摘要：新建一個項目選擇自己的文件勾選項目構造如下設置項目配置快捷鍵選擇配置紅色框選擇時，運行成功會會自動運行下方的鏈接測試運行出現如下便創建成功編寫第一個代碼，測試環境是否設置成功第一個設置響應內容類型實際的邏輯是

Flies --> new --> project-->ProjectSDK選擇自己的JDK文件-->勾選Web Appliction -->Next

File --> Project Structure (快捷鍵：Ctrl + Shift + Alt + S) --> 選擇Module ：

紅色框選擇時，運行成功會會自動運行下方的URL鏈接

出現如下便創建成功

@WebServlet("/firstServlet")
public class test extends HttpServlet {

    private String message;

    @Override
    public void init() throws ServletException {
        message = "第一個servlet";
    }

    public void doGet(HttpServletRequest request,
                      HttpServletResponse response)
            throws ServletException, IOException
    {
        // 設置響應內容類型
//        response.setContentType("text/html");
        response.setHeader("Content-type","text/html;charset=UTF-8");

        // 實際的邏輯是在這里
        PrintWriter out = response.getWriter();
        out.println("
" + message + "
");
    }

    public void destroy()
    {
        // 什么也不做
    }
}

注解@WebServlet是設置該類的URL，也可以在web.xml里設置，如下：

    test//設置該servlet的名字，可以隨便定義
    test.test//對應的java的文件（包名.類名）



    test//上面定義的名字
    /HelloWorld//自己定義URL

運行Tomcat,打開瀏覽器輸入http://localhost:8080/firstServlet或者http://localhost:8080/HelloWorld結果：

資源：mysql-connector-java-5.1.39-bin.jar
鏈接：http://note.youdao.com/notesh...

public class connectionUtil {
    private static String  driver;
    private static String  url;
    private static String  username;
    private static String password;

    static {
        try {

            //獲取配置文件的信息
            driver = "com.mysql.jdbc.Driver";
            url = "jdbc:mysql://localhost:3306/test";
            username = "root";
//            password = "admin";
            password = "touwen";

            //加載驅動類
            Class.forName(driver);

        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }

    }

    public static Connection getConnection() throws SQLException {
        return DriverManager.getConnection(url,username,password);
    }

    public static void release(Connection connection, Statement statement, ResultSet resultSet) {

        if (resultSet != null) {
            try {
                resultSet.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (statement != null) {
            try {
                statement.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (connection != null) {
            try {
                connection.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

注冊邏輯

@WebServlet("/registered")
public class registered extends HttpServlet {


    public registered(){
        super();
    }
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        String username = new String(request.getParameter("username").getBytes("ISO8859-1"),"UTF-8");
        String password1 = request.getParameter("password1");
        String password2 = request.getParameter("password2");
        if(password1 == null || password2 == null){
            System.out.println("請輸入密碼");
        }
        if(password1.equals(password2)){
            Connection conn = null;
            ResultSet rs = null;
            PreparedStatement ptst = null;
            try{
                conn = connectionUtil.getConnection();
                String sql = "SELECT username FROM user";
                ptst = conn.prepareStatement(sql);
                rs = ptst.executeQuery();
                while (rs.next()) {
                    if(username.equals(rs.getString("username"))){
                        System.out.println("用戶名已存在");
                        return;
                    }
                }
                String ins = "insert into user(username,password) values (?,?)";
                ptst = conn.prepareStatement(ins);
                ptst.setString(1,username);
                ptst.setString(2,password1);
                int i = ptst.executeUpdate();
                if(i==1) {
                    System.out.println("注冊成功");
                }else {
                    System.out.println("注冊失敗");
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }finally {
                connectionUtil.release(conn,ptst,rs);
            }
        }else {
            System.out.println("兩次密碼不一致");
        }

    }

    // 處理 POST 方法請求的方法
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

}

登錄邏輯

@WebServlet("/login")
public class login extends HttpServlet {

    public login(){
        super();
    }

    @Override
    // 處理 POST 方法請求的方法
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{
        Connection conn = null;
        PreparedStatement ptst = null;
        ResultSet rs = null;

        String username = new String(request.getParameter("username").getBytes("ISO8859-1"),"UTF-8");
        String password = request.getParameter("password");
        if(username == null || password == null){
            System.out.println("請輸入賬號或者密碼");
        }
        try {
            conn = connectionUtil.getConnection();
            String sql = "SELECT * FROM user where username = ?";
            ptst = conn.prepareStatement(sql);
            ptst.setString(1,username);
            rs = ptst.executeQuery();
            while (rs.next()){
                if(password.equals(rs.getString("password"))){
                    System.out.println("登陸成功");
                }else {
                    System.out.println("賬號密碼不正確");
                }
            }

        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            connectionUtil.release(conn,ptst,rs);
        }
    }
}

如果一直連接不上數據庫時，需要在java的運行環境外部也需要導入JDBC的包，路徑是安裝的java文件夾下的jrelibext