我想使用servlet从mysql数据库中检索图像，并在表中显示该图像以及该用户的详细信息 [英] I want to retrieve image from mysql database using servlet and show that image along with that user details in table
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问题描述
一切正常.当我删除用于获取图像的代码时，我会在表中获得用户详细信息，而当我将代码与打印用户详细信息的代码一起用于获取图像时，我只会获取图像作为输出. 我想同时显示它们和表中的内容.
Everything is working well. When I delete Code for Retrieving image then I get user details in table and when I put the code to retrieve image along with the code of printing user details then I only get image as an output. I wanted to print both of them and inside the table as other details appears.
代码如下所示:
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class Welcome
*/
public class Welcome extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public Welcome() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
ServletOutputStream out =response.getOutputStream();
response.setContentType("text/html");
String uniroll =(String) request.getAttribute("UROLL");
out.println("<html>");
out.println("<link rel=\"stylesheet\" type=\"text/css\" href=\"Bootstrap/bootstrap.min.css\">");
out.println(" <link rel=\"stylesheet\" type=\"text/css\" href=\"style.css\">");
out.println("<body>");
out.println("<div class='container'>");
out.println("<h3>Welcome</h3> ");
try{
Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/college_record","root","20wasadk");
String query="SELECT * FROM students_detail WHERE University_Roll=?";
PreparedStatement ps = con.prepareStatement(query);
ps.setString(1, uniroll);
ResultSet rs =ps.executeQuery();
while(rs.next()){
String imgLen="";
imgLen=rs.getString(11);
int len=imgLen.length();
byte[] rb =new byte[len];
InputStream readImg =rs.getBinaryStream(11);
int index=readImg.read(rb, 0, len);
out.println("<section class='col-md-6' id=\"signupbox\" >");
out.println("<table class='table table-hover'>");
out.println("<tr><th>First Name</th><td>"+ rs.getString(1)+"</td></tr>");
out.println("<tr><th>Last Name</th><td>"+ rs.getString(2)+"</td></tr>");
out.println("<tr><th>Sex</th><td>"+ rs.getString(3)+"</td></tr>");
out.println("<tr><th>Father's Name</th><td>"+ rs.getString(4)+"</td></tr>");
out.println("<tr><th>Class Roll</th><td>"+ rs.getString(5)+"</td></tr>");
out.println("<tr><th>University Roll</th><td>"+ rs.getString(6)+"</td></tr>");
out.println("<tr><th>Branch</th><td>"+ rs.getString(7)+"</td></tr>");
out.println("<tr><th>Contact No</th><td>"+ rs.getString(8)+"</td></tr>");
out.println("<tr><th>Permanent Address</th><td>"+ rs.getString(9)+"</td></tr>");
out.println("<tr><th>Password</th><td>"+ rs.getString(10)+"</td></tr>");
out.println("<tr><th>Index</th><td>"+index +"</td></tr>");
ps.close();
response.reset();
response.getOutputStream().write(rb,0,len);
response.getOutputStream().flush();
}
out.println("<table>");
}
catch(ClassNotFoundException ce){
ce.printStackTrace();
}
catch(SQLException se){
se.printStackTrace();
}
out.println("<section >");
out.println("<div>");
out.println("</body>");
out.println("</html>");
}
}
推荐答案
您可以对图像数据进行Base64编码，并使用img标签的src属性中的"nofollow">数据URI ，例如<img src="data:image/png;base64,iVBORw0KGgoAAAANS... (the Base64 encoded image data) ...8bgAAAAASUVORK5CYII=>.
You could Base64-encode your image data and use the data URI in the src attribute of an img tag, e.g. <img src="data:image/png;base64,iVBORw0KGgoAAAANS... (the Base64 encoded image data) ...8bgAAAAASUVORK5CYII=">.
一些注意事项:
- 在旧版本的IE(不支持IE8且IE8中数据大小受到限制)中不支持该功能；
- 我认为以这种方式嵌入动态图像不是一个好主意，正确的方法是拥有一个单独的servlet来仅为图像提供服务，并在
src属性中使用普通的URI.请参阅上面链接页面中的重要说明部分.
- It is not supported in old IE versions (older than IE8, and the size of data is limited in IE8);
- I don't think it is a good idea to embed the dynamic images this way, proper way would be to have a separate servlet just to serve the images, and use a normal URI in the
srcattribute. See the Important Notes part in the above linked page.
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