从数据库提取数据通过jstl显示在jsp页面上

从数据库提取数据通过jstl显示在jsp页面上

1.ConnectDB.java连接数据库，把数据转换成list

public class ConnectDB {
 private final static String strDriver = "oracle.jdbc.driver.OracleDriver";
 private final static String strConnect = "jdbc:oracle:thin:@localhost:1521:ORCL";
 private final static String strDBUserName = "scott";
 private final static String strDBPWD = "tiger";
 private Connection conn = null;
 private Statement stat = null;
 private ResultSet rs = null;

//连接oracle数据库
 private void getConnectFromOracle() throws ClassNotFoundException,
   SQLException {
  Class.forName(strDriver);// 实例化oracle.jdbc.driver.OracleDriver
  conn = DriverManager.getConnection(strConnect, strDBUserName, strDBPWD);
  stat = conn.createStatement();
 }

//记录基每行数据存放到值对象，然后把值对象存放一个链表
 public List<EMPVO> getListWithVOFromRS() {
  String sql = "select * from emp";
  List<EMPVO> rowList = new LinkedList<EMPVO>();
  EMPVO emp = null;
  try {
   getConnectFromOracle();
   rs = stat.executeQuery(sql);
   while (rs.next()) {
    emp = new EMPVO();
    // 为了简单仅取2个值
    emp.setEname(rs.getString("ename"));
    emp.setHiredate(rs.getString("hiredate"));
    rowList.add(emp);
   }
   closeConnection();
  } catch (ClassNotFoundException e) {
  } catch (SQLException e) {
  }
  return rowList;
 }

//记录基每行数据存放到1个链表，然后把这个链表存放另一个链表
 public List<List<String>> getListWithListFromRS() {
  String sql = "select * from emp";
  List<List<String>> rowList = new LinkedList<List<String>>();
  List<String> colList = null;
  try {
   getConnectFromOracle();
   rs = stat.executeQuery(sql);
   int columnCount = rs.getMetaData().getColumnCount();
   while (rs.next()) {
    colList = new LinkedList<String>();
    for (int i = 1; i <= columnCount; i++) {
     colList.add(rs.getString(i));
    }
    rowList.add(colList);
   }
   closeConnection();
  } catch (ClassNotFoundException e) {
  } catch (SQLException e) {
  }
  return rowList;
 }

//关闭数据库
 public void closeConnection() throws SQLException {
  if (rs != null)
   rs.close();
  if (stat != null)
   stat.close();
  if (conn != null)
   conn.close();
 }
}
2.EMPVO.java emp表的值对象

public class EMPVO {
 private String empno;
 private String ename;
 private String job;
 private String mgr;
 private String hiredate;
 private String sal;
 private String comm;
 private String deptno;

public String getComm() {
  return comm;
 }

public void setComm(String comm) {
  this.comm = comm;
 }

public String getDeptno() {
  return deptno;
 }

public void setDeptno(String deptno) {
  this.deptno = deptno;
 }

public String getEmpno() {
  return empno;
 }

public void setEmpno(String empno) {
  this.empno = empno;
 }

public String getEname() {
  return ename;
 }

public void setEname(String ename) {
  this.ename = ename;
 }

public String getHiredate() {
  return hiredate;
 }

public void setHiredate(String hiredate) {
  this.hiredate = hiredate;
 }

public String getJob() {
  return job;
 }

public void setJob(String job) {
  this.job = job;
 }

public String getMgr() {
  return mgr;
 }

public void setMgr(String mgr) {
  this.mgr = mgr;
 }

public String getSal() {
  return sal;
 }

public void setSal(String sal) {
  this.sal = sal;
 }
}

3.JstlServlet 调用ConnectDB，把List放入request对象，跳转到jstl.jsp

public class JstlServlet extends HttpServlet {

private static final long serialVersionUID = 7129164252442979467L;

public void doGet(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  ConnectDB db = new ConnectDB();
  request.setAttribute("listinlist", db.getListWithListFromRS());
  request.setAttribute("voinlist", db.getListWithVOFromRS());
  request.getRequestDispatcher("jstl.jsp").forward(request, response);
 }

public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  doGet(request, response);
 }
}

4.jstl.jsp

<%@ page language="java" pageEncoding="ISO-8859-1"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>  
  <body>   
   <table>    
    <tr><h1>listinlist</h1></tr>
    <c:forEach items="${listinlist}" var="rowlist">
     <tr>
     <c:forEach items="${rowlist}" var="collist">
      <td>${collist}</td>
     </c:forEach>
     </tr>
    </c:forEach>
   </table>
   <table>
    <tr><h1>voinlist</h1></tr>
    <c:forEach items="${voinlist}" var="empvo">
     <tr>
      <td>${empvo.ename}</td><td>${empvo.hiredate}</td>
     </tr>
    </c:forEach>
   </table>
  </body>
</html>