JDBC 使用 mysql Blob类型

Posted 2022-11-29 _jerrytiger

package com.zf.test;

import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileInputStream;
import java.sql.Blob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import org.apache.commons.io.IOUtils;

public class JDBCTest 
	
	private final String url = "jdbc:mysql:///ssh";
	private final String driverClass = "com.mysql.jdbc.Driver";
	private final String username  = "zf";
	private final String password = "0";
	
	
		try 
			Class.forName(driverClass);   
		 catch (ClassNotFoundException e) 
			e.printStackTrace();
		 
	
	
	/* 获取连接 */
	public Connection openConnection()
		try 
			return DriverManager.getConnection(url, username , password);
		 catch (SQLException e) 
			e.printStackTrace();
			return null ;
		
	
	
	/*创建表*/
	public void createTable()
		try 
			Connection conn = openConnection();
			boolean delete = conn.prepareStatement("drop table if exists tab").execute();
			System.out.println(delete ? "删除tab 失败" : "删除tab成功");
			PreparedStatement ps =
				conn.prepareStatement  
				("CREATE TABLE `tab` (`id`  integer NULL AUTO_INCREMENT ,`file`  blob NULL ,`img`  blob NULL ,PRIMARY KEY (`id`))");
			boolean result = ps.execute();
			System.out.println(result ? "创建tab失败" : "创建tab成功");
			
			ps.close();  
			conn.close();
		 catch (SQLException e) 
			e.printStackTrace();  
		
	
	
	/*插入一条记录*/
	public void insertTotab()
		try 
			Connection conn = openConnection();
			PreparedStatement ps =
					conn.prepareStatement("insert into tab(file , img) values(? , ?)");
			//设置类型为Blob
			ps.setBlob(1, new FileInputStream(new File("c:/xxx.txt")));
			ps.setBlob(2 , new FileInputStream(new File("C:/logo.gif")) );
			int i = ps.executeUpdate();  
			System.out.println(i > 0 ? "保存成功" : "保存失败");
			ps.close();
			conn.close();
		 catch (Exception e) 
			e.printStackTrace();
		
	
	
	/* 读取内容 */
	public void readContent()
		try 
			Connection conn = openConnection();
			PreparedStatement ps =
					conn.prepareStatement("select * from tab");
			ResultSet rs = ps.executeQuery();
			if(rs.next())
				
				Blob file = rs.getBlob(2);
				Blob img = rs.getBlob(3);

				System.out.println("------------file-----------");
				//读取文件流
				System.out.println(
						IOUtils.toString(file.getBinaryStream()));
				
				//读取图片流
				BufferedImage bi = ImageIO.read(img.getBinaryStream());
				
				//将图片流转换为图片显示出来
				showImg(bi); 
				System.out.println("读取成功");
			
			
			rs.close();
			ps.close();  
			conn.close();
		 catch (Exception e) 
			e.printStackTrace();
		
	
	
	/* 使用JFrame显示图片 */
	public void showImg(final BufferedImage bi )
		JFrame frame = new JFrame("图片测试")
			@Override
			public void paint(Graphics g) 
				super.paint(g);
				g.drawImage(bi, 50 , 50 , null );
			  
		;
		frame.setVisible(true);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setBounds(0, 0, 500, 500);
	
	
	public static void main(String[] args) 
		JDBCTest jt = new JDBCTest();
		jt.createTable();
		jt.insertTotab();
		jt.readContent();