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相信大家都有过需求需要加载从后台返回的部分HTML代码到我们的Android手机上需求，现有的android 原生控件有WebView 和 TextView 可以去加载HTML，由于现在的需求我们需要记载一段HTML代码在RecyclerView中显示去报，一开始我的思路直接就是直接在Item中镶嵌WebView，这个办法简单粗暴，我试了一下，结果发现不可以因为由于现在RecyclerView在滚动的时候不断地去刷新View ，导致如果在HTML有图片的话，也会不停的加载，这样是不行的，后来就转战TextView了 ，下面我们分析一下TextView。
首先我们要了解TextView加载HTML基本的方法
mTextView.setMovementMethod(ScrollingMovementMethod.getInstance());// 滚动
mTextView.setMovementMethod(LinkMovementMethod.getInstance());//设置超链接可以打开网页
Html.ImageGetter imageGetter = new Html.ImageGetter() {
public Drawable getDrawable(String source) {
Drawable drawable = null;
URL url;
try {
url = new URL(source);
//Android 4.4 以后这步需要放在子线程中去操作
drawable = Drawable.createFromStream(url.openStream(), ""); // 获取网路图片
} catch (Exception e) {
e.printStackTrace();
return null;
}
//这个后面我们要用到，可以控制显示在Textview上的图片大小
drawable.setBounds(0, 0, drawable.getIntrinsicWidth(),
drawable.getIntrinsicHeight());
return drawable;
}
};
//这个第二个参数imageGetter是加载图片使用的，第三个参数是过滤标签使用的，我们后面要用到，做点击图片的处理
mTextView.setText(Html.fromHtml(htmlforImage, imageGetter, null));
上面就是在网上可以百度到的基本操作，下面我们去做其他处理，其实就是加载图片的处理，比如图片的缩放和缓存
**重点内容**
我相信大部分同学在加载的话都会用webview去直接加载到一个Actiity中，这种的话webview就可以满足我们大本分的需求，可是现在我们需要把Html放在RecyclerView中去显示，webview就不在适用了，二用textview去加载就会出现各种问题，下面我们就去列出会出现的问题然后一一去解决他们
1， 在recyclerview滚动事会不断刷新Textview的内容，这个如果textview中只有文本的话当然不是问题，不过现在我们还包括图片，当然不能重复刷新，浪费流量，而且加载还特别慢，所以我们把加载过一次的图片缓存到本地就可以供下次加载使用了，不多少了，下面上代码
/**
* Created by jh on 2016/10/10.
*/
public class TextToHtmlUtils {
private Context mContext;
private Dialog mDialog;
private int mPosition;
private static TextToHtmlUtils mInstance;
private static HashMap<String, Bitmap> sPostDetialHashMap;
private static HashMap<String, HashMap<String, Bitmap>> sHashMapHashMap;
public static String TEAM_NEWS = "team_news";
public static String POST_DETIAL = "post_detial";
private static HashMap<String, Bitmap> sTeamNewsHashMap;
public TextToHtmlUtils() {
EventBus.getDefault().register(this);
}
public static TextToHtmlUtils getInstance() {
if (mInstance == null) {
synchronized (OkHttpManager.class) {
if (mInstance == null) {
mInstance = new TextToHtmlUtils();
//用map来存储图片，为之后回收图片做准备
sHashMapHashMap = new HashMap<>();
sPostDetialHashMap = new HashMap<>();
sTeamNewsHashMap = new HashMap<>();
}
}
}
return mInstance;
}
public void getBitmap(final ToHtml compressBitmap, final String url, final Context context,
final TextView textView, int position, final String type) {
this.mPosition = position;
this.mContext = context;
//利用Rxjava去处理线程，把耗时线程放在子线程中
Observable.create(new Observable.OnSubscribe<CharSequence>() {
@Override
public void call(Subscriber<? super CharSequence> subscriber) {
//这里去加载图片
// CharSequence test = Html.fromHtml(url);
textView.setText("loading...");
CharSequence getbitmap = getbitmap(url, type);
subscriber.onNext(getbitmap);
subscriber.onCompleted();
}
})
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Observer<CharSequence>() {
@Override
public void onNext(CharSequence bitmap) {
compressBitmap.toFile(bitmap);
}
@Override
public void onCompleted() {
}
@Override
public void onError(Throwable e) {
}
});
}
private CharSequence getbitmap(String url, final String type) {
Html.ImageGetter imageGetter = new Html.ImageGetter() {
@Override
public Drawable getDrawable(String source) {
URL url;
Drawable drawable = null;
try {
String filename = checkUrl(source);
String saveFilePaht = Constants.IMAGE + filename;
File file = new File(saveFilePaht);
//判断图片是否已经存储
if (!file.exists()) {
Response response = OkHttpManager.getInstanceSimaple(mContext).getAsyn1(source);
byte[] bytes = response.body().bytes();
//利用BitmapFactory去显小图片避免oom，关于BitmapFactory不会用的自行百度
BitmapFactory.Options opts = new BitmapFactory.Options();
opts.inJustDecodeBounds = true;
//BitmapFactory.decodeStream(inputStream, null, opts);
BitmapFactory.decodeByteArray(bytes, 0, bytes.length, opts);
//根据你想要的图片的大小去自动计算缩小倍数
int i = computeSampleSize(opts, -1, 1000 * 1000);
opts.inSampleSize = i;
opts.inJustDecodeBounds = false;
opts.inInputShareable = true;
opts.inPurgeable = true;
opts.inPreferredConfig = Bitmap.Config.ARGB_4444;
//把byte转换为bitmap
Bitmap bitmap = BitmapFactory.decodeByteArray(bytes, 0, bytes.length, opts);
BitmapUtils.compressAndSaveBitmapToSDCard(bitmap, filename, 80);
drawable = BitmapUtils.bitmaptodrawable(bitmap);
//吧bitmap存到map中
if (type.equals(POST_DETIAL)) {
sPostDetialHashMap.put(filename, bitmap);
sHashMapHashMap.put(type, sPostDetialHashMap);
} else if (type.equals(TEAM_NEWS)) {
sTeamNewsHashMap.put(filename, bitmap);
sHashMapHashMap.put(type, sTeamNewsHashMap);
}
Logger.d("mmmmHtml","不存在");
} else {
boolean recycle = isRecycle(filename, type);
//图片已经存在，去内存中或者本地去加载
if (recycle) {
//内存中不存在，本地加载
Bitmap bitmap = BitmapUtils.getBitmapInputStreamFromSDCard(filename);
drawable = BitmapUtils.bitmaptodrawable(bitmap);
if (type.equals(POST_DETIAL)) {
sPostDetialHashMap.put(filename, bitmap);
sHashMapHashMap.put(type, sPostDetialHashMap);
} else if (type.equals(TEAM_NEWS)) {
sTeamNewsHashMap.put(filename, bitmap);
sHashMapHashMap.put(type, sTeamNewsHashMap);
}
Logger.d("mmmmHtml","SD卡");
} else {
//内存加载
HashMap<String, Bitmap> stringBitmapHashMap = sHashMapHashMap.get(type);
Bitmap bitmap = stringBitmapHashMap.get(filename);
drawable = BitmapUtils.bitmaptodrawable(bitmap);
Logger.d("mmmmHtml","Map");
}
}
//drawable.setBounds(0, 0, drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight());
//这个方法去计算你想要的图片的大小
matchDrawable(drawable);
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return drawable;
}
};
CharSequence test = Html.fromHtml(url, imageGetter, new MyTagHandler());
return test;
}
private boolean isRecycle(String filename, String type) {
if (sHashMapHashMap.containsKey(type)) {
HashMap<String, Bitmap> stringBitmapHashMap = sHashMapHashMap.get(type);
if (stringBitmapHashMap.containsKey(filename)) {
Bitmap bitmap1 = stringBitmapHashMap.get(filename);
boolean recycled = bitmap1.isRecycled();
return recycled;
}
}
return true;
}
private void matchDrawable(Drawable drawable) {
if (drawable.getIntrinsicHeight() < 300 && drawable.getIntrinsicWidth() < 500 &&
drawable.getIntrinsicHeight() > 10 && drawable.getIntrinsicWidth() > 10) {
float i = 800 / drawable.getIntrinsicWidth();
float j = 400 / drawable.getIntrinsicHeight();
if (i <= j) {
int width = (int) (drawable.getIntrinsicWidth() * j);
int height = (int) (drawable.getIntrinsicHeight() * j);
drawable.setBounds(0, 0, width, height);
} else {
int width = (int) (drawable.getIntrinsicWidth() * i);
int height = (int) (drawable.getIntrinsicHeight() * i);
drawable.setBounds(0, 0, width, height);
}
} else {
drawable.setBounds(0, 0, drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight());
}
}
private String checkUrl(String source) {
String[] split = source.split("/");
for (String sp : split) {
if (sp.equals("attachments")) {
String s = split[split.length - 1];
return s;
}
}
String s = split[split.length - 3];
return s;
}
public static abstract class ToHtml {
public abstract void toFile(CharSequence bitmap);
}
/**
* 用来通知当解析器遇到无法识别的标签时该作出何种处理
*/
class MyTagHandler implements Html.TagHandler {
/**
* 参数：
* opening：为true时表示某个标签开始解析,为false时表示该标签解析完
* tag:当前解析的标签
* output:文本中的内容
* xmlReader:xml解析器
*/
@Override
public void handleTag(boolean opening, String tag, Editable output, XMLReader xmlReader) {
if (tag.toLowerCase().equals("img")) {//解析<img/>标签（注意标签格式不是<img></img>）
// Logger.e("opening-->", opening + "");
int len = output.length();
ImageSpan[] images = output.getSpans(len - 1, len, ImageSpan.class);
String imgURL = images[0].getSource();
//添加点击事件
output.setSpan(new ImageClickSpan(mContext, imgURL), len - 1, len, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
} else if (tag.equalsIgnoreCase("strike")) {//自定义解析<strike></strike>标签
int len = output.length();
Logger.e("opening-->", opening + "");
if (opening) {//开始解析该标签，打一个标记
output.setSpan(new StrikethroughSpan(), len, len, Spannable.SPAN_MARK_MARK);
} else {//解析结束，读出所有标记，取最后一个标记为当前解析的标签的标记（因为解析方式是便读便解析）
StrikethroughSpan[] spans = output.getSpans(0, len, StrikethroughSpan.class);
if (spans.length > 0) {
for (int i = spans.length - 1; i >= 0; i--) {
if (output.getSpanFlags(spans[i]) == Spannable.SPAN_MARK_MARK) {
int start = output.getSpanStart(spans[i]);
output.removeSpan(spans[i]);
if (start != len) {
output.setSpan(new StrikethroughSpan(), start, len, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
}
break;
}
}
}
}
} else {//其他标签不再处理
}
}
}
class ImageClickSpan extends ClickableSpan {
private Context context;
private String url;
public ImageClickSpan(Context context, String url) {
this.context = context;
this.url = url;
}
@Override
public void onClick(View widget) {
showPicDialog(url);
}
}
private void showPicDialog(String url) {
String filename = checkUrl(url);
String saveFilePaht = Constants.IMAGE + filename;
Intent intent = new Intent(mContext, BigImageActivity.class);
intent.putExtra("path", saveFilePaht);
mContext.startActivity(intent);
}
public static int computeSampleSize(BitmapFactory.Options options,
int minSideLength, int maxNumOfPixels) {
int initialSize = computeInitialSampleSize(options, minSideLength,
maxNumOfPixels);
int roundedSize;
if (initialSize <= 8) {
roundedSize = 1;
while (roundedSize < initialSize) {
roundedSize <<= 1;
}
} else {
roundedSize = (initialSize + 7) / 8 * 8;
}
return roundedSize;
}
public static int computeInitialSampleSize(BitmapFactory.Options options,
int minSideLength, int maxNumOfPixels) {
double w = options.outWidth;
double h = options.outHeight;
int lowerBound = (maxNumOfPixels == -1) ? 1 :
(int) Math.ceil(Math.sqrt(w * h / maxNumOfPixels));
int upperBound = (minSideLength == -1) ? 128 :
(int) Math.min(Math.floor(w / minSideLength),
Math.floor(h / minSideLength));
if (upperBound < lowerBound) {
return lowerBound;
}
if ((maxNumOfPixels == -1) &&
(minSideLength == -1)) {
return 1;
} else if (minSideLength == -1) {
return lowerBound;
} else {
return upperBound;
}
//回收bitmap
public void clearBitmap(String type) {
for (String type1 : sHashMapHashMap.keySet()) {
if (type1.equals(type)) {
HashMap<String, Bitmap> stringBitmapHashMap = sHashMapHashMap.get(type1);
for (String path : stringBitmapHashMap.keySet()) {
Bitmap bitmap = stringBitmapHashMap.get(path);
if (!bitmap.isRecycled() && bitmap != null) {
bitmap.recycle();
Logger.d("mmmrecyBitmapeventbus", bitmap.toString() + type1);
}
}
}
}
}
}
}
经过上面一系列的操作就可以在recyclerview中加载了
在activity调用如下
TextToHtmlUtils instance = getInstance();
instance.getBitmap(new TextToHtmlUtils.ToHtml() {
@Override
public void toFile(CharSequence html) {
holder.mTextView.setText(html);
}
}, Html, context, holder.mtextview, position,TextToHtmlUtils.POST_DETIAL);
最有谢谢大家观看，有什么更好的建议请留言给我
源码已经上传github
网址https://github.com/renxh4/TextViewForHtml
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