public class MainActivity extends AppCompatActivity {
   private TextView textView;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     setContentView(R.layout.activity_main);
     textView= (TextView) findViewById(R.id.text);
     AssetManager assets = getAssets();
     Typeface fromAsset = Typeface.createFromAsset(assets, "fonts/fzlt.ttf");
     textView.setTypeface(fromAsset);
  }
}

public class CustomTextView extends TextView {
 
   public CustomTextView(Context context) {
     super(context);
     // TODO Auto-generated constructor stub
   }
 
   public CustomTextView(Context context, AttributeSet attrs) {
     super(context,attrs);
     // TODO Auto-generated constructor stub
   }
 
   public CustomTextView(Context context, AttributeSet attrs,int defStyle) {
     super(context,attrs,defStyle);
     // TODO Auto-generated constructor stub
   }
 
   public void setTypeface(Typeface tf, int style) {
     super.setTypeface(AppContext.getInstance().getTypeface());
   }
 
}

<style>
@font-face {
   font-family: 'myface';
   src: url('file:///android_asset/fonts/fzlt.ttf');
}
body {
   margin: 0;
   padding: 0;
   font-family:'myface','方正兰亭纤黑简体';
}
.textbar{ box-sizing:border-box; width:100%; padding:5px;}
.textbar p{ font-size:16px; text-align:justify; color:#333;line-height:24px; margin:0 0 0 0;}
.textbar h1{ font-size:18px; margin:10px 0 10px 0;color:#000}
</style>

view.loadUrl("javascript:!function(){" + "s=document.createElement('style');s.innerHTML=" + "\"@font-face{font-family:myhyqh;src:url('**injection**/hyqh.ttf');}*{font-family:myhyqh !important;}\";"
+ "document.getElementsByTagName('head')[0].appendChild(s);" +
"document.getElementsByTagName('body')[0].style.fontFamily = \"myhyqh\";}()");
 
//由于网页上是没有权限访问本地的asset文件夹的，因此我们需要拦截请求来加载本地的文件，我这里替换了`file:
//android_assets/`为 `**injection**/`了，我们还需要重写`shouldInterceptRequest`
//在请求为我们这个字体文件的时候，加载本地文件：
@Override
public WebResourceResponse shouldInterceptRequest (WebView view, String url){
   WebResourceResponse response = super.shouldInterceptRequest(view, url);
   Log.i("load intercept request:" + url);
   if (url != null && url.contains("**injection**/")) {
     //String assertPath = url.replace("**injection**/", "");
     String assertPath = url.substring(url.indexOf("**injection**/") + "**injection**/".length(), url.length());
     try {
        response = new WebResourceResponse("application/x-font-ttf", "UTF8", getAssets().open(assertPath));
     } catch (IOException e) {
        e.printStackTrace();
     }
   }
   return response;
}