使用Java在Postgresql中存储和检索图像

Question

我是Java编程新手,我正在搜索Java代码以在PostgreSQL中存储图像并检索图像.

在PostgreSQL中,我使用了Bytea Data-type.图像已存储.但是当我检索时我得到了NULL.我无法得到图像.

对此或任何其他建议的任何示例都会有所帮助.

Answer 1

postgresql jdbc文档的第7章处理存储二进制数据并使用图像(*.gif文件)作为示例.你可能想读它.

将图像插入数据库(来自上面的链接)

File file = new File("myimage.gif");
FileInputStream fis = new FileInputStream(file);
PreparedStatement ps = conn.prepareStatement("INSERT INTO images VALUES (?, ?)");
ps.setString(1, file.getName());
ps.setBinaryStream(2, fis, (int)file.length());
ps.executeUpdate();
ps.close();
fis.close();

从数据库中读取图像(也来自上面的链接)

// Get the Large Object Manager to perform operations with
LargeObjectManager lobj = ((org.postgresql.PGConnection)conn).getLargeObjectAPI();

PreparedStatement ps = conn.prepareStatement("SELECT imgoid FROM imageslo WHERE imgname = ?");
ps.setString(1, "myimage.gif");
ResultSet rs = ps.executeQuery();
while (rs.next()) {
    // Open the large object for reading
    int oid = rs.getInt(1);
    LargeObject obj = lobj.open(oid, LargeObjectManager.READ);

    // Read the data
    byte buf[] = new byte[obj.size()];
    obj.read(buf, 0, obj.size());
    // Do something with the data read here

    // Close the object
    obj.close();
}
rs.close();
ps.close();