看效果图：
public void lanyaClick(View v) {//点击确定之后转向登陆框LayoutInflater factory = LayoutInflater.from(Beforestart.this);//得到自定义对话框final View DialogView = factory.inflate(R.layout.item_alert_dialog, null);//创建对话框android.app.AlertDialog dlg = new AlertDialog.Builder(Beforestart.this).setTitle("").setView(DialogView).setPositiveButton("登录", new DialogInterface.OnClickListener() {@Overridepublic void onClick(DialogInterface dialog, int whichButton) {Button Button1 = (Button) findViewById(R.id.blechongdian);//添加按钮点击事件的监听器Button1.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View view) {binder.setData("Loginpassword", //实现界面跳转Intent intent = new Intent();intent.setClass(Beforestart.this, BluetoothCharging.class);startActivity(intent);}});}}).create();dlg.getWindow().setBackgroundDrawableResource(R.drawable.yuanjiao5); //设置对话框的样式dlg.show();Button button = dlg.getButton(AlertDialog.BUTTON_POSITIVE);LinearLayout.LayoutParams cancelBtnPara = (LinearLayout.LayoutParams) button.getLayoutParams();//设置按钮的大小cancelBtnPara.height = LinearLayout.LayoutParams.WRAP_CONTENT;cancelBtnPara.width = LinearLayout.LayoutParams.MATCH_PARENT;//设置文字居中cancelBtnPara.gravity = Gravity.CENTER;//设置按钮左上右下的距离cancelBtnPara.setMargins(100, 50, 100, 30);button.setLayoutParams(cancelBtnPara);button.setBackground(ContextCompat.getDrawable(this, R.drawable.bg_yuanjiao));button.setTextColor(ContextCompat.getColor(this, R.color.white));button.setTextSize(16);}主要的代码是show下面的：
