js下载文件并修改文件名

var a = document.createelement("a");
a.href = "http://xxx.com/audiostream/8a9dbae9d0859e48fc1f590fcf6d4ccc.mp3"；
a.download ="test.mp3";
a.click();

public void downfiles(httpservletresponse response,string url,string workinfoid,int type){
    try{
      string prefix = type == 1 ? "wav" : "txt";
      url = type == 1 ? url : (url + "?textinfoid="+workinfoid);
      httpentity entity = request.get(url).
          execute().returnresponse().getentity();
      byte[] bys = entityutils.tobytearray(entity);
      //获取作品名称
      works works = this.worksdao.findbyworkid(workinfoid);
      string name = (works!=null && stringutils.isnotblank(works.getname())) ? works.getname() : long.tostring(new date().gettime());
      response.setheader("content-disposition", "attachment; filename="+ new string(name.getbytes("utf-8"), "iso-8859-1")+"."+prefix);
      outputstream out = response.getoutputstream();
      out.write(bys);
      out.close();
    }catch (exception e){
      e.printstacktrace();
    }

  }