将BufferedInputStream转换为图像?mysql

首先，先确认uploadedInputStream是有效图像，然后再使用将其写出来ImageIO.write。您始终可以使用ImageIO.read读回的图像并将其写回到ByteArrayInputStream;）

我使用H2数据库进行了快速测试。

我注意到了几件事。 Blob#length返回long，而Blob#getBytes期望则返回int，这可能意味着您正在截断字节流。

另外，从H2的文档来看，似乎Blob内容没有保存在内存中，因此我改用了getBinaryStream。

import java.awt.image.BufferedImage; import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.io.File; import java.io.IOException; 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.ImageIcon; import javax.swing.JLabel; import javax.swing.JOptionPane; import javax.swing.JScrollPane;

public class TestImageDatbase {

private Connection con;

public static void main(String[] args) {
    new TestImageDatbase();
}

public TestImageDatbase() {
    try {
        clearDatabase();
        saveImage();
        loadImage();
    } catch (ClassNotFoundException | SQLException | IOException exp) {
        exp.printStackTrace();
    }
}

protected Connection getConnection() throws ClassNotFoundException, SQLException {
    Class.forName("org.h2.Driver");
    return DriverManager.getConnection("jdbc:h2:d:\\Image", "sa", "");
}

protected void clearDatabase() throws IOException, ClassNotFoundException, SQLException {

    Connection con = null;
    PreparedStatement stmt = null;

    try {

        con = getConnection();
        System.out.println("Cleaning database");
        stmt = con.prepareStatement("delete from images");
        int updated = stmt.executeUpdate();
        System.out.println("Updated " + updated + " rows");

    } finally {
        try {
            stmt.close();
        } catch (Exception e) {
        }
        try {
            con.close();
        } catch (Exception e) {
        }
    }

}

protected void saveImage() throws IOException, ClassNotFoundException, SQLException {

    Connection con = null;
    PreparedStatement stmt = null;
    ByteArrayOutputStream baos = null;
    ByteArrayInputStream bais = null;

    try {

        baos = new ByteArrayOutputStream();

        File source = new File("/path/to/file");
        System.out.println("Source size = " + source.length());
        BufferedImage img = ImageIO.read(source);
        ImageIO.write(img, "png", baos);

        baos.close();

        bais = new ByteArrayInputStream(baos.toByteArray());

        con = getConnection();
        stmt = con.prepareStatement("insert into images (image) values (?)");
        stmt.setBinaryStream(1, bais);
        int updated = stmt.executeUpdate();
        System.out.println("Updated " + updated + " rows");

    } finally {
        try {
            bais.close();
        } catch (Exception e) {
        }
        try {
            baos.close();
        } catch (Exception e) {
        }
        try {
            stmt.close();
        } catch (Exception e) {
        }
        try {
            con.close();
        } catch (Exception e) {
        }
    }

}

protected void loadImage() throws IOException, ClassNotFoundException, SQLException {

    Connection con = null;
    PreparedStatement stmt = null;
    ResultSet rs = null;

    try {

        con = getConnection();
        stmt = con.prepareStatement("select image from images");
        rs = stmt.executeQuery();

        while (rs.next()) {

            System.out.println("Getting blob");
            Blob blob = rs.getBlob(1);
            System.out.println("Reading image");
            BufferedImage img = ImageIO.read(blob.getBinaryStream());
            System.out.println("img = " + img);
            JOptionPane.showMessageDialog(null, new JScrollPane(new JLabel(new ImageIcon(img))));

        }

    } finally {
        try {
            rs.close();
        } catch (Exception e) {
        }
        try {
            stmt.close();
        } catch (Exception e) {
        }
        try {
            con.close();
        } catch (Exception e) {
        }
    }

}

}来源：stack overflow