我想通过 Hibernate 使用 BLOB 列类型将文件插入到 Oracle？
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I want to insert a file to Oracle using BLOB column type over Hibernate?
提问by firstthumb
I want to save my file on Oracle Instance. I am using Hibernate for data objects. How can I insert files into Oracle Blob. Is there any sample code for this?
我想将我的文件保存在 Oracle 实例上。我正在将 Hibernate 用于数据对象。如何将文件插入 Oracle Blob。是否有任何示例代码？
回答by Vanger
In first you must annotate your entity field with @javax.persistance.Lob annotation. Like this:
首先，您必须使用 @javax.persistance.Lob 注释来注释您的实体字段。像这样：
public class InfoMessage {
private byte[] body;
@Lob
public byte[] getBody() {
return body;
}
public void setBody(byte[] body) {
this.body = body;
}
}
and set it with bytes array. It's depends on wich File class you use. The first google result for java.io.File. I guess there's better solution for this operation.
并用字节数组设置它。这取决于您使用的 File 类。java.io.File 的第一个谷歌结果。我想这个操作有更好的解决方案。
public static byte[] getBytesFromFile(File file) throws IOException {
InputStream is = new FileInputStream(file);
// Get the size of the file
long length = file.length();
if (length > Integer.MAX_VALUE) {
// File is too large
}
// Create the byte array to hold the data
byte[] bytes = new byte[(int)length];
// Read in the bytes
int offset = 0;
int numRead = 0;
while (offset < bytes.length
&& (numRead=is.read(bytes, offset, bytes.length-offset)) >= 0) {
offset += numRead;
}
// Ensure all the bytes have been read in
if (offset < bytes.length) {
throw new IOException("Could not completely read file "+file.getName());
}
// Close the input stream and return bytes
is.close();
return bytes;
}
}
回答by Vanger
The @Lobannotation is not Hibernate's one. It's javax.persistenceand you can use it in entity bean with any hibernate mapping.
Yes, the big file is obvious problem for such example. But i can't find any workaround for this case. FileInputStreamusing int type value to represent offset point.
I googled this one with similiar problem: http://www.coderanch.com/t/449055/Streams/java/JAVA-HEAP-SIZE-files-byteYou can use solution with SQLPrepareSteatementif you use Java 1.6. Othwerwise you can try to use BufferedReaderand somehow convert results to byteArray[]and try to beat another problem: you'll need so much memory as file size is.
该@Lob注解并非是Hibernate的一个。它是javax.persistence，您可以在具有任何休眠映射的实体 bean 中使用它。是的，对于这样的例子，大文件是明显的问题。但是我找不到针对这种情况的任何解决方法。FileInputStream使用 int 类型值来表示偏移点。我用类似的问题搜索了这个：http: //www.coderanch.com/t/449055/Streams/java/JAVA-HEAP-SIZE-files-byteSQLPrepareSteatement如果您使用 Java 1.6，您可以使用解决方案。否则，您可以尝试使用BufferedReader并以某种方式将结果转换为byteArray[]并尝试解决另一个问题：您将需要与文件大小一样多的内存。
EDITED:Another thing: Oracle can append data to it's clob\blob fields using dbms_lob.writeappend() procedure so you can avoid having all file in memory, but will GC perform clean as fast as BufferedReaderread from file. And seems it's not a hibernate work to do this... jdbc and PreparedStatements back again.
编辑：另一件事：Oracle 可以使用 dbms_lob.writeappend() 过程将数据附加到它的 clob\blob 字段，这样您就可以避免将所有文件都放在内存中，但 GC 执行清理的速度会与BufferedReader从文件读取的速度一样快。并且似乎它不是一个休眠的工作来做这个...... jdbc 和 PreparedStatements 又回来了。
