【web开发】之常用上传下载代码
1、常用上传代码
/**
*
* @param upload 上传文件
* @param reaName 名称
* @param uploadType 类型
* @return
* @throws IOException
*/
public String uploadFile(File upload, String reaName,
String uploadType) throws IOException {
String uploadpath="D:/csg";
String uploadpath2="/upload/p_w_picpath/";
String fileDir = uploadpath +uploadpath2;
OutputStream os = null;
InputStream is = null;
File file=new File(fileDir);
if(!file.exists()){
file.mkdirs();
}
try {
is = new FileInputStream(upload);
os = new FileOutputStream(fileDir + reaName);
int bytesRead = 0;
byte[] buffer = new byte[8192];
while ((bytesRead = is.read(buffer, 0, 8192)) != -1)
os.write(buffer, 0, bytesRead);
} catch (IOException e) {
e.printStackTrace();
} finally {
if (os != null) {
os.close();
}
if (is != null) {
is.close();
}
}
return uploadpath2+reaName;
}此方法基本上可以上传所有附件
2、上传缩略图代码(按一定比例缩放)
public String uploadFile(File upload, String reaName,
String uploadType) throws IOException {
String uploadpath="D:/csg";
String uploadpath2="/upload/p_w_picpath/small/";
String fileDir = uploadpath +uploadpath2;
InputStream is = null;
BufferedImage bis = null;
is = new FileInputStream(upload);
File file=new File(fileDir);
if(!file.exists()){
file.mkdirs();
}
try {
File reviaryFile = new File(fileDir + "small20130606.jpg");
AffineTransform transform = new AffineTransform();
bis = ImageIO.read(is);
int w = bis.getWidth();
int h = bis.getHeight();
int newWidth = (int) (w * 0.1D);
int newHight = (int) (h * 0.1D);
transform.setToScale(0.1, 0.1);
AffineTransformOp ato = new AffineTransformOp(transform, null);
BufferedImage bid = new BufferedImage(newWidth, newHight, 5);
ato.filter(bis, bid);
ImageIO.write(bid, "jpg", reviaryFile);
} catch (Exception e) {
System.out.println("上传缩略图失败");
}finally{
if (is != null) {
is.close();
}
}
return fileDir;
}3、上传缩略图代码(指定比例缩放)
public String uploadFile(File upload, String reaName,
String uploadType) throws IOException {
String uploadpath="D:/csg";
String uploadpath2="/upload/p_w_picpath/small/";
String fileDir = uploadpath +uploadpath2;
InputStream is = null;
BufferedImage bis = null;
Image srcUpload = null;
is = new FileInputStream(upload);
File file=new File(fileDir);
if(!file.exists()){
file.mkdirs();
}
try {
srcUpload = ImageIO.read(is);
int newWidth = 0, newHight = 0;
int w = srcUpload.getWidth(null);
int h = srcUpload.getHeight(null);
if (w >= h) {
newWidth = 90;
newHight = h * 90 / w;
} else {
newHight = 90;
newWidth = w * 90 / h;
}
BufferedImage p_w_picpath = new BufferedImage(newWidth, newHight,
BufferedImage.TYPE_3BYTE_BGR);
p_w_picpath.getGraphics().drawImage(srcUpload.getScaledInstance(newWidth, newHight, Image.SCALE_SMOOTH), 0, 0, null);
FileOutputStream out = new FileOutputStream(fileDir + "/" + "small123.jpg");
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
encoder.encode(p_w_picpath);
p_w_picpath.flush();
out.flush();
out.close();
System.gc();
} catch (Exception e) {
System.out.println("上传缩略图失败");
}finally{
if (is != null) {
is.close();
}
}
return fileDir;
}4、常用下载代码（根据路劲下载）
Dao dao = new Dao();
UploadFiles files = dao.querykById(id);
String uploadpath = "D:/csg";
String path = uploadpath + files.getPath();
InputStream bis = null;
OutputStream bos = null;
try {
File fileInstance = new File(path);
if (!fileInstance.exists()) {
System.out.println("---------下载文件不存在，请联系管理员-------------");
} else {
HttpServletResponse response = (HttpServletResponse) ActionContext
.getContext().get(ServletActionContext.HTTP_RESPONSE);
bis = new BufferedInputStream(new FileInputStream(fileInstance));
bos = new BufferedOutputStream(response.getOutputStream());
response.setContentType("application/octet-stream;charset=UTF-8");
response.setHeader("Content-Disposition","p_w_upload;filename="+ URLEncoder.encode(files.getUploadRealName(),"UTF-8"));
byte[] buff = new byte[1024];
int bytesRead;
while (-1 != (bytesRead = bis.read(buff, 0, buff.length))) {
// 将buff中的数据写到客户端的内存
bos.write(buff, 0, bytesRead);
}
bos.close();
bis.close();
}
} catch (IOException e) {
System.out.println("下载失败");
} finally {
bos.close();
bis.close();
}
return null;
}此方法基本可以下载所有附件
5、直接下载(无路径，后台生成之后直接下载适合Excel，word，pdf等)
Excel:
public static void export(HttpServletResponse response,Workbook wb,String fileName)throws Exception{
response.setHeader("Content-Disposition", "p_w_upload;filename="+new String(fileName.getBytes("utf-8"),"iso8859-1"));
response.setContentType("application/ynd.ms-excel;charset=UTF-8");
OutputStream out=response.getOutputStream();
wb.write(out);
out.flush();
out.close();
}PDF:
ByteArrayOutputStream ba = new ByteArrayOutputStream();
PdfWriter writer = PdfWriter.getInstance(document, ba);
// 打开文档，生成页头页脚等信息在open之前
document.open();
//省略n行生成table的代码
document.add(table);
document.close();
// 关闭文本，释放资源
HttpServletResponse response=super.getResponse();
response.setContentLength(ba.size());
response.setContentType("application/octet-stream;charset=UTF-8");
String str="审核表.pdf";
response.setHeader("Content-Disposition", "p_w_upload;filename="+new String(str.getBytes("utf-8"),"iso8859-1"));
ServletOutputStream out = response.getOutputStream();
ba.writeTo(out);
out.flush();ps:直接下载就是在生成之后直接将文本信息传进来，就行了。而Excel这个例子是需要将生成之后的Workbook返回去，传给export方法！PDF，Excel，word直接下载方法基本类似！
上传下载说白了，其实就是输入，输出流的问题！了解输入输出流的本质这些基本上就不是问题了！
以上代码都是经本人测试之后拷贝出来直接可以使用！
有问题，请举手！
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