无法使用此servlet处理POST请求

时间：2017-04-01 21:58:11

标签： javascript java html json servlets

这是我的servlet 

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

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

//import org.json.JSONObject;
import org.json.simple.JSONObject;

import com.mysql.jdbc.Statement;
/**
 * Servlet implementation class Login
 */
@WebServlet("/Login")
public class Login extends HttpServlet {
    private static final long serialVersionUID = 1L;
    private Connection connection;
    /**
     * @see HttpServlet#HttpServlet()
     */
    public Login() {
        super();
        // TODO Auto-generated constructor stub
    }

    public void init(ServletConfig config) throws ServletException {
        ServletContext context = config.getServletContext();
        String url = context.getInitParameter("dbUrl");
        String dbUser = context.getInitParameter("dbUser");
        String dbPassword = context.getInitParameter("dbPassword");
        try {
            Class.forName("com.mysql.jdbc.Driver");
            connection = DriverManager.getConnection(url, dbUser, dbPassword);
        } catch (ClassNotFoundException | SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    public void destroy() {
        if (connection != null) {
            try {
                connection.close();
            } catch (SQLException e) {
            }
        }
    }
    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);

    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("plain/text");

        JSONObject json = new JSONObject();
        PrintWriter out = response.getWriter(); 
        String usernameV = request.getParameter("usernameV");
        String passwordV = request.getParameter("passwordV");

        json.put("ris", 0);
        try {
            String sql = "SELECT * FROM user WHERE username = ? AND password = ? ";         
            PreparedStatement stmt = connection.prepareStatement(sql);
            stmt.setString(1, usernameV);
            stmt.setString(2, passwordV);
            json.put("password", usernameV);
            json.put("username", usernameV);

            out.print(json.toJSONString());
            ResultSet rs = stmt.executeQuery();
            if (rs.next()) {
                json.replace("ris", 1);
                out.print(json.toJSONString());
                stmt.close();
                rs.close();
                return;
            }
            stmt.close();
            rs.close();
        } catch (SQLException e) {
            json.replace("err", e.getMessage());
            out.print(json.toJSONString());

        }


        out.print(json.toJSONString());``
    }

    }

这是我的javascript

＆＃13;
＆＃13; 
$(document).ready(function() {
	$(window).keydown(function(event){//impedisco l'invio del form premendo invio
		if(event.keyCode == 13) {
			event.preventDefault();
			return false;
		}
	});
	
	$("#bottone").click(function(){
		$("#risultato").attr("style", "color: black;");
		$("#risultato").html("Caricamento...");	
		var username = $("#username").val();
		var password = $("#password").val();
		$.ajax({
			type: "POST",
			url: "Register",
			//data: {"username" : username, "password": password},
			data: "username=" + username + "&password=" + password,
			dataType: "text",
			success: function(msg)
			{				
				var result = $.parseJSON(msg);				
				if(result.error){
					switch (result.error) {
					case 1:
						Step();
						      
						break;
					default:
						$("#risultato").html(msg);
					break;
					}
				}else{
					$("#bottone").prop('disabled', true);
					$("#risultato").attr("style", "color: black;");
					$("#risultato").html("Benvenuto " + username + "!");
				}					        
			},
			error: function()
			{
				$("#risultato").attr("style", "color: red;");
				$("#risultato").html("Errore di connessione!");
			}
		});
	});
});

function Step() {
	$("#risultato").attr("style", "color: red;");
	$("#risultato").html("Username gi&agrave; esistente!<br>");
	$("#risultato").append("<p>Inserisci la tua password : <input type='password' name='passwordV' id='passwordV'> <input type='button' id='bottone1' value='Login'> </p>");
	
	$("#bottone1").click(function(){
		$("#res").attr("style", "color: black;");
		$("#res").html("Caricamento...");	
		var username = $("#username").val();
		var password = $("#passwordV").val();
	$.ajax({
		type: "POST",
		url: "Login",
		data: "usernameV=" + username + "&passwordV=" + password,
		dataType: "text",
		success: function(msg)
		{				
			var resulto = $.parseJSON(msg);				
			if(resulto.ris){
				switch (resulto.ris) {
				case 1:
					$("#res").attr("style", "color: red;");
					$("#res").html("Benvenuto " + username + "!");
					      
					break;
				default:
					$("#res").html(msg);
				break;
				}
			}else{
				$("#bottone1").prop('disabled', true);
				$("#res").attr("style", "color: black;");
				$("#res").html("password errata:"+ password);
				$("#stack").attr("style", "color: black;");
				$("#stack").html(msg);
			}					        
		},
		error: function()
		{
			$("#res").attr("style", "color: red;");
			$("#res").html("Errore di connessione!");
		}
	});
	});
}
＆＃13;
＆＃13;
＆＃13;  如果有帮助，我也会发布default.jsp页面：

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Chat Room</title>
<script type="text/javascript" src="jquery-3.2.0.js"></script>
<script type="text/javascript" src="script.js"></script>
</head>
<body>

    <form name="modulo" action="">
        <p>
            Nome utente: <input type="text" name="username" id="username">
            Password:    <input type="password" name="password" id="password">
            <input type="button" id="bottone" value="Registrati!">
        </p>
    </form>
    <div id="risultato"></div>
    <div id ="res"></div>
    <div id="stack"></div>


</body>
</html>

我还添加了Register.java servlet ..这个工作正常，而且，正如您所看到的，它几乎与登录的一样。

package it.marco.chat.servlets;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

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

//import org.json.JSONObject;
import org.json.simple.JSONObject;

import com.mysql.jdbc.Statement;

/**
 * Servlet implementation class Register
 */
@WebServlet("/Register")
public class Register extends HttpServlet {
    private static final long serialVersionUID = 1L;
    private Connection connection;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public Register() {
        super();
    }

    /**
     * @see Servlet#init(ServletConfig)
     */
    public void init(ServletConfig config) throws ServletException {
        ServletContext context = config.getServletContext();
        String url = context.getInitParameter("dbUrl");
        String dbUser = context.getInitParameter("dbUser");
        String dbPassword = context.getInitParameter("dbPassword");
        try {
            Class.forName("com.mysql.jdbc.Driver");
            connection = DriverManager.getConnection(url, dbUser, dbPassword);
        } catch (ClassNotFoundException | SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    /**
     * @see Servlet#destroy()
     */
    public void destroy() {
        if (connection != null) {
            try {
                connection.close();
            } catch (SQLException e) {
            }
        }
    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doPost(request, response);
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
     *      response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("plain/text");

        JSONObject json = new JSONObject();
        PrintWriter out = response.getWriter();
        json.put("error", 0);


        String username = request.getParameter("username");
        String password = request.getParameter("password");


        try {
            String sql = "SELECT * FROM user WHERE username = ?";           
            PreparedStatement stmt = connection.prepareStatement(sql);
            stmt.setString(1, username);
            ResultSet rs = stmt.executeQuery();
            if (rs.next()) {
                json.replace("error", 1);
                out.print(json.toJSONString());
                stmt.close();
                rs.close();
                return;
            }
            stmt.close();
            rs.close();
        } catch (SQLException e) {
        }


        int uid = -1;

        try {
            String sql = "INSERT INTO user(username,password) VALUES(?,?)";
            PreparedStatement stmt = connection.prepareStatement(sql, Statement.RETURN_GENERATED_KEYS);
            stmt.setString(1, username);
            stmt.setString(2, password);
            stmt.execute();
            ResultSet rs = stmt.getGeneratedKeys(); 
            if (rs.next()) {
                uid = rs.getInt(1);
            }
            stmt.close();
            rs.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }


        json.put("uid", uid);

        out.print(json.toJSONString());
    }

}

我无法理解为什么servlet无法处理POST请求。我的意思是，我已经设置了一个servlet来处理寄存器部分并且它工作正常。 我整个晚上都试着让它发挥作用，我很确定这是一个我无法看到的愚蠢错误，这就是我来这里的原因。 我希望有人能够帮助我。 谢谢

1 个答案:

答案 0 :(得分：0)

改变这个：

@WebServlet("/Login")

到

@WebServlet(name = "Login", urlPatterns = { "/Login" })

它会起作用相信我

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