如何创建BLOB对象? [英] How to create BLOB object?

问题描述

1. 如何用Java创建BLOB对象?
2. 如何从数据库设置BLOB值?
3. 如何在数据库中设置BLOB值?

我已经这样创建了BLOB对象:

I have create the BLOB object like this:

byte [] fileId = b.toByteArray();
Blob blob = new SerialBlob(fileId);

但这给我一个错误.

推荐答案

1. 要创建BLOB，请使用Connection.createBlob

使用PreparedStatement.setBlob

要从DB读取BLOB，请使用ResultSet.getBlob

to read BLOB from DB use ResultSet.getBlob

假设您具有BLOB列b1的表t1:

Assuming you have table t1 with BLOB column b1:

Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "root", "root");
Blob b1 = conn.createBlob();
b1.setBytes(1, new byte[10]); // first position is 1. Otherwise you get: Value of offset/position/start should be in the range [1, len] where len is length of Large Object[LOB]

PreparedStatement ps = conn.prepareStatement("update t1 set c1 = ?");
ps.setBlob(1, b1);
ps.executeUpdate();

Statement st = conn.createStatement();
ResultSet rs = st.executeQuery("select c1 from t1");
Blob b2 = rs.getBlob(1);

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