Java随机生成验证码

/**

*

* @author Renault_zjl

* @param length 你所需要验证码的长度

* @param type 所需验证码里面的类型

* @return

*/

public String getCode(int length, int type)

{

StringBuffer buffer = null; //所输出的最终验证码

StringBuffer sb = new StringBuffer();

Random r = new Random();

switch (type)

{

case 0:

buffer = new StringBuffer("0123456789");

break;

case 1:

buffer = new StringBuffer("abcdefghijklmnopqrstuvwxyz");

break;

case 2:

buffer = new StringBuffer("ABCDEFGHIJKLMNOPQRSTUVWXYZ");

break;

case 3:

buffer = new StringBuffer(

"0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ");

break;

}

if (type != 0)

{

int range = buffer.length();

for (int i = 0; i < length; ++i)

{

sb.append(buffer.charAt(r.nextInt(range)));

}

}

return sb.toString();

}