在jsp页面中显示图像而不是图像url [复制]

Posted 2021-03-29

这个问题在这里已有答案：

• How to retrieve and display images from a database in a JSP page? 5个答案

我试图在JSP页面中显示存储在我的oracle数据库中的图像。图像存储为BLOB数据。

这是我的代码：

<%@page import="utils.MyUtils"%>
<%@ page import="java.sql.*" %> 
<%@ page import="java.io.*" %> 
<% 

 Connection con = MyUtils.getStoredConnection(request);

 String strSQL = "SELECT IMAGE " 
 + "FROM CUSTOMER " 
 + "WHERE CUST_ID= 113"; 
 Statement stmt = con.createStatement(); 
 ResultSet rs = stmt.executeQuery(strSQL); 
 rs.next(); 

 response.setHeader("expires", "0"); 
 response.setContentType("jpeg"); 

 out.clear(); 
 OutputStream os = response.getOutputStream(); 
 os.write(rs.getBytes("IMAGE")); 
 out.flush(); 

%> 

这是MyUtils类：

package utils;

import beans.CreateAcc;
import java.sql.Connection;

import javax.servlet.ServletRequest;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import beans.UserAccount;

public class MyUtils {

    public static final String ATT_NAME_CONNECTION = "ATTRIBUTE_FOR_CONNECTION";

    private static final String ATT_NAME_USER_NAME = "ATTRIBUTE_FOR_STORE_USER_NAME_IN_COOKIE";

    // Store Connection in request attribute.
    // (Information stored only exist during requests)
    public static void storeConnection(ServletRequest request, Connection conn) {
        request.setAttribute(ATT_NAME_CONNECTION, conn);
    }

    // Get the Connection object has been stored in attribute of the request.
    public static Connection getStoredConnection(ServletRequest request) {
        Connection conn = (Connection) request.getAttribute(ATT_NAME_CONNECTION);
        return conn;
    }

    // Store user info in Session.
    public static void storeLoginedUser(HttpSession session, UserAccount loginedUser) {
        // On the JSP can access via ${loginedUser}
        session.setAttribute("loginedUser", loginedUser);
    }

    // Get the user information stored in the session.
    public static UserAccount getLoginedUser(HttpSession session) {
        UserAccount loginedUser = (UserAccount) session.getAttribute("loginedUser");
        return loginedUser;
    }
}

但是当我运行我的代码时，它只显示存储在我的电脑而不是图像中的图像的URL路径。

我该怎么办？

答案

从blob对象获取字节流。将字节流转换为base 64编码的字符串。然后在img标记中使用base 64编码的字符串。您可以使用base 64编码字符串html图像标记。浏览器将渲染图像。

对于以下几点，您将获得大量关于堆栈溢出的帖子

• 如何通过流/数组转换blob数据
• 如何将字节流转换为Base 64编码的字符串
• 如何在HTML图像标记中使用base 64编码的字符串。