浅析Android加载字体包及封装的方法

以下是针对“浅析Android加载字体包及封装的方法”的完整攻略：

1. 加载字体包的方式

Android中加载字体包的方式有两种：通过assets文件夹加载字体包和通过网络下载加载字体包。

1.1 通过assets文件夹加载字体包

1. 将字体包放入assets文件夹中。

2. 通过Typeface类的createFromAsset()方法来加载字体包，具体代码可参考下面的示例：

```
// 加载字体文件
Typeface typeface = Typeface.createFromAsset(getAssets(), "fonts/font_name.ttf");

// 设置控件字体
TextView textView = findViewById(R.id.text_view);
textView.setTypeface(typeface);
```

1.2 通过网络下载加载字体包

1. 在AndroidManifest.xml文件中添加以下权限：

<uses-permission android:name="android.permission.INTERNET"/>

1. 异步下载字体包，并通过Typeface类的createFromAsset()方法来加载字体包，具体代码可参考下面的示例：

```
// 下载字体文件
String url = "http://example.com/fonts/font_name.ttf";
DownloadManager.Request request = new DownloadManager.Request(Uri.parse(url));
request.setTitle("Font Download");
request.setDescription("Download in progress");
request.setDestinationInExternalFilesDir(this, Environment.DIRECTORY_DOWNLOADS, "font_name.ttf");
DownloadManager manager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE);
long downloadId = manager.enqueue(request);

DownloadManager.Query query = new DownloadManager.Query();
query.setFilterById(downloadId);
Cursor cursor = manager.query(query);
cursor.moveToFirst();
int columnIndex = cursor.getColumnIndex(DownloadManager.COLUMN_STATUS);
if (DownloadManager.STATUS_SUCCESSFUL == cursor.getInt(columnIndex)) {
// 加载字体文件
String filePath = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).getPath() + "/font_name.ttf";
Typeface typeface = Typeface.createFromFile(filePath);

   // 设置控件字体
   TextView textView = findViewById(R.id.text_view);
   textView.setTypeface(typeface);

}
```

2. 封装加载字体包的方法

针对以上两种加载字体包的方式，可以通过封装方法来实现对字体的统一管理。以下是一个字体加载封装类的示例：

public class FontManager {

    public static final String ASSETS_FONT_PATH = "fonts/";

    public static void loadFont(Context context, String fontName, TextView textView) {
        Typeface typeface = Typeface.createFromAsset(context.getAssets(), ASSETS_FONT_PATH + fontName);
        textView.setTypeface(typeface);
    }

    public static void downloadFont(Context context, String url, final String fontName, final TextView textView) {
        DownloadManager.Request request = new DownloadManager.Request(Uri.parse(url));
        request.setTitle(fontName + " Download");
        request.setDescription(fontName + " download in progress");
        request.setDestinationInExternalFilesDir(context, Environment.DIRECTORY_DOWNLOADS, fontName);
        DownloadManager manager = (DownloadManager) context.getSystemService(Context.DOWNLOAD_SERVICE);
        long downloadId = manager.enqueue(request);

        DownloadManager.Query query = new DownloadManager.Query();
        query.setFilterById(downloadId);
        BroadcastReceiver receiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                DownloadManager manager = (DownloadManager) context.getSystemService(Context.DOWNLOAD_SERVICE);
                DownloadManager.Query query = new DownloadManager.Query();
                query.setFilterById(intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, 0));
                Cursor cursor = manager.query(query);
                cursor.moveToFirst();
                int columnIndex = cursor.getColumnIndex(DownloadManager.COLUMN_STATUS);
                if (DownloadManager.STATUS_SUCCESSFUL == cursor.getInt(columnIndex)) {
                    String filePath = context.getExternalFilesDir(Environment.DIRECTORY_DOWNLOADS).getPath() + "/" + fontName;
                    Typeface typeface = Typeface.createFromFile(filePath);
                    textView.setTypeface(typeface);
                }
                context.unregisterReceiver(this);
            }
        };
        context.registerReceiver(receiver, new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE));
    }
}

可以看到，封装类中包含了两个方法 loadFont() 和 downloadFont()，用于加载本地字体和下载字体后加载。具体使用方式可参考下面的示例：

// 加载本地字体
FontManager.loadFont(this, "font_name.ttf", textView);

// 下载字体并加载
String url = "http://example.com/fonts/font_name.ttf";
FontManager.downloadFont(this, url, "font_name.ttf", textView);