Java如何从数据库读取BLOB数据？
本示例说明如何从数据库表读取BLOB数据。
package org.nhooo.example.jdbc;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
public class BlobReadDemo {
private static final String URL = "jdbc:mysql://localhost/nhooo";
private static final String USERNAME = "root";
private static final String PASSWORD = "";
public static void main(String[] args) {
try (Connection conn =
DriverManager.getConnection(URL, USERNAME, PASSWORD)) {
String sql = "SELECT name, image FROM product_images";
PreparedStatement stmt = conn.prepareStatement(sql);
ResultSet rs = stmt.executeQuery();
while (rs.next()) {
String name = rs.getString("name");
File image = new File(name);
try (FileOutputStream fos = new FileOutputStream(image)) {
byte[] buffer = new byte[1024];
//获取我们的BLOB数据的二进制流
InputStream is = rs.getBinaryStream("image");
while (is.read(buffer) > 0) {
fos.write(buffer);
}
} catch (IOException e) {
e.printStackTrace();
}
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}表结构product_images
CREATE TABLE `product_images` ( `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT, `product_id` bigint(20) unsigned NOT NULL, `name` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL, `description` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL, `image` blob, PRIMARY KEY (`id`), KEY `product_id` (`product_id`), CONSTRAINT `product_images_ibfk_1` FOREIGN KEY (`product_id`) REFERENCES `products` (`id`) ) ENGINE=InnoDB;
Maven依赖
<!-- https://search.maven.org/remotecontent?filepath=mysql/mysql-connector-java/8.0.17/mysql-connector-java-8.0.17.jar -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.17</version>
</dependency>