java使用jsp从数据库中删除行
问题在于,当我点击userNotes中的按钮DELETE时。deleteData中的jsp测试函数-out.println(value)
,有效-它向我显示单击按钮的内容的当前值,但不显示其他内容。它不会从数据库中删除数据,也不会在响应时发送重定向,我需要做什么
userNotes。jsp
<table id="notes" border="2">
<tr>
<td>note name</td>
<td>note</td>
</tr>
<%
PrintWriter writer = response.getWriter();
int id = Integer.parseInt(request.getParameter("r"));
try {
Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/evernoteDB",
"evernoteDB", "0633739768z");
Statement st = con.createStatement();
ResultSet rs;
rs = st.executeQuery("SELECT * FROM note");
while (rs.next())
{
%>
<tr>
<td><%=rs.getString(1) %></td>
<td><%=rs.getString(2) %></td>
<td>
<a href=deleteData?id=<%=rs.getString(1) %>> Delete </a>
</td>
</tr>
<%
}
rs.close();
st.close();
con.close();
}
catch(ClassNotFoundException e)
{
writer.println("Couldn't load database driver: " + e.getMessage());
}
catch(SQLException e)
{
writer.println("SQLException caught: " + e.getMessage());
}
catch (Exception e)
{
writer.println(e);
}
%>
</table>
删除数据-servlet
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.*;
import java.sql.*;
@WebServlet("/deleteData")
public class deleteData extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
String value = request.getParameter("id");
try {
Class.forName("com.mysql.jdbc.Driver");
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/evernoteDB",
"evernoteDB", "0633739768z");
Statement st = conn.createStatement();
st.executeUpdate("DELETE FROM note WHERE noteName=" + value);
out.print(value);
response.sendRedirect("http://localhost:8080/userNotes.jsp");
conn.close();
}
catch(Exception e){
e.printStackTrace();
}
}
}
# 1 楼答案
列
noteName
属于String
类型,因此执行查询应该引用该值考虑使用^ {< CD3>}。它是安全的,也会处理此类错误
既然你在重定向,你就不应该试图设置任何内容头。删除以下内容,因为servlet不应该编写任何响应,而是重定向
另外,不要像那样硬编码主机和端口号,否则您将无法在其他服务器上部署生成的war。使用类似
sendRedirect()
的相对URL