1.String ->Date

　　String StrDate = "2012-12-12";

      SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");
      Date date = new Date();
      date=sdf.parse(StrDate);

2.Date ->String

　  String  StrDate = "";

     Date date = new Date();

　  SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");

　  StrDate= sdf.format(date);

String和Date 互相转换