AlertDialog弹出框android

一，概念与作用

AlertDialog是用来创建对话框，可以在当前活动界面弹出一个对话框，弹出一个选项框，弹出一个提示框，用于提示一些重要信息或是警告内容或者可输入内容。

二，实现原理

1，首先创建 AlertDialog.Builder 对象用来 new一个点creare();

2，绑定自定义布局绑定UI

3，重要的方法，setView() setCanceledOnTouchOutside(); show();

代码如下

AlertDialog mDialog = new AlertDialog.Builder(mContext, R.style.MyDialog).create();

 View layoutId = LinearLayout.inflate(mContext, R.layout.type_dialog_layout, null);

 mDialog.setView(layoutId, 0, 0, 0, 0);
 mDialog.setCanceledOnTouchOutside(true);
 mDialog.show();

1,2,3这三步是非常重要的，接下来，看源码

create()方法创建，然后直接返回 AlertDialog对象

 public AlertDialog create() {
            // We can't use Dialog's 3-arg constructor with the createThemeContextWrapper param,
            // so we always have to re-set the theme
            final AlertDialog dialog = new AlertDialog(P.mContext, mTheme);
            P.apply(dialog.mAlert);
            dialog.setCancelable(P.mCancelable);
            if (P.mCancelable) {
                dialog.setCanceledOnTouchOutside(true);
            }
            dialog.setOnCancelListener(P.mOnCancelListener);
            dialog.setOnDismissListener(P.mOnDismissListener);
            if (P.mOnKeyListener != null) {
                dialog.setOnKeyListener(P.mOnKeyListener);
            }
            return dialog;
        }

setView() 这个方法是设置显示的位置

 /**
     * Set the view to display in the dialog, specifying the spacing to appear around that
     * view.  This method has no effect if called after {@link #show()}.
     *
     * @param view              The view to show in the content area of the dialog
     * @param viewSpacingLeft   Extra space to appear to the left of {@code view}
     * @param viewSpacingTop    Extra space to appear above {@code view}
     * @param viewSpacingRight  Extra space to appear to the right of {@code view}
     * @param viewSpacingBottom Extra space to appear below {@code view}
     */
    public void setView(View view, int viewSpacingLeft, int viewSpacingTop, int viewSpacingRight,
            int viewSpacingBottom) {
        mAlert.setView(view, viewSpacingLeft, viewSpacingTop, viewSpacingRight, viewSpacingBottom);
    }

那么 setCanceledOnTouchOutside（）是设置触摸窗口外，也可以收回弹出框

  /**
     * Sets whether this dialog is canceled when touched outside the window's
     * bounds. If setting to true, the dialog is set to be cancelable if not
     * already set.
     * 
     * @param cancel Whether the dialog should be canceled when touched outside
     *            the window.
     */
    public void setCanceledOnTouchOutside(boolean cancel) {
        if (cancel && !mCancelable) {
            mCancelable = true;
        }
        
        mWindow.setCloseOnTouchOutside(cancel);
    }

三，效果

四，gif图走起

五，贴上代码

import android.app.Activity;
import android.os.Bundle;
import android.support.v7.app.AlertDialog;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.LinearLayout;
import android.widget.TextView;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button b = (Button) findViewById(R.id.ok_send);
        b.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                showCoin();
            }
        });
    }

    //弹出提示
    public void showCoin() {
        final AlertDialog mDialog = new AlertDialog.Builder(this, R.style.MyDialog).create();
        View layoutId = LinearLayout.inflate(this, R.layout.coin_type_dialog_layout, null);
    
        mDialog.setView(layoutId, 0, 0, 0, 0);
        mDialog.setCanceledOnTouchOutside(true);
        mDialog.show();
        // 得到当前显示设备的宽度
        int mWidth = getWindowManager().getDefaultDisplay().getWidth();
        // 得到此AlertDialog界面的参数对象
        WindowManager.LayoutParams params = mDialog.getWindow().getAttributes();
        // 设置AlertDialog的界面宽度
        params.width = mWidth - (mWidth / 6);
        // 设置AlertDialog高度为包裹内容
        params.height = ViewGroup.LayoutParams.WRAP_CONTENT;
        // 设置AlertDialog的重心
        params.gravity = Gravity.CENTER;
        // 设置AlertDialog的大小, 不能设置重心参数, 推荐用Attributes设置
        mDialog.getWindow().setLayout(mWidth - (mWidth / 3), ViewGroup.LayoutParams.WRAP_CONTENT);
        mDialog.getWindow().setAttributes(params);
    }
}

六，简介

android开发，少不了弹出框。自定义弹出，以一变通百。学好一个demo后面就好办了。

看了效果图，感觉很吸引人嘛，弹出框里，还能弹出框，看代码，

代码下载链接： AlertDialog弹出框