初学Android,使用菜单资源(十九)

Android里面也可用XML定义菜单资源，菜单分两种，一种是OptionMenu(点系统"Menu"键出来)，一种是ContextMenu

下面定义两种菜单XML到res\menu文件夹下

my_menu为OptionMenu

<?xml version="1.0" encoding="utf-8"?><menu xmlns:android="http://schemas.android.com/apk/res/android" >  <item android:title="@string/font_size"    android:icon="@drawable/font">    <menu>      <!-- 定义一组单选菜单项 -->      <group android:checkableBehavior="single">        <!-- 定义多个菜单项 -->        <item android:id="@+id/font_10"           android:title="@string/font_10"/>        <item android:id="@+id/font_12"           android:title="@string/font_12"/>        <item android:id="@+id/font_14"           android:title="@string/font_14"/>        <item android:id="@+id/font_16"           android:title="@string/font_16"/>        <item android:id="@+id/font_18"           android:title="@string/font_18"/>      </group>    </menu>  </item>  <item>  </item>  <!-- 定义一个普通菜单项 -->  <item android:id="@+id/plain_item"     android:title="@string/plain_item">  </item>  <item android:id="@string/font_color"     android:title="@drawable/color">    <menu>      <!-- 定义一组普通的菜单项 -->      <group>        <!-- 定义3个菜单项 -->        <item android:id="@+id/red_font"          android:title="@string/red_title"/>        <item android:id="@+id/green_font"          android:title="@string/green_title"/>        <item android:id="@+id/blue_font"          android:title="@string/blue_title"/>      </group>    </menu>  </item></menu>

context.xml为ContextMenu

<?xml version="1.0" encoding="utf-8"?><menu xmlns:android="http://schemas.android.com/apk/res/android" >    <!-- 定义一组单选菜单项目 -->    <group android:checkableBehavior="single">        <!-- 定义三个菜单项 -->        <item android:id="@+id/red"            android:title="@string/red_title"            android:alphabeticShortcut="r"></item>        <item android:id="@+id/green"            android:title="@string/green_title"            android:alphabeticShortcut="g"></item>        <item android:id="@+id/blue"            android:title="@string/blue_title"            android:alphabeticShortcut="b"></item>    </group></menu>

定义两个res\value下的xml，用来指定颜色，字体

colors.xml

<?xml version="1.0" encoding="UTF-8"?><resources><color name="red">#ff0000</color><color name="green">#00ff00</color><color name="blue">#0000ff</color></resources>

strings.xml

<?xml version="1.0" encoding="utf-8"?><resources><string name="hello">Hello World, ContextMenuTest!</string><string name="app_name">上下文菜单</string><string name="red_title">红色</string><string name="blue_title">蓝色</string><string name="green_title">绿色</string><string name="font_size">字体大小</string><string name="font_color">字体颜色</string><string name="plain_item">普通菜单项</string><string name="font_10">10号字体</string><string name="font_12">12号字体</string><string name="font_14">14号字体</string><string name="font_16">16号字体</string><string name="font_18">18号字体</string></resources>

下面代码将实现两种菜单

package WangLi.Resource.MenuResTest;import android.app.Activity;import android.graphics.Color;import android.os.Bundle;import android.view.ContextMenu;import android.view.Menu;import android.view.MenuInflater;import android.view.MenuItem;import android.view.View;import android.widget.TextView;import android.widget.Toast;public class MenuResTest extends Activity {    /** Called when the activity is first created. */private TextView txt;    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        txt = (TextView)findViewById(R.id.txt);        //为文本框注册上下文菜单        registerForContextMenu(txt);    }    public boolean onCreateOptionsMenu(Menu menu)    {    MenuInflater inflator = new MenuInflater(this);    //装填R.menu.my_menu对应的菜单,并添加到menu中    inflator.inflate(R.menu.my_menu, menu);    return super.onCreateOptionsMenu(menu);    }        //每次创建上下文菜单时都会触发该方法    public void onCreateContextMenu(ContextMenu menu,View source,    ContextMenu.ContextMenuInfo menuInfo)    {    MenuInflater inflator = new MenuInflater(this);    //装填R.menu.context对应的菜单,并添加到menu中    inflator.inflate(R.menu.context, menu);    menu.setHeaderIcon(R.drawable.tools);    menu.setHeaderTitle("请选择背景色");    }        //上下文菜单中菜单项被单击时触发该方法    public boolean onContextItemSelected(MenuItem mi)    {    switch(mi.getItemId())    {        case R.id.red:        mi.setChecked(true);        txt.setBackgroundColor(Color.RED);        break;        case R.id.green:        mi.setChecked(true);        txt.setBackgroundColor(Color.GREEN);        break;        case R.id.blue:        mi.setChecked(true);        txt.setBackgroundColor(Color.BLUE);        break;    }    return true;    }        //菜单项被单击后的回调方法    public boolean onOptionsItemSelected(MenuItem mi)    {    //判断单击的是哪个菜单项,并针对性地做出响应    switch(mi.getItemId())    {        case R.id.font_10:        txt.setTextSize(10*2);        break;        case R.id.font_12:        txt.setTextSize(12*2);        break;        case R.id.font_14:        txt.setTextSize(14*2);        break;        case R.id.font_16:        txt.setTextSize(16*2);        break;        case R.id.font_18:        txt.setTextSize(18*2);        break;        case R.id.red_font:        txt.setTextColor(Color.RED);        mi.setChecked(true);        break;        case R.id.green_font:        txt.setTextColor(Color.GREEN);        mi.setChecked(true);        break;        case R.id.blue_font:        txt.setTextColor(Color.BLUE);        mi.setChecked(true);        break;        case R.id.plain_item:        Toast toast = Toast.makeText(MenuResTest.this, "您单击了普通项菜单", Toast.LENGTH_SHORT);        toast.show();        break;    }    return true;    }}

下面是程序运行效果图，刚启动时是一个TextView

点击后，在手机屏幕下方出现OptionMenu

点击字体大小或普通菜单项，出现子菜单

选择就可改变TextView的字体

如下点击"普通菜单项",会出现一个Toast提示,过几秒就会消失

那么怎么弹出ContextMenu呢，就是对着TextView长按就可以了

选择后，背景色就改变了

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