java：从url下载文件消耗大量的内存RAM？为什么？

Question

我使用HttpUrlConnection和inputstream以及bufferedInputStream和outputstream以及BufferedOutputstream从我的wampserver下载文件，并且它正常工作但是当我跟踪任务管理器和性能选项卡时，我看到我的ram从2.02 GB增加到大约3 GB：

这是我的代码：

---

private void downloadFile() {
        try {
            this.response = this.con.getInputStream();
            this.bis = new BufferedInputStream(this.response, 1024 * 1024);
            this.responseContentSize = this.con.getContentLength();

            if (this.responseContentSize == (this.end_range - this.start_range) + 1) {

                byte buffer[] = new byte[MAX_BUFFER_SIZE];
                makeTmpFile();
                out = new FileOutputStream(this.tmpdir + this.tmpFilename);
                bos = new BufferedOutputStream(out, 1024 * 1024);
                while (true) {
                    int read = bis.read(buffer, 0, this.MAX_BUFFER_SIZE);
                    if (read == -1)
                        break;

                    bos.write(buffer, 0, read);
                    downloadedBytes += read;

                }

                if (bos != null)
                    bos.close();
                if (out != null)
                    out.close();
                if (fpointer != null)
                    fpointer.close();
                if (bis != null)
                    bis.close();
                if (response != null)
                    response.close();
                2);//finish
            }
        } catch (IOException e) {
            sharedDownloadStatus.setCell(this.threadIndex, STATUS, 0);//error
            log.setLog("func : downloadFile =>\n couldnt download file\n" + e.getMessage());
        }

}

我在类中创建了这个func，它实现了Runnable以在另一个线程中开始它的任务