汉字的乱码，与字符的过滤

public String filter(String str) {
str = str.replaceAll("&", "&amp");
str = str.replaceAll("<", "&lt");
str = str.replaceAll(">", "&gt");
str = str.replaceAll(" ", "&nbsp");
str = str.replaceAll("'", "&#39;");
str = str.replaceAll("\"", "&quot");
str = str.replaceAll("\n", "<br>");
try {
str = new String(str.getBytes("ISO-8859-1"));
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
return str;
}