public static String html(String content) {
if(content==null) return "";
String html = content;
// html = html.replace( "'", "'");
html = html.replaceAll( "&", "&");
html = html.replace( "\"", """); //"
html = html.replace( "\t", " ");// 替换跳格
html = html.replace( " ", " ");// 替换空格
html = html.replace("<", "<");
html = html.replaceAll( ">", ">");
return html;
}