Java: resume download in urlconnection

I wrote a program to download some files from some servers

....

File fcheck=new File(SaveDir+"/"+filename);
if(resume@R_138_2419@.isSelected() && fcheck.exists()){
    connection.setRequestProperty("Range","Bytes="+(fcheck.length())+"-");
}

connection.setDoInput(true);
connection.setDoOutput(true);

BufferedInputStream in = new BufferedInputStream (connection.getInputStream()); 

pbar.setIndeterminate(false);
pbar.setStringPainted(true);

java.io.FileOutputStream fos ;
if(resume@R_138_2419@.isSelected()){
    if(fcheck.exists()){
        if(connection.getHeaderField("Accept-Ranges").equals("bytes")){
            fos = new java.io.FileOutputStream(SaveDir+"/"+filename,true);
        }else{
            fos = new java.io.FileOutputStream(SaveDir+"/"+filename);
        }
    }else{
        fos = new java.io.FileOutputStream(SaveDir+"/"+filename);
    }
}else{
    fos = new java.io.FileOutputStream(SaveDir+"/"+filename);
}

....@H_419_6@ 
 
我正在我知道支持的服务器上进行测试.
我下载了一些字节(72720)
然后尝试恢复它.
然后我用一个十六进制编辑器打开文件,在偏移72720,第一个字节被重复：
字节0-36：FLV ………….«………. onMetaData
字节72720-72756：FLV ………….«………. onMetaData
它从开始开始下载！
当我通过wget做它正确和Content-Range字段的响应！
wget日志中的“302 FOUND”和“206 Partial Content”的服务器响应.
“302 FOUND”能否引起问题？
 
 
问题是什么 ？
谢谢.

Solution

Try:

connection. setRequestProperty(“Range”,“bytes =”fcheck.length()“ – ”);

Lower case range specifier according to specification In addition, if some of your files are 500 bytes, your byte range is 0-499, and you want 500