Java实现下载文件的6种方式
作者：佳德_Boy
本文主要介绍了Java实现下载文件的6种方式，文中通过示例代码介绍的非常详细，对大家的学习或者工作具有一定的参考学习价值，需要的朋友们下面随着小编来一起学习学习吧
一、以流的方式下载
public HttpServletResponse download(String path, HttpServletResponse response) {
try {
// path是指欲下载的文件的路径。
File file = new File(path);
// 取得文件名。
String filename = file.getName();
// 取得文件的后缀名。
String ext = filename.substring(filename.lastIndexOf(".") + 1).toUpperCase();
// 以流的形式下载文件。
InputStream fis = new BufferedInputStream(new FileInputStream(path));
byte[] buffer = new byte[fis.available()];
fis.read(buffer);
fis.close();
// 清空response
response.reset();
// 设置response的Header
response.addHeader("Content-Disposition", "attachment;filename=" + new String(filename.getBytes()));
response.addHeader("Content-Length", "" + file.length());
OutputStream toClient = new BufferedOutputStream(response.getOutputStream());
response.setContentType("application/octet-stream");
toClient.write(buffer);
toClient.flush();
toClient.close();
} catch (IOException ex) {
ex.printStackTrace();
}
return response;
}二、下载本地文件
public void downloadLocal(HttpServletResponse response) throws FileNotFoundException {
// 下载本地文件
String fileName = "Operator.doc".toString(); // 文件的默认保存名
// 读到流中
InputStream inStream = new FileInputStream("c:/Operator.doc");// 文件的存放路径
// 设置输出的格式
response.reset();
response.setContentType("bin");
response.addHeader("Content-Disposition", "attachment; filename=\"" + fileName + "\"");
// 循环取出流中的数据
byte[] b = new byte[100];
int len;
try {
while ((len = inStream.read(b)) > 0)
response.getOutputStream().write(b, 0, len);
inStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}三、下载网络文件
public void downloadNet(HttpServletResponse response) throws MalformedURLException {
// 下载网络文件
int bytesum = 0;
int byteread = 0;
URL url = new URL("windine.blogdriver.com/logo.gif");
try {
URLConnection conn = url.openConnection();
InputStream inStream = conn.getInputStream();
FileOutputStream fs = new FileOutputStream("c:/abc.gif");
byte[] buffer = new byte[1204];
int length;
while ((byteread = inStream.read(buffer)) != -1) {
bytesum += byteread;
System.out.println(bytesum);
fs.write(buffer, 0, byteread);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}public void downLoadFile(HttpServletResponse response, String httpUrl) {
ServletOutputStream out = null;
try {
//与服务器建立连接
URL url = new URL(httpUrl);
URLConnection conn = url.openConnection();
InputStream inputStream = conn.getInputStream();
try {
//1.设置文件ContentType类型，这样设置，会自动判断下载文件类型
response.setContentType("multipart/form-data");
} catch (Exception e){
e.printStackTrace();
}
out = response.getOutputStream();
// 读取文件流
int len = 0;
byte[] buffer = new byte[1024 * 10];
while ((len = inputStream.read(buffer)) != -1) {
out.write(buffer, 0, len);
}
out.flush();
out.close();
inputStream.close();
} catch (Exception e){
e.printStackTrace();
}
}四、在线打开的方式
public void downLoad(String filePath, HttpServletResponse response, boolean isOnLine) throws Exception {
File f = new File(filePath);
if (!f.exists()) {
response.sendError(404, "File not found!");
return;
}
BufferedInputStream br = new BufferedInputStream(new FileInputStream(f));
byte[] buf = new byte[1024];
int len = 0;
response.reset(); // 非常重要
if (isOnLine) { // 在线打开方式
URL u = new URL("file:///" + filePath);
response.setContentType(u.openConnection().getContentType());
response.setHeader("Content-Disposition", "inline; filename=" + f.getName());
// 文件名应该编码成UTF-8
} else { // 纯下载方式
response.setContentType("application/x-msdownload");
response.setHeader("Content-Disposition", "attachment; filename=" + f.getName());
}
OutputStream out = response.getOutputStream();
while ((len = br.read(buf)) > 0)
out.write(buf, 0, len);
br.close();
out.close();
}五、将文件转换成base64
/**
* 将文件转为base64
*/
public static String getBase64FromFile(File file) throws IOException {
FileInputStream in = null;
ByteArrayOutputStream out = null;
try {
in = new FileInputStream(file);
out = new ByteArrayOutputStream();
int read = 0;
byte[] buffer = new byte[1024];
while ((read = in.read(buffer, 0, 1024)) != -1) {
out.write(buffer, 0, read);
}
return Base64.getEncoder().encodeToString(out.toByteArray());
} catch (IOException e) {
throw e;
} finally {
if (in != null) {
in.close();
}
if (out != null){
out.close();
}
}
}六、将MultipartFile转换为File
/**
* 将MultipartFile转换为File
*/
public static File MultipartFileToFile(MultipartFile multiFile) throws IOException {
String fileName = multiFile.getOriginalFilename();
String prefix = fileName.substring(fileName.lastIndexOf("."));
InputStream in = null;
OutputStream out = null;
try {
File file = File.createTempFile(fileName, prefix);
out = new FileOutputStream(file);
in = multiFile.getInputStream();
int read = 0;
byte[] buffer = new byte[1024];
while ((read = in.read(buffer, 0, 1024)) != -1) {
out.write(buffer, 0, read);
}
return file;
} catch (Exception e) {
throw e;
}finally {
if (in != null){
in.close();
}
if (out != null){
out.close();
}
}
}到此这篇关于Java实现下载文件的6种方式的文章就介绍到这了,更多相关Java 下载文件内容请搜索脚本之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之家！