Android修改字体样式的示例代码

在Android实际开发中根据UI的设计图，经常要去改变系统默认的字体样式

这样做会使apk变大很多啊

而且为什么android要使用ios的字体-_-#

单独设置字体样式

（1）Android系统提供了几种字体样式可供选择

通过设置typeface属性或者fontFamily属性设置

typeface属性：

1. normal
2. serif
3. sans
4. monospace

fontFamily属性：

1. casual
2. cursive
3. serif
4. monospace
5. sans-serif
6. sans-serif-condensed
7. serif-monospace
8. sans-serif-smallcaps

※typeface和fontFamily区别

android:typeface属性是增加API1

android:fontFamily在API16（4.1）中添加了属性

※当同时设置typeface和fontFamily时，只有fontFamily生效

查看一波TextView的源码

  private void setTypefaceFromAttrs(String familyName, int typefaceIndex, int styleIndex) {
    Typeface tf = null;
    if (familyName != null) {
      tf = Typeface.create(familyName, styleIndex);
      if (tf != null) {
        setTypeface(tf);
        return;
      }
    }
    switch (typefaceIndex) {
      case SANS:
        tf = Typeface.SANS_SERIF;
        break;

      case SERIF:
        tf = Typeface.SERIF;
        break;

      case MONOSPACE:
        tf = Typeface.MONOSPACE;
        break;
    }

    setTypeface(tf, styleIndex);
  }

从方法setTypefaceFromAttrs()看，如果你有set fontFamily属性，那么typefaceattribute将被忽略。

这边会发现这样设置typeface和fontFamily属性对中文不生效，这时候就需要引用外部的字体样式（这里谷歌设计规范推荐使用NOTO字体https://www.google.com/get/noto/）

（2）使用字体样式文件设置(otf，ttf文件都可以)

在assets下新建一个fonts文件，把字体样式文件放进去

在代码中设置

AssetManager mgr = getAssets();
Typeface tf = Typeface.createFromAsset(mgr, "fonts/NotoSansCJKsc-Black.otf");
tv_1.setTypeface(tf);

批量设置字体样式

（1）自定义TextView

public class CustomTextView extends TextView
{

  public CustomTextView(Context context, AttributeSet attrs)
  {
    super(context, attrs);
  }

  //重写设置字体方法
  @Override
  public void setTypeface(Typeface tf)
  {
    tf = Typeface.createFromAsset(getContext().getAssets(), "fonts/NotoSansCJKsc-Light.otf");
    super.setTypeface(tf);
  }
}

之后在XML布局文件中使用CustomTextView代替TextView

  <com.test.fontfamily.CustomTextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:padding="6dp"
    android:text="自定义字体"
    android:textSize="24dp"
    />

（2）更换整个App的字体

思路：遍历找到所有的TextView然后替换字体

百度了一下找到下面工具类

package com.test.fontfamily;

import android.app.Application;
import android.content.Context;
import android.graphics.Typeface;
import android.support.annotation.NonNull;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import java.lang.ref.SoftReference;
import java.lang.reflect.Field;
import java.util.HashMap;
import java.util.Map;

/**
 * Created by Administrator on 2017/10/24.
 */

public class FontUtils
{

  private static final String TAG = FontUtils.class.getSimpleName();
  private Map<String, SoftReference<Typeface>> mCache = new HashMap<>();
  private static FontUtils sSingleton = null;

  public static Typeface DEFAULT = Typeface.DEFAULT;

  // disable instantiate
  private FontUtils()
  {
  }

  public static FontUtils getInstance()
  {
    // double check
    if (sSingleton == null)
    {
      synchronized (FontUtils.class)
      {
        if (sSingleton == null)
        {
          sSingleton = new FontUtils();
        }
      }
    }
    return sSingleton;
  }

  /**
   * <p>Replace the font of specified view and it's children</p>
   *
   * @param root   The root view.
   * @param fontPath font file path relative to 'assets' directory.
   */
  public void replaceFontFromAsset(@NonNull View root, @NonNull String fontPath)
  {
    replaceFont(root, createTypefaceFromAsset(root.getContext(), fontPath));
  }

  /**
   * <p>Replace the font of specified view and it's children</p>
   *
   * @param root   The root view.
   * @param fontPath font file path relative to 'assets' directory.
   * @param style  One of {@link Typeface#NORMAL}, {@link Typeface#BOLD}, {@link Typeface#ITALIC}, {@link Typeface#BOLD_ITALIC}
   */
  public void replaceFontFromAsset(@NonNull View root, @NonNull String fontPath, int style)
  {
    replaceFont(root, createTypefaceFromAsset(root.getContext(), fontPath), style);
  }

  /**
   * <p>Replace the font of specified view and it's children</p>
   *
   * @param root   The root view.
   * @param fontPath The full path to the font data.
   */
  public void replaceFontFromFile(@NonNull View root, @NonNull String fontPath)
  {
    replaceFont(root, createTypefaceFromFile(fontPath));
  }

  /**
   * <p>Replace the font of specified view and it's children</p>
   *
   * @param root   The root view.
   * @param fontPath The full path to the font data.
   * @param style  One of {@link Typeface#NORMAL}, {@link Typeface#BOLD}, {@link Typeface#ITALIC}, {@link Typeface#BOLD_ITALIC}
   */
  public void replaceFontFromFile(@NonNull View root, @NonNull String fontPath, int style)
  {
    replaceFont(root, createTypefaceFromFile(fontPath), style);
  }

  /**
   * <p>Replace the font of specified view and it's children with specified typeface</p>
   */
  private void replaceFont(@NonNull View root, @NonNull Typeface typeface)
  {
    if (root == null || typeface == null)
    {
      return;
    }

    if (root instanceof TextView)
    { // If view is TextView or it's subclass, replace it's font
      TextView textView = (TextView) root;
      // Extract previous style of TextView
      int style = Typeface.NORMAL;
      if (textView.getTypeface() != null)
      {
        style = textView.getTypeface().getStyle();
      }
      textView.setTypeface(typeface, style);
    } else if (root instanceof ViewGroup)
    { // If view is ViewGroup, apply this method on it's child views
      ViewGroup viewGroup = (ViewGroup) root;
      for (int i = 0; i < viewGroup.getChildCount(); ++i)
      {
        replaceFont(viewGroup.getChildAt(i), typeface);
      }
    } // else return
  }

  /**
   * <p>Replace the font of specified view and it's children with specified typeface and text style</p>
   *
   * @param style One of {@link Typeface#NORMAL}, {@link Typeface#BOLD}, {@link Typeface#ITALIC}, {@link Typeface#BOLD_ITALIC}
   */
  private void replaceFont(@NonNull View root, @NonNull Typeface typeface, int style)
  {
    if (root == null || typeface == null)
    {
      return;
    }
    if (style < 0 || style > 3)
    {
      style = Typeface.NORMAL;
    }

    if (root instanceof TextView)
    { // If view is TextView or it's subclass, replace it's font
      TextView textView = (TextView) root;
      textView.setTypeface(typeface, style);
    } else if (root instanceof ViewGroup)
    { // If view is ViewGroup, apply this method on it's child views
      ViewGroup viewGroup = (ViewGroup) root;
      for (int i = 0; i < viewGroup.getChildCount(); ++i)
      {
        replaceFont(viewGroup.getChildAt(i), typeface, style);
      }
    } // else return
  }

  /**
   * <p>Create a Typeface instance with specified font file</p>
   *
   * @param fontPath font file path relative to 'assets' directory.
   * @return Return created typeface instance.
   */
  private Typeface createTypefaceFromAsset(Context context, String fontPath)
  {
    SoftReference<Typeface> typefaceRef = mCache.get(fontPath);
    Typeface typeface = null;
    if (typefaceRef == null || (typeface = typefaceRef.get()) == null)
    {
      typeface = Typeface.createFromAsset(context.getAssets(), fontPath);
      typefaceRef = new SoftReference<>(typeface);
      mCache.put(fontPath, typefaceRef);
    }
    return typeface;
  }

  private Typeface createTypefaceFromFile(String fontPath)
  {
    SoftReference<Typeface> typefaceRef = mCache.get(fontPath);
    Typeface typeface = null;
    if (typefaceRef == null || (typeface = typefaceRef.get()) == null)
    {
      typeface = Typeface.createFromFile(fontPath);
      typefaceRef = new SoftReference<>(typeface);
      mCache.put(fontPath, typefaceRef);
    }
    return typeface;
  }

  /**
   * <p>Replace system default font. <b>Note:</b>you should also add code below to your app theme in styles.xml. </p>
   * {@code <item name="android:typeface">monospace</item>}
   * <p>The best place to call this method is {@link Application#onCreate()}, it will affect
   * whole app font.If you call this method after view is visible, you need to invalid the view to make it effective.</p>
   *
   * @param context {@link Context Context}
   * @param fontPath font file path relative to 'assets' directory.
   */
  public void replaceSystemDefaultFontFromAsset(@NonNull Context context, @NonNull String fontPath)
  {
    replaceSystemDefaultFont(createTypefaceFromAsset(context, fontPath));
  }

  /**
   * <p>Replace system default font. <b>Note:</b>you should also add code below to your app theme in styles.xml. </p>
   * {@code <item name="android:typeface">monospace</item>}
   * <p>The best place to call this method is {@link Application#onCreate()}, it will affect
   * whole app font.If you call this method after view is visible, you need to invalid the view to make it effective.</p>
   *
   * @param context {@link Context Context}
   * @param fontPath The full path to the font data.
   */
  public void replaceSystemDefaultFontFromFile(@NonNull Context context, @NonNull String fontPath)
  {
    replaceSystemDefaultFont(createTypefaceFromFile(fontPath));
  }

  /**
   * <p>Replace system default font. <b>Note:</b>you should also add code below to your app theme in styles.xml. </p>
   * {@code <item name="android:typeface">monospace</item>}
   * <p>The best place to call this method is {@link Application#onCreate()}, it will affect
   * whole app font.If you call this method after view is visible, you need to invalid the view to make it effective.</p>
   */
  private void replaceSystemDefaultFont(@NonNull Typeface typeface)
  {
    modifyObjectField(null, "MONOSPACE", typeface);
  }

  private void modifyObjectField(Object obj, String fieldName, Object value)
  {
    try
    {
      Field defaultField = Typeface.class.getDeclaredField(fieldName);
      defaultField.setAccessible(true);
      defaultField.set(obj, value);

    } catch (NoSuchFieldException e)
    {
      e.printStackTrace();
    } catch (IllegalAccessException e)
    {
      e.printStackTrace();
    }
  }
}

阅读源码发现这里面主要方法有

replaceFont()

替换一个页面中的所有字体。用递归的方式去查找view是否是TextView或者TextView的子类，然后进行替换。不过这种方法效率不高

用法：在页面中

FontUtils.getInstance().replaceFontFromAsset(View root, String fontPath)

modifyObjectField()

替换App所有字体。利用反射替换系统默认字体

用法：

a.新建一个BaseApplication继承Application在onCreate方法中

FontUtils.getInstance().replaceSystemDefaultFontFromAsset(this,"fonts/NotoSansCJKsc-Thin.otf");

b.在AppTheme中添加

<item name="android:typeface">monospace</item>

c.清单文件中使用BaseApplication

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