系出名門Android(2) - 佈局(Layout)和菜單(Menu)

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系出名門Android(2) - 佈局(Layout)和菜單(Menu)

作者：webabcd


介紹
在 Android 中各種佈局的應用，以及菜單效果的實現 

• 各種佈局方式的應用，FrameLayout, LinearLayout, TableLayout, AbsoluteLayout, RelativeLayout  
• 爲指定元素配置上下文菜單，爲應用程序配置選項菜單，以及多級菜單的實現 

1、各種佈局方式的演示
res/layout/main.xml

<?xml version="1.0" encoding="utf-8"?>
<!--    
layout_width - 寬。fill_parent: 寬度跟着父元素走；wrap_content: 寬度跟着本身的內容走；直接指定一個 px 值來設置寬
layout_height - 高。fill_parent: 高度跟着父元素走；wrap_content: 高度跟着本身的內容走；直接指定一個 px 值來設置高
-->

<!--
LinearLayout - 線形佈局。
        orientation - 容器內元素的排列方式。vertical: 子元素們垂直排列；horizontal: 子元素們水平排列
        gravity - 內容的排列形式。常用的有 top, bottom, left, right, center 等，詳見文檔
-->
<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 - 層疊式佈局。以左上角爲起點，將    FrameLayout 內的元素一層覆蓋一層地顯示
        -->
        <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 - 表格式佈局。
                TableRow - 表格內的行，行內每一個元素算作一列
                collapseColumns - 設置 TableLayout 內的 TableRow 中需要隱藏的列的列索引，多個用“,”隔開
                stretchColumns - 設置 TableLayout 內的 TableRow 中需要拉伸（該列會拉伸到所有可用空間）的列的列索引，多個用“,”隔開
                shrinkColumns - 設置 TableLayout 內的 TableRow 中需要收縮（爲了使其他列不會被擠到屏幕外，此列會自動收縮）的列的列索引，多個用“,”隔開
        -->
        <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 - 絕對定位佈局。
                layout_x - x 座標。以左上角爲頂點
                layout_y - y 座標。以左上角爲頂點
        -->
        <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 - 相對定位佈局。
                layout_centerInParent - 將當前元素放置到其容器內的水平方向和垂直方向的中央位置（類似的屬性有 ：layout_centerHorizontal, layout_alignParentLeft 等）
                layout_marginLeft - 設置當前元素相對於其容器的左側邊緣的距離
                layout_below - 放置當前元素到指定的元素的下面
                layout_alignRight - 當前元素與指定的元素右對齊
        -->
        <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、上下文菜單，選項菜單，子菜單
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;

// 演示兩種菜單的實現方式：上下文菜單（通過在某元素上長按，來呼出菜單）和選項菜單（通過按手機上的菜單按鈕，來呼出菜單）
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);

                // 爲 R.id.txt1 註冊一個上下文菜單（在此 TextView 上長按，則會呼出上下文菜單）
                // 具體呼出的菜單內容需要重寫 onCreateContextMenu 來創建
                TextView txt1 = (TextView) this.findViewById(R.id.txt1);
                this.registerForContextMenu(txt1);

                // 爲 R.id.txt2 註冊一個上下文菜單
                TextView txt2 = (TextView) this.findViewById(R.id.txt2);
                this.registerForContextMenu(txt2);
        }

        // 重寫 onCreateContextMenu 用以創建上下文菜單
        // 重寫 onContextItemSelected 用以響應上下文菜單
        @Override
        public void onCreateContextMenu(ContextMenu menu, View v,
                        ContextMenuInfo menuInfo) {
                super.onCreateContextMenu(menu, v, menuInfo);

                // 創建 R.id.txt1 的上下文菜單
                if (v == (TextView) this.findViewById(R.id.txt1)) {
                        
                        // ContextMenu.setIcon() - 設置菜單的圖標
                        // ContextMenu.setHeaderTitle() - 設置菜單的標題
                        menu.setHeaderIcon(R.drawable.icon01);
                        menu.setHeaderTitle("我是菜單");
                        
                        // 用 ContextMenu.add() 來增加菜單項，返回值爲 MenuItem
                        // 第一個參數：組ID
                        // 第二個參數：菜單項ID
                        // 第三個參數：順序號
                        // 第四個參數：菜單項上顯示的內容
                        menu.add(1, 0, 0, "菜單1");
                        
                        // MenuItem - 新增菜單項後的返回類型，針對菜單項的其他設置在此對象上操作    
                        menu.add(1, 1, 1, "菜單2").setCheckable(true);
                        
                }
                // 創建 R.id.txt2 的上下文菜單（多級上下文菜單）
                else if (v == (TextView) this.findViewById(R.id.txt2)) {
                        
                        // ContextMenu.addSubMenu("菜單名稱") - 用來添加子菜單。子菜單其實就是一個特殊的菜單
                        SubMenu sub = menu.addSubMenu("父菜單1");
                        sub.setIcon(R.drawable.icon01);
                        sub.add(0, 0, 0, "菜單1");
                        sub.add(0, 1, 1, "菜單2");
                        sub.setGroupCheckable(1, true, true);

                        SubMenu sub2 = menu.addSubMenu("父菜單2");
                        sub2.setIcon(R.drawable.icon01);
                        sub2.add(1, 0, 0, "菜單3");
                        sub2.add(1, 1, 1, "菜單4");
                        sub2.setGroupCheckable(1, true, false);
                        
                }
        }
        
        
        // 重寫 onCreateOptionsMenu 用以創建選項菜單
        @Override
        public boolean onCreateOptionsMenu(Menu menu) {

                MenuItem menuItem = menu.add(0, 0, 0, "菜單111111111111111111111");
                
                // MenuItem.setIcon() - 設置菜單項的圖標
                // MenuItem.setTitleCondensed() - 菜單的簡標題，如果指定了簡標題的話，菜單項上的標題將會以此簡標題爲準
                // MenuItem.setAlphabeticShortcut() - 設置選中此菜單項的快捷鍵
                // 注：菜單項超過 6 個的話，第 6 個菜單將會變爲    More 菜單，多餘的菜單會在單擊 More 菜單之後顯示出來
                menuItem.setIcon(R.drawable.icon01);
                menuItem.setTitleCondensed("菜單1");
                menuItem.setAlphabeticShortcut('a');

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

                return true;
        }

        // 重寫 onOptionsItemSelected 用以響應選項菜單
        @Override
        public boolean onOptionsItemSelected(MenuItem item) {
                super.onOptionsItemSelected(item);
                
                Toast.makeText(Main.this, "被單擊的菜單項爲：" + String.valueOf(item.getItemId()), Toast.LENGTH_SHORT).show();

                return false;
        }
}

 

 

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