由于用IO流下载.xlsx .docx 文件时报文件损坏的错误修复，找了半天原因，终于解决了，记录一下原因，以及解决方案
一.出现损坏的原因：
并不是每次都能读到1024个字节，所有用len作为每次读取数据的长度，否则会出现文件损坏的错误
二.解决方法（注意红的部分代码）
1.原本文件下载代码如下：
public void Downloads(HttpServletResponse response , String url){
try {
File file = new File(url);
String str = new SimpleDateFormat("yyyyMMddHHmmss").format(new Date());
String name=str+".xlsx";
if(file.exists()){ //判断文件父目录是否存在
response.setContentType("application/force-download");
response.setHeader("Content-Disposition", "attachment;fileName=" + URLEncoder.encode(name, "UTF-8"));
response.setHeader("Pragma", URLEncoder.encode(name, "UTF-8"));
byte[] buffer = new byte[1024];
FileInputStream fis = null; //文件输入流
BufferedInputStream bis = null;
OutputStream os = null; //输出流
os = response.getOutputStream();
fis = new FileInputStream(file);
bis = new BufferedInputStream(fis);
while(bis.read(buffer) != -1){
os.write(buffer);
}
bis.close();
fis.close();
}
}catch (Exception e){
e.printStackTrace();
logger.warn("sys:zydownload:Downloads--userId:"+ ShiroUtils.getUserId()+"===="+e.getMessage());
}
}
注：这种写法会出现IO流下载.xlsx .docx 文件时报文件损坏的错误修复，改成下面的写法则可以解决
2.改进后的代码
public void Downloads(HttpServletResponse response , String url){
try {
File file = new File(url);
String str = new SimpleDateFormat("yyyyMMddHHmmss").format(new Date());
String name=str+".xlsx";
if(file.exists()){ //判断文件父目录是否存在
response.setCharacterEncoding("UTF-8");
response.setHeader("content-Type", "application/vnd.ms-excel");
response.setHeader("Content-Disposition", "attachment;fileName=" + URLEncoder.encode(name, "UTF-8"));
response.setHeader("Pragma", URLEncoder.encode(name, "UTF-8"));
byte[] buffer = new byte[1024];
FileInputStream fis = null; //文件输入流
BufferedInputStream bis = null;
OutputStream os = null; //输出流
os = response.getOutputStream();
fis = new FileInputStream(file);
bis = new BufferedInputStream(fis);
int len = 0;
while((len = bis.read(buffer)) >0){
os.write(buffer, 0, len);
}
bis.close();
fis.close();
}
}catch (Exception e){
e.printStackTrace();
logger.warn("sys:zydownload:Downloads--userId:"+ ShiroUtils.getUserId()+"===="+e.getMessage());
}
}
