新手快速入门---Android菜单

菜单与双击退出

普通菜单

在reg文件夹下创建menu文件夹

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <item android:id="@+id/red" android:title="红色" android:icon="@mipmap/ic_launcher" app:showAsAction="ifRoom"></item>
    <item android:id="@+id/blue" android:title="蓝色"></item>
</menu>

加载菜单文件

 @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu, menu);
        return super.onCreateOptionsMenu(menu);
    }
    ```
    ==点击事件==
    ```java
    @Override
    public boolean onOptionsItemSelected(@NonNull MenuItem item) {
        int itemId = item.getItemId();
        switch (itemId) {
            case R.id.red:
                Toast.makeText(this, "红色", Toast.LENGTH_SHORT).show();
                break;
            case R.id.blue:
                Toast.makeText(this, item.getTitle(), Toast.LENGTH_SHORT).show();
                break;
        }
        return super.onOptionsItemSelected(item);
    }

上下文菜单

在reg文件夹下创建menu文件夹

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <item android:id="@+id/red" android:title="红色" android:icon="@mipmap/ic_launcher" app:showAsAction="ifRoom"></item>
    <item android:id="@+id/blue" android:title="蓝色"></item>
</menu>

加载菜单文件

 @Override
    public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
        super.onCreateContextMenu(menu, v, menuInfo);
        getMenuInflater().inflate(R.menu.menu, menu);
    }
    ```
    ==点击事件==
    ```java
    @Override
    public boolean onContextItemSelected(@NonNull MenuItem item) {
        int itemId = item.getItemId();
        switch (itemId) {
            case R.id.red:
                Toast.makeText(this, "红色", Toast.LENGTH_SHORT).show();
                tv.setTextColor(Color.RED);//更换文字颜色
                break;
            case R.id.blue:
                Toast.makeText(this, item.getTitle(), Toast.LENGTH_SHORT).show();
                tv.setTextColor(Color.BLUE);
                break;
        }
        return super.onContextItemSelected(item);
    }

弹出窗口

public void bnt(View view) {
        //弹出窗口
        final PopupWindow popupWindow = new PopupWindow(this);
        //布局
        View inflate = LayoutInflater.from(this).inflate(R.layout.pop_layout, null);
        //点击外部可取消
        popupWindow.setOutsideTouchable(true);
        //点击事件
        final TextView textView1 = inflate.findViewById(R.id.pop_tv);
        final TextView textView2 = inflate.findViewById(R.id.pop_tv2);
        textView1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(MainActivity.this, textView1.getText(), Toast.LENGTH_SHORT).show();
                popupWindow.dismiss();
            }
        });
        //点击事件

        textView2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(MainActivity.this, textView2.getText(), Toast.LENGTH_SHORT).show();
                popupWindow.dismiss();
            }
        });
        //弹出窗口聚焦显示  改变外部透明度
        WindowManager.LayoutParams attributes = getWindow().getAttributes();
        attributes.alpha=0.5f;
        getWindow().setAttributes(attributes);
        //消失监听器
        popupWindow.setOnDismissListener(new PopupWindow.OnDismissListener() {
            @Override
            public void onDismiss() {
                WindowManager.LayoutParams attributes = getWindow().getAttributes();
                attributes.alpha=1f;
                getWindow().setAttributes(attributes);
            }
        });
        popupWindow.setAnimationStyle(R.style.pop);

        popupWindow.setContentView(inflate);
        //宽
        popupWindow.setWidth(400);
        //高
        popupWindow.setHeight(300);
        //显示在哪里
        //popupWindow.showAsDropDown(tv,10,10);
        //居中显示  还有BUTTOM和TOP属性
        View inflate2 = LayoutInflater.from(this).inflate(R.layout.activity_main, null);
        popupWindow.showAtLocation(inflate2, Gravity.CENTER,0,0);
    }

xml布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:orientation="horizontal"
    android:gravity="center"
    android:layout_height="match_parent">
    <TextView
        android:layout_gravity="center"
        android:layout_width="wrap_content"
        android:layout_weight="1"
        android:layout_height="wrap_content"
        android:text="确定"
        android:id="@+id/pop_tv"/>
    <TextView
        android:layout_gravity="center"
        android:layout_width="wrap_content"
        android:layout_weight="1"
        android:layout_height="wrap_content"
        android:text="取消"
        android:id="@+id/pop_tv2"/>
</LinearLayout>

在onCreate方法中绑定控件

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
        registerForContextMenu(tv);//与控件绑定
        tv2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //创建一个PopupMenu对象
                PopupMenu popupMenu = new PopupMenu(MainActivity.this, tv);
                //加载布局
                popupMenu.inflate(R.menu.menu);
                //点击事件
                popupMenu.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
                    @Override
                    public boolean onMenuItemClick(MenuItem item) {
                        int itemId = item.getItemId();
                        switch (itemId) {
                            case R.id.red:
                                tv.setTextColor(Color.RED);//更换文字颜色
                                break;
                            case R.id.blue:
                                tv.setTextColor(Color.BLUE);
                                break;
                        }
                        return false;
                    }
                });
                popupMenu.show();
            }
        });
    }

双击推出

@Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        //如果按得是回退键就提示用户
        if (keyCode==KeyEvent.KEYCODE_BACK){
            //再次按下在两秒之内
            if (System.currentTimeMillis()- time>2000){
                Toast.makeText(this, "再按退出", Toast.LENGTH_SHORT).show();
                time=System.currentTimeMillis();
                return true;
            }else {
                finish();
            }
        }
        return super.onKeyDown(keyCode, event);
    }