servlet里面删除怎么写，谁能帮忙补充一下

Question

package com.awu.servlet;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
/**

• Servlet 获得填写的表单数据
  */
  public class DeleteServlet extends HttpServlet {
  private static final long serialVersionUID = 1L;

  protected void doGet(HttpServletRequest request, HttpServletResponse response)
  throws ServletException, IOException {
  try{
  request.setCharacterEncoding("UTF-8");
  
  try {
  Class.forName("com.mysql.jdbc.Driver");
  } catch (ClassNotFoundException e) {
  e.printStackTrace();
  }
  String url = "jdbc:mysql://localhost:3306/mysql" ;//mysql为数据库的名称
  String user = "root"; //数据库的登录名
  String password = "123456"; //数据库的登录密码
  Connection conn=null;
  conn=DriverManager.getConnection(url, user, password);

          String flag=request.getParameter("flag");
          String users=request.getParameter("id");//用数组接受前台传来的被选中的复选框的值
          System.out.printf(users,flag);
          String[] Id=users.split(",");           
          int m=0;
          if (Id.length>0) {      
              for (int i = 0; i < Id.length; i++){
              int id1=Integer.parseInt(Id[i]);
              String sql = "delete from test where id="+id1;  //test为要查询的表    
              System.out.println(id1);                                        
                      m++;
              //根据前台选中的id值循环删除
  
              //将删除落实到数据库删除     ？？？                           
  
              //当删除次数等于选中复选框传过来的个数时，删除成功，否则失败，分别返回两种页面        
  
                  }               
          }           
          if (m==Id.length) {
              request.setAttribute("delete_infos", "删除成功");   
              request.getRequestDispatcher("success.jsp").forward(request, response);     
           }else{
               request.setAttribute("delete_infos", "删除失败");
               request.getRequestDispatcher("login.jsp").forward(request, response);          
                  }
          } catch (SQLException e) {
                  System.out.println(e.getMessage());
                                      } 
          }
  }                                                                                   
  

Answer 1

方法补充了一下，另外建议用预处理和事物去做。
public class DeleteServlet extends HttpServlet {
private static final long serialVersionUID = 1L;

@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException,
                                                                               IOException {
    try {
        request.setCharacterEncoding("UTF-8");

        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        String url = "jdbc:mysql://localhost:3306/mysql";// mysql为数据库的名称
        String user = "root"; // 数据库的登录名
        String password = "123456"; // 数据库的登录密码
        Connection conn = null;
        PreparedStatement pstm = null;
        conn = DriverManager.getConnection(url, user, password);

        String flag = request.getParameter("flag");
        String users = request.getParameter("id");// 用数组接受前台传来的被选中的复选框的值
        System.out.printf(users, flag);
        String[] Id = users.split(",");
        int m = 0;
        int deleteNum = 0;// 实际删除成功的行数
        if (Id.length > 0) {
            for (int i = 0; i < Id.length; i++) {
                int id1 = Integer.parseInt(Id[i]);
                String sql = "delete from test where id=" + id1; // test为要查询的表
                System.out.println(id1);
                m++;
                // 根据前台选中的id值循环删除
                pstm = conn.prepareStatement(sql);
                int row = pstm.executeUpdate();
                deleteNum = deleteNum + row;
            }
        }
        // 当删除次数等于选中复选框传过来的个数时，删除成功，否则失败，分别返回两种页面
        if (deleteNum == Id.length) { // m肯定是等于复选框的数量的
            request.setAttribute("delete_infos", "删除成功");
            request.getRequestDispatcher("success.jsp").forward(request, response);
        } else {
            request.setAttribute("delete_infos", "删除失败");
            request.getRequestDispatcher("login.jsp").forward(request, response);
        }
    } catch (SQLException e) {
        System.out.println(e.getMessage());
    }
}

}