viewcategory.java

一个jsp+javabean实例的简单应用

package com.jspdev.ch12;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;

import com.jspdev.util.DataBaseConnection;

public class ViewCategory {
	private Connection con;
	
	//公共方法，获得数据库连接
	public ViewCategory() {
		this.con = DataBaseConnection.getConnection();
	}
	/**
	 *返回商品的所有分类，返回的Collection中包含Category值对象 
	 */
	public Collection getAllCategory() throws Exception {
		Statement stmt = null;
		try {
			stmt = con.createStatement();
		} catch(Exception e) {
			e.printStackTrace();
		}
		ResultSet rst = stmt.executeQuery("select * from category");
		Collection ret = new ArrayList();
		while(rst.next()) {
			Category temp = new Category();
			temp.setCategoryId(rst.getString("catid"));
			temp.setName(rst.getString("name"));
			temp.setDescription(rst.getString("descn"));
			ret.add(temp);
		}
		//关闭连接，rst和stmt将自己关闭
		con.close();
		return ret;
	}
	
	public static void main(String[] args) {
		ViewCategory a = new ViewCategory();
		Collection b = null;
		try {
			b = a.getAllCategory();
		} catch (Exception e) {
			e.printStackTrace();
		}
//		if(b != null) {
//			System.out.print("到这里是正确的！");
//		}
		Iterator ite = b.iterator() ;
		while(ite.hasNext()) {
			Category temp = (Category)ite.next();
			System.out.print(temp.getCategoryId());
		}
	}
}