风沙电脑技术网

<form name="form" method="post" onSubmit="return check_form(this)" action="save.jsp">//onSubmit是语句执行的必要前提
<tr>
                      <td style="color:#999900;">昵称:</td>
                      <td width="6"></td>
                      <td>
                        <input name=name type=text class="inp_set1" id="name" value="" size="30" maxlength="10">
//此处id是下面判断的依据。id="name"
         </td>
                    </tr>
<tr>
                <td valign="middle">
                  <input type="submit" value="我写好咯" class="inp_set1" onFocus="this.style.backgroundColor='#fffdf7'"

onBlur="this.style.backgroundColor='#FFFFFF'" name="submit">
                </td>
                <td width="5"></td>
                <td valign="middle">
                  <input type="reset" value="重写一回" class="inp_set1" onFocus="this.style.backgroundColor='#fffdf7'"

onBlur="this.style.backgroundColor='#FFFFFF'" name="reset">
                </td>
              </tr>

<script language="JavaScript" type="text/JavaScript">
function check_form(form1)
    {
        if (form.name.value=="")
        {
            alert("昵称好像忘了填?");
            form.name.focus();
            return false;
        }
        
    }
</script>

另外还有以下几个

if (form.name.value.length>300)
  {
   alert("输入数据太多，请减少数据");
   form.text.focus();
   return false;
  }

if (form.email.value!="")
  {

   if (form.email.value.indexOf ('@') == -1||form.email.value.indexOf ('.') == -1)
    {
    alert("E-mail格式可能不对噢?！");
    form.email.focus();
    return false;
    }
  }

<a href="http://wpa.qq.com/msgrd?V=1&Uin=<%=getStr(rs.getString("qq"))%>&Site=<%=getStr(rs.getString("name"))%>&Menu=yes" target="_blank"><img src="pic/qq.gif" alt="点击给我发消息" width="23" height="16" border="0"></a></td>

<tr>
<td style="color:#999900;">验证码:</td>
<td></td>
<td><input name=rand type=text class="inp_set1" id="rand" onFocus="this.style.backgroundColor='#fffdf7'" onBlur="this.style.backgroundColor='#FFFFFF'" size="6" maxlength="4">
<img src="image.jsp" width="60" height="20"></td>
</tr>

<%@ page contentType="image/jpeg" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" %>
<%!
Color getRandColor(int fc,int bc){//给定范围获得随机颜色
        Random random = new Random();
        if(fc>255) fc=255;
        if(bc>255) bc=255;
        int r=fc+random.nextInt(bc-fc);
        int g=fc+random.nextInt(bc-fc);
        int b=fc+random.nextInt(bc-fc);
        return new Color(r,g,b);
        }
%>
<%
//设置页面不缓存
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);

// 在内存中创建图象
int width=60, height=20;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

// 获取图形上下文
Graphics g = image.getGraphics();

//生成随机类
Random random = new Random();

// 设定背景色
g.setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height);

//设定字体
g.setFont(new Font("Times New Roman",Font.PLAIN,18));

//画边框
//g.setColor(new Color());
//g.drawRect(0,0,width-1,height-1);


// 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
g.setColor(getRandColor(160,200));
for (int i=0;i<155;i++)
{
 int x = random.nextInt(width);//Random.nextInt可以自定义随机数范围，如Random.nextInt（100）可以返回0到100之间的整数
 int y = random.nextInt(height);
        int xl = random.nextInt(12);
        int yl = random.nextInt(12);
 g.drawLine(x,y,x+xl,y+yl);
}

// 取随机产生的认证码(4位数字)
String sRand="";
for (int i=0;i<4;i++){
    String rand=String.valueOf(random.nextInt(10));
    sRand+=rand;
    // 将认证码显示到图象中
    g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));//调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
    g.drawString(rand,13*i+6,16);
}

// 将认证码存入SESSION
session.setAttribute("rand",sRand);


// 图象生效
g.dispose();

// 输出图象到页面
ImageIO.write(image, "JPEG", response.getOutputStream());


%>