java - 如何链接 JSP、servlet 和 Java 视图 bean？

Question

如何链接 JSP、servlet 和 Java 视图 bean？我不想在 JSP 中有任何脚本。我如何要求我的 JSP 调用 servlet 来设置隐式请求和响应对象，然后在 jsp 上显示来自视图 bean 的属性。

我需要将请求和响应对象从 jsp 传递到 servlet，然后我想将视图 bean 中定义的属性显示到 JSP 页面。

JSP -> Servlet -> 查看 Bean -> JSP

如何做到这一点？

Answer 1

无需向 bean/model 传递请求和响应，因为您的模型类是在或中实例化的。JSPsServlets

您必须选择以 servlet 为中心的方法。

ViewBean.java

---

package in.abc.model;

public class Employee{
     private Integer id;
     private String  name;
     public Employee() { id=0; name="";}
     public Employee(Integer id, String name) { this.id=id; this.name=name;}
     public Integer getId()  { return id;}
     public String getName() { return name;}
     public void setId(Integer id) { this.id=id;}
     public void setName(String name) { this.name=name;}
}

ViewServlet.java

---

package in.abc.servlets;

@WebServlet(name = "ViewServlet", urlPatterns = {"/view"})
public class ViewServlet extends HttpServlet{
  public doGet(HttpServletRequest request,
               HttpServletResponse response) 
                 throws ServletException, IOException {

         //Instantiate the model 
         Employee emp=new Employee(10,"Mr.A");

         //Insert "model" object to request
         request.setAttribute("emp",emp);

         //forward the request to view.jsp
         request.getRequestDispatcher("/view.jsp").
                  forward(request,response);
  }

 public doPost(HttpServletRequest request,
               HttpServletResponse response) 
                 throws ServletException, IOException {

         //Instantiate the model 
         Employee emp=new Employee();

         //Read the request
         try{
             emp.setId(Integer.parseInt(request.getParameter("id"));
         }catch(Exception ex) {}
         emp.setName(request.getParameter("name"));

         //Insert "model" object to request
         request.setAttribute("emp",emp);

         //forward the request to view.jsp
         request.getRequestDispatcher("/view.jsp").
                  forward(request,response);
  }
}

视图.jsp

---

<h3>Employee info</h3>
<p>ID : ${emp.id}</p>
<p>Name : ${emp.name}</p>

<form method="post" action="view">
   <br/> <input type="text" name="id"/> 
   <br/> <input type="text" name="name"/>
   <br/> <input type="submit"/>
</form>

索引.jsp

---

<h1>
  <a href="view">View Employee details</a>
</h1>