java – 如何在Session的帮助下通过Bean将参数从Servlet传递到JSP页面？

2019年8月3日 149次阅读

如下所述,我对代码进行了更改,如下例所示,但它没有在JSP中显示firstname和lastname：

Servlet代码：

//....
HttpSession session = request.getSession();
Person person = (Person) session.getAttribute("person");
if (person == null) {
    person = new Person();                      
}
person.setNewId(newId);
person.setFirstName(firstName);
person.setLastName(lastName);
session.setAttribute("person", person);

RequestDispatcher rd = request.getRequestDispatcher("jsp Address");
rd.forward(request, response);

人豆代码：

private int newId;
private String firstName;
private String lastName;

// Default Constructor
public Person() {}

public Person(int newId, String firstName, String lastName) {
    setNewId(newId);
    setFirstName(firstName);
    setLastName(lastName);
}

//Getter and Setter Methods
public int getNewId() {return newId;}
public void setNewId(int newID) {this.newId = newID;}
public String getFirstName() {return firstName;}
public void setFirstName(String FirstName) {this.firstName = FirstName;}
public String getLastName() {return lastName;}
public void setLastName(String LastName) {this.lastName = LastName;}

在JSP代码中：

<jsp:useBean id="person" type="app.models.Person" scope="session">
    <jsp:getProperty name="person" property="firstName" />
    <jsp:getProperty name="person" property="lastName" />
</jsp:useBean>

此JSP页面的输出：无

预期输出：firstName lastName

问题：

1. How can i pass parameters from Servlets to JSP via Bean with help of Session? 
2. Is there a better way to do this code? I am using MVC architecture.

最佳答案 摆脱< jsp：useBean>.当使用type属性而不是class时,它不会检查作用域中是否已有实例,它将使用新的空白默认构造实例覆盖您在servlet中创建的Person实例.

使用“MVC架构”时,< jsp：useBean>标签没用.删除它,只需使用通常的EL访问它：

${person.firstName} ${person.lastName}

或者更好的是,要防止XSS attacks,请使用JSTL< c：out>.

<c:out value="${person.firstName} ${person.lastName}" />
点赞