Android textview展示富文本内容-编程知识

今天实现的内容，就是上图的效果，通过Span方式展示图片，需要支持文字颜色改变、加粗。支持style=\"color:green; font-weight:bold;\"展示。尤其style标签中的font-size、font-weight是在原生中不被支持的。

所以我们今天需要使用自定义的方式来实现实现。

val result = "<spanExt>攀钢钒钛所属行业为\n" +  
"<spanExt style=\"color:#333333; font-weight:bold; font-size:18px;\">其他采掘</spanExt>；\n" +  
"</spanExt>\n" +  
"<img src=\"https://www.baidu.com/img/PCtm_d9c8750bed0b3c7d089fa7d55720d6cf.png\">" +  
"<br/>\n" +  
"<spanExt>当日攀钢钒钛行情整体表现<spanExt style=\"color:green; font-weight:bold;\">弱于</spanExt>所属行业表现；</spanExt>\n" +  
"<br/>\n" +  
"<img src=\"https://hbimg.huaban.com/4829401262ba0574fe8328b9f7f4b871d53850df7cd4-wVjrLB_fw658\">" +  
"<spanExt>攀钢钒钛所属概念中<spanExt style=\"color:#333333; font-weight:bold; \">有色金属</spanExt>表现相对优异；</spanExt>\n" +  
"<br/>\n" +  
"<img src=\"https://bkimg.cdn.bcebos.com/pic/50da81cb39dbb6fd526675ca147cbc18972bd507999d?x-bce-process=image/watermark,image_d2F0ZXIvYmFpa2U5Mg==,g_7,xp_5,yp_5/format,f_auto\">" +  
"<spanExt>其涨跌幅在有色金属中位列<spanExt style=\"color:#F43737; font-weight:bold; \">81</spanExt>/<spanExt style=\"color:black; font-weight:bold; \">122</spanExt>。</spanExt>"

计划渲染的目标内容，这里的spanExt是由于系统本身是支持span标签，但是对于span标签的支持不够完善，我需要自定义一个新的标签，但是html解析的时候，是识别的标签，所以需要将展示内容的span标签替换为了spanExt。防止被系统的span标签直接解析了。

渲染内容中，主要是需要自定义span标签和图片的展示。接下来就从这两个方面出发说明。

自定义tag优化span标签

package org.fireking.basic.textview.html;import android.content.Context;
import android.content.res.ColorStateList;
import android.content.res.Resources;
import android.graphics.Color;
import android.graphics.Typeface;
import android.text.Editable;
import android.text.Html;
import android.text.Spannable;
import android.text.Spanned;
import android.text.TextUtils;
import android.text.style.AbsoluteSizeSpan;
import android.text.style.ForegroundColorSpan;
import android.text.style.StyleSpan;
import android.text.style.TextAppearanceSpan;
import android.util.Log;import org.xml.sax.XMLReader;import java.lang.reflect.Field;
import java.util.HashMap;
import java.util.Map;public class SpanExtTagHandler implements Html.TagHandler {private final String TAG = "CustomTagHandler";private int startIndex = 0;private int stopIndex = 0;private final ColorStateList mOriginColors;private final Context mContext;public SpanExtTagHandler(Context context, ColorStateList originColors) {mContext = context;mOriginColors = originColors;}@Overridepublic void handleTag(boolean opening, String tag, Editable output,XMLReader xmlReader) {processAttributes(xmlReader);if (tag.equalsIgnoreCase("spanExt")) {if (opening) {startSpan(tag, output, xmlReader);} else {endSpan(tag, output, xmlReader);attributes.clear();}}}public void startSpan(String tag, Editable output, XMLReader xmlReader) {startIndex = output.length();}public void endSpan(String tag, Editable output, XMLReader xmlReader) {stopIndex = output.length();String color = attributes.get("color");String size = attributes.get("size");String style = attributes.get("style");if (!TextUtils.isEmpty(style)) {analysisStyle(startIndex, stopIndex, output, style);}if (!TextUtils.isEmpty(size)) {size = size.split("px")[0];}if (!TextUtils.isEmpty(color)) {if (color.startsWith("@")) {Resources res = Resources.getSystem();String name = color.substring(1);int colorRes = res.getIdentifier(name, "color", "android");if (colorRes != 0) {output.setSpan(new ForegroundColorSpan(colorRes), startIndex, stopIndex, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);}} else {try {output.setSpan(new ForegroundColorSpan(Color.parseColor(color)), startIndex, stopIndex, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);} catch (Exception e) {e.printStackTrace();reductionFontColor(startIndex, stopIndex, output);}}}if (!TextUtils.isEmpty(size)) {int fontSizePx = 16;if (null != mContext) {fontSizePx = DisplayUtil.sp2px(mContext, Integer.parseInt(size));}output.setSpan(new AbsoluteSizeSpan(fontSizePx), startIndex, stopIndex, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);}}final HashMap<String, String> attributes = new HashMap<String, String>();private void processAttributes(final XMLReader xmlReader) {try {Field elementField = xmlReader.getClass().getDeclaredField("theNewElement");elementField.setAccessible(true);Object element = elementField.get(xmlReader);Field attsField = element.getClass().getDeclaredField("theAtts");attsField.setAccessible(true);Object atts = attsField.get(element);Field dataField = atts.getClass().getDeclaredField("data");dataField.setAccessible(true);String[] data = (String[]) dataField.get(atts);Field lengthField = atts.getClass().getDeclaredField("length");lengthField.setAccessible(true);int len = (Integer) lengthField.get(atts);for (int i = 0; i < len; i++)attributes.put(data[i * 5 + 1], data[i * 5 + 4]);} catch (Exception e) {e.printStackTrace();}}/*** 还原为原来的颜色*/private void reductionFontColor(int startIndex, int stopIndex, Editable editable) {if (null != mOriginColors) {editable.setSpan(new TextAppearanceSpan(null, 0, 0, mOriginColors, null),startIndex, stopIndex,Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);} else {editable.setSpan(new ForegroundColorSpan(0xff2b2b2b), startIndex, stopIndex, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);}}/*** 解析style属性*/private void analysisStyle(int startIndex, int stopIndex, Editable editable, String style) {Log.e(TAG, "style：" + style);String[] attrArray = style.split(";");Map<String, String> attrMap = new HashMap<>();if (null != attrArray) {for (String attr : attrArray) {String[] keyValueArray = attr.split(":");if (null != keyValueArray && keyValueArray.length == 2) {// 记住要去除前后空格attrMap.put(keyValueArray[0].trim(), keyValueArray[1].trim());}}}Log.e(TAG, "attrMap：" + attrMap.toString());String color = attrMap.get("color");String fontSize = attrMap.get("font-size");String fontWeight = attrMap.get("font-weight");if (!TextUtils.isEmpty(fontWeight) && "bold".equalsIgnoreCase(fontWeight)) {editable.setSpan(new StyleSpan(Typeface.BOLD), startIndex, stopIndex, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);} else if (!TextUtils.isEmpty(fontWeight) && "italic".equalsIgnoreCase(fontWeight)) {editable.setSpan(new StyleSpan(Typeface.ITALIC), startIndex, stopIndex, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);}if (!TextUtils.isEmpty(fontSize)) {fontSize = fontSize.split("px")[0];}if (!TextUtils.isEmpty(color)) {if (color.startsWith("@")) {Resources res = Resources.getSystem();String name = color.substring(1);int colorRes = res.getIdentifier(name, "color", "android");if (colorRes != 0) {editable.setSpan(new ForegroundColorSpan(colorRes), startIndex, stopIndex, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);}} else {try {editable.setSpan(new ForegroundColorSpan(Color.parseColor(color)), startIndex, stopIndex, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);} catch (Exception e) {e.printStackTrace();reductionFontColor(startIndex, stopIndex, editable);}}}if (!TextUtils.isEmpty(fontSize)) {int fontSizePx = 16;if (null != mContext) {fontSizePx = DisplayUtil.sp2px(mContext, Integer.parseInt(fontSize));}editable.setSpan(new AbsoluteSizeSpan(fontSizePx), startIndex, stopIndex, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);}}
}

代码整体上非常简单，首先判断需要解析的标签。根据#public void handleTag(boolean opening, String tag, Editable output, XMLReader xmlReader)的isOpen判断是开标签还是关标签。

> 开标签<span 
> 关标签</span>

对于开标签，不需要过多关注，只需要知道开始的位置即可。重点关注的还是关标签。

这里需要使用xmlReader解析出来对应的属性和文本内容，然后将内容转换为对应的span设置给Editable output即可。

自定义Html.ImageGetter支持加载网络图片

BitmapTarget.java

BitmapTarget用户装载Glide加载的图片对象

public class BitmapTarget extends SimpleTarget<Bitmap> {  private final DrawableWrapper drawableWrapper;  private Context context;  private TextView textView;  public BitmapTarget(TextView textView, DrawableWrapper drawableWrapper, Context context) {  this.drawableWrapper = drawableWrapper;  this.context = context;  this.textView = textView;  }  @Override  public void onResourceReady(@NonNull Bitmap resource, @Nullable Transition<? super Bitmap> transition) {  Drawable drawable = new BitmapDrawable(context.getResources(), resource);  int width = drawable.getIntrinsicWidth();  int height = drawable.getIntrinsicHeight();  drawable.setBounds(0, 0, width, height);  drawableWrapper.setBounds(0, 0, width, height);  drawableWrapper.setDrawable(drawable);  textView.setText(textView.getText());  textView.invalidate();  }  
}

DrawableWrapper.java

DrawableWrapper用来承接渲染到ImageSpan的drawable

public class DrawableWrapper extends BitmapDrawable {  private Drawable drawable;  DrawableWrapper() {  }  @Override  public void draw(Canvas canvas) {  if (drawable != null){  drawable.draw(canvas);  }  }  public Drawable getDrawable() {  return drawable;  }  public void setDrawable(Drawable drawable) {  this.drawable = drawable;  }  
}

MyImageGetter.java

MyImageGetter 使用Glide进行图片的下载，并且渲染到drawable中，用于ImageSpan展示使用。

public class MyImageGetter implements Html.ImageGetter {  private Context context;  private TextView textView;  public MyImageGetter(Context context, TextView textView) {  this.context = context;  this.textView = textView;  }  @Override  public Drawable getDrawable(String source) {  DrawableWrapper drawableWrapper = new DrawableWrapper();  Drawable drawable = new BitmapDrawable(Bitmap.createBitmap(200, 200, Bitmap.Config.ARGB_8888));  drawable.setBounds(0, 0, drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight());  drawableWrapper.setDrawable(drawable);  Glide.with(context).asBitmap().load(source).into(new BitmapTarget(textView, drawableWrapper, context));  return drawableWrapper;  }  
}