java 判断字符串什么编码类型

     public static String getEncoding(String str) {
         String encode = "GB2312";
        try {
            if (str.equals(new String(str.getBytes(encode), encode))) {
                 String s = encode;
                return s;
             }
         } catch (Exception exception) {
         }
         encode = "ISO-8859-1";
        try {
            if (str.equals(new String(str.getBytes(encode), encode))) {
                 String s1 = encode;
                return s1;
             }
         } catch (Exception exception1) {
         }
         encode = "UTF-8";
        try {
            if (str.equals(new String(str.getBytes(encode), encode))) {
                 String s2 = encode;
                return s2;
             }
         } catch (Exception exception2) {
         }
         encode = "GBK";
        try {
            if (str.equals(new String(str.getBytes(encode), encode))) {
                 String s3 = encode;
                return s3;
             }
         } catch (Exception exception3) {
         }
        return "";
     }    

 String encode = "ISO-8859-1";     //应用延伸
            try {
                if (customer.equals(new String(customer.getBytes(encode), encode))) {
                    customer = new String(customer.getBytes(encode),"utf-8");
                 }
             } catch (Exception exception1) {
             }