Dodoke9月3日学习笔记

课程大纲

1、jsp表单数据更改
2、表单method get和post区别；
3、字符编码

课程笔记

一、jsp表单数据更改

//先通过id查询数据库，显示在表单中
<%
    String id = request.getParameter("id");
    String name ="";
    Class.forName("com.mysql.jdbc.Driver");
    Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/datt", "root", "1");
    PreparedStatement pst = conn.prepareStatement("SELECT name FROM stu WHERE id="+id);
    ResultSet rs =pst.executeQuery();
    if(rs.next()){
        name = rs.getString("name");
    }
    rs.close();
    pst.close();
    conn.close();
%>
//<%= %>直接输出变量、表达式内容
<form action="update.jsp?id=<%=id %>" method = "post" onsubmit="return edit()">
    <input type = "text" name = "username1" value ="<%=name%>"/>
    <input type = "submit" value = "修改">
</form>
//确认弹框事件
<script>
    var edit = function(){
        if(confirm("确认修改吗？")){
            return true;
        } else {
            return false;
        }
    }
</script>

<%

    request.setCharacterEncoding("utf-8");
    //获取editPre.jsp里面inputid和username的值
    String username1 = request.getParameter("username1");
    String id = request.getParameter("id");

    Class.forName("com.mysql.jdbc.Driver");
    Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/datt", "root", "1");
    //简化代码，用？后面setString和SetInt方法赋值；Integer.valueOf()--将String转化为int
    PreparedStatement pst = conn.prepareStatement("UPDATE stu SET name =? WHERE id=?");
    pst.setString(1, username1);
    pst.setInt(2,Integer.valueOf(id));
    int rs = pst.executeUpdate();
    //int rs = pst.executeUpdate();
    pst.close();
    conn.close(); 
    // jdbc编程
    out.print("<h1>修改"+rs+"条数据</h1>");
%>

二、表单里面method属性 get和post区别

<form action="update.jsp?id=<%=id %>" method = "post" >
    <input type = "text" name = "username1" value ="<%=name%>"/>
    <input type = "submit" value = "修改">
</form>

当里面的method为get时，传入的value = “<%=name%>会显示在URL上，安全性弱，且get不能重点内容传入action="update.jsp?id=<%=id %>"的id值
当里面的method为post时，id和name都会传入下一页面，且值不会显示在URL地址上，安全性高；

三、更改字符编码
①eclipses–>windows–>preferences–>搜索Encoding–>utf-8
②Servers–>server.xml–>端口号加URIEncoding=”UTF-8”
③表单method为post时加request.setCharacterEncoding(“utf-8”);