hibernate版本从Oracle中读取Blob数据

雨点打透心脏的1/2处 2021-12-10 06:45 306阅读 0赞

转自：[https://blog.csdn.net/qq\_34239028/article/details/81293252][https_blog.csdn.net_qq_34239028_article_details_81293252]

1.  hibernate3.2是采用的SerializableBlob类来处理Blob对象的。

public byte[] getPic(String isbn) throws Exception { 
    	byte[] pic = null;
    	String sql = "select pic from tbook where isbn = ?";
    	this.openConnection();
    	SQLQuery q = this.session.createSQLQuery(sql);
    	q.setString(0, isbn);
    	Iterator it = q.list().iterator();
    	while(it.hasNext()){ 
    		Object obj=it.next();
    		SerializableBlob blob= (SerializableBlob)obj;
    		pic=blob.getBytes(1, (int)blob.length());
    		
    	}
    	return pic;
    }

1.  在Hibernate3.5之后去掉了SerializableBlob这个类，但同时又增加了SerializableBlobProxy来处理Blob字段值。Blob字段是Hibernate返回的Blob对象实际上是代理类SerializableBlobProxy的实例，提供了java.sql.Blob接口定义的方法（通过反射的方式）  
    注意：不能把这个实例转换成oracle.sql.Blob类型，会发生类型转换异常（java.lang.ClassCastException）,提供信息为cannot be cast to oracle.sql.BLOB

public byte[] getPic(String isbn) throws Exception { 
    	byte[] pic = null;
    	
    	String sql = "select pic from tbook where isbn = ?";
    	this.openConnection();
    	SQLQuery q = this.session.createSQLQuery(sql);
    	q.setString(0, isbn);
    	Iterator it = q.list().iterator();
    	while(it.hasNext()){ 
    		Object obj=it.next();
    		SerializableBlobProxy proxy=(SerializableBlobProxy)Proxy.getInvocationHandler(obj);
    		java.sql.Blob blob = proxy.getWrappedBlob();
    		pic=blob.getBytes(1, (int)blob.length());
    	}
    	return pic;
    }

[https_blog.csdn.net_qq_34239028_article_details_81293252]: https://blog.csdn.net/qq_34239028/article/details/81293252