Java实现批量下载文件的示例代码
作者：西瓜喵
这篇文章主要为大家详细介绍了Java如何实现批量下载文件,并以压缩输出流的形式返回前端,文中的示例代码讲解详细,需要的小伙伴可以参考一下
我需要调取第三方接口的数据存到本地服务器上，然后在以输出流的形式响应
zipUtil（工具类，直接复制即可，这个是我从别的博主那里复制来的，亲测有效）
public class ZipUtil {
private static Logger logger = LoggerFactory.getLogger(ZipUtils.class);
// 目录标识判断符
public static final String PATCH = "/";
// 基目录
public static final String BASE_DIR = "";
// 缓冲区大小
private static final int BUFFER = 2048;
// 字符集
public static final String CHAR_SET = "GBK";
/**
*
* 描述: 压缩文件
* @author wanghui
* @created 2017年10月27日
* @param fileOutName
* @param files
* @throws Exception
*/
public static void compress(String fileOutName, List<File> files) throws Exception {
try {
FileOutputStream fileOutputStream = new FileOutputStream(fileOutName);
ZipOutputStream zipOutputStream = new ZipOutputStream(fileOutputStream);
zipOutputStream.setEncoding(CHAR_SET);
if (files != null && files.size() > 0) {
for (int i = 0,size = files.size(); i < size; i++) {
compress(files.get(i), zipOutputStream, BASE_DIR);
}
}
// 冲刷输出流
zipOutputStream.flush();
// 关闭输出流
zipOutputStream.close();
} catch (Exception e) {
throw new Exception(e.getMessage(),e);
}
}
/**
*
* 描述:压缩文件并进行Base64加密
* @author wanghui
* @created 2017年10月27日
* @param files
* @return
* @throws Exception
*/
public static String compressToBase64(List<File> files) throws Exception {
try {
ByteArrayOutputStream bos = new ByteArrayOutputStream();
ZipOutputStream zipOutputStream = new ZipOutputStream(bos);
zipOutputStream.setEncoding(CHAR_SET);
if (files != null && files.size() > 0) {
for (int i = 0,size = files.size(); i < size; i++) {
compress(files.get(i), zipOutputStream, BASE_DIR);
}
}
// 冲刷输出流
zipOutputStream.flush();
// 关闭输出流
zipOutputStream.close();
byte[] data = bos.toByteArray();
return new String(Base64.encodeBase64(data));
} catch (Exception e) {
throw new Exception(e.getMessage(),e);
}
}
/**
*
* 描述: 压缩
* @author wanghui
* @created 2017年10月27日
* @param srcFile
* @param zipOutputStream
* @param basePath
* @throws Exception
*/
public static void compress(File srcFile, ZipOutputStream zipOutputStream, String basePath) throws Exception {
if (srcFile.isDirectory()) {
compressDir(srcFile, zipOutputStream, basePath);
} else {
compressFile(srcFile, zipOutputStream, basePath);
}
}
/**
*
* 描述:压缩目录下的所有文件
* @author wanghui
* @created 2017年10月27日
* @param dir
* @param zipOutputStream
* @param basePath
* @throws Exception
*/
private static void compressDir(File dir, ZipOutputStream zipOutputStream, String basePath) throws Exception {
try {
// 获取文件列表
File[] files = dir.listFiles();
if (files.length < 1) {
ZipEntry zipEntry = new ZipEntry(basePath + dir.getName() + PATCH);
zipOutputStream.putNextEntry(zipEntry);
zipOutputStream.closeEntry();
}
for (int i = 0,size = files.length; i < size; i++) {
compress(files[i], zipOutputStream, basePath + dir.getName() + PATCH);
}
} catch (Exception e) {
throw new Exception(e.getMessage(), e);
}
}
/**
*
* 描述:压缩文件
* @author wanghui
* @created 2017年10月27日
* @param file
* @param zipOutputStream
* @param dir
* @throws Exception
*/
private static void compressFile(File file, ZipOutputStream zipOutputStream, String dir) throws Exception {
try {
// 压缩文件
ZipEntry zipEntry = new ZipEntry(dir + file.getName());
zipOutputStream.putNextEntry(zipEntry);
// 读取文件
BufferedInputStream bis = new BufferedInputStream(new FileInputStream(file));
int count = 0;
byte data[] = new byte[BUFFER];
while ((count = bis.read(data, 0, BUFFER)) != -1) {
zipOutputStream.write(data, 0, count);
}
bis.close();
zipOutputStream.closeEntry();
} catch (Exception e) {
throw new Exception(e.getMessage(),e);
}
}
/**
*
* 描述: 文件Base64加密
* @author wanghui
* @created 2017年10月27日 上午9:27:38
* @param srcFile
* @return
* @throws Exception
*/
public static String encodeToBASE64(File srcFile) throws Exception {
try {
ByteArrayOutputStream bos = new ByteArrayOutputStream();
// 读取文件
BufferedInputStream bis = new BufferedInputStream(new FileInputStream(srcFile));
int count = 0;
byte data[] = new byte[BUFFER];
while ((count = bis.read(data, 0, BUFFER)) != -1) {
bos.write(data, 0, count);
}
bis.close();
byte[] base64Data = Base64.encodeBase64(bos.toByteArray());
if (null == base64Data) {
bos.close();
return null;
}
bos.close();
return new String(base64Data, CHAR_SET);
} catch (Exception e) {
throw new Exception(e.getMessage(),e);
}
}
/**
*
* 描述: 文件Base64解密
* @author wanghui
* @created 2017年10月27日
* @param destFile
* @param encodeStr
* @throws Exception
*/
public static void decodeToBase64(File destFile, String encodeStr) throws Exception {
try {
byte[] decodeBytes = Base64.decodeBase64(encodeStr.getBytes());
ByteArrayInputStream bis = new ByteArrayInputStream(decodeBytes);
// 读取文件
FileOutputStream fileOutputStream = new FileOutputStream(destFile);
int count = 0;
byte data[] = new byte[BUFFER];
while ((count = bis.read(data, 0, BUFFER)) != -1) {
fileOutputStream.write(data, 0, count);
}
fileOutputStream.close();
bis.close();
} catch (Exception e) {
throw new Exception(e.getMessage(),e);
}
}
/**
*
* 描述: 解压缩
* @author wanghui
* @created 2017年10月27日
* @param srcFileName
* @param destFileName
* @throws Exception
*/
@SuppressWarnings("unchecked")
public static void decompress(String srcFileName, String destFileName) throws Exception {
try {
ZipFile zipFile = new ZipFile(srcFileName);
Enumeration<ZipEntry> entries = zipFile.getEntries();
File destFile = new File(destFileName);
InputStream inputStream = null;
while(entries.hasMoreElements()) {
ZipEntry zipEntry = (ZipEntry)entries.nextElement();
String dir = destFile.getPath() + File.separator + zipEntry.getName();
File dirFile = new File(dir);
if (zipEntry.isDirectory()) {
dirFile.mkdirs();
} else {
fileProber(dirFile);
inputStream = zipFile.getInputStream(zipEntry);
decompressFile(dirFile, inputStream);
}
}
zipFile.close();
} catch (Exception e) {
throw new Exception(e.getMessage(),e);
}
}
/**
*
* 描述: 解压文件
* @author wanghui
* @created 2017年10月27日
* @param destFile
* @param inputStream
* @throws Exception
*/
private static void decompressFile(File destFile, InputStream inputStream) throws Exception {
try {
// 文件输入流
BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(destFile));
int count = 0;
byte data[] = new byte[BUFFER];
while ((count = inputStream.read(data, 0, BUFFER)) != -1) {
bos.write(data, 0, count);
}
bos.close();
inputStream.close();
} catch (Exception e) {
throw new Exception(e.getMessage(), e);
}
}
/**
*
* 描述:文件探测
* @author wanghui
* @created 2017年10月27日
* @param dirFile
*/
private static void fileProber(File dirFile) {
File parentFile = dirFile.getParentFile();
if (!parentFile.exists()) {
// 递归寻找上级目录
fileProber(parentFile);
parentFile.mkdir();
}
}
/**
* 递归删除目录下的所有文件及子目录下所有文件
* @param dir 将要删除的文件目录
* @return boolean Returns "true" if all deletions were successful.
* If a deletion fails, the method stops attempting to
* delete and returns "false".
*/
public static boolean deleteDir(File dir) {
if (dir.isDirectory()) {
String[] children = dir.list();
//递归删除目录中的子目录下
for (int i=0; i<children.length; i++) {
boolean success = deleteDir(new File(dir, children[i]));
if (!success) {
return false;
}
}
}
// 目录此时为空，可以删除
return dir.delete();
}Controller层
public void bathDownScript(HttpServletResponse response, String paths) throws Exception {
String uuid = UUID.randomUUID().toString().replaceAll("-","");
//1.新建文件夹，用来存放下载下来的文件，最后进行压缩
File folder = new File("/tmp/"+uuid);
System.out.println(folder.getName());
if (!folder.exists() && !folder.isDirectory()) {
boolean flag = folder.mkdirs();
}
//2.遍历读取文件放入文件夹中
String[] path= paths.split(",");
Configuration conf = new Configuration();
conf.set("fs.defaultFS", HdfsUtils.HDFSURL);
List<File> files = new ArrayList<File>();
for(String huePath:path){
//通过hdfs读取文件
byte[] res = HdfsUtils.readFile(conf,huePath);
//定义文件名称
String fileName = huePath.substring(huePath.lastIndexOf("/"));
//定义文件路径
File f = new File("/tmp/"+uuid+fileName);
InputStream in = new ByteArrayInputStream(res);
byte[] buff = new byte[1024];
FileOutputStream out = new FileOutputStream(f);
try {
int i = in.read(buff);
while (i != -1) {
out.write(buff, 0, buff.length);
out.flush();
i = in.read(buff);
}
} catch (IOException e) {
e.printStackTrace();
} finally {
if (in != null) {
try {
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
files.add(f);
}
//3.响应前端数据
String zipName = "myfile.zip";
response.setHeader("content-type", "application/octet-stream");
response.setCharacterEncoding("utf-8");
// 设置浏览器响应头对应的Content-disposition
response.setHeader("Content-disposition",
"attachment;filename=" + new String(zipName.getBytes("gbk"), "iso8859-1"));
ZipOutputStream zipOutputStream = new ZipOutputStream(response.getOutputStream());
zipOutputStream.setEncoding(ZipUtil.CHAR_SET);
if (CollectionUtils.isEmpty(files) == false) {
for (int i = 0,size = files.size(); i < size; i++) {
ZipUtil.compress(files.get(i), zipOutputStream, ZipUtil.BASE_DIR);
}
}
// 冲刷输出流
zipOutputStream.flush();
// 关闭输出流
zipOutputStream.close();
//4.下载完删除deleteDir
boolean flag = ZipUtil.deleteDir(folder);
System.out.println("删除文件："+flag);
}以上就是Java实现批量下载文件的示例代码的详细内容，更多关于Java批量下载文件的资料请关注脚本之家其它相关文章！