Referencing servlet in HTML file for .war file in Tomcat

问题

I have created an index.html file for a Java (.war) application that I deployed on tomcat.

I already have a Java Servlet file that queries a remote db server for a picture i stored there.

The java servlet file is called ImageServlet.java.

I need the HTML page to display that image that the ImageServlet.java queries.

I just don't know how I'm able to reference to the servlet as it retrieves my picture.

Below is the ImageServlet file:

package test;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.sql.Blob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.xml.bind.DatatypeConverter;

public class ImageServlet extends HttpServlet
{
  Connection con = null;

  public Connection getConnection()
  {
    try {
      Class.forName("com.mysql.jdbc.Driver");
      String url = System.getenv("FUJI_MYSQL_URL");
      return DriverManager.getConnection(url,             
System.getenv("FUJI_MYSQL_USER"), System.getenv("FUJI_MYSQL_PASS"));
    }
    catch (Exception ex)
    {
      System.out.println(ex.getMessage());
    }return null;
  }

  public static byte[] getImageById(Connection con)
  {
    String query = "select photo from photos where picid = 1";
    try
    {
      PreparedStatement stmt = con.prepareStatement(query);

      stmt.execute();
      ResultSet resultSet = stmt.getResultSet();
      resultSet.first();
      Blob blob = resultSet.getBlob(1);
      stmt.close();
      con.close();
      return blob.getBytes(1L, (int)blob.length());
    } catch (Exception ex) {
      System.out.println(ex.getMessage());
    }return null;
  }

  public void doGet(HttpServletRequest req, HttpServletResponse res)
    throws ServletException, IOException
  {
    PrintWriter out = res.getWriter();

    Connection con = null;
    con = getConnection();
    byte[] data = getImageById(con);

    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    baos.write(data);

    out.println("<!DOCTYPE html><html xmlns=\"http://www.w3.org/1999/xhtml\"><head><title>PI_SQLogo.png</title></head><body><img src='data:image/png;base64," + DatatypeConverter.printBase64Binary(baos.toByteArray()) + "'></body></html>");
    out.close();
  }
}

回答1:

@WebServlet("/")
public class ImageServlet extends HttpServlet {
    //...
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //...
        byte[] data = getImageById(con);
        response.setContentType("image/jpeg"); // Assuming your image is .jpg
        response.setContentLength(data.length);
        response.getOutputStream().write(data);
    }
    //..
}

Then in your index.html or index.jsp:

<img src="${pageContext.request.contextPath}/foo.jpg">

来源：https://stackoverflow.com/questions/61063101/referencing-servlet-in-html-file-for-war-file-in-tomcat

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java

html

jsp

Tomcat

servlets