request常用方法，登录案例

@WebServlet(name = "HangServlet",urlPatterns = "/hangServlet")
public class HangServlet extends HttpServlet {
　　protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
　　　　doGet(request,response);
　　}
 
　　protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
　　　　String method = request.getMethod();
　　　　System.out.println("method = " + method);
 
　　　　StringBuffer requestURL = request.getRequestURL();
　　　　System.out.println("requestURL = " + requestURL);
 
　　　　String requestURI = request.getRequestURI();
　　　　System.out.println("requestURI = " + requestURI);
 
　　　　String remoteAddr = request.getRemoteAddr();
　　　　System.out.println("remoteAddr = " + remoteAddr);
 
　　　　String protocol = request.getProtocol();
　　　　System.out.println("protocol = " + protocol);
 
　　　　String contextPath = request.getContextPath();
　　　　System.out.println("contextPath = " + contextPath);
 
　　　　String queryString = request.getQueryString();
　　　　System.out.println("queryString = " + queryString);
 
　　}
}
 

@WebServlet(name = "TouServlet", urlPatterns = "/touServlet")
public class TouServlet extends HttpServlet {
　　protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
　　　　doGet(request,response);
 　　　　
　　}
 
　　protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
　　　　String userName = request.getHeader("host");
　　　　System.out.println("userName = " + userName);
 
　　　　Enumeration<String> headerNames = request.getHeaderNames();
　　　　while(headerNames.hasMoreElements()){
　　　　System.out.println("headerNames.nextElement() = " + headerNames.nextElement());
　　　　}
　　}
}

@WebServlet(name = "TiServlet",urlPatterns="/tiServlet")
public class TiServlet extends HttpServlet {
　　protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
　　　　doGet(request,response);
　　}
　　protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
　　　　request.setCharacterEncoding("utf-8");
　　　　String username = request.getParameter("username");
　　　　System.out.println("username = " + username);
 
　　　　String[] hobbies = request.getParameterValues("hobby");
　　　　System.out.println("Arrays. = " + Arrays.toString(hobbies));
　　}
}

@WebServlet(name = "ForwardServlet", urlPatterns="/forward1")
public class ForwardServlet extends HttpServlet {
　　protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
　　　　doGet(request,response);
　　}
 
　　protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
　　　　request.setAttribute("name","张三");
　　　　request.getRequestDispatcher("/forward2").forward(request,response);
　　　}

}
 
　　

@WebServlet(name = "ForwardServlet2", urlPatterns="/forward2")
public class ForwardServlet2 extends HttpServlet {
　　protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
　　　　doGet(request,response);
　　}
 
　　protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
　　　　Object name = request.getAttribute("name");
　　　　System.out.println("name = " + name);
　　}
}

@WebServlet(name = "ForwardServlet3", urlPatterns="/forward3")
public class ForwardServlet3 extends HttpServlet {
　　protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
　　　　doGet(request,response);
　　}
 
　　protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
　　　　request.getRequestDispatcher("/login.html").forward(request,response);
　　}
}

public class JdbcTemplateUtil {
 
private static ComboPooledDataSource cpds = null;
private static JdbcTemplate jdbcTemplate = null;
 
static {
cpds = new ComboPooledDataSource();
}
 
public static JdbcTemplate getJdbcTemplate(){
jdbcTemplate = new JdbcTemplate(cpds);
return jdbcTemplate;
}
 
}

<c3p0-config>
<default-config>
<property name="driverClass">com.mysql.jdbc.Driver</property>
<property name="jdbcUrl">jdbc:mysql://localhost:3306/demo_login</property>
<property name="user">root</property>
<property name="password">123</property>
</default-config>
</c3p0-config>

public class LoginDao {
public User getUser(User user){
JdbcTemplate jdbcTemplate = JdbcTemplateUtil.getJdbcTemplate();
String sql = "select * from login where username=? and password=?";
Object[] args = {user.getUsername(),user.getPassword()};
List<User> list = jdbcTemplate.query(sql, new BeanPropertyRowMapper<>(User.class), args);
if(list.isEmpty()){
return null;
}
return list.get(0);
}
}

@WebServlet(name = "LoginServlet", urlPatterns="/loginServlet")
public class LoginServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
 
String userName = request.getParameter("userName");
String password = request.getParameter("password");
 
LoginDao dao = new LoginDao();
User testUser = new User();
testUser.setUsername(userName);
testUser.setPassword(password);
 
User user = dao.getUser(testUser);
if(user != null){
request.getRequestDispatcher("success.html").forward(request,response);
}else{
request.getRequestDispatcher("error.html").forward(request,response);
}
}
 
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request,response);
}
}

<div>
<form action="/loginServlet" method="post">
<h2 >登录页面</h2>
<input type="text" name="userName" placeholder="用户名" >
<input type="password" name="password" placeholder="密码">
<button type="submit">登录</button>
</form>
</div>