【发布时间】：2016-02-26 13:27:08
【问题描述】：
我有以下 DAO 文件。
package org.DAO;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.RequestDispatcher;
import org.bean.UserBean;
import org.code.general.DBConnection;
public class GetDataDAO {
DBConnection dbConnection = new DBConnection();
public List<UserBean> list() throws Exception {
List<UserBean> userBeans = new ArrayList<UserBean>();
try {
Connection conn = dbConnection.conn;
Statement stmt = dbConnection.stmt;
ResultSet rs = dbConnection.rs;
PreparedStatement ps = dbConnection.ps;
String excelPath = dbConnection.excelPath;
String queryString = null;
dbConnection.createClassForName();
conn = DriverManager.getConnection(
"jdbc:odbc:Driver={Microsoft Excel Driver (*.xls)};DBQ=" + excelPath + "; READONLY=FALSE;");
System.out.println("Connecting to database…");
System.out.println("Oracle JDBC Driver Registered!");
if (conn != null) {
System.out.println("You made it, take control your database now!");
} else {
System.out.println("Failed to make connection!");
}
stmt = conn.createStatement();
queryString = "Select * from [report1448039568905$] where ([Case Owner] = 'SSHD' or [Case Owner] = 'Hyderabad Operations' or [Case Owner] = 'Customer Service- Core')";
rs = stmt.executeQuery(queryString);
ResultSetMetaData rsmd = rs.getMetaData();
int rowCount = rsmd.getColumnCount();
System.out.println("bno of cols are " + rsmd.getColumnCount());
for (int i = 0; i < rowCount; i++) {
System.out.print(rsmd.getColumnName(i + 1) + " \t");
System.out.println(rsmd.getColumnTypeName(i + 1));
}
while (rs.next()) {
UserBean userBean = new UserBean();
userBean.setCaseNumber(rs.getString(1));
userBean.setCaseOwner(rs.getString(2));
userBean.setStatus(rs.getString(4));
userBean.setIssue(rs.getString(5));
userBean.setReason(rs.getString(6));
userBean.setDateOpened(rs.getString(7));
userBean.setAge(rs.getInt(8));
userBeans.add(userBean);
}
} catch (Exception e) {
e.printStackTrace();
}
return userBeans;
}
}
还有下面的Servlet
package org.servlet;
import org.DAO.*;
import org.bean.UserBean;
import java.io.IOException;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/GetData")
public class GetData extends HttpServlet {
private static final long serialVersionUID = 1L;
public GetData() {
super();
}
GetDataDAO getdatadao = null;
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// set content type
try {
getdatadao = new GetDataDAO();
List<UserBean> userBeans = getdatadao.list();
request.setAttribute("userBeans", userBeans);
request.getRequestDispatcher("DisplayTable.jsp").forward(request, response);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
在这里，我尝试使用以下代码在 jsp 文本框中打印第一个值 (caseNumber)。
<body>
<table border=2 width="45%">
<tr>
<td colspan="2" align="center"><b>Comedy Movies</b></td>
</tr>
<tr>
<td><b>Title</b></td>
<td><b>Description</b></td>
</tr>
<tr>
<td>Case Number</td>
<td><c:out value="${userBeans[0].toString()}" /></td>
</tr>
</table>
</body>
但我得到的输出如下。
org.bean.UserBean@16c8f41
但不是这个，我需要那里的确切值。请让我知道我哪里出错了，我该如何解决。
【问题讨论】：
-
确切的值是什么？ UserBean 有 7 个我们知道的属性。您正在调用 toString() 。这将调用... toString()。所以如果你没有重写 toString()，它将默认为 Object 的 toString() 实现。如果要显示 UserBean 的案例编号，请使用...
userBeans[0].caseNumber，而不是userBeans[0].toString()。 -
说真的，休息一下，阅读一本不错的 Java 书籍/教程，然后阅读 JSP/JavaEE 书籍/教程。