AlertDialog(对话框)详解

本节引言:

本节继续给大家带来是显示提示信息的第三个控件AlertDialog(对话框),同时它也是其他 Dialog的的父类!比如ProgressDialog,TimePickerDialog等,而AlertDialog的父类是:Dialog! 另外,不像前面学习的Toast和Notification,AlertDialog并不能直接new出来,如果你打开 AlertDialog的源码,会发现构造方法是protected的,如果我们要创建AlertDialog的话,我们 需要使用到该类中的一个静态内部类:public static class Builder,然后来调用AlertDialog 里的相关方法,来对AlertDialog进行定制,最后调用show()方法来显示我们的AlertDialog对话框! 好的,下面我们就来学习AlertDialog的基本用法,以及定制我们的AlertDialog! 官方文档:AlertDialog


1.基本使用流程

  • Step 1:创建AlertDialog.Builder对象;
  • Step 2:调用setIcon()设置图标,setTitle()setCustomTitle()设置标题;
  • Step 3:设置对话框的内容:setMessage()还有其他方法来指定显示的内容;
  • Step 4:调用setPositive/Negative/NeutralButton()设置:确定,取消,中立按钮;
  • Step 5:调用create()方法创建这个对象,再调用show()方法将对话框显示出来;

2.几种常用的对话框使用示例

运行效果图:

核心代码

MainActivity.java

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private Button btn_dialog_one;
    private Button btn_dialog_two;
    private Button btn_dialog_three;
    private Button btn_dialog_four;

    private Context mContext;
    private boolean[] checkItems;

    private AlertDialog alert = null;
    private AlertDialog.Builder builder = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mContext = MainActivity.this;
        bindView();


    }

    private void bindView() {
        btn_dialog_one = (Button) findViewById(R.id.btn_dialog_one);
        btn_dialog_two = (Button) findViewById(R.id.btn_dialog_two);
        btn_dialog_three = (Button) findViewById(R.id.btn_dialog_three);
        btn_dialog_four = (Button) findViewById(R.id.btn_dialog_four);
        btn_dialog_one.setOnClickListener(this);
        btn_dialog_two.setOnClickListener(this);
        btn_dialog_three.setOnClickListener(this);
        btn_dialog_four.setOnClickListener(this);
    }


    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            //普通对话框
            case R.id.btn_dialog_one:
                alert = null;
                builder = new AlertDialog.Builder(mContext);
                alert = builder.setIcon(R.mipmap.ic_icon_fish)
                        .setTitle("系统提示:")
                        .setMessage("这是一个最普通的AlertDialog,\n带有三个按钮,分别是取消,中立和确定")
                        .setNegativeButton("取消", new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                Toast.makeText(mContext, "你点击了取消按钮~", Toast.LENGTH_SHORT).show();
                            }
                        })
                        .setPositiveButton("确定", new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                Toast.makeText(mContext, "你点击了确定按钮~", Toast.LENGTH_SHORT).show();
                            }
                        })
                        .setNeutralButton("中立", new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                Toast.makeText(mContext, "你点击了中立按钮~", Toast.LENGTH_SHORT).show();
                            }
                        }).create();             //创建AlertDialog对象
                alert.show();                    //显示对话框
                break;
            //普通列表对话框
            case R.id.btn_dialog_two:
                final String[] lesson = new String[]{"语文", "数学", "英语", "化学", "生物", "物理", "体育"};
                alert = null;
                builder = new AlertDialog.Builder(mContext);
                alert = builder.setIcon(R.mipmap.ic_icon_fish)
                        .setTitle("选择你喜欢的课程")
                        .setItems(lesson, new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                Toast.makeText(getApplicationContext(), "你选择了" + lesson[which], Toast.LENGTH_SHORT).show();
                            }
                        }).create();
                alert.show();
                break;
            //单选列表对话框
            case R.id.btn_dialog_three:
                final String[] fruits = new String[]{"苹果", "雪梨", "香蕉", "葡萄", "西瓜"};
                alert = null;
                builder = new AlertDialog.Builder(mContext);
                alert = builder.setIcon(R.mipmap.ic_icon_fish)
                        .setTitle("选择你喜欢的水果,只能选一个哦~")
                        .setSingleChoiceItems(fruits, 0, new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                Toast.makeText(getApplicationContext(), "你选择了" + fruits[which], Toast.LENGTH_SHORT).show();
                            }
                        }).create();
                alert.show();
                break;
            //多选列表对话框
            case R.id.btn_dialog_four:
                final String[] menu = new String[]{"水煮豆腐", "萝卜牛腩", "酱油鸡", "胡椒猪肚鸡"};
                //定义一个用来记录个列表项状态的boolean数组
                checkItems = new boolean[]{false, false, false, false};
                alert = null;
                builder = new AlertDialog.Builder(mContext);
                alert = builder.setIcon(R.mipmap.ic_icon_fish)
                        .setMultiChoiceItems(menu, checkItems, new DialogInterface.OnMultiChoiceClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which, boolean isChecked) {
                                checkItems[which] = isChecked;
                            }
                        })
                        .setPositiveButton("确定", new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                String result = "";
                                for (int i = 0; i < checkItems.length; i++) {
                                    if (checkItems[i])
                                        result += menu[i] + " ";
                                }
                                Toast.makeText(getApplicationContext(), "客官你点了:" + result, Toast.LENGTH_SHORT).show();
                            }
                        })
                        .create();
                alert.show();
                break;
        }
    }
}

布局就是四个简单的按钮,这里就不贴出来了,用法非常简单~无非就是创建一个Builder对象后, 进行相关设置,然后create()生成一个AlertDialog对象,最后调用show()方法将AlertDialog 显示出来而已!另外,细心的你可能发现我们点击对话框的外部区域,对话框就会消失,我们 可以为builder设置setCancelable(false)即可解决这个问题!


3.通过Builder的setView()定制显示的AlertDialog

我们可以自定义一个与系统对话框不同的布局,然后调用setView()将我们的布局加载到 AlertDialog上,上面我们来实现这个效果:

运行效果图

关键代码

首先是两种不同按钮的selctor的drawable文件:

btn_selctor_exit.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true" android:drawable="@mipmap/iv_icon_exit_pressed"/>
    <item android:drawable="@mipmap/iv_icon_exit_normal"/>
</selector>

btn_selctor_choose.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true" android:drawable="@mipmap/bg_btn_pressed"/>
    <item android:drawable="@mipmap/bg_btn_normal"/>
</selector>

接着是自定义的Dialog布局:view_dialog_custom.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/RelativeLayout1"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <RelativeLayout
        android:id="@+id/titlelayout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:background="#53CC66"
        android:padding="5dp">

        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_centerVertical="true"
            android:text="提示信息"
            android:textColor="#ffffff"
            android:textSize="18sp"
            android:textStyle="bold" />

        <Button
            android:id="@+id/btn_cancle"
            android:layout_width="30dp"
            android:layout_height="30dp"
            android:layout_alignParentRight="true"
            android:background="@drawable/btn_selctor_exit" />

    </RelativeLayout>


    <LinearLayout
        android:id="@+id/ly_detail"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_below="@+id/titlelayout"
        android:layout_centerInParent="true"
        android:orientation="vertical">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="10dp"
            android:layout_marginTop="20dp"
            android:text="通过setView()方法定制AlertDialog"
            android:textColor="#04AEDA"
            android:textSize="18sp" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="10dp"
            android:layout_marginTop="10dp"
            android:text="作者:Coder-pig"
            android:textColor="#04AEDA"
            android:textSize="18sp" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/ly_detail"
        android:layout_marginTop="10dp"
        android:orientation="horizontal">

        <Button
            android:id="@+id/btn_blog"
            android:layout_width="match_parent"
            android:layout_height="40dp"
            android:layout_margin="5dp"
            android:layout_weight="1"
            android:background="@drawable/btn_selctor_choose"
            android:text="访问博客"
            android:textColor="#ffffff"
            android:textSize="20sp" />

        <Button
            android:id="@+id/btn_close"
            android:layout_width="match_parent"
            android:layout_height="40dp"
            android:layout_margin="5dp"
            android:layout_weight="1"
            android:background="@drawable/btn_selctor_choose"
            android:text="关闭"
            android:textColor="#ffffff"
            android:textSize="20sp" />

    </LinearLayout>

</RelativeLayout>  

最后是MainActivity.java

public class MainActivity extends AppCompatActivity {

    private Button btn_show;
    private View view_custom;
    private Context mContext;
    private AlertDialog alert = null;
    private AlertDialog.Builder builder = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mContext = MainActivity.this;
        btn_show = (Button) findViewById(R.id.btn_show);

        //初始化Builder
        builder = new AlertDialog.Builder(mContext);

        //加载自定义的那个View,同时设置下
        final LayoutInflater inflater = MainActivity.this.getLayoutInflater();
        view_custom = inflater.inflate(R.layout.view_dialog_custom, null,false);
        builder.setView(view_custom);
        builder.setCancelable(false);
        alert = builder.create();

        view_custom.findViewById(R.id.btn_cancle).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                alert.dismiss();
            }
        });

        view_custom.findViewById(R.id.btn_blog).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(getApplicationContext(), "访问博客", Toast.LENGTH_SHORT).show();
                Uri uri = Uri.parse("http://blog.csdn.net/coder_pig");
                Intent intent = new Intent(Intent.ACTION_VIEW, uri);
                startActivity(intent);
                alert.dismiss();
            }
        });

        view_custom.findViewById(R.id.btn_close).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(getApplicationContext(), "对话框已关闭~", Toast.LENGTH_SHORT).show();
                alert.dismiss();
            }
        });

        btn_show.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                alert.show();
            }
        });
    }
}

4.示例代码下载

AlertDialogDemo.zip

AlertDialogDemo1.zip


本节小结:

好的,本节给大家介绍了一下AlertDialog的基本使用,写了几个调用AlertDialog的例子, 最后还通过setView方法自定义了一下我们的AlertDialog!是不是还意犹未尽呢?但这说不上 真正的自定义控件,我们把自定义控件放到进阶系列,到时后会有个专题来和大家探讨 下自定义控件~敬请期待~就说这么多,谢谢~