设定当前视图中所有控件字体的方法

　　本范例实现的是对界面中所有的控件一次性的设置字体样式。思路是找到父控件，然后遍历子控件。如果子控件是可以修改文字的控件，那么就设置文字。这用到了控件的继承，很多控件都是继承与textview的，所以将控件均转为textview，最后设置字体即可。

布局文件

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="${relativePackage}.${activityClass}" >

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="113dp"
        android:text="Small Text"
        android:textAppearance="?android:attr/textAppearanceSmall" />

    <EditText
        android:id="@+id/editText1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/textView1"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="41dp"
        android:hint="kale"
        android:gravity="center_horizontal"
        android:ems="10" >

        <requestFocus />
    </EditText>

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/textView1"
        android:layout_below="@+id/editText1"
        android:layout_marginTop="50dp"
        android:text="Button" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_alignRight="@+id/textView1"
        android:text="设置文字大小"
        android:textAppearance="?android:attr/textAppearanceSmall" />

    <SeekBar
        android:id="@+id/seekBar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/textView2"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="27dp"
        android:max="40"
        android:progress="16" />

</RelativeLayout>

MainActivity

package com.kale.font;


import android.app.Activity;
import android.graphics.Typeface;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;
import android.widget.TextView;

public class MainActivity extends Activity {

    private static int FLAG = 0;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        // Sets fonts for all
        final Typeface mFont = Typeface.createFromAsset(getAssets(), "Roboto-Thin.ttf");
        final ViewGroup root = (ViewGroup) findViewById(R.id.layout);
        setFont(root, mFont,16);
        FLAG = 1;//初始化完成后标志位为1，滑动滑块只修改字体大小。不重复指定字体了。
        
        ((SeekBar) findViewById(R.id.seekBar)).setOnSeekBarChangeListener(new OnSeekBarChangeListener() {
            
            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {
                
            }
            
            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {
                
            }
            
            @Override
            public void onProgressChanged(SeekBar seekBar, int progress,
                    boolean fromUser) {
                 setFont(root, mFont,progress);
            }
        });
    }
    
    /*
     * Sets the font on all TextViews in the ViewGroup. Searches recursively for
     * all inner ViewGroups as well. Just add a check for any other views you
     * want to set as well (EditText, etc.)
     */
    public void setFont(ViewGroup group, Typeface font ,int textSize) {
        int count = group.getChildCount();
        View v;
        for (int i = 0; i < count; i++) {
            v = group.getChildAt(i);
            if (v instanceof TextView || v instanceof EditText || v instanceof Button) {
                if (FLAG == 0) {
                    ((TextView) v).setTypeface(font);
                }
                ((TextView)v).setTextSize(textSize);
            } else if (v instanceof ViewGroup)
                setFont((ViewGroup) v, font,textSize);
        }
    }
}