插入

package com.study.jdbc;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;

public class JDBC_blob_insert {
    public static void main(String[] args) {
        Connection conn = null;
        PreparedStatement ps = null;
        FileInputStream in = null;

        try {
            conn = DBUtil.getConnection();
            String sql = "insert into t_img(name,img) values (?, ?)";
            ps = conn.prepareStatement(sql);
            ps.setString(1,"测试图片");
            in = new FileInputStream("F:\\Administrator\\Pictures\\1.jpg");
            ps.setBlob(2, in);
            int count = ps.executeUpdate();
            System.out.println("插入" + count +"条数据");
        } catch (SQLException | FileNotFoundException e) {
            throw new RuntimeException(e);
        } finally {
            if(in != null){
                try{
                    in.close();
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            DBUtil.close(conn,ps,null);
        }
    }
}

查询

package com.study.jdbc;

import java.io.*;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class JDBC_blob_query {
    public static void main(String[] args) {
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;

        try {
            conn = DBUtil.getConnection();
            String sql = "select img from t_img where name = ?";
            ps = conn.prepareStatement(sql);
            ps.setString(1,"测试图片");
            rs = ps.executeQuery();
            while (rs.next()){
                InputStream in = rs.getBinaryStream("img");// 通过结果集列名 获取内容 赋值给输入流
                OutputStream out = new FileOutputStream("E:/读取文件.jpg"); // 定义一个输出流将 内容输出到电脑指定位置
                byte[] bytes = new byte[1024];  // 定义字节大小
                int readCount = 0;  // 读取内容初始值
                while((readCount = in.read(bytes)) != -1){ // 当读取的内容 不为空时
                    out.write(bytes,0,readCount); // 将读取的内容写入输出流
                }
                out.flush(); // 刷新输出流
                in.close();  // 关闭输入流
                out.close(); // 关闭输出流
            }
        } catch (SQLException e) {
            throw new RuntimeException(e);
        } catch (FileNotFoundException e) {
            throw new RuntimeException(e);
        } catch (IOException e) {
            throw new RuntimeException(e);
        } finally {
            DBUtil.close(conn,ps,rs);
        }
    }
}