Android中為TextView增加自定義的HTML標簽

Android中的TextView，本身就支持部分的Html格式標簽。這其中包括常用的字體大小顏色設置，文本鏈接等。使用起來也比較方便，只需要使用Html類轉換一下即可。比如：

textView.setText(Html.fromHtml(str));

然而，有一種場合，默認支持的標簽可能不夠用。比如，我們需要在textView中點擊某種鏈接，返回到應用中的某個界面，而不僅僅是網絡連接，如何實現？

經過幾個小時對android中的Html類源代碼的研究，找到了解決辦法，並且測試通過。

先看Html類的源代碼中有這樣一段：

1. /** 
2.     * Is notified when HTML tags are encountered that the parser does 
3.     * not know how to interpret. 
4.     */  
5.    public static interface TagHandler {  
6.        /** 
7.         * This method will be called whenn the HTML parser encounters 
8.         * a tag that it does not know how to interpret. 
9.         */  
10.        public void handleTag(boolean opening, String tag,  
11.                                 Editable output, XMLReader xmlReader);  

這裡定義了一個接口，接口用於什麼呢？

再繼續看代碼，看到對Html的tag進行解析部分的代碼：

1. private void handleStartTag(String tag, Attributes attributes) {  
2.         if (tag.equalsIgnoreCase("br")) {  
3.             // We don't need to handle this. TagSoup will ensure that there's a </br> for each <br>   
4.             // so we can safely emite the linebreaks when we handle the close tag.   
5.         } else if (tag.equalsIgnoreCase("p")) {  
6.             handleP(mSpannableStringBuilder);  
7.         } else if (tag.equalsIgnoreCase("div")) {  
8.             handleP(mSpannableStringBuilder);  
9.         } else if (tag.equalsIgnoreCase("em")) {  
10.             start(mSpannableStringBuilder, new Bold());  
11.         } else if (tag.equalsIgnoreCase("b")) {  
12.             start(mSpannableStringBuilder, new Bold());  
13.         } else if (tag.equalsIgnoreCase("strong")) {  
14.             start(mSpannableStringBuilder, new Italic());  
15.         } else if (tag.equalsIgnoreCase("cite")) {  
16.             start(mSpannableStringBuilder, new Italic());  
17.         } else if (tag.equalsIgnoreCase("dfn")) {  
18.             start(mSpannableStringBuilder, new Italic());  
19.         } else if (tag.equalsIgnoreCase("i")) {  
20.             start(mSpannableStringBuilder, new Italic());  
21.         } else if (tag.equalsIgnoreCase("big")) {  
22.             start(mSpannableStringBuilder, new Big());  
23.         } else if (tag.equalsIgnoreCase("small")) {  
24.             start(mSpannableStringBuilder, new Small());  
25.         } else if (tag.equalsIgnoreCase("font")) {  
26.             startFont(mSpannableStringBuilder, attributes);  
27.         } else if (tag.equalsIgnoreCase("blockquote")) {  
28.             handleP(mSpannableStringBuilder);  
29.             start(mSpannableStringBuilder, new Blockquote());  
30.         } else if (tag.equalsIgnoreCase("tt")) {  
31.             start(mSpannableStringBuilder, new Monospace());  
32.         } else if (tag.equalsIgnoreCase("a")) {  
33.             startA(mSpannableStringBuilder, attributes);  
34.         } else if (tag.equalsIgnoreCase("u")) {  
35.             start(mSpannableStringBuilder, new Underline());  
36.         } else if (tag.equalsIgnoreCase("sup")) {  
37.             start(mSpannableStringBuilder, new Super());  
38.         } else if (tag.equalsIgnoreCase("sub")) {  
39.             start(mSpannableStringBuilder, new Sub());  
40.         } else if (tag.length() == 2 &&  
41.                    Character.toLowerCase(tag.charAt(0)) == 'h' &&  
42.                    tag.charAt(1) >= '1' && tag.charAt(1) <= '6') {  
43.             handleP(mSpannableStringBuilder);  
44.             start(mSpannableStringBuilder, new Header(tag.charAt(1) - '1'));  
45.         } else if (tag.equalsIgnoreCase("img")) {  
46.             startImg(mSpannableStringBuilder, attributes, mImageGetter);  
47.         } else if (mTagHandler != null) {  
48.             mTagHandler.handleTag(true, tag, mSpannableStringBuilder, mReader);  
49.         }  
50.     }  
51.   
52.     private void handleEndTag(String tag) {  
53.         if (tag.equalsIgnoreCase("br")) {  
54.             handleBr(mSpannableStringBuilder);  
55.         } else if (tag.equalsIgnoreCase("p")) {  
56.             handleP(mSpannableStringBuilder);  
57.         } else if (tag.equalsIgnoreCase("div")) {  
58.             handleP(mSpannableStringBuilder);  
59.         } else if (tag.equalsIgnoreCase("em")) {  
60.             end(mSpannableStringBuilder, Bold.class, new StyleSpan(Typeface.BOLD));  
61.         } else if (tag.equalsIgnoreCase("b")) {  
62.             end(mSpannableStringBuilder, Bold.class, new StyleSpan(Typeface.BOLD));  
63.         } else if (tag.equalsIgnoreCase("strong")) {  
64.             end(mSpannableStringBuilder, Italic.class, new StyleSpan(Typeface.ITALIC));  
65.         } else if (tag.equalsIgnoreCase("cite")) {  
66.             end(mSpannableStringBuilder, Italic.class, new StyleSpan(Typeface.ITALIC));  
67.         } else if (tag.equalsIgnoreCase("dfn")) {  
68.             end(mSpannableStringBuilder, Italic.class, new StyleSpan(Typeface.ITALIC));  
69.         } else if (tag.equalsIgnoreCase("i")) {  
70.             end(mSpannableStringBuilder, Italic.class, new StyleSpan(Typeface.ITALIC));  
71.         } else if (tag.equalsIgnoreCase("big")) {  
72.             end(mSpannableStringBuilder, Big.class, new RelativeSizeSpan(1.25f));  
73.         } else if (tag.equalsIgnoreCase("small")) {  
74.             end(mSpannableStringBuilder, Small.class, new RelativeSizeSpan(0.8f));  
75.         } else if (tag.equalsIgnoreCase("font")) {  
76.             endFont(mSpannableStringBuilder);  
77.         } else if (tag.equalsIgnoreCase("blockquote")) {  
78.             handleP(mSpannableStringBuilder);  
79.             end(mSpannableStringBuilder, Blockquote.class, new QuoteSpan());  
80.         } else if (tag.equalsIgnoreCase("tt")) {  
81.             end(mSpannableStringBuilder, Monospace.class,  
82.                     new TypefaceSpan("monospace"));  
83.         } else if (tag.equalsIgnoreCase("a")) {  
84.             endA(mSpannableStringBuilder);  
85.         } else if (tag.equalsIgnoreCase("u")) {  
86.             end(mSpannableStringBuilder, Underline.class, new UnderlineSpan());  
87.         } else if (tag.equalsIgnoreCase("sup")) {  
88.             end(mSpannableStringBuilder, Super.class, new SuperscriptSpan());  
89.         } else if (tag.equalsIgnoreCase("sub")) {  
90.             end(mSpannableStringBuilder, Sub.class, new SubscriptSpan());  
91.         } else if (tag.length() == 2 &&  
92.                 Character.toLowerCase(tag.charAt(0)) == 'h' &&  
93.                 tag.charAt(1) >= '1' && tag.charAt(1) <= '6') {  
94.             handleP(mSpannableStringBuilder);  
95.             endHeader(mSpannableStringBuilder);  
96.         } else if (mTagHandler != null) {  
97.             mTagHandler.handleTag(false, tag, mSpannableStringBuilder, mReader);  
98.         }  
99.     }