在student.java方法"student1()"中获取空值.来自studentDAO.java? [英] Getting null values in student.java method "student1()" from studentDAO.java?
问题描述
student.java
student.java
import java.io.*;
public class Student implements Serializable {
String name;
String id1,phone,clas;
public Student() {
}
public String showStudent() {
return "Name: "+name+" Address: "+clas+" Phone: "+phone+" ID: "+id1;
}
public void Student1(String id,String n,String c,String ph) {
name=n;
id1=id;
phone=ph;
clas=c;
}
}
StudentDAO.java
StudentDAO.java
import java.sql.*;
import java.io.*;
public class StudentDAO implements Serializable {
static String id,detailsi,nam,ph,clas,i;
public void searchinfo(String id2) {
id=id2;
try {
String url="jdbc:ucanaccess://C:\\Users\\Asim Iqbal\\Documents\\IT.accdb";
Connection conn = DriverManager.getConnection(url);
String sql= "SELECT * FROM Student WHERE ID=?";
PreparedStatement stmt = conn.prepareStatement(sql);
stmt.setString(1,id);
ResultSet rs=stmt.executeQuery();
if (rs.next()) {
i=rs.getString("ID");
nam=rs.getString("Name");
clas=rs.getString("Class");
ph=rs.getString("Phone");
Student studentinfo=new Student();
studentinfo.Student1(i, nam, clas, ph);
}
} catch (SQLException e) {
}
}
}
second.jsp
second.jsp
<html>
<body>
<%
String id =request.getParameter("ID1");
StudentDAO std=new StudentDAO();
Student st=new Student();
std.searchinfo("id");
%>
<h1> <%=st.showStudent()%> </h1>
</body>
</html>
从studentDAO.java中在student.java方法"student1()"中获取空值? StudentDAO.java正确连接了数据库，并分别正确地给出了结果..但不将值作为参数传递给Student.java文件中的"student1()". 请建议我哪里错了...
Getting null values in student.java method "student1()" from studentDAO.java?? StudentDAO.java connects DB properly and give result properly as individually.. But not passing values as a parameter to "student1()" in Student.java file.. Please suggest where i am getting wrong...
推荐答案
将public void searchinfo(String id2)更改为public Student searchinfo(String id2)并返回studentinfo [即学生对象].
Change public void searchinfo(String id2) to public Student searchinfo(String id2) and return studentinfo[i.e. Student object].
//JSP更正
String id = request.getParameter("ID1");
StudentDAO std = new StudentDAO();
Student st = std.searchinfo(id);
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