Question

朋友我有一个jsp页面，它从sql表中检索数据并以表格的形式显示它们。我还将显示另一列，其中包含一个用于从sql表中删除该行/条目的按钮。以下是我的jsp页面的代码：

 <%@ page import="java.sql.*" %>
    <%
            Class.forName ("com.mysql.jdbc.Driver");            
            Connection  conn=null;  
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/demo","root","pass");
            %>
    <body>
    <center>
        <h1>USERS TABLE</h1>
        <table>
            <tr>
                <th>UserId</th>
                <th>Username</th>
            </tr>
        <%
            Statement stm = conn.createStatement();
            String s = "SELECT * FROM login";
            ResultSet r = stm.executeQuery(s);
            while ( r.next() )
             { 
                 out.print("<tr>");
                 out.print("<td>" +  r.getString ("userid") + "</td>" ); 
                 out.print("<td>" +  r.getString ("username") + "</td>");
                 out.print("<td>" +  "<input type=button value='Delete'/>"+ "</td>");
                 out.print("</tr>");
             }
         %>     
        </table>
    </center>
    </body>

现在我希望我的删除按钮提取用户ID并传递查询以从数据库中删除所选用户。我对如何实现此用户标识提取和处理查询感到困惑。

Answer 1

我建议你这样做

1}首先创建一个servlet（比如Display.java）并将数据库内容存储在响应属性中。将响应属性发送到jsp（比如home.jsp）

2}在jsp文件中检索响应属性并创建一个删除按钮，当调用OnClick时，运行一个脚本，将脚本指向执行删除操作的servlet（比如deleteData1.java）。

我附上以下相应的代码。

（Display.java）它将数据库内容存储在arrayList对象中。此外，arrayList对象将存储在response属性中并发送到jsp（home.jsp）。

public Display() {
    super();
    // TODO Auto-generated constructor stub
}


protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    doPost(request, response);
}


protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    response.setContentType("text/html");
    PrintWriter out = response.getWriter();
    Connection conn = null;

    Statement st;
    try {
        Class.forName("com.mysql.jdbc.Driver");
        conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/demo","root","pass");

        ArrayList al=null;
        ArrayList userList =new ArrayList();
        String query = "select userid,username from login";

        st = conn.createStatement();
        ResultSet  rs = st.executeQuery(query);


        while(rs.next())
        {
            al  = new ArrayList();
            al.add(rs.getInt(1));
            al.add(rs.getString(2));
            userList.add(al);
        }

        request.setAttribute("userList",userList);

        RequestDispatcher dispatcher = getServletContext().getRequestDispatcher("/home.jsp");
        dispatcher.forward(request,response);
        conn.close();

    } catch (Exception e) {
    e.printStackTrace();
    } 
}
}

（针对home.jsp）

它将检索从Display.java发送的响应属性。单击删除按钮时会调用一个脚本，该脚本会将其转发到一个servlet，该servlet将执行与该id相对应的删除操作。

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%@ page import="java.util.*;" %>    
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>

<script language ="javascript">

function deleteData(id){
    window.location.href="http://localhost:8080/First/deleteData1?id="+id;  
}


</script>

</head>
<body>
<br>
<table align="center">
</table>
<br>

<table border='1' width='300' cellpadding='1' cellspacing='0'>
<tr><td colspan=3 align="center"></td></tr>
<tr>
 <td>UserId</td><td>userName</td>
</tr>                       

<%

List Li = new ArrayList();
Iterator  lr;

if(request.getAttribute("userList")!=null && request.getAttribute("userList")!="")
{
    List userList =  (ArrayList)request.getAttribute("userList");
    Iterator itr = userList.iterator();

    while(itr.hasNext())
    {

        Li = (ArrayList)itr.next();
        lr = Li.iterator();
        Integer id = (Integer)lr.next();
        %>
        <tr>
        <td><%=id%></td>
        <%  
        while(lr.hasNext())
        {

            %>
            <td> <%=lr.next()%></td>

            <%

        }
        %>
        <td><input type="button" name="delete" value="Delete" onclick="deleteData(<%=id%>);"></td>
        </tr>
        <%
    }
}
%>

}
</table>
</body>
</html>

最后，当单击删除按钮时，脚本将运行，这将指向将执行删除操作的servlet（deleteData1.java）

（deleteData1.java）

@WebServlet("/deleteData1")
public class deleteData1 extends HttpServlet {
private static final long serialVersionUID = 1L;


public deleteData1() {
    super();
    // TODO Auto-generated constructor stub
}

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    response.setContentType("text/html");
    PrintWriter out = response.getWriter();

    Connection conn = null;
    int id = Integer.parseInt(request.getParameter("id"));
    try {
        Class.forName("com.mysql.jdbc.Driver");
        conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test?user=root&password=Tpg@1234");
        String query = "delete from login where id="+id;
        Statement stmt = conn.createStatement();
        int i = stmt.executeUpdate(query);
        if(i>0){
            response.sendRedirect("http://localhost:8080/First/Display");
        }
        conn.close();
    }
    catch(Exception e){
        e.printStackTrace();
    }
}


protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub
}

}

Answer 2

您可以这样做：

out.print("<td>"+"<input type='button' value='Delete' id='"+r.getString("userid")+"'/>"+</td>");

并检查要删除的用户ID，如下所示：

$(document).ready(function(){

$(":button").click(function(){
    alert("Deleting user id: "+this.id);
});

});

工作小提琴：http://jsfiddle.net/robertrozas/fvAMD/

Answer 3

使用超链接代替按钮

<td>
   <a href="Edit?userd=<%=rs.getString(1) %>"> Activate </a>
<td>

然后你必须创建Edit servlet或jsp页面来编写你的Query

使用jsp中的按钮检索id并删除查询

3 个答案: