使用Java将文件(pdf,JPEG / FIF)上传到mysql

时间:2018-07-30 22:27:22

标签: java mysql file-upload blob binary-data

有什么方法可以将文件附加到Java中的mysql吗?我需要将文件放置在数据库中而不是路径中。

2 个答案:

答案 0 :(得分:0)

这是示例代码如何将二进制文件(如PDF文档,MS Excel电子表格,JPG / PNG图像文件或ZIP文件等)写入BLOB类型的数据库表列并进行读取的示例代码从数据库中获取。

在Java SE 7或更高版本中,我分别在Apache Derby(又名Java DB)和MySQL数据库中使用了这些功能。

德比: 写入数据库:

Path path = Paths.get("MyPic.jpg");
InputStream instream = Files.newInputStream(path);
PreparedStatement pstmnt = getConnection().prepareStatement(dml); // dml is an sql Insert   
pstmnt.setBinaryStream(1, instream);
// pstmnt.setNull(1, Types.BLOB); // to set null value in db
pstmnt.executeUpdate();
pstmnt.close();
instream.close();

从数据库读取:

PreparedStatement pstmnt = getConnection().prepareStatement(sql); // sql is a Select
ResultSet rs = pstmnt.executeQuery();
rs.next();
InputStream instream = rs.getBinaryStream("col_name");
Path path = Paths.get("MyPic.jpg");
OutputStream outstream = Files.newOutputStream(path);
int len = 0;
byte [] buf = new byte [1024];
while ((len = instream.read(buf)) > 0) {
    outstream.write(buf, 0, len);
}
instream.close();
outstream.flush();
outstream.close();      
pstmnt.close();


MySQL: 写入数据库:

PreparedStatement pstmnt_= conn.prepareStatement(DML) // sql Insert
InputStream instream = Files.newInputStream(filePath); // filePath is of type Path
pstmnt.setBinaryStream(1, instream);
pstmnt.executeUpdate();
// close resources here

从数据库读取:

PreparedStatement pstmnt = conn.prepareStatement(DML); // sql Select
ResultSet rs = pstmnt.executeQuery();
rs.next();
Blob blob = rs.getBlob("col_name");
long len = blob.length();
byte [] fileBytes = blob.getBytes(1L, (int) len); // start pos = 1L
OutputStream out = ...
out.write(fileBytes);
out.flush();
out.close();

请注意,在使用JDBC对象(例如PreparedStatement)和文件io流(例如InputStream)之后,请确保这些资源已关闭。

答案 1 :(得分:-1)

使用base64 enconding并将其另存为BLOB数据

这是编码示例:

/**
 * Method used for encode the file to base64 binary format
 * @param file
 * @return encoded file format
 */
private String encodeFileToBase64Binary(File file){
    String encodedfile = null;
    try {
        FileInputStream fileInputStreamReader = new FileInputStream(file);
        byte[] bytes = new byte[(int)file.length()];
        fileInputStreamReader.read(bytes);
        encodedfile = Base64.encodeBase64(bytes).toString();
    } catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    return encodedfile;
}