4096;
public static void unzip(byte[] data, String dirName) throws IOException {
File destDir = new File(dirName);
if (!destDir.exists()) {
destDir.mkdir();
}
ZipInputStream zipIn = new ZipInputStream(new ByteArrayInputStream(data));
ZipEntry entry = zipIn.getNextEntry();
while (entry != null) {
String filePath = dirName + File.separator + entry.getName();
if (!entry.isDirectory()) {
// if the entry is a file, extracts it
extractFile(zipIn, filePath);
} else {
// if the entry is a directory, make the directory
File dir = new File(filePath);
dir.mkdir();
}
zipIn.closeEntry();
entry = zipIn.getNextEntry();
}
zipIn.close();
}
private static void extractFile(ZipInputStream zipIn, String filePath) throws IOException {
BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(filePath));
byte[] bytesIn = new byte[BUFFER_SIZE];
int read = 0;
while ((read = zipIn.read(bytesIn)) != -1) {
bos.write(bytesIn, 0, read);
}
bos.close();
}
}
Then you use this utility like so:
ZipHelper.unzip(downloadedBytes, "/path/to/directory");
The requesdt body should be like this:
@RequestMapping(value = "/push/{id}", method = RequestMethod.POST, consumes = MediaType.APPLICATION_OCTET_STREAM_VALUE, produces=MediaType.APPLICATION_JSON_VALUE)
@ResponseStatus(HttpStatus.OK)
public String pushTransactions(@PathVariable("id") String id, @RequestBody byte[] str) throws MessagingException, JsonParseException, JsonMappingException, IOException {
and in controller, you can do this:
GZIPInputStream gis = new GZIPInputStream(new ByteArrayInputStream(str));
ByteArrayOutputStream out = new ByteArrayOutputStream();
int len;
while ((len = gis.read(buffer)) > 0) {
out.write(buffer, 0, len);
}
gis.close();
out.close();
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