摘要：新建一個(gè)項(xiàng)目選擇自己的文件勾選項(xiàng)目構(gòu)造如下設(shè)置項(xiàng)目配置快捷鍵選擇配置紅色框選擇時(shí)，運(yùn)行成功會(huì)會(huì)自動(dòng)運(yùn)行下方的鏈接測(cè)試運(yùn)行出現(xiàn)如下便創(chuàng)建成功編寫(xiě)第一個(gè)代碼，測(cè)試環(huán)境是否設(shè)置成功第一個(gè)設(shè)置響應(yīng)內(nèi)容類型實(shí)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(shí)，運(yùn)行成功會(huì)會(huì)自動(dòng)運(yùn)行下方的URL鏈接

出現(xiàn)如下便創(chuàng)建成功

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

    private String message;

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

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

        // 實(shí)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(shè)置該類的URL，也可以在web.xml里設(shè)置，如下：

    test//設(shè)置該servlet的名字，可以隨便定義
    test.test//對(duì)應(yīng)的java的文件（包名.類名）



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

運(yùn)行Tomcat,打開(kāi)瀏覽器輸入http://localhost:8080/firstServlet或者h(yuǎn)ttp://localhost:8080/HelloWorld結(jié)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(qū)動(dòng)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(cè)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(qǐng)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(cè)成功");
                }else {
                    System.out.println("注冊(cè)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(qǐng)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(qǐng)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(qǐng)輸入賬號(hào)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(hào)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(shù)據(jù)庫(kù)時(shí)，需要在java的運(yùn)行環(huán)境外部也需要導(dǎo)入JDBC的包，路徑是安裝的java文件夾下的jrelibext