servlet2a.java

自己编写的JSP上传组件。呵呵！！！要用自己下吧

import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;

public class servlet2a extends HttpServlet {
	
	private ServletConfig config;
	/**
	* 初始化servlet
	*/
	final public void init(ServletConfig config) throws ServletException {
		this.config = config;
	}
	
	final public ServletConfig getServletConfig() {
		return config;
	}
	/**
	* 处理 GET 类型请求
	*/
	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
               String pic_id = request.getParameter("id");
               showpic(response,pic_id);
	}
	
	/**
	* 处理 POST 类型请求
	*/
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
               String pic_id = request.getParameter("id");
               showpic(response,pic_id);
        }

	/**
	* 显示图片
	*/
	public void  showpic (HttpServletResponse response,String id) {
               //设置文件类型为jpeg图片
               response.setContentType("image/jpeg");
               String jdbcDriver = "com.mysql.jdbc.Driver";
               String jdbcURL = "jdbc:mysql://localhost:3306/test";
               String user = "root";
               String password = "";
               PreparedStatement pstmt = null;
               ResultSet rs = null;
               String sql = null;

               try {
                 //注册驱动程序，并连接数据库
                 Class.forName(jdbcDriver).newInstance();
                 Connection conn = DriverManager.getConnection(jdbcURL, user, password);

                 //从数据库里读取图片
                 sql = "SELECT FILE FROM FILES WHERE ID = "+id;
                 pstmt = conn.prepareStatement(sql);
                 rs = pstmt.executeQuery();
                 rs.next();
                 byte[] buffer = rs.getBytes(1);

                 //显示图片
                 BufferedOutputStream out = new BufferedOutputStream(response.getOutputStream());
                 out.write(buffer);
                 out.flush();
                 out.close();
     
                 //关闭数据库连接
                 rs.close();
                 pstmt.close();
                 conn.close();
                 }
                 catch (Exception e) {
                   System.out.println(e.toString());
                 }
	}        
        
	/**
	* 注销servlet
	*/
	public void  destroy () {
	}

}