public class MarkdownView extends WebView {private static final String TAG = MarkdownView.class.getSimpleName();// 带有点击的图片 => 为了防止被转换，提前转化为 html// [text ![text](image_url) text](link) => <a href="link" ><img src="data:image_url" /></a>private static final String IMAGE_LINK_PATTERN = "\\[(.*)!\\[(.*)\\]\\((.*)\\)(.*)\\]\\((.*)\\)";private static final String IMAGE_LINK_REPLACE = "<a href=\"$5\" >$1<img src=\"$3\" />$4</a>";// 纯图片 => 添加点击跳转，方便后期拦截// ![text](image_url) => <img class="gcs-img-sign" src="data:image_url" />private static final String IMAGE_PATTERN = "!\\[(.*)\\]\\((.*)\\)";private static final String IMAGE_REPLACE = "<img class=\"gcs-img-sign\" src=\"$2\" />";private String mPreviewText;public MarkdownView(Context context) {this(context, null);}public MarkdownView(Context context, AttributeSet attrs) {this(context, attrs, 0);}@SuppressLint({"AddJavascriptInterface", "SetJavaScriptEnabled"})public MarkdownView(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);if (isInEditMode()) {return;}WebSettings settings = getSettings();settings.setJavaScriptEnabled(true);settings.setDomStorageEnabled(true);settings.setDatabaseEnabled(true);initialize();}private void initialize() {loadUrl("file:///android_asset/html/preview.html");if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {getSettings().setAllowUniversalAccessFromFileURLs(true);}if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {getSettings().setMixedContentMode(WebSettings.MIXED_CONTENT_ALWAYS_ALLOW);}setWebChromeClient(new WebChromeClient() {@SuppressLint("JavascriptInterface")@Overridepublic void onProgressChanged(WebView view, int newProgress) {super.onProgressChanged(view, newProgress);if (newProgress == 100) {if (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) {loadUrl(mPreviewText);} else {evaluateJavascript(mPreviewText, null);}}}});}public void loadMarkdownFromFile(File markdownFile) {String mdText = "";try {FileInputStream fileInputStream = new FileInputStream(markdownFile);InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream);BufferedReader bufferedReader = new BufferedReader(inputStreamReader);String readText;StringBuilder stringBuilder = new StringBuilder();while ((readText = bufferedReader.readLine()) != null) {stringBuilder.append(readText);stringBuilder.append("\n");}fileInputStream.close();mdText = stringBuilder.toString();} catch (FileNotFoundException e) {Log.e(TAG, "FileNotFoundException:" + e);} catch (IOException e) {Log.e(TAG, "IOException:" + e);}setMarkDownText(mdText);}public void loadMarkdownFromAssets(String assetsFilePath) {try {StringBuilder buf = new StringBuilder();InputStream json = getContext().getAssets().open(assetsFilePath);BufferedReader in = new BufferedReader(new InputStreamReader(json, "UTF-8"));String str;while ((str = in.readLine()) != null) {buf.append(str).append("\n");}in.close();setMarkDownText(buf.toString());} catch (IOException e) {e.printStackTrace();}}public void setMarkDownText(String markdownText) {String injectMdText = injectImageLink(markdownText);String escMdText = escapeForText(injectMdText);if (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) {mPreviewText = String.format("javascript:preview('%s')", escMdText);} else {mPreviewText = String.format("preview('%s')", escMdText);}initialize();}/*** 注入图片链接*/private String injectImageLink(String mdText) {// TODO 修复代码区md格式图片被替换问题mdText = mdText.replaceAll(IMAGE_LINK_PATTERN, IMAGE_LINK_REPLACE);mdText = mdText.replaceAll(IMAGE_PATTERN, IMAGE_REPLACE);return mdText;}private String escapeForText(String mdText) {String escText = mdText.replace("\n", "\\\\n");escText = escText.replace("'", "\\\'");escText = escText.replace("\r", "");return escText;}@Overrideprotected void onDraw(Canvas canvas) {super.onDraw(canvas);if (isInEditMode()) {canvas.drawColor(Color.WHITE);canvas.translate(canvas.getWidth() / 2, 30);Paint paint = new Paint();paint.setTextAlign(Paint.Align.CENTER);paint.setTextSize(30);paint.setColor(Color.GRAY);canvas.drawText("MarkdownView", -30, 0, paint);}}
}