純粹是個(gè)人學(xué)習(xí)總結(jié)，如有不對(duì)的地方請(qǐng)吐槽。
//在dialog show方法之前添加如下代碼，表示該dialog是一個(gè)系統(tǒng)的dialog
dialog.getWindow().setType((WindowManager.LayoutParams.TYPE_SYSTEM_ALERT));

測(cè)試代碼：

Builder builder = new AlertDialog.Builder(this);
builder.setTitle("提示");
builder.setMessage("在service中打開的dialog");
builder.setNegativeButton("取消", new OnClickListener() {
    @Override
    public void onClick(DialogInterface dialog, int which) {

    }
});
builder.setPositiveButton("確定", new OnClickListener() {
    @Override
    public void onClick(DialogInterface dialog, int which) {

    }
});
final AlertDialog dialog = builder.create();
//在dialog  show方法之前添加如下代碼，表示該dialog是一個(gè)系統(tǒng)的dialog**
dialog.getWindow().setType((WindowManager.LayoutParams.TYPE_SYSTEM_ALERT));
new Thread(){
    public void run() {
        SystemClock.sleep(4000);
        hanlder.post(new Runnable() {
            @Override
            public void run() {
                dialog.show();
            }
        });
        };
   }.start();
}