在servlet连接mysql下的最简单增删查改

添加

package com.jquery.register;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class add extends HttpServlet {

    public void destroy() {
        super.destroy(); 
    }
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
            doPost(request,response);
    }
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        request.setCharacterEncoding("utf-8"); 
         response.setCharacterEncoding("utf-8");
         Connection conn = null;
         PreparedStatement stmt = null;
         ResultSet rs = null;
         String name="li";
         String password="12345";
         String drive = "com.mysql.jdbc.Driver";
         System.out.println("ajax后台交互成功");  
         try{
             Class.forName(drive);
             conn = DriverManager
                     .getConnection("jdbc:mysql://localhost:3306/test?user=root&password=123");
             System.out.println("数据库连接成功");
             String sql="insert  into user_table(name,password)";
             sql+=" values(?,?)";
             stmt = conn.prepareStatement(sql);
             stmt.setString(1,name);
             stmt.setString(2,password);
             stmt.executeUpdate();
             System.out.println("success");
//        out.flush();
//        out.close();
    }catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            try {
                //注意关闭原则：从里到外
                    if (rs != null) {
                        rs.close();
                    }
                    if (stmt != null) {
                        stmt.close();
                    }
                    if (conn != null) {
                        conn.close();
                    }
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
    }
    public void init() throws ServletException {
        // Put your code here
    }

}

删除

package com.jquery.register;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class delete extends HttpServlet {

    public void destroy() {
        super.destroy();
    }
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
            doPost(request,response);
    }
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        request.setCharacterEncoding("utf-8");
         response.setCharacterEncoding("utf-8");
         Connection conn = null;
         PreparedStatement stmt = null;
         ResultSet rs = null;
         String drive = "com.mysql.jdbc.Driver";
         System.out.println("ajax后台交互成功");  
         try{
             Class.forName(drive);
             conn = DriverManager
                     .getConnection("jdbc:mysql://localhost:3306/test?user=root&password=123");
             System.out.println("数据库连接成功");
             String sql="delete  from user_table where name='zhang'";
             stmt = conn.prepareStatement(sql);
             stmt.executeUpdate();
             System.out.println("success");
//        out.flush();
//        out.close();
    }catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            try {
                //注意关闭原则：从里到外
                    if (rs != null) {
                        rs.close();
                    }
                    if (stmt != null) {
                        stmt.close();
                    }
                    if (conn != null) {
                        conn.close();
                    }
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
    }
    public void init() throws ServletException {
        // Put your code here
    }

}

查找

package com.jquery.register;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class search extends HttpServlet {

    public void destroy() {
        super.destroy(); 
    }
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
            doPost(request,response);
    }
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        request.setCharacterEncoding("utf-8"); 
         response.setCharacterEncoding("utf-8");
         Connection conn = null;
         PreparedStatement stmt = null;
         ResultSet rs = null;
         
         String drive = "com.mysql.jdbc.Driver";
         System.out.println("ajax后台交互成功");  
         try{
             Class.forName(drive);
             conn = DriverManager
                     .getConnection("jdbc:mysql://localhost:3306/test?user=root&password=123");
             System.out.println("数据库连接成功");
             String sql="select  *  from user_table ";
             
             stmt = conn.prepareStatement(sql);
             
             rs=stmt.executeQuery();
             
             System.out.println("success");
             while(rs.next()){
                 String name = rs.getString(1);
                String password = rs.getString(2);
                System.out.println(name + ", " + password);
             }
//        out.flush();
//        out.close();
    }catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            try {
                //注意关闭原则：从里到外
                    if (rs != null) {
                        rs.close();
                    }
                    if (stmt != null) {
                        stmt.close();
                    }
                    if (conn != null) {
                        conn.close();
                    }
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
    }
    public void init() throws ServletException {
        // Put your code here
    }

}

修改

package com.jquery.register;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class update extends HttpServlet {

    public void destroy() {
        super.destroy(); 
    }
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
            doPost(request,response);
    }
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        request.setCharacterEncoding("utf-8"); 
         response.setCharacterEncoding("utf-8");
         Connection conn = null;
         PreparedStatement stmt = null;
         ResultSet rs = null;
         String password="654321";
         String drive = "com.mysql.jdbc.Driver";
         System.out.println("ajax后台交互成功");  
         try{
             Class.forName(drive);
             conn = DriverManager
                     .getConnection("jdbc:mysql://localhost:3306/test?user=root&password=123");
             System.out.println("数据库连接成功");
             String sql="update user_table set password='"+password+"' where name='li'";
             
             stmt = conn.prepareStatement(sql);
             
             stmt.executeUpdate();
             
             System.out.println("success");
             
//        out.flush();
//        out.close();
    }catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            try {
                //注意关闭原则：从里到外
                    if (rs != null) {
                        rs.close();
                    }
                    if (stmt != null) {
                        stmt.close();
                    }
                    if (conn != null) {
                        conn.close();
                    }
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
    }
    public void init() throws ServletException {
        // Put your code here
    }

}