hibernate大字段处理-优快云博客

本文介绍如何使用Hibernate处理大字段，例如存储图片等二进制数据。以Photo类为例，演示了如何定义POJO类和映射文件来支持Blob类型，并提供了web层的主要代码实现。

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hibernate大字段处理：以mysql为例
比如传张图片，把图片存到某个字段里。
POJO类里大字段类型为：[color=red]java.sql.Blob[/color]
1.Photo.java



import java.sql.Blob;


public class Photo implements java.io.Serializable {

	private Integer pid;

	private String pname;

	private Blob photo;

	public Photo() {
	}

	public Photo(String pname) {
		this.pname = pname;
	}


	public Integer getPid() {
		return this.pid;
	}

	public void setPid(Integer pid) {
		this.pid = pid;
	}

	public String getPname() {
		return this.pname;
	}

	public void setPname(String pname) {
		this.pname = pname;
	}

	public Blob getPhoto() {
		return photo;
	}

	public void setPhoto(Blob photo) {
		this.photo = photo;
	}


}

2.Photo.hbm.xml



<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
    <class name="com.pojo.Photo" table="photo" >
        <id name="pid" type="java.lang.Integer">
            <column name="pid" />
            <generator class="native" />
        </id>
        <property name="pname" type="java.lang.String">
            <column name="pname" length="10" not-null="true" />
        </property>
        <property name="photo" type="java.sql.Blob">
            <column name="photo" />
        </property>
    </class>
</hibernate-mapping>

3.web层主要代码：



IndexForm indexForm = (IndexForm) form;
		String pname = indexForm.getPanme();
		FormFile photo = indexForm.getPhoto();
		System.out.println(pname + "  " + photo.getFileSize());
		Photo p = new Photo();
		p.setPname(pname);
		try {
			byte[] buf = photo.getFileData();
			//通过Hibernate类将存图片内容的buf数组转成Blob类型
			Blob ph = Hibernate.createBlob(buf);
			p.setPhoto(ph);
			PhotoDAO dao = new PhotoDAO();
			dao.addPhoto(p);
			//读取
			Photo temp = dao.getByName(pname);
			//通过java.sql.Blob.getBinaryStream()获得输入流，然后通过输出流输出到一个临时图片
			InputStream in = temp.getPhoto().getBinaryStream();
			OutputStream out = new FileOutputStream(new File("c:\\zk.jpg"));
			in.read(buf);
			out.write(buf);
			in.close();
			out.close();
			request.getSession().setAttribute("link", "c:\\zk.jpg");
			dao.closeSession();
		} catch (FileNotFoundException e) {
			  e.printStackTrace();
		} catch (IOException e) {
				e.printStackTrace();
		} catch (SQLException e) {
				e.printStackTrace();
		}