我正在做一个学校项目，我需要使用JSF制作CRUD应用。我正在使用MySQL数据库，并设法列出所有对象，删除按钮，并且在编辑按钮时遇到了麻烦。
[单击编辑后，将我重定向到edit.xhtml页面，获取ID并根据该ID填写所有字段。当我单击编辑页面上的更新按钮时，它将始终更改id = 0的客户。
我有一个带有getter，setter和方法的java文档有两个视图index.xhtml和edit.xhtml和一页包含与数据库连接的方法。
除更新外，所有其他方法都可以正常工作。
Customer.java
@ManagedBean
@RequestScoped
public class Customer {
private int id;
private String username;
private String adress;
private int quantity;
private double price;
private Map<String, Object> sessionMap = FacesContext.getCurrentInstance().getExternalContext().getSessionMap();
public String edit() {
FacesContext fc = FacesContext.getCurrentInstance();
Map<String, String> params = fc.getExternalContext().getRequestParameterMap();
String primarId = params.get("action");
System.out.println(primarId);
try {
DatabaseConnection dbc = new DatabaseConnection();
Connection connection = dbc.getConnection();
Statement st = connection.createStatement();
ResultSet rs = st.executeQuery("select * from customer where customer_id=" + primarId);
Customer customer = new Customer();
rs.next();
customer.setUsername(rs.getString("username"));
customer.setAdress(rs.getString("adress"));
customer.setQuantity(rs.getInt("quantity"));
customer.setPrice(rs.getDouble("price"));
sessionMap.put("editcustomer", customer);
} catch (SQLException ex) {
System.out.println(ex);
}
return "/edit.xhtml?faces-redirect=true";
}
public String updateCustomer() {
FacesContext fc = FacesContext.getCurrentInstance();
Map<String, String> params = fc.getExternalContext().getRequestParameterMap();
String fieldId = params.get("action");
System.out.println(fieldId);
try {
DatabaseConnection dbc = new DatabaseConnection();
Connection connection = dbc.getConnection();
PreparedStatement ps = connection.prepareStatement("update customer set username=?,adress=?,quantity=?,price=? where customer_id=?");
ps.setString(1, username);
ps.setString(2, adress);
ps.setInt(3, quantity);
ps.setDouble(4, price);
ps.setInt(5, id);
System.out.println(id);
ps.executeUpdate();
} catch (SQLException ex) {
System.out.println(ex);
}
return "/index.xhtml?faces-redirect=true";
}
edit.xhtml
<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://xmlns.jcp.org/jsf/html"
xmlns:f="http://java.sun.com/jsf/core">
<h:head>
<title>Facelet Title</title>
</h:head>
<h:body>
<center>
<h:form>
Username: <h:inputText value="#{editcustomer.username}"></h:inputText> <br/>
Adress: <h:inputText value="#{editcustomer.adress}"></h:inputText> <br/>
Quantity: <h:inputText value="#{editcustomer.quantity}"></h:inputText> <br/>
Price: <h:inputText value="#{editcustomer.price}"></h:inputText> <br/><br/>
<h:commandButton value="Update" action="#{editcustomer.updateCustomer()}">
<f:param name="action" value="#{editcustomer.id}" />
</h:commandButton>
</h:form>
</center>
</h:body>
</html>
当我运行此代码时，ID保持为0
我认为问题是bean中的@RequestScoped批注。使用此注释数据，仅“存在”在当前页面中。当您重定向到另一个URL（虽然它是相同的）时，您所做的更改会丢失（更多考虑到您将客户置于会话映射中。请尝试使用@SessionScoped。
希望它起作用。