java后台增强for循环遍历map

假如传来一个参数：Map<String,String>  m

if (m != null) {

for (String k : m.keySet()) {

if (m.get(k) == null) {

where = where + " " + k + " is null and";

} else

where = where + " " + k + "='" + m.get(k) + "'  and";

}

if (where != null && !where.equals("") && where.indexOf("and") > -1) {

where = where.substring(0, where.length() - 3);

where = "where " + where;

}

}