velocity+struts2实例，适合开发和整合使用

package com.ape.service; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.util.Iterator; import java.util.Random; import java.util.Vector; import com.ape.po.User; import com.ape.util.DBHelper; public class UserService { private Connection conn = null; private PreparedStatement ps = null; private ResultSet rs = null; private String sql = ""; public static void main(String[] args) { UserService service = new UserService(); for (int i = 10; i < 500; i++) { User user1 = new User(i, "" + Math.abs(new Random().nextInt())); service.insert(user1); } Vector<User> vector = service.retrieve(); System.out.println("总数量有：" + vector.size()); for (Iterator<User> iterator = vector.iterator(); iterator.hasNext();) { User user = iterator.next(); System.out.println(user.getId() + ": " + user.getName()); } } public Vector<User> retrieve() { Vector<User> vector = new Vector<User>(); try { sql = "SELECT * FROM `user` LIMIT 0, 100"; conn = DBHelper.getConn(); ps = conn.prepareStatement(sql); rs = ps.executeQuery(); User user = null; while (rs.next()) { user = new User(rs.getInt(1), rs.getString(2)); vector.add(user); } } catch (SQLException e) { e.printStackTrace(); } finally { DBHelper.closeAll(conn, ps, rs); } return vector; } public void insert(User user) { try { sql = "insert into user(id,name) values(?,?)"; conn = DBHelper.getConn(); ps = conn.prepareStatement(sql); ps.setInt(1, user.getId()); ps.setString(2, user.getName()); // 成功返回false，否则true ps.execute(); } catch (SQLException e) { e.printStackTrace(); } finally { DBHelper.closeAll(conn, ps); } } }