系出名门Android(2) - 布局(Layout)和菜单(Menu)

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系出名门Android(2) - 布局(Layout)和菜单(Menu)

作者：webabcd


介绍
在 Android 中各种布局的应用，以及菜单效果的实现 

• 各种布局方式的应用，FrameLayout, LinearLayout, TableLayout, AbsoluteLayout, RelativeLayout  
• 为指定元素配置上下文菜单，为应用程序配置选项菜单，以及多级菜单的实现 

1、各种布局方式的演示
res/layout/main.xml

<? xml version ="1.0" encoding ="utf-8" ?>
<!--     
layout_width - 宽。fill_parent: 宽度跟着父元素走；wrap_content: 宽度跟着本身的内容走；直接指定一个 px 值来设置宽
layout_height - 高。fill_parent: 高度跟着父元素走；wrap_content: 高度跟着本身的内容走；直接指定一个 px 值来设置高
-->

<!--
LinearLayout - 线形布局。
        orientation - 容器内元素的排列方式。vertical: 子元素们垂直排列；horizontal: 子元素们水平排列
        gravity - 内容的排列形式。常用的有 top, bottom, left, right, center 等，详见文档
-->
< LinearLayout xmlns:android ="http://schemas.android.com/apk/res/android"
         android:orientation ="vertical" android:gravity ="right"
         android:layout_width ="fill_parent" android:layout_height ="fill_parent" >

        <!--
        FrameLayout - 层叠式布局。以左上角为起点，将    FrameLayout 内的元素一层覆盖一层地显示
        -->
         < FrameLayout android:layout_height ="wrap_content"
                 android:layout_width ="fill_parent" >
                 < TextView android:layout_width ="wrap_content"
                         android:layout_height ="wrap_content" android:text ="FrameLayout" >
                 </ TextView >
                 < TextView android:layout_width ="wrap_content"
                         android:layout_height ="wrap_content" android:text ="Frame Layout" >
                 </ TextView >
         </ FrameLayout >

         < TextView android:layout_width ="wrap_content"
                 android:layout_height ="wrap_content" android:text ="@string/hello" />

        <!--
        TableLayout - 表格式布局。
                TableRow - 表格内的行，行内每一个元素算作一列
                collapseColumns - 设置 TableLayout 内的 TableRow 中需要隐藏的列的列索引，多个用“,”隔开
                stretchColumns - 设置 TableLayout 内的 TableRow 中需要拉伸（该列会拉伸到所有可用空间）的列的列索引，多个用“,”隔开
                shrinkColumns - 设置 TableLayout 内的 TableRow 中需要收缩（为了使其他列不会被挤到屏幕外，此列会自动收缩）的列的列索引，多个用“,”隔开
        -->
         < TableLayout android:id ="@+id/TableLayout01"
                 android:layout_width ="fill_parent" android:layout_height ="wrap_content"
                 android:collapseColumns ="1" >
                 < TableRow android:id ="@+id/TableRow01" android:layout_width ="fill_parent"
                         android:layout_height ="wrap_content" >
                         < TextView android:layout_width ="wrap_content"
                                 android:layout_weight ="1" android:layout_height ="wrap_content"
                                 android:text ="行1列1" />
                         < TextView android:layout_width ="wrap_content"
                                 android:layout_weight ="1" android:layout_height ="wrap_content"
                                 android:text ="行1列2" />
                         < TextView android:layout_width ="wrap_content"
                                 android:layout_weight ="1" android:layout_height ="wrap_content"
                                 android:text ="行1列3" />
                 </ TableRow >
                 < TableRow android:id ="@+id/TableRow01" android:layout_width ="wrap_content"
                         android:layout_height ="wrap_content" >
                         < TextView android:layout_width ="wrap_content"
                                 android:layout_height ="wrap_content" android:text ="行2列1" />
                 </ TableRow >
         </ TableLayout >

        <!--
        AbsoluteLayout - 绝对定位布局。
                layout_x - x 坐标。以左上角为顶点
                layout_y - y 坐标。以左上角为顶点
        -->
         < AbsoluteLayout android:layout_height ="wrap_content"
                 android:layout_width ="fill_parent" >
                 < TextView android:layout_width ="wrap_content"
                         android:layout_height ="wrap_content" android:text ="AbsoluteLayout"
                         android:layout_x ="100px"    
                         android:layout_y ="100px" />
         </ AbsoluteLayout >

        <!--
        RelativeLayout - 相对定位布局。
                layout_centerInParent - 将当前元素放置到其容器内的水平方向和垂直方向的中央位置（类似的属性有 ：layout_centerHorizontal, layout_alignParentLeft 等）
                layout_marginLeft - 设置当前元素相对于其容器的左侧边缘的距离
                layout_below - 放置当前元素到指定的元素的下面
                layout_alignRight - 当前元素与指定的元素右对齐
        -->
         < RelativeLayout android:id ="@+id/RelativeLayout01"
                 android:layout_width ="fill_parent" android:layout_height ="fill_parent" >
                 < TextView android:layout_width ="wrap_content" android:id ="@+id/abc"
                         android:layout_height ="wrap_content" android:text ="centerInParent=true"
                         android:layout_centerInParent ="true" />
                 < TextView android:layout_width ="wrap_content"
                         android:layout_height ="wrap_content" android:text ="marginLeft=20px"
                         android:layout_marginLeft ="20px" />
                 < TextView android:layout_width ="wrap_content"
                         android:layout_height ="wrap_content" android:text ="xxx"
                         android:layout_below ="@id/abc" android:layout_alignRight ="@id/abc" />
         </ RelativeLayout >

</ LinearLayout >

 

res/values/strings.xml

<? xml version ="1.0" encoding ="utf-8" ?>
< resources >
         < string name ="hello" >Hello Layout </ string >
         < string name ="app_name" >webabcd_layout </ string >
</ resources >

 

Main.java

package com.webabcd.layout;

import android.app.Activity;
import android.os.Bundle;

public class Main extends Activity {
         /** Called when the activity is first created. */
        @Override
         public void onCreate(Bundle savedInstanceState) {
                 super.onCreate(savedInstanceState);
                setContentView(R.layout.main);
        }
}

 

 

2、上下文菜单，选项菜单，子菜单
res/layout/main.xml

<? xml version ="1.0" encoding ="utf-8" ?>
< LinearLayout xmlns:android ="http://schemas.android.com/apk/res/android"
         android:orientation ="vertical" android:layout_width ="fill_parent"
         android:layout_height ="fill_parent" >
        
         < TextView android:id ="@+id/txt1" android:layout_width ="fill_parent"
                 android:layout_height ="wrap_content" android:text ="@string/hello_contextMenu" />
                
         < TextView android:id ="@+id/txt2" android:layout_width ="fill_parent"
                 android:layout_height ="wrap_content" android:text ="@string/hello_subMenu" />
                
</ LinearLayout >

 

res/values/strings.xml

<? xml version ="1.0" encoding ="utf-8" ?>
< resources >
         < string name ="hello_contextMenu" >Hello Context Menu </ string >
         < string name ="hello_subMenu" >Hello Context Sub Menu </ string >
         < string name ="app_name" >webabcd_menu </ string >
</ resources >

 

Main.java

package com.webabcd.menu;

import android.app.Activity;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.Menu;
import android.view.MenuItem;
import android.view.SubMenu;
import android.view.View;
import android.view.ContextMenu.ContextMenuInfo;
import android.widget.TextView;
import android.widget.Toast;

// 演示两种菜单的实现方式：上下文菜单（通过在某元素上长按，来呼出菜单）和选项菜单（通过按手机上的菜单按钮，来呼出菜单）
public class Main extends Activity {
         /** Called when the activity is first created. */
        @Override
         public void onCreate(Bundle savedInstanceState) {
                 super.onCreate(savedInstanceState);
                setContentView(R.layout.main);

                 // 为 R.id.txt1 注册一个上下文菜单（在此 TextView 上长按，则会呼出上下文菜单）
                 // 具体呼出的菜单内容需要重写 onCreateContextMenu 来创建
                TextView txt1 = (TextView) this.findViewById(R.id.txt1);
                 this.registerForContextMenu(txt1);

                 // 为 R.id.txt2 注册一个上下文菜单
                TextView txt2 = (TextView) this.findViewById(R.id.txt2);
                 this.registerForContextMenu(txt2);
        }

         // 重写 onCreateContextMenu 用以创建上下文菜单
         // 重写 onContextItemSelected 用以响应上下文菜单
        @Override
         public void onCreateContextMenu(ContextMenu menu, View v,
                        ContextMenuInfo menuInfo) {
                 super.onCreateContextMenu(menu, v, menuInfo);

                 // 创建 R.id.txt1 的上下文菜单
                 if (v == (TextView) this.findViewById(R.id.txt1)) {
                        
                         // ContextMenu.setIcon() - 设置菜单的图标
                         // ContextMenu.setHeaderTitle() - 设置菜单的标题
                        menu.setHeaderIcon(R.drawable.icon01);
                        menu.setHeaderTitle( "我是菜单");
                        
                         // 用 ContextMenu.add() 来增加菜单项，返回值为 MenuItem
                         // 第一个参数：组ID
                         // 第二个参数：菜单项ID
                         // 第三个参数：顺序号
                         // 第四个参数：菜单项上显示的内容
                        menu.add(1, 0, 0, "菜单1");
                        
                         // MenuItem - 新增菜单项后的返回类型，针对菜单项的其他设置在此对象上操作    
                        menu.add(1, 1, 1, "菜单2").setCheckable( true);
                        
                }
                 // 创建 R.id.txt2 的上下文菜单（多级上下文菜单）
                 else if (v == (TextView) this.findViewById(R.id.txt2)) {
                        
                         // ContextMenu.addSubMenu("菜单名称") - 用来添加子菜单。子菜单其实就是一个特殊的菜单
                        SubMenu sub = menu.addSubMenu( "父菜单1");
                        sub.setIcon(R.drawable.icon01);
                        sub.add(0, 0, 0, "菜单1");
                        sub.add(0, 1, 1, "菜单2");
                        sub.setGroupCheckable(1, true, true);

                        SubMenu sub2 = menu.addSubMenu( "父菜单2");
                        sub2.setIcon(R.drawable.icon01);
                        sub2.add(1, 0, 0, "菜单3");
                        sub2.add(1, 1, 1, "菜单4");
                        sub2.setGroupCheckable(1, true, false);
                        
                }
        }
        
        
         // 重写 onCreateOptionsMenu 用以创建选项菜单
        @Override
         public boolean onCreateOptionsMenu(Menu menu) {

                MenuItem menuItem = menu.add(0, 0, 0, "菜单111111111111111111111");
                
                 // MenuItem.setIcon() - 设置菜单项的图标
                 // MenuItem.setTitleCondensed() - 菜单的简标题，如果指定了简标题的话，菜单项上的标题将会以此简标题为准
                 // MenuItem.setAlphabeticShortcut() - 设置选中此菜单项的快捷键
                 // 注：菜单项超过 6 个的话，第 6 个菜单将会变为    More 菜单，多余的菜单会在单击 More 菜单之后显示出来
                menuItem.setIcon(R.drawable.icon01);
                menuItem.setTitleCondensed( "菜单1");
                menuItem.setAlphabeticShortcut('a');

                menu.add(0, 1, 1, "菜单2").setIcon(R.drawable.icon02);
                menu.add(0, 2, 2, "菜单3").setIcon(R.drawable.icon03);
                menu.add(0, 3, 3, "菜单4");
                menu.add(0, 4, 4, "菜单5");
                menu.add(0, 5, 5, "菜单6");
                menu.add(0, 6, 6, "菜单7").setIcon(R.drawable.icon04);
                menu.add(0, 7, 7, "菜单8").setIcon(R.drawable.icon05);

                 return true;
        }

         // 重写 onOptionsItemSelected 用以响应选项菜单
        @Override
         public boolean onOptionsItemSelected(MenuItem item) {
                 super.onOptionsItemSelected(item);
                
                Toast.makeText(Main. this, "被单击的菜单项为：" + String.valueOf(item.getItemId()), Toast.LENGTH_SHORT).show();

                 return false;
        }
}

 

 

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