今日总结5.22

servlet访问数据库

package com.runoob.test;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.*;

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

/**
 * Servlet implementation class DatabaseAccess
 */
@WebServlet("/DatabaseAccess")
public class DatabaseAccess extends HttpServlet {
    private static final long serialVersionUID = 1L;
    // JDBC 驱动名及数据库 URL
    static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";  
    static final String DB_URL = "jdbc:mysql://localhost:3306/RUNOOB";
    
    // 数据库的用户名与密码，需要根据自己的设置
    static final String USER = "root";
    static final String PASS = "123456"; 
    /**
     * @see HttpServlet#HttpServlet()
     */
    public DatabaseAccess() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        Connection conn = null;
        Statement stmt = null;
        // 设置响应内容类型
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        String title = "Servlet Mysql 测试 - 菜鸟教程";
        String docType = "<!DOCTYPE html>\n";
        out.println(docType +
        "<html>\n" +
        "<head><title>" + title + "</title></head>\n" +
        "<body bgcolor=\"#f0f0f0\">\n" +
        "<h1 align=\"center\">" + title + "</h1>\n");
        try{
            // 注册 JDBC 驱动器
            Class.forName("com.mysql.jdbc.Driver");
            
            // 打开一个连接
            conn = DriverManager.getConnection(DB_URL,USER,PASS);

            // 执行 SQL 查询
            stmt = conn.createStatement();
            String sql;
            sql = "SELECT id, name, url FROM websites";
            ResultSet rs = stmt.executeQuery(sql);

            // 展开结果集数据库
            while(rs.next()){
                // 通过字段检索
                int id  = rs.getInt("id");
                String name = rs.getString("name");
                String url = rs.getString("url");
    
                // 输出数据
                out.println("ID: " + id);
                out.println(", 站点名称: " + name);
                out.println(", 站点 URL: " + url);
                out.println("<br />");
            }
            out.println("</body></html>");

            // 完成后关闭
            rs.close();
            stmt.close();
            conn.close();
        } catch(SQLException se) {
            // 处理 JDBC 错误
            se.printStackTrace();
        } catch(Exception e) {
            // 处理 Class.forName 错误
            e.printStackTrace();
        }finally{
            // 最后是用于关闭资源的块
            try{
                if(stmt!=null)
                stmt.close();
            }catch(SQLException se2){
            }
            try{
                if(conn!=null)
                conn.close();
            }catch(SQLException se){
                se.printStackTrace();
            }
        }
       
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protectedvoid doPost(HttpServletRequest request,HttpServletResponse response)throwsServletException,IOException{
        // TODO Auto-generated method stub
        doGet(request, response);
    }}
posted @ 2023-06-10 15:52  北·岛  阅读(4)  评论(0)    收藏  举报