int result = 0;
File file = null;
String path = null;
JFileChooser fileChooser = new JFileChooser();
FileSystemView fsv = FileSystemView.getFileSystemView();  //注意了,这里重要的一句
System.out.println(fsv.getHomeDirectory());                //得到桌面路径
fileChooser.setCurrentDirectory(fsv.getHomeDirectory());
fileChooser.setDialogTitle("请选择要上传的文件...");
fileChooser.setApproveButtonText("确定");
fileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
result = fileChooser.showOpenDialog(chatFrame);
if (JFileChooser.APPROVE_OPTION == result) {
           path=fileChooser.getSelectedFile().getPath();
           System.out.println("path: "+path);
   }

这是另外一种方法得到桌面路径:
File desktop = new File(System.getProperty("user.home")+System.getProperty("file.separator")+"XX");

filechooser.setCurrentDirectory(desktop);

我的文档 路径:  fsv.getDefaultDirectory());