如何在servlet中显示数据库中的图像？

Question

This is the code have no error 这是代码没有错误

import java.io.IOException;
import java.io.InputStream;
import java.sql.Blob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class DisplayBlobServlet extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException,
            ServletException {
        String photoid = request.getParameter("txtid");
        Blob photo = null;
        Connection conn = null;
        Statement stmt = null;
        ResultSet rs = null;
        String query = "select oimage from orderform where  cuname = '" + photoid + "'";
        ServletOutputStream out = response.getOutputStream();

        try {
            conn = getMySqlConnection();
        } catch (Exception e) {
            response.setContentType("text/html");
            out.println("<html><head><title>Person Photo</title></head>");
            out.println("<body><h1>Database Connection Problem.</h1></body></html>");
            return;
        }

        try {
            stmt = conn.createStatement();
            rs = stmt.executeQuery(query);
            if (rs.next()) {
                photo = rs.getBlob(9);

            } else {
                response.setContentType("text/html");
                out.println("<html><head><title>Person Photo</title></head>");
                out.println("<body><h1>No photo found for id= 001 </h1></body></html>");
                return;
            }

            response.setContentType("image/gif");
            InputStream in = photo.getBinaryStream();
            int length = (int) photo.length();

            int bufferSize = 1024;
            byte[] buffer = new byte[bufferSize];

            while ((length = in.read(buffer)) != -1) {
                System.out.println("writing " + length + " bytes");
                out.write(buffer, 0, length);
            }

            in.close();
            out.flush();
        } catch (SQLException e) {
            response.setContentType("text/html");
            out.println("<html><head><title>Error: Person Photo</title></head>");
            out.println("<body><h1>Error=" + e.getMessage() + "</h1></body></html>");
            return;
        } finally {
            try {
                rs.close();
                stmt.close();
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    /*private static Connection getHSQLConnection() throws Exception {
    Class.forName("jdbc.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
    }*/
    public static Connection getMySqlConnection() throws Exception {
        String driver = "com.jdbc.mysql.Driver";
        String url = "jdbc:mysql://localhost/studio";
        String username = "root";
        String password = " ";

        Class.forName(driver);
        Connection conn = DriverManager.getConnection(url, username, password);
        return conn;
    }

    /*public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:databaseName";
    String username = "username";
    String password = "password";

    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
    }*/
}

Answer 1

You need to tell the user's browser that the content is an image: 您需要告诉用户的浏览器内容是图像：

response.setContentType("image/jpg")

Otherwise the browser will attempt to display the bytestream as text. 否则，浏览器将尝试将字节流显示为文本。 But since you don't specify which "Error" you are getting, I can't help any further at this point in time. 但是，由于您没有指定要获取的“错误”，因此目前我无济于事。

Answer 2

Well, you dont need to use Blob.inputStream, you could just write image binary data to outputstream as shown below ; 好吧，您不需要使用Blob.inputStream，您只需将图像二进制数据写入outputstream，如下所示；

out.write(photo,0,photo.length);

instead of ; 代替 ;

 InputStream in = photo.getBinaryStream();             
int length = (int) photo.length();              
int bufferSize = 1024;             
byte[] buffer = new byte[bufferSize];              
while ((length = in.read(buffer)) != -1) {                
 System.out.println("writing " + length + " bytes");                 
out.write(buffer, 0, length);             
}              
in.close();

Answer 3

The error is in out.write(photo,0,photo.length); 错误在out.write(photo,0,photo.length);

The method write(char[], int, int) in the type PrintWriter is not applicable for the arguments (Blob, int, long) 类型为PrintWriter的方法write(char[], int, int)不适用于参数(Blob, int, long)

如何在servlet中显示数据库中的图像？

问题描述

3 个解决方案

解决方案1
4 2011-01-31 08:53:33

解决方案2
0 2011-01-31 08:48:10

解决方案3
0 2012-02-06 10:32:14

如何在servlet中显示数据库中的图像？

问题描述

3 个解决方案

解决方案1 4 2011-01-31 08:53:33

解决方案2 0 2011-01-31 08:48:10

解决方案3 0 2012-02-06 10:32:14

解决方案1
4 2011-01-31 08:53:33

解决方案2
0 2011-01-31 08:48:10

解决方案3
0 2012-02-06 10:32:14