final EditText inputServer = new EditText(this);

       AlertDialog.Builder builder = new AlertDialog.Builder(this);

       builder.setTitle("Server").setIcon(android.R.drawable.ic_dialog_info).setView(inputServer)

               .setNegativeButton("Cancel", null);

       builder.setPositiveButton("Ok", new DialogInterface.OnClickListener() {

           public void onClick(DialogInterface dialog, int which) {

              inputServer.getText().toString()；

            }

       });

       builder.show();

OR

见SDK自带的源代码Api Demos里的：

App -> Dialog -> Text Entry dialog