DataInputStream读取大文件压缩包未读完，导致文件损坏。解决方案循环读

错误读法（小文件可以）
int filesize = Integer.parseInt(recBodyEmt.element("filesize").getText());
byte[] buffer = new byte[filesize];

din.read（buffer）；

FileUtil.write(request.getBody().getLocalpath(),request.getBody().getFilename() , buffer);

解决方法

int filesize = Integer.parseInt(recBodyEmt.element("filesize").getText());
byte[] buffer = new byte[filesize];
int count = 0;
while(count<filesize){
    int available = din.available();
    if(available>buffer.length-count){
        available=buffer.length-count;
    }
    count += din.read(buffer,count,available);
}

FileUtil.write(request.getBody().getLocalpath(),request.getBody().getFilename() , buffer);