“Android Utils“ 实现TextView 区域自定义点击

Posted 2021-06-26 斯音

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需求

项目中常有需求：要求长段文本中实现点击局部文本并执行自定义事件。本文针对类似需求进行简易的分析并编写相关工具类。

分析

首先多TextView实现肯定是不行的：一是代码冗余；二是若可点击文本换行时不好处理。

接着看其效果类似超链接，自然想到使用html.fromHtml，将可点击区域加上a标签。可是点击a标签默认会调用外部浏览器打开指定链接。跟进Html.fromHtml方法可知，其返回的是一个Spanned

public static Spanned fromHtml(String source)

既然是Spanned，那自然是可以自定义的。

思路：给可点击文本加上a标签，获取Html.fromHtml返回的Spanned中的UrlSpan部分，在相同位置添加自定义ClickSpan实现自定义事件，代码如下：

Spanned html = Html.fromHtml(text);
URLSpan[] spans = html.getSpans(0, text.length(), URLSpan.class);
SpannableStringBuilder builder = new SpannableStringBuilder(html);
builder.clearSpans();
for (URLSpan span : spans) {
	  String url = span.getURL();//获取a标签中的url
  	//添加点击事件
}

同时创建一个map，key可以为url，value为相应的点击事件。添加ClickSpan同时可以添加其他样式Span。

完整代码：

public class ClickSpanUtils {
    public static class ClickOption {
        public Runnable runnable;
        public int color;
        public boolean underline;

        public ClickOption(Runnable runnable, int color, boolean underline) {
            this.runnable = runnable;
            this.color = color;
            this.underline = underline;
        }

        public ClickOption(Runnable runnable, int color) {
            this(runnable, color, true);
        }

        public ClickOption(Runnable runnable) {
            this(runnable, 0);
        }
    }

    public static Spanned parse(String text, Map<String, ClickOption> eventMap) {
        Spanned html = Html.fromHtml(text);
        URLSpan[] spans = html.getSpans(0, text.length(), URLSpan.class);
        SpannableStringBuilder builder = new SpannableStringBuilder(html);
        builder.clearSpans();
        for (URLSpan span : spans) {
            String url = span.getURL();
            ClickOption option = eventMap.get(url);
            if (option != null) {
                //点击事件
                builder.setSpan(new ClickSpan(option.runnable, option.underline),
                        html.getSpanStart(span),
                        html.getSpanEnd(span), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
                //颜色
                if (option.color != 0) {
                    builder.setSpan(new ForegroundColorSpan(option.color),
                            html.getSpanStart(span),
                            html.getSpanEnd(span), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
                }
            }
        }
        return builder;
    }

    public static class ClickSpan extends ClickableSpan {
        Runnable mRunnable;
        boolean mUnderline;

        public ClickSpan(Runnable runnable, boolean underline) {
            mRunnable = runnable;
            mUnderline = underline;
        }

        @Override
        public void onClick(View view) {
            mRunnable.run();
        }

        @Override
        public void updateDrawState(@NonNull TextPaint ds) {
            //下划线
            ds.setUnderlineText(mUnderline);
        }
    }
}

使用

Map<String, ClickSpanUtils.ClickOption> events = new HashMap<>();
events.put("event_one",new ClickSpanUtils.ClickOption(
  () -> Toast.makeText(this, "事件1", Toast.LENGTH_SHORT).show(), 0xFF0000));
events.put("event_two",new ClickSpanUtils.ClickOption(
  () -> Toast.makeText(this, "事件2", Toast.LENGTH_SHORT).show(), 0x0000FF, false));

textView.setText(ClickSpanUtils.parse("This is the <a href='event_one'>interface</a> for text that has markup <a href='event_two'>objects</a> attached to ranges of it. ",events));
textView.setMovementMethod(LinkMovementMethod.getInstance());//必须