图片以二进制保存到Oracle,取出并显示到页面示例

  用过数据库的人都知道,像文件、图片、视频等这些大对象可以用两种方式来存取:1.将这些对象放到服务器的某个文件中,将它们的路径保存到数据库;2.直接将这些文件对象以二进制形式保存到数据库中,用时再通过流对象读取出来。
  可能大多数人采用第一种方式,这里我主要试下第二种方式保存数据,原理主要是通过Oracle里面的BLOB数据类型来实现。
  这个示例主要是将页面的学生信息录入数据库,然后点击查看按钮马上可以查看当前保存用户的资料,实现截图如下:
 

  新建一张学生表,字段如下:

  Student类
 

/**
 * 学生类
 * 
 */
public class Student {
	private int id;
	private String sex;
	private String username;
	private String picName;

	public String getPicName() {
		return picName;
	}

	public void setPicName(String picName) {
		this.picName = picName;
	}

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getSex() {
		return sex;
	}

	public void setSex(String sex) {
		this.sex = sex;
	}

	public String getUsername() {
		return username;
	}

	public void setUsername(String username) {
		this.username = username;
	}

	public String toString() {
		return "id: " + id + " username: " + username + " sex: " + sex;
	}
}
  

 
  Oracle数据库连接
 

/**
 * 与Oracle数据库连接
 * 
 */
public class OracleConnection {
	private static String ojdbcURL = "jdbc:oracle:thin:@localhost:1521:xe";
	private static String ojdbcDriver = "oracle.jdbc.driver.OracleDriver";
	private static String userName = "czc";
	private static String password = "netjava";
	private static Connection connec;

	public static Connection getConnec() {
		if (connec != null) {
			return connec;
		}
		try {
			Class.forName(ojdbcDriver);
			connec = DriverManager.getConnection(ojdbcURL, userName,     password);
			System.out.println("与oracle数据库连接成功...");
		} catch (Exception e) {
			System.out.println("与oracle数据库连接失败...");
			e.printStackTrace();
		}
		return connec;
	}
}
  

  Student操作类
 

/**
 * 数据操作
 */
public class StudentDAO {

	/**
	 * 将学生信息保存到数据库
	 * 
	 * @param stu:学生对象
	 * @return :是否成功
	 */
	public boolean savaStuMsg(Student stu) {
		try {
			// 取得数据库连接对象
			Connection connec = OracleConnection.getConnec();
			// 写插入SQL
			String sql = "insert into student(name,sex,picture) values(?,?,?)";
			// 得到预编译对象
			PreparedStatement pstm = connec.prepareStatement(sql);
			pstm.setString(1, stu.getUsername());
			pstm.setString(2, stu.getSex());
			// 创建一个文件输入流对象
			FileInputStream fins = new FileInputStream(stu.getPicName());
			// 将图片以二制数据保存到数据库
			pstm.setBinaryStream(3, fins, fins.available());
			pstm.addBatch();
			pstm.executeBatch();
			System.out.println("学生信息保存成功!");
			return true;
		} catch (Exception e) {
			e.printStackTrace();
		}
		return false;
	}

	/**
	 * 根据学生名字查询学生信息
	 * 
	 * @param username:姓名
	 * @return
	 */
	public Student getStuMsg(String username) {
		try {
			Connection connec = OracleConnection.getConnec();
			// 注：where后varchar字段必须加''
			String sql = "select id,sex from student where name='" + username
					+ "'";
			Statement stmt = connec.createStatement();
			ResultSet rset = stmt.executeQuery(sql);
			Student stu = new Student();
			if (rset.next()) {
				stu.setId(rset.getInt("id"));
				stu.setSex(rset.getString("sex"));
				stu.setUsername(username);
			}
			return stu;
		} catch (Exception e) {
			e.printStackTrace();
		}
		return null;
	}

	/**
	 * 查找要显示图片
	 * 
	 * @param id:图片id
	 * @return:缓冲输入流
	 */
	public BufferedInputStream getPicMsg(int id) {
		// 定义一个BLOB对象,这是一种数据对象,关键是这个BLOB对象的作用
		BLOB blob = null;
		try {
			Connection connec = OracleConnection.getConnec();
			String sql = "select picture from student where id=" + id;
			Statement stmt = connec.createStatement();
			ResultSet rset = stmt.executeQuery(sql);
			if (rset.next()) {
				// 得到图片BLOB对象
				blob = (BLOB) rset.getBlob("picture");
			}
			// 得到图片输入流
			InputStream in = blob.getBinaryStream();
			// 包装成缓冲输入流
			BufferedInputStream bfin = new BufferedInputStream(in);
			return bfin;
		} catch (Exception e) {
			e.printStackTrace();
		}
		return null;
	}
}
  

  SaveServlet:处理页面提交信息的Servlet类
 

/**
 * 将提交上来的数据保存到数据库
 *  
 */
public class SaveServlet extends HttpServlet {

	public void service(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		request.setCharacterEncoding("utf-8");
		response.setContentType("text/html;charset=utf-8");
		String username = request.getParameter("username");
		String sex = request.getParameter("sex");
		String picture = request.getParameter("picture");
		System.out.println("username:" + username + " sex:" + sex + " picture:"
				+ picture);
		// 创建一个学生对象
		Student stu = new Student();
		stu.setUsername(username);
		stu.setSex(sex);
		stu.setPicName(picture);
		// 将学生信息保存到数据库
		StudentDAO sdao = new StudentDAO();
		boolean isSuccess = sdao.savaStuMsg(stu);
		if (isSuccess) {
			//将学生的名字放到request中
			request.setAttribute("username", username);
			request.getRequestDispatcher("/success.jsp").forward(request, response);
		}else{
			request.getRequestDispatcher("/error.jsp").forward(request, response);
		}
	}
}
  

SelectServlet:将保存的学生对象信息查询出来的Servlet
 

/**
 * 将保存的学生查找出来
 * 
 */
public class SelectServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		request.setCharacterEncoding("utf-8");
		response.setContentType("text/html;charset=utf-8");
		String username = request.getParameter("username");
		System.out.println("要查询的学生名字是: " + username);
		StudentDAO sdao = new StudentDAO();
		// 根据学生名字得到学生对象
		Student stu = sdao.getStuMsg(username);
		if (stu != null) {
			// 将对象放到session对象中
			request.getSession().setAttribute("stu", stu);
			request.getRequestDispatcher("/display.jsp").forward(request, response);
		}
	}
}
  

核心代码--DisplayServlet:显示图片的Servlet
 

/**
 * 处理显示图片的servlet:将图片显示到页面
 * 
 */
public class DisplayServlet extends HttpServlet {

	public void service(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		response.setContentType("image/jpg");
		// 从session对象中得到学生对象
		Student stu = (Student) request.getSession().getAttribute("stu");
		// 得到图片流对象
		StudentDAO sdao = new StudentDAO();
		BufferedInputStream bfin = sdao.getPicMsg(stu.getId());
		// 将ServletOutputStream包装成BufferedOutputStream
		BufferedOutputStream bout = new BufferedOutputStream(response
				.getOutputStream());
		int i = 0;
		while ((i = bfin.read()) != -1) {
			bout.write(i);
		}
		bfin.close();
		bout.flush();
		bout.close();
	}
}
  

 
  display.jsp:显示学生信息的JSP页面
 

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@ page import="cn.netjava.pojo.Student"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
	<head>
		<base href="<%=basePath%>">

		<title>学生信息</title>

		<meta http-equiv="pragma" content="no-cache">
		<meta http-equiv="cache-control" content="no-cache">
		<meta http-equiv="expires" content="0">
		<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
		<meta http-equiv="description" content="This is my page">
		<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->

	</head>

	<body>
		<%
  			//得到学生对象
  			Student stu =(Student)request.getSession().getAttribute("stu");
  		 %>
		<div style="text-align:center">
			<table>
				<caption>学生信息</caption>
				<tr>
						<td>姓名</td>
						<td><%=stu.getUsername()%></td>
						<!-- 核心代码:显示图片 -->
						<td rowspan="2"><img src="DisplayServlet"></img></td>
				</tr>
				<tr>
						<td>性别</td>
						<td><%=stu.getSex()%></td>
				</tr>
			</table>
		</div>
	</body>
</html>
  

  这个示例的代码已打包,如果有人感兴趣,或有人有更好的实现方法,欢迎大家一起讨论。

评论

5 楼 间谍james 2012-04-03  

PS：追加一下，楼主显示图片是通过id，没有id无法显示

4 楼 间谍james 2012-04-03  

感谢楼主，但是楼主给的jsp代码是否未考虑id，index界面没有增加id，不知道是不是楼主在设计数据库是设为自动增加。
感谢楼主的代码，

3 楼 ~音乐盒~ 2011-11-24  

非常好，谢谢

2 楼 My*Love 2011-04-26  

梦中有你 写道

楼主选的MM 不错

1 楼 梦中有你 2011-04-18  

楼主选的MM 不错