testsplitstring.java

这个程序实现了在网络上截获邮件数据并还原邮件。仅供学习参考

class SplitString 
{
     private String str;
     private int byteNum;

     public SplitString(){}

     public SplitString(String str,int byteNum)
     {
          this.str=str;
          this.byteNum=byteNum;
    }
 
     public void splitIt()
     {

          byte bt[]=str.getBytes();
          System.out.println("Length of this String ===>"+bt.length);
          if(byteNum>1)
          {
               if(bt[byteNum]<0)
               {
                pBinInt("bt[byteNum]",bt[byteNum]);
                System.out.println("bt["+byteNum+"] = "+bt[byteNum]);//1
                System.out.println("bt["+byteNum+"] = "+(int)bt[byteNum]);//2
                System.out.println("bt["+byteNum+"] = "+(bt[byteNum]&0x000000FF));//3
                System.out.println("bt["+byteNum+"] = "+(bt[byteNum+1]&0XFF));//4
                String substrx=new String(bt,0,--byteNum);
                System.out.println(substrx);
               }
               else
               {
                String substrex=new String(bt,0,byteNum);
                System.out.println(substrex);
               }
   
          }
          else
          { 
               if(byteNum==1)
               {
                if(bt[byteNum]<0)
                {
                     String substr1=new String(bt,0,++byteNum);
                     System.out.println(substr1);
                }
                else
                { 
                     String subStr2=new String(bt,0,byteNum);
                     System.out.println(subStr2);
                }
               }
               else
               {
                System.out.println("输入错误！！！请输入大于零的整数：");
               }
          }
     }
     static void pBinInt(String s, int i) {
    System.out.println(
      s + ", int: " + i + ", binary: ");
    System.out.print("   ");
    for(int j = 31; j >=0; j--)
      if(((1 << j) &  i) != 0)
        System.out.print("1");
      else
        System.out.print("0");
    System.out.println();
  }
}
class TestSplitString
{
 public static void main(String args[])
 {
  String str="我ABCe啊DEFe";
  int num=7;
  SplitString sptstr = new SplitString(str,num);
  sptstr.splitIt();
 }
}