2019-02-20

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.sql.*;

//导入必需的 java 库
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

// 扩展 HttpServlet 类
public class a extends HttpServlet {
 
  private String message;
  private String name;

  public void init() throws ServletException
  {
      
      System.out.println("连接数据库...");
      // 执行必需的初始化
      message = "Hello World";
      String JDBC_DRIVER = "com.mysql.jdbc.Driver";  
      String DB_URL = "jdbc:mysql://cdb-4gsyv8oy.bj.tencentcdb.com:10071/rdk";
   
      // 数据库的用户名与密码，需要根据自己的设置
      String USER = "root";
      String PASS = "***********";
      
      
      Connection conn = null;
      Statement stmt = null;
      
      System.out.println("123...");
      try {
        Class.forName("com.mysql.jdbc.Driver");
        // 打开链接
        System.out.println("连接数据库...");
        conn = DriverManager.getConnection(DB_URL, USER, PASS);
        // 执行查询
        System.out.println(" 实例化Statement对象...");
        stmt = conn.createStatement();
        String sql;
        sql = "SELECT id, name, url FROM websites";
        ResultSet rs = stmt.executeQuery(sql);
        
        name = "没有脸上数据库";
        while(rs.next()){
            // 通过字段检索
            int id  = rs.getInt("id");
            name = rs.getString("name");
            String url = rs.getString("url");

            // 输出数据
            System.out.print("ID: " + id);
            System.out.print(", 站点名称: " + name);
            System.out.print(", 站点 URL: " + url);
            System.out.print("\n");
        }
        // 完成后关闭
        rs.close();
        stmt.close();
        conn.close();
    } catch (Exception e) {
        System.out.println(" 实例化Statement对象...");
        e.printStackTrace();
    }
  
      
  }

  public void doGet(HttpServletRequest request,
                    HttpServletResponse response)
            throws ServletException, IOException
  {
      // 设置响应内容类型
      response.setContentType("text/html");

      // 实际的逻辑是在这里
      PrintWriter out = response.getWriter();
      out.println("<h1>" + message + "</h1>");
      out.println("<h1>" + name + "</h1>");
  }
  
  public void destroy()
  {
      // 什么也不做
  }
}