Erro:
HTTP Status 400 - type Status report
message description The request sent by the client was syntactically incorrect.
Apache Tomcat/7.0.78
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/fmt" prefix="fmt" %>
<!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>Insert title here</title>
</head>
<body>
<h3>Alterar Contas</h3>
<form action="alteraConta" method="post">
Descrição: <br>
<textarea rows="5" cols="100" name="descricao">${conta.descricao}</textarea>
<br><br>
Valor: <br>
<input type="text" name="valor" value="${conta.valor}">
<br><br>
Tipo: <br>
<select name="tipo">
<option value="ENTRADA" ${conta.tipo=='ENTRADA' ? 'selected':''}>Entrada</option>
<option value="SAIDA" ${conta.tipo=='SAIDA' ? 'selected':''}>Saída</option>
</select>
<br><br>
Pago? <input type="checkbox" name="paga" ${conta.paga?'checked':''} />
<br><br>
Data de Pagamento: />
<br><br>
<input type="hidden" id="id" name="id" value="${conta.id}">
<input type="submit" value="Alterar Conta">
</form>
</body>
</html>
@RequestMapping("/alteraConta")
public String altera(Conta conta) {
ContaDAO contaDAO = new ContaDAO();
contaDAO.altera(conta);
return "redirect:listaConta";
}
`