database - 从数据库中检索图像并使用 JSTL 在 JSP 中显示它

Question

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Answer 1

是的，您可以使用 JSTL & EL .对于数据库访问，请使用 JSTL SQL Tag library .

How to display images in JSP that is stored in database?

我希望您使用 BLOB 类型的列在数据库中存储图像。只需点击一个传递记录 id 的 Servlet 并发送 byte[] 作为响应。

为了更好的用户体验，我为每张图片创建了单独的请求。

注意:数据库代码最好移到Servlet中

JSP:

<%@ taglib prefix="sql" uri="http://java.sun.com/jsp/jstl/sql"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>

<sql:setDataSource var="webappDataSource"
    driver="com.mysql.jdbc.Driver" url="jdbc:mysql://localhost:3306/test"
    user="root" password="root" />

<sql:query dataSource="${webappDataSource}"
    sql="select id,username from users" var="result" />

<table width="100%" border="1">
    <c:forEach var="row" items="${result.rows}">
        <tr>
            <td>${row.id}</td>
            <td>${row.username}</td>
            <td>
               <img src="${pageContext.servletContext.contextPath }/photoServlet?id=${row.id}" />
            </td>
        </tr>
    </c:forEach>
</table>

Servlet (PhotoServlet.java):

protected void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {

    final String JDBC_DRIVER = "com.mysql.jdbc.Driver";
    final String DB_URL = "jdbc:mysql://localhost:3306/test";
    final String User = "root";
    final String Password = "root";
    try {
        Class.forName(JDBC_DRIVER);
        Connection conn = DriverManager.getConnection(DB_URL, User, Password);

        PreparedStatement stmt = conn.prepareStatement("select photo from users where id=?");
        stmt.setLong(1, Long.valueOf(request.getParameter("id")));
        ResultSet rs = stmt.executeQuery();
        if (rs.next()) {
            response.getOutputStream().write(rs.getBytes("photo"));
        }
        conn.close();
    } catch (Exception e) {
        e.printStackTrace();
    }
}

web.xml:

<servlet>
    <servlet-name>PhotoServlet</servlet-name>
    <servlet-class>com.server.servlet.PhotoServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>PhotoServlet</servlet-name>
    <url-pattern>/photoServlet</url-pattern>
</servlet-mapping>

表结构:(用户)

+----------+-------------+------+-----+---------+-------+
| Field    | Type        | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| id       | int(11)     | NO   | PRI | NULL    |       |
| username | varchar(30) | YES  |     | NULL    |       |
| password | varchar(20) | YES  |     | NULL    |       |
| photo    | blob        | YES  |     | NULL    |       |
+----------+-------------+------+-----+---------+-------+