minha página da erro 400

Minha conexão dá erro 400

mensagem: The server cannot or will not process the request due to something that is perceived to be a client error (e.g., malformed request syntax, invalid request message framing, or deceptive request routing)

meu código:

import javax.persistence.EntityManager; import javax.persistence.PersistenceContext;

import org.springframework.stereotype.Repository; import org.springframework.transaction.annotation.Transactional;

import br.com.ihsl.cq.models.Amostra;

@Repository @Transactional public class AmostrasDAO {

@PersistenceContext
private EntityManager manager;

public void gravar(Amostra amostra) {
    manager.persist(amostra);
    System.out.println("inserido");
}

}

@Entity @Table(name = "AMOSTRA") public class Amostra {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String numero;
private String perfil;
private String cliente;
private double volume;
private Date dataEntrada;
private Date dataColeta;
private Date dataLaudo;
private String lote;

public String toString() {
    return "Amostra[amostra =" + numero + "perfil =" + perfil +  "cliente =" + cliente + ", volume=" + volume + ", dataEntrada=" + dataEntrada + ", dataColeta="
        + dataColeta + ", lote" + lote;

package br.com.ihsl.cq.controllers;

import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping;

import br.com.ihsl.cq.daos.AmostrasDAO; import br.com.ihsl.cq.models.Amostra;

@Controller public class InserirController {

@Autowired
private AmostrasDAO dao;

@RequestMapping("/inserir-amostra")
public String iserir() {
    System.out.println("Cadastro CQ");
    return "cadastro";
}

@RequestMapping(value ="/ok")
public String gravar(Amostra amostra) {
    System.out.println(amostra);
    dao.gravar(amostra);
    return "ok";
}

}

package br.com.ihsl.cq.conf;

import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.ComponentScan; import org.springframework.web.servlet.config.annotation.EnableWebMvc; import org.springframework.web.servlet.view.InternalResourceViewResolver;

import br.com.ihsl.cq.controllers.HomeController; import br.com.ihsl.cq.daos.AmostrasDAO;

@EnableWebMvc @ComponentScan(basePackageClasses= {HomeController.class, AmostrasDAO.class }) public class AppWebConfiguration {

@Bean
public InternalResourceViewResolver internalResourceViewResolver() {
    InternalResourceViewResolver resolver = new InternalResourceViewResolver();
    resolver.setPrefix("/WEB-INF/views/");
    resolver.setSuffix(".jsp");
    return resolver;
}

}