java将字符串转成正则表达式的形式

public String returnString(String str){
String reg = "\\d+";
String reg1 = "\\\\:";
String reg2 = "\\\\+";
String reg3 = "\\\\(";
String reg4 = "\\\\)";
String reg5 = "\\\\[";
String reg6 = "\\\\]";
String reg7 = "\\\\$";
String reg8 = "\\\\*";
String tmp = str.replaceAll("\\+",reg2);
String tmp1 = tmp.replaceAll(reg,"\\\\d+");
String tmp2 = tmp1.replaceAll("\\:",reg1);
String tmp3 = tmp2.replaceAll("\\(",reg3);
String tmp4 = tmp3.replaceAll("\\)",reg4);
String tmp5 = tmp4.replaceAll("\\[",reg5);
String tmp6 = tmp5.replaceAll("\\]",reg6);
String tmp7 = tmp6.replaceAll("\\$",reg7);
String tmp8 = tmp7.replaceAll("\\*",reg8);
return tmp8;
}