【java小案例】java+mysql实现保存图片到数据库，以及读取数据库存储的图片

转载自：https://www.cnblogs.com/warrior4236/p/5682830.html 

一：建表

 

二：获取数据库连接

1：导入mysql的驱动jar包，mysql-connector-java-5.1.8-bin.jar

2：写代码连接数据库，如下：

package pagehelper.mysql.test;


import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

/**
 * @author Administrator
 * 
 */
public class DBUtil {
    // 定义数据库连接参数
    public static final String DRIVER_CLASS_NAME = "com.mysql.jdbc.Driver";
    public static final String URL = "jdbc:mysql://localhost:3306/first_test";
    public static final String USERNAME = "root";
    public static final String PASSWORD = "root";

    // 注册数据库驱动
    static {
        try {
            Class.forName(DRIVER_CLASS_NAME);
        } catch (ClassNotFoundException e) {
            System.out.println("注册失败！");
            e.printStackTrace();
        }
    }

    // 获取连接
    public static Connection getConn() throws SQLException {
        return DriverManager.getConnection(URL, USERNAME, PASSWORD);
    }

    // 关闭连接
    public static void closeConn(Connection conn) {
        if (null != conn) {
            try {
                conn.close();
            } catch (SQLException e) {
                System.out.println("关闭连接失败！");
                e.printStackTrace();
            }
        }
    }
    //测试
    public static void main(String[] args) throws SQLException {
        System.out.println(DBUtil.getConn());
    }

}

三：封装读取图片的流

package pagehelper.mysql.test;


import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;

/**
 * @author Administrator
 * 
 */
public class ImageUtil {

    // 读取本地图片获取输入流
    public static FileInputStream readImage(String path) throws IOException {
        return new FileInputStream(new File(path));
    }

    // 读取表中图片获取输出流
    public static void readBin2Image(InputStream in, String targetPath) {
        File file = new File(targetPath);
        String path = targetPath.substring(0, targetPath.lastIndexOf("/"));
        if (!file.exists()) {
            new File(path).mkdir();
        }
        FileOutputStream fos = null;
        try {
            fos = new FileOutputStream(file);
            int len = 0;
            byte[] buf = new byte[1024];
            while ((len = in.read(buf)) != -1) {
                fos.write(buf, 0, len);
            }
            fos.flush();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (null != fos) {
                try {
                    fos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

四：实现图片（本地、数据库互相传输）

package pagehelper.mysql.test;


import java.io.FileInputStream;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

/**
 * @author Administrator 测试写入数据库以及从数据库中读取
 */
public class ImageDemo {

    // 将图片插入数据库
    public static void readImage2DB() {
        String path = "D:/timg.jpg";
        Connection conn = null;
        PreparedStatement ps = null;
        FileInputStream in = null;
        try {
            in = ImageUtil.readImage(path);
            conn = DBUtil.getConn();
//            String sql = "insert into photo (id,name,photo) values(?,?,?)";
            String sql = "insert into photo (name,photo) values(?,?)";
            ps = conn.prepareStatement(sql);
//            ps.setInt(1, 1);
            ps.setString(1, "Tom2");
            ps.setBinaryStream(2, in, in.available());
            int count = ps.executeUpdate();
            if (count > 0) {
                System.out.println("插入成功！");
            } else {
                System.out.println("插入失败！");
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            DBUtil.closeConn(conn);
            if (null != ps) {
                try {
                    ps.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }

    }

    // 读取数据库中图片
    public static void readDB2Image() {
    	//String targetPath = "D:/image/1.png";
    	String targetPath_base = "D:/image/";
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        
        int numOfPicture = 2;
        try {
            conn = DBUtil.getConn();
            
            String sql = "select * from photo where id =?";
            ps = conn.prepareStatement(sql);
            for(int i=1;i<=numOfPicture;i++) {
            	ps.setInt(1, i);
                rs = ps.executeQuery();
                
                String name = null;
                
                while (rs.next()) {
                	name = rs.getString(2);
                    InputStream in = rs.getBinaryStream("photo");
                    ImageUtil.readBin2Image(in, targetPath_base+name+".jpg");
                }
            }
            
            
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            DBUtil.closeConn(conn);
            if (rs != null) {
                try {
                    rs.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
            if (ps != null) {
                try {
                    ps.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }

        }
    }
    //测试
    public static void main(String[] args) {
//        readImage2DB();
        readDB2Image();
    }
}