Hibernate、iBATIS 与 BLOB

在存储图片、可执行文件等二进制信息时(当然直接放在文件系统上也行),BLOB 数据就派上用场了。本文无太多深度可言,能为大家在开发过程中提供参考足亦!

Hibernate SQL Server BLOB

BLOB 数据在 SQL Server 数据库中主要由 IMAGE 类型体现,最大容量为 2GB。其存储方式不同于普通的数据类型,对于普通类型的数据系统直接在用户定义的字段上存储数据值,而对于 IMAGE 类型数据,系统开辟新的存储页面来存放这些数据,表中 IMAGE 类型数据字段存放的仅是一个 16 字节的指针,该指针指向存放该条记录的 IMAGE 数据的页面。如果你对 Hibernate 还不熟息,请看这里

新建名为 “BLOB_TEST” 的表,字段分别是 INT 类型的 “ID” IMAGE 类型的 “MYBLOB”。从文件系统读取 “sample.jpg” 并转换成字节数组再放进 BlobTest 对象实例。写入程序如下:

import java.io.*;

import net.sf.hibernate.*;
import net.sf.hibernate.cfg.*;

import bo.*;

public class Tester {

 public void DoTest() {
  InputStream in = null;
  BlobTest blobTest = null;
  Configuration cfg = null;
  SessionFactory sessions = null;
  Session session = null;
  Transaction tx = null;
  try {
   //begin InputStream
   in = new FileInputStream("d:/sample.jpg");
   byte[] b = new byte[in.available()];
   in.read(b);
   in.close();

   //begin BlobTest
   blobTest = new BlobTest();
   blobTest.setMyblob(b);

   //begin Hibernate Session
   cfg = new Configuration().configure();
   sessions = cfg.buildSessionFactory();
   session = sessions.openSession();
   tx = session.beginTransaction();
   session.save(blobTest);
   tx.commit();
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   try {
    session.close();
   } catch (Exception e1) {
    e1.printStackTrace();
   }
  }
 }
}

  

import java.io.*;

import net.sf.hibernate.*;
import net.sf.hibernate.cfg.*;

import bo.*;

public class Tester {

 public void DoTest() {
  InputStream in = null;
  BlobTest blobTest = null;
  Configuration cfg = null;
  SessionFactory sessions = null;
  Session session = null;
  Transaction tx = null;
  try {
   //begin InputStream
   in = new FileInputStream("d:/sample.jpg");
   byte[] b = new byte[in.available()];
   in.read(b);
   in.close();

   //begin BlobTest
   blobTest = new BlobTest();
   blobTest.setMyblob(b);

   //begin Hibernate Session
   cfg = new Configuration().configure();
   sessions = cfg.buildSessionFactory();
   session = sessions.openSession();
   tx = session.beginTransaction();
   session.save(blobTest);
   tx.commit();
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   try {
    session.close();
   } catch (Exception e1) {
    e1.printStackTrace();
   }
  }
 }
}

  

import java.io.*;

import net.sf.hibernate.*;
import net.sf.hibernate.cfg.*;

import bo.*;

public class Tester {

 public void DoTest() {
  InputStream in = null;
  BlobTest blobTest = null;
  Configuration cfg = null;
  SessionFactory sessions = null;
  Session session = null;
  Transaction tx = null;
  try {
   //begin InputStream
   in = new FileInputStream("d:/sample.jpg");
   byte[] b = new byte[in.available()];
   in.read(b);
   in.close();

   //begin BlobTest
   blobTest = new BlobTest();
   blobTest.setMyblob(b);

   //begin Hibernate Session
   cfg = new Configuration().configure();
   sessions = cfg.buildSessionFactory();
   session = sessions.openSession();
   tx = session.beginTransaction();
   session.save(blobTest);
   tx.commit();
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   try {
    session.close();
   } catch (Exception e1) {
    e1.printStackTrace();
   }
  }
 }
}

  

取出程序如下:

import java.io.*;

import net.sf.hibernate.*;
import net.sf.hibernate.cfg.*;

import bo.*;

public class Tester {

 public void DoTest() {
  OutputStream out = null;
  BlobTest blobTest = null;
  Configuration cfg = null;
  SessionFactory sessions = null;
  Session session = null;
  try {
   //begin Hibernate Session
   cfg = new Configuration().configure();
   sessions = cfg.buildSessionFactory();
   session = sessions.openSession();

   //begin BlobTest
   blobTest = new BlobTest();
   blobTest = (BlobTest) session.load(BlobTest.class, new Integer(23));

   //begin OutputStream
   out = new FileOutputStream("d:/sample.jpg");
   out.write(blobTest.getMyblob());
   out.flush();
   out.close();
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   try {
    session.close();
   } catch (Exception e1) {
    e1.printStackTrace();
   }
  }
 }
}

 

import java.io.*;

import net.sf.hibernate.*;
import net.sf.hibernate.cfg.*;

import bo.*;

public class Tester {

 public void DoTest() {
  OutputStream out = null;
  BlobTest blobTest = null;
  Configuration cfg = null;
  SessionFactory sessions = null;
  Session session = null;
  try {
   //begin Hibernate Session
   cfg = new Configuration().configure();
   sessions = cfg.buildSessionFactory();
   session = sessions.openSession();

   //begin BlobTest
   blobTest = new BlobTest();
   blobTest = (BlobTest) session.load(BlobTest.class, new Integer(23));

   //begin OutputStream
   out = new FileOutputStream("d:/sample.jpg");
   out.write(blobTest.getMyblob());
   out.flush();
   out.close();
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   try {
    session.close();
   } catch (Exception e1) {
    e1.printStackTrace();
   }
  }
 }
}

 

import java.io.*;

import net.sf.hibernate.*;
import net.sf.hibernate.cfg.*;

import bo.*;

public class Tester {

 public void DoTest() {
  OutputStream out = null;
  BlobTest blobTest = null;
  Configuration cfg = null;
  SessionFactory sessions = null;
  Session session = null;
  try {
   //begin Hibernate Session
   cfg = new Configuration().configure();
   sessions = cfg.buildSessionFactory();
   session = sessions.openSession();

   //begin BlobTest
   blobTest = new BlobTest();
   blobTest = (BlobTest) session.load(BlobTest.class, new Integer(23));

   //begin OutputStream
   out = new FileOutputStream("d:/sample.jpg");
   out.write(blobTest.getMyblob());
   out.flush();
   out.close();
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   try {
    session.close();
   } catch (Exception e1) {
    e1.printStackTrace();
   }
  }
 }
}

 

Hibernate MySQL BLOB

    MySQL 中的 BLOB 数据由四种类型体现,分别是 TINYBLOB 其容量为 256 字节、BLOB 其容量为 64KBMEDIUMBLOB 其容量为 16MBLONGBLOB 其容量为 4GB

新建名为 “BLOB_TEST” 的表,字段分别是 INTEGER 类型的 “ID” MEDIUMBLOB 类型的 “MYBLOB”。从文件系统读取 “sample.jpg” 并转换成字节数组再放进 BlobTest 对象实例。写入、取出程序和上面的 SQL Server 一样。

Hibernate Oracle BLOB

    为了不使用 “for update” 锁住数据库,遂打算让 Oracle LONG RAW 类型保存大对象,最大容量 2GB。经过测试后发现,直接写 JDBC 代码可以保存,但 Hibernate 只能保存 4K 大小内容,换成 Hibernate 3.0 beta3 也未能成功。偶然的机会在邮件列表上发现这是 JDBC Driver 的问题,换成 Oracle 10g 的驱动后问题解决。

新建名为 “BLOB_TEST” 的表,字段分别是 NUMBER 类型的 “ID” LONG RAW 类型的 “MYBLOB”。从文件系统读取 “sample.jpg” 并转换成字节数组再放进 BlobTest 对象实例。写入、取出程序和 SQL Server 一样。

如果你一定要用 Oracle BLOB 类型,接着往下看:

    Hibernate 处理 Oracle BLOB 类型较特殊从文件系统读取 “sample.jpg” 放进 BlobTest 对象实例的是 java.sql.Blob 类型,而不是字节数组。

import java.io.*;

import net.sf.hibernate.*;
import net.sf.hibernate.cfg.*;
import oracle.sql.*;

import bo.*;

public class Tester {

 public void DoTest() {
  BLOB blob = null;
  InputStream in = null;
  OutputStream out = null;
  BlobTest blobTest = null;
  Configuration cfg = null;
  SessionFactory sessions = null;
  Session session = null;
  Transaction tx = null;
  try {
   //begin InputStream
   in = new FileInputStream("d:/sample.jpg");
   byte[] b = new byte[in.available()];
   in.read(b);
   in.close();
   
   //begin BlobTest
   blobTest = new BlobTest();
   blobTest.setMyblob(BLOB.empty_lob());
   
   //begin Hibernate Session
   cfg = new Configuration().configure();
   sessions = cfg.buildSessionFactory();
   session = sessions.openSession();
   tx = session.beginTransaction();
   session.save(blobTest);
   session.flush();
   session.refresh(blobTest, LockMode.UPGRADE);
   blob = (BLOB) blobTest.getMyblob();
   out = blob.getBinaryOutputStream();
   out.write(b);
   out.close();
   session.flush();
   tx.commit();
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   try {
    session.close();
   } catch (Exception e1) {
    e1.printStackTrace();
   }
  }
 }
}

  

import java.io.*;

import net.sf.hibernate.*;
import net.sf.hibernate.cfg.*;
import oracle.sql.*;

import bo.*;

public class Tester {

 public void DoTest() {
  BLOB blob = null;
  InputStream in = null;
  OutputStream out = null;
  BlobTest blobTest = null;
  Configuration cfg = null;
  SessionFactory sessions = null;
  Session session = null;
  Transaction tx = null;
  try {
   //begin InputStream
   in = new FileInputStream("d:/sample.jpg");
   byte[] b = new byte[in.available()];
   in.read(b);
   in.close();
   
   //begin BlobTest
   blobTest = new BlobTest();
   blobTest.setMyblob(BLOB.empty_lob());
   
   //begin Hibernate Session
   cfg = new Configuration().configure();
   sessions = cfg.buildSessionFactory();
   session = sessions.openSession();
   tx = session.beginTransaction();
   session.save(blobTest);
   session.flush();
   session.refresh(blobTest, LockMode.UPGRADE);
   blob = (BLOB) blobTest.getMyblob();
   out = blob.getBinaryOutputStream();
   out.write(b);
   out.close();
   session.flush();
   tx.commit();
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   try {
    session.close();
   } catch (Exception e1) {
    e1.printStackTrace();
   }
  }
 }
}

  

import java.io.*;

import net.sf.hibernate.*;
import net.sf.hibernate.cfg.*;
import oracle.sql.*;

import bo.*;

public class Tester {

 public void DoTest() {
  BLOB blob = null;
  InputStream in = null;
  OutputStream out = null;
  BlobTest blobTest = null;
  Configuration cfg = null;
  SessionFactory sessions = null;
  Session session = null;
  Transaction tx = null;
  try {
   //begin InputStream
   in = new FileInputStream("d:/sample.jpg");
   byte[] b = new byte[in.available()];
   in.read(b);
   in.close();
   
   //begin BlobTest
   blobTest = new BlobTest();
   blobTest.setMyblob(BLOB.empty_lob());
   
   //begin Hibernate Session
   cfg = new Configuration().configure();
   sessions = cfg.buildSessionFactory();
   session = sessions.openSession();
   tx = session.beginTransaction();
   session.save(blobTest);
   session.flush();
   session.refresh(blobTest, LockMode.UPGRADE);
   blob = (BLOB) blobTest.getMyblob();
   out = blob.getBinaryOutputStream();
   out.write(b);
   out.close();
   session.flush();
   tx.commit();
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   try {
    session.close();
   } catch (Exception e1) {
    e1.printStackTrace();
   }
  }
 }
}

  

取出程序和其他两种数据库操作几乎一样。

iBATIS SQL Maps SQL Server BLOB

    建表过程和 Hibernate 操作 SQL Server 一样,如果你对 iBATIS SQL Maps 还不熟息,请看这里

映射文件如下:

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE sqlMap
    PUBLIC "-//iBATIS.com//DTD SQL Map 2.0//EN"
    "
http://www.ibatis.com/dtd/sql-map-2.dtd">

<sqlMap>

    <insert id="insertBlob" parameterClass="bo.BlobTest">
      <![CDATA[
        insert into blob_test (myblob) values (#myblob#)
      ]]>
      <selectKey resultClass="java.lang.Integer" keyProperty="id">
        <![CDATA[
          SELECT @@IDENTITY AS ID
        ]]>
      </selectKey>
    </insert>

    <resultMap id="get-blob-result" class="bo.BlobTest">
      <result property="id" column="id"/>
      <result property="myblob" column="myblob"/>
    </resultMap>

    <select id="getBlob" resultMap="get-blob-result" parameterClass="bo.BlobTest">
      <![CDATA[
        select * from blob_test where id=#id#
      ]]>
    </select>
       
</sqlMap>

 

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE sqlMap
    PUBLIC "-//iBATIS.com//DTD SQL Map 2.0//EN"
    "
http://www.ibatis.com/dtd/sql-map-2.dtd">

<sqlMap>

    <insert id="insertBlob" parameterClass="bo.BlobTest">
      <![CDATA[
        insert into blob_test (myblob) values (#myblob#)
      ]]>
      <selectKey resultClass="java.lang.Integer" keyProperty="id">
        <![CDATA[
          SELECT @@IDENTITY AS ID
        ]]>
      </selectKey>
    </insert>

    <resultMap id="get-blob-result" class="bo.BlobTest">
      <result property="id" column="id"/>
      <result property="myblob" column="myblob"/>
    </resultMap>

    <select id="getBlob" resultMap="get-blob-result" parameterClass="bo.BlobTest">
      <![CDATA[
        select * from blob_test where id=#id#
      ]]>
    </select>
       
</sqlMap>

 

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE sqlMap
    PUBLIC "-//iBATIS.com//DTD SQL Map 2.0//EN"
    "
http://www.ibatis.com/dtd/sql-map-2.dtd">

<sqlMap>

    <insert id="insertBlob" parameterClass="bo.BlobTest">
      <![CDATA[
        insert into blob_test (myblob) values (#myblob#)
      ]]>
      <selectKey resultClass="java.lang.Integer" keyProperty="id">
        <![CDATA[
          SELECT @@IDENTITY AS ID
        ]]>
      </selectKey>
    </insert>

    <resultMap id="get-blob-result" class="bo.BlobTest">
      <result property="id" column="id"/>
      <result property="myblob" column="myblob"/>
    </resultMap>

    <select id="getBlob" resultMap="get-blob-result" parameterClass="bo.BlobTest">
      <![CDATA[
        select * from blob_test where id=#id#
      ]]>
    </select>
       
</sqlMap>

 

写入程序如下:

import java.io.*;

import com.ibatis.sqlmap.client.*;
import com.ibatis.common.resources.*;

import bo.*;

public class Tester {

 public void DoTest() {
  byte[] b=null;
  Reader reader = null;
  InputStream in = null;
  BlobTest blobTest = null;
  SqlMapClient sqlMap = null;
  String resource = "SqlMapConfig.xml";
  try {
   //begin InputStream
   in = new FileInputStream("d:/sample.jpg");
   b = new byte[in.available()];
   in.read(b);
   in.close();

   //begin BlobTest
   blobTest = new BlobTest();
   blobTest.setMyblob(b);

   //begin SqlMapClient
   reader = Resources.getResourceAsReader(resource);
   sqlMap = SqlMapClientBuilder.buildSqlMapClient(reader);
   sqlMap.startTransaction();
   sqlMap.insert("insertBlob", blobTest);
   sqlMap.commitTransaction();
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   try {
    sqlMap.endTransaction();
   } catch (Exception e1) {
    e1.printStackTrace();
   }
  }
 }
}

 

import java.io.*;

import com.ibatis.sqlmap.client.*;
import com.ibatis.common.resources.*;

import bo.*;

public class Tester {

 public void DoTest() {
  byte[] b=null;
  Reader reader = null;
  InputStream in = null;
  BlobTest blobTest = null;
  SqlMapClient sqlMap = null;
  String resource = "SqlMapConfig.xml";
  try {
   //begin InputStream
   in = new FileInputStream("d:/sample.jpg");
   b = new byte[in.available()];
   in.read(b);
   in.close();

   //begin BlobTest
   blobTest = new BlobTest();
   blobTest.setMyblob(b);

   //begin SqlMapClient
   reader = Resources.getResourceAsReader(resource);
   sqlMap = SqlMapClientBuilder.buildSqlMapClient(reader);
   sqlMap.startTransaction();
   sqlMap.insert("insertBlob", blobTest);
   sqlMap.commitTransaction();
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   try {
    sqlMap.endTransaction();
   } catch (Exception e1) {
    e1.printStackTrace();
   }
  }
 }
}

 

import java.io.*;

import com.ibatis.sqlmap.client.*;
import com.ibatis.common.resources.*;

import bo.*;

public class Tester {

 public void DoTest() {
  byte[] b=null;
  Reader reader = null;
  InputStream in = null;
  BlobTest blobTest = null;
  SqlMapClient sqlMap = null;
  String resource = "SqlMapConfig.xml";
  try {
   //begin InputStream
   in = new FileInputStream("d:/sample.jpg");
   b = new byte[in.available()];
   in.read(b);
   in.close();

   //begin BlobTest
   blobTest = new BlobTest();
   blobTest.setMyblob(b);

   //begin SqlMapClient
   reader = Resources.getResourceAsReader(resource);
   sqlMap = SqlMapClientBuilder.buildSqlMapClient(reader);
   sqlMap.startTransaction();
   sqlMap.insert("insertBlob", blobTest);
   sqlMap.commitTransaction();
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   try {
    sqlMap.endTransaction();
   } catch (Exception e1) {
    e1.printStackTrace();
   }
  }
 }
}

 

取出程序如下:

import java.io.*;

import com.ibatis.sqlmap.client.*;
import com.ibatis.common.resources.*;

import bo.*;

public class Tester {

 public void DoTest() {
  Reader reader = null;
  OutputStream out = null;
  BlobTest blobTest = null;
  SqlMapClient sqlMap = null;
  String resource = "SqlMapConfig.xml";
  try {
   //begin BlobTest
   blobTest = new BlobTest();
   blobTest.setId(new Integer(21));

   //begin SqlMapClient
   reader = Resources.getResourceAsReader(resource);
   sqlMap = SqlMapClientBuilder.buildSqlMapClient(reader);
   blobTest = (BlobTest) sqlMap.queryForObject("getBlob", blobTest);

   //begin OutputStream
   out = new FileOutputStream("d:/sample.jpg");
   out.write(blobTest.getMyblob());
   out.close();
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   try {
    sqlMap.endTransaction();
   } catch (Exception e1) {
    e1.printStackTrace();
   }
  }
 }
}

import java.io.*;

import com.ibatis.sqlmap.client.*;
import com.ibatis.common.resources.*;

import bo.*;

public class Tester {

 public void DoTest() {
  Reader reader = null;
  OutputStream out = null;
  BlobTest blobTest = null;
  SqlMapClient sqlMap = null;
  String resource = "SqlMapConfig.xml";
  try {
   //begin BlobTest
   blobTest = new BlobTest();
   blobTest.setId(new Integer(21));

   //begin SqlMapClient
   reader = Resources.getResourceAsReader(resource);
   sqlMap = SqlMapClientBuilder.buildSqlMapClient(reader);
   blobTest = (BlobTest) sqlMap.queryForObject("getBlob", blobTest);

   //begin OutputStream
   out = new FileOutputStream("d:/sample.jpg");
   out.write(blobTest.getMyblob());
   out.close();
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   try {
    sqlMap.endTransaction();
   } catch (Exception e1) {
    e1.printStackTrace();
   }
  }
 }
}

import java.io.*;

import com.ibatis.sqlmap.client.*;
import com.ibatis.common.resources.*;

import bo.*;

public class Tester {

 public void DoTest() {
  Reader reader = null;
  OutputStream out = null;
  BlobTest blobTest = null;
  SqlMapClient sqlMap = null;
  String resource = "SqlMapConfig.xml";
  try {
   //begin BlobTest
   blobTest = new BlobTest();
   blobTest.setId(new Integer(21));

   //begin SqlMapClient
   reader = Resources.getResourceAsReader(resource);
   sqlMap = SqlMapClientBuilder.buildSqlMapClient(reader);
   blobTest = (BlobTest) sqlMap.queryForObject("getBlob", blobTest);

   //begin OutputStream
   out = new FileOutputStream("d:/sample.jpg");
   out.write(blobTest.getMyblob());
   out.close();
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   try {
    sqlMap.endTransaction();
   } catch (Exception e1) {
    e1.printStackTrace();
   }
  }
 }
}

iBATIS SQL Maps MySQL BLOB

    这个主题很简单,需要注意映射文件 insert 元素主键生成方式,写入、取出程序和上面的 SQL Server 一样

    <insert id="insertBlob" parameterClass="bo.BlobTest">
      <![CDATA[
        insert into blob_test (myblob) values (#myblob#)
      ]]>
      <selectKey resultClass="java.lang.Integer" keyProperty="id">
    <![CDATA[
          select last_insert_id();
    ]]>
      </selectKey>
  </insert>
  

    <insert id="insertBlob" parameterClass="bo.BlobTest">
      <![CDATA[
        insert into blob_test (myblob) values (#myblob#)
      ]]>
      <selectKey resultClass="java.lang.Integer" keyProperty="id">
    <![CDATA[
          select last_insert_id();
    ]]>
      </selectKey>
  </insert>
  

    <insert id="insertBlob" parameterClass="bo.BlobTest">
      <![CDATA[
        insert into blob_test (myblob) values (#myblob#)
      ]]>
      <selectKey resultClass="java.lang.Integer" keyProperty="id">
    <![CDATA[
          select last_insert_id();
    ]]>
      </selectKey>
  </insert>
  

iBATIS SQL Maps Oracle BLOB

    使用 Oracle LONG RAW 类型,注意映射文件 insert 元素主键生成方式,写入、取出程序和上面的 SQL Server 一样

    <insert id="insertBlob" parameterClass="bo.BlobTest">
      <selectKey resultClass="int" keyProperty="id">
        <![CDATA[
          select hibernate_sequence.nextval from dual
        ]]>
      </selectKey>
      <![CDATA[
        insert into blob_test (id,myblob) values (#id#,#myblob#)
      ]]>
    </insert>

 

    <insert id="insertBlob" parameterClass="bo.BlobTest">
      <selectKey resultClass="int" keyProperty="id">
        <![CDATA[
          select hibernate_sequence.nextval from dual
        ]]>
      </selectKey>
      <![CDATA[
        insert into blob_test (id,myblob) values (#id#,#myblob#)
      ]]>
    </insert>

 

    <insert id="insertBlob" parameterClass="bo.BlobTest">
      <selectKey resultClass="int" keyProperty="id">
        <![CDATA[
          select hibernate_sequence.nextval from dual
        ]]>
      </selectKey>
      <![CDATA[
        insert into blob_test (id,myblob) values (#id#,#myblob#)
      ]]>
    </insert>

 

如果你一定要用 Oracle BLOB 类型,接着往下看:

    iBATIS 2.0.9 以前,处理 Oracle BLOB 类型相当麻烦,要自己实现TypeHandlerCallback 接口。iBATIS 2.0.9 提供了 BlobTypeHandlerCallback 实现类,写入、取出程序和上面的 SQL Server 一样。只是映射文件 resultMap 元素需要修改:


    <resultMap id="get-blob-result" class="bo.BlobTest">
      <result property="id" column="id"/>
      <result property="myblob" column="myblob"
              typeHandler="com.ibatis.sqlmap.engine.type.BlobTypeHandlerCallback"/>
    </resultMap>


    <resultMap id="get-blob-result" class="bo.BlobTest">
      <result property="id" column="id"/>
      <result property="myblob" column="myblob"
              typeHandler="com.ibatis.sqlmap.engine.type.BlobTypeHandlerCallback"/>
    </resultMap>


    <resultMap id="get-blob-result" class="bo.BlobTest">
      <result property="id" column="id"/>
      <result property="myblob" column="myblob"
              typeHandler="com.ibatis.sqlmap.engine.type.BlobTypeHandlerCallback"/>
    </resultMap>


    <resultMap id="get-blob-result" class="bo.BlobTest">
      <result property="id" column="id"/>
      <result property="myblob" column="myblob"
              typeHandler="com.ibatis.sqlmap.engine.type.BlobTypeHandlerCallback"/>
    </resultMap>

内容概要:《2024年中国城市低空经济发展指数报告》由36氪研究院发布,指出低空经济作为新质生产力的代表,已成为中国经济新的增长点。报告从发展环境、资金投入、创新能力、基础支撑和发展成效五个维度构建了综合指数评价体系,评估了全国重点城市的低空经济发展状况。北京和深圳在总指数中名列前茅,分别以91.26和84.53的得分领先,展现出强大的资金投入、创新能力和基础支撑。低空经济主要涉及无人机、eVTOL(电动垂直起降飞行器)和直升机等产品,广泛应用于农业、物流、交通、应急救援等领域。政策支持、市场需求和技术进步共同推动了低空经济的快速发展,预计到2026年市场规模将突破万亿元。 适用人群:对低空经济发展感兴趣的政策制定者、投资者、企业和研究人员。 使用场景及目标:①了解低空经济的定义、分类和发展驱动力;②掌握低空经济的主要应用场景和市场规模预测;③评估各城市在低空经济发展中的表现和潜力;④为政策制定、投资决策和企业发展提供参考依据。 其他说明:报告强调了政策监管、产业生态建设和区域融合错位的重要性,提出了加强法律法规建设、人才储备和基础设施建设等建议。低空经济正加速向网络化、智能化、规模化和集聚化方向发展,各地应找准自身比较优势,实现差异化发展。
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