Android在TextView中实现RichText风格

参考：

Android实战技巧：用TextView实现Rich Text---在同一个TextView中设置不同的字体风格

Demo：

    private SpannableStringBuilder content = new SpannableStringBuilder();
    private static final ForegroundColorSpan STYLE_ERROR = new ForegroundColorSpan(Color.RED);
    private static final ForegroundColorSpan STYLE_INFO = new ForegroundColorSpan(Color.BLACK);
    private int start = 0;
    private int end = 0;

    public void appendLog(String msg,int type){
        TextView logView  = (TextView)findViewById(R.id.logView);

        content.append(msg);
        start = end;
        end += msg.length();
        switch (type){
            case Log.TYPE_ERROR:
                content.setSpan(STYLE_ERROR,start,end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
                break;
            case Log.TYPE_INFO:
                content.setSpan(STYLE_INFO,start,end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
                break;
            default:
                break;
        }
        if(logView!=null){
            logView.setText(content);

            //scroll to the end
            int offset = logView.getLineCount() * logView.getLineHeight();
            if(offset > logView.getHeight()){
                logView.scrollTo(0,offset - logView.getHeight());
            }
        }
    }