当Android开发处理错误信息时，经常会以Dialog的形式显示错误信息，但是每次都new一个Dialog，很麻烦，也增加程序的开销，所以今天就分享一种自定义单例AlertDialog

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public class AlertDialog {
  private static AlertDialog alertDialog = null;
  private Context context;
  private Dialog dialog;
  private LinearLayout lLayout_bg;
  private TextView txt_title;
  private TextView txt_msg;
  private Button btn_neg;
  private Button btn_pos;
  private ImageView img_line;
  private Display display;
  private boolean showTitle = false;
  private boolean showMsg = false;
  private boolean showPosBtn = false;
  private boolean showNegBtn = false;

  public static AlertDialog getInstance(Context context){
    if (alertDialog==null){
      synchronized (AlertDialog.class) {
        if (alertDialog == null) {
          alertDialog = new AlertDialog(context).builder();
        }
      }
    }
    return alertDialog;
  }
  public AlertDialog(Context context) {
    this.context = context;
    WindowManager windowManager = (WindowManager) context
        .getSystemService(Context.WINDOW_SERVICE);
    display = windowManager.getDefaultDisplay();
  }

  public AlertDialog builder() {
    // 获取Dialog布局
    View view = LayoutInflater.from(context).inflate(R.layout.view_alertdialog, null);

    // 获取自定义Dialog布局中的控件
    lLayout_bg = (LinearLayout) view.findViewById(R.id.lLayout_bg);
    txt_title = (TextView) view.findViewById(R.id.txt_title);
    txt_title.setVisibility(View.GONE);
    txt_msg = (TextView) view.findViewById(R.id.txt_msg);
    txt_msg.setVisibility(View.GONE);
    btn_neg = (Button) view.findViewById(R.id.btn_neg);
    btn_neg.setVisibility(View.GONE);
    btn_pos = (Button) view.findViewById(R.id.btn_pos);
    btn_pos.setVisibility(View.GONE);
    img_line = (ImageView) view.findViewById(R.id.img_line);
    img_line.setVisibility(View.GONE);

    // 定义Dialog布局和参数
    dialog = new Dialog(context, R.style.AlertDialogStyle);
    dialog.setContentView(view);

    // 调整dialog背景大小
    lLayout_bg.setLayoutParams(new FrameLayout.LayoutParams((int) (display
        .getWidth() * 0.85), LayoutParams.WRAP_CONTENT));

    return this;
  }

  public AlertDialog setTitle(String title) {
    showTitle = true;
    if ("".equals(title)) {
      txt_title.setText("标题");
    } else {
      txt_title.setText(title);
    }
    return this;
  }

  public AlertDialog setMsg(String msg) {
    showMsg = true;
    if ("".equals(msg)) {
      txt_msg.setText("内容");
    } else {
      txt_msg.setText(msg);
    }
    return this;
  }
  public AlertDialog setMsg(int rId) {
    showMsg = true;
    txt_msg.setText(rId);
    return this;
  }

  public AlertDialog setCancelable(boolean cancel) {
    dialog.setCancelable(cancel);
    return this;
  }

  public AlertDialog setPositiveButton(String text,
      final OnClickListener listener) {
    showPosBtn = true;
    if ("".equals(text)) {
      btn_pos.setText("确定");
    } else {
      btn_pos.setText(text);
    }
    btn_pos.setOnClickListener(new OnClickListener() {
      @Override
      public void onClick(View v) {
        if(listener!=null) {
          listener.onClick(v);
        }
        dialog.dismiss();
      }
    });
    return this;
  }

  public AlertDialog setNegativeButton(String text,
      final OnClickListener listener) {
    showNegBtn = true;
    if ("".equals(text)) {
      btn_neg.setText("取消");
    } else {
      btn_neg.setText(text);
    }
    btn_neg.setOnClickListener(new OnClickListener() {
      @Override
      public void onClick(View v) {
        if(listener!=null) {
          listener.onClick(v);
        }
        dialog.dismiss();
      }
    });
    return this;
  }

  private void setLayout() {
    if (!showTitle && !showMsg) {
      txt_title.setText("");
      txt_title.setVisibility(View.VISIBLE);
    }

    if (showTitle) {
      txt_title.setVisibility(View.VISIBLE);
    }

    if (showMsg) {
      txt_msg.setVisibility(View.VISIBLE);
    }

    if (!showPosBtn && !showNegBtn) {
      btn_pos.setText("确定");
      btn_pos.setVisibility(View.VISIBLE);
      btn_pos.setBackgroundResource(R.drawable.alertdialog_single_selector);
      btn_pos.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
          dialog.dismiss();
        }
      });
    }

    if (showPosBtn && showNegBtn) {
      btn_pos.setVisibility(View.VISIBLE);
      btn_pos.setBackgroundResource(R.drawable.alertdialog_right_selector);
      btn_neg.setVisibility(View.VISIBLE);
      btn_neg.setBackgroundResource(R.drawable.alertdialog_left_selector);
      img_line.setVisibility(View.VISIBLE);
    }

    if (showPosBtn && !showNegBtn) {
      btn_pos.setVisibility(View.VISIBLE);
      btn_pos.setBackgroundResource(R.drawable.alertdialog_single_selector);
    }

    if (!showPosBtn && showNegBtn) {
      btn_neg.setVisibility(View.VISIBLE);
      btn_neg.setBackgroundResource(R.drawable.alertdialog_single_selector);
    }
  }

  public void show() {
    setLayout();
    dialog.show();
  }
}

标题名称：Android自定义单例AlertDialog详解-创新互联
本文来源：http://kswjz.com/article/deggcg.html