从数据库中检索图像并在另一个jsp页面中显示 [英] Retrieve Image from Database and display in another jsp page
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问题描述
我正在尝试从数据库中检索多个图像并在另一个 JSP 页面中显示这些图像.首先，我尝试在特定的 JSP 页面中显示单个图像，我检索了但显示显示为文件类型，我想在特定的 JSP 页面中显示该图像.我正在使用 MySQL 数据库.
我的 servlet 代码:
import java.io.IOException;导入 java.sql.Connection;导入 java.sql.DriverManager;导入 java.sql.PreparedStatement;导入 java.sql.ResultSet;导入 java.sql.SQLException;导入 javax.servlet.RequestDispatcher;导入 javax.servlet.ServletException;导入 javax.servlet.annotation.WebServlet;导入 javax.servlet.http.HttpServlet;导入 javax.servlet.http.HttpServletRequest;导入 javax.servlet.http.HttpServletResponse;@WebServlet("/检索")公共类检索扩展 HttpServlet {静止的 {尝试 {Class.forName("com.mysql.jdbc.Driver");} catch (ClassNotFoundException e) {e.printStackTrace();}}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{ 连接 con = null;PreparedStatement ps = null;结果集 rs = null;尝试 {con = DriverManager.getConnection("jdbc:mysql://localhost:3306/vikas", "root", "root");ps = con.prepareStatement("从粗略中选择*");rs=ps.executeQuery();如果(rs.next()){byte[] content = rs.getBytes("image");response.setContentLength(content.length);response.getOutputStream().write(content);request.setAttribute("图片", 内容);RequestDispatcher rd=request.getRequestDispatcher("View.jsp");rd.forward(请求，响应)；} 别的 {response.sendError(HttpServletResponse.SC_NOT_FOUND);//404.}} catch (SQLException e) {throw new ServletException("SQL/DB 级别出现问题.", e);}}}jsp 代码:
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"pageEncoding="ISO-8859-1"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><头><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>显示图片</title><身体><div>显示</div><div style="width:25%; height:25%"><%request.getAttribute("图片");％＞</html>
解决方案
尝试使用 Base64 编码，
使用 Apache Commons Codec 进行 Base64 编码.
byte[] content = rs.getBytes("image");String base64Encoded = new String(Base64.encodeBase64(content), "UTF-8");request.setAttribute("imageBt", base64Encoded);从 JSP 中检索它
<img src="data:image/png;base64,${requestScope['imageBt']}"/>对于多个图像，您可以尝试这样的操作，(我没有尝试过)
List图像 = 新的 ArrayList();如果(rs.next()){byte[] content = rs.getBytes("image");图像.添加(新字符串(Base64.encodeBase64(内容)，UTF-8"))；}request.setAttribute("imageBt", 图像); 在 JSP 中
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%><c:forEach var="img" items="${imageBt}"><img src="data:image/png;base64, ${img}"/></c:forEach>I am trying to retrieve multiple images from database and display those images in another JSP page. First, I tried single image to display in particular JSP page, I retrieved but the display is showing as file type, I want to display that image in particular JSP page. I am using MySQL database.
my servlet code:
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/Retrieve")
public class Retrieve extends HttpServlet {
static {
try {
Class.forName("com.mysql.jdbc.Driver");
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{ Connection con = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
con = DriverManager.getConnection("jdbc:mysql://localhost:3306/vikas", "root", "root");
ps = con.prepareStatement("select * from rough");
rs=ps.executeQuery();
if (rs.next()) {
byte[] content = rs.getBytes("image");
response.setContentLength(content.length);
response.getOutputStream().write(content);
request.setAttribute("image", content);
RequestDispatcher rd=request.getRequestDispatcher("View.jsp");
rd.forward(request, response);
} else {
response.sendError(HttpServletResponse.SC_NOT_FOUND); // 404.
}
} catch (SQLException e) {
throw new ServletException("Something failed at SQL/DB level.", e);
}
}
}
jsp code:
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Display Image</title>
</head>
<body>
<div>THE DISPLAY</div>
<div style="width:25%; height:25%">
<%request.getAttribute("image"); %>
</div>
</body>
</html>
解决方案
Try using Base64 encoding,
Use Apache Commons Codec to do Base64 encodings.
byte[] content = rs.getBytes("image");
String base64Encoded = new String(Base64.encodeBase64(content), "UTF-8");
request.setAttribute("imageBt", base64Encoded);
Retrieve it from JSP
<img src="data:image/png;base64,${requestScope['imageBt']}"/>
For multiple images you could try something like this, (i didnt try this)
List<String> images = new ArrayList<>();
if (rs.next()) {
byte[] content = rs.getBytes("image");
images.add(new String(Base64.encodeBase64(content), "UTF-8"));
}
request.setAttribute("imageBt", images);
In JSP
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<c:forEach var="img" items="${imageBt}">
<img src="data:image/png;base64, ${img}"/>
</c:forEach>
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