mybatis如何读取clob数据 详细过程

转载：http://zhidao.baidu.com/link?url=txmt7GCPoIuDnBxDtFDqdq_0T41kR7NQ7gYVHPtPkfTp6oSA_o14TJasV4U7txzcYkCghP5axWgCq87dHJaO5TAzL1pg4TGVicVBLTDMTnS

例子：

表结构

CREATE  TABLE  USERINFO(USERID VARCHAR2(5),
                         USERNAME VARCHAR2(20),
                         MEMO CLOB,
                        constraint  PK_USERINFO   primary  key (USERID));

java代码：

public  class  OracleClobTypeHandlerCallback  implements  TypeHandlerCallback {
    public  void  setParameter(ParameterSetter setter, Object obj)
            throws  SQLException {
        CLOB clob = CLOB.empty_lob();
        clob.setString( 1 , (String)obj);
        setter.setClob(clob);
    }
    public  Object getResult(ResultGetter getter)  throws  SQLException {
        CLOB clob = (CLOB) getter.getClob();
        return  (clob ==  null  || clob.length() ==  0  )?  null  :clob.getSubString(( long ) 1 , ( int )clob.length());
    }
    public  Object valueOf(String param) {
        return  null ;
    }
}

sqlmap配置：

< resultMap  id = "userResult"  class = "com.prs.application.ehld.sample.common.dto.UserInfoDTO" >
    < result  property = "userID"  column = "USERID"  columnIndex = "1" />
    < result  property = "userName"  column = "USERNAME"  columnIndex = "2" />
    < result  property = "memo"   column = "memo"  jdbcType = "CLOB"  javaType = "java.lang.String"  typeHandler =" OracleClobTypeHandlerCallback "/>
resultMap >

1、MyBatis介绍

    MyBatis 本是apache的一个开源项目iBatis, 2010年这个项目由apache software foundation 迁移到了google code，并且改名为MyBatis 。2013年11月迁移到Github。

    iBATIS一词来源于“internet”和“abatis”的组合，是一个基于Java的持久层框架。iBATIS提供的持久层框架包括SQL Maps和Data Access Objects（DAO）

2、CLOB

    SQL CLOB 是内置类型，它将字符大对象 (Character Large Object) 存储为数据库表某一行中的一个列值。默认情况下，驱动程序使用 SQL locator(CLOB) 实现 Clob 对象，这意味着 CLOB 对象包含一个指向 SQL CLOB 数据的逻辑指针而不是数据本身。Clob 对象在它被创建的事务处理期间有效。

3、MyBatis对CLOB类型数据实现增删改查

oracle表结构

create  table  T_USERS
(
  ID      NUMBER  not  null ,
  NAME     VARCHAR2(30),
  SEX     VARCHAR2(3),
  BIRS     DATE ,
  MESSAGE CLOB
)
create  sequence  SEQ_T_USERS_ID
minvalue 1
maxvalue 99999999
start  with  1
increment  by  1
cache 20;

配置mybatis配置文件UsersMapper.xml

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

  PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN">

< mapper  namespace = "examples.mapper.UsersMapper"  >


    < resultMap  type = "examples.bean.Users"  id = "BaseResultMap" >
        < result  property = "id"  column = "id"  />
        < result  property = "name"  column = "name"  />
        < result  property = "sex"  column = "sex"  />
        < result  property = "birs"  column = "birs"  jdbcType = "TIMESTAMP" />
        < result  property = "message"  column = "message"  jdbcType = "CLOB"
            javaType = "java.lang.String"  typeHandler ="examples.service.OracleClobTypeHandler"/>
    resultMap >

    < sql  id = "Tabel_Name" >
        t_users
    sql >


    < sql  id = "Base_Column_List"  >
        id,name,sex,birs,message
    sql >


    < sql  id = "Example_Where_Clause" >
        where 1=1
        < trim  suffixOverrides = "," >
            < if  test = "id != null" >
                and id = #{id}
            if >
            < if  test = "name != null and name != ''" >
                and name like concat(concat('%', '${name}'), '%')
            if >
            < if  test = "sex != null and sex != ''" >
                and sex like concat(concat('%', '${sex}'), '%')
            if >
            < if  test = "birs != null" >
                and birs = #{birs}
            if >
            < if  test = "message != null" >
                and message = #{message}
            if >
        trim >
    sql >


    < select  id = "queryByList"  resultMap = "BaseResultMap"  parameterType = "Object" >
        select
        < include  refid = "Base_Column_List"  />
        from t_users
        < include  refid = "Example_Where_Clause" />
    select >
mapper >

Mapper类接口

package  examples.mapper;

import  java.util.List;

public  interface  UsersMapper {

    public  List queryBySelective(T t);

    public  List queryByList(T t);

}

类型转换工具类

package  examples.service;

import  java.sql.CallableStatement;
import  java.sql.PreparedStatement;
import  java.sql.ResultSet;
import  java.sql.SQLException;

import  oracle.sql.CLOB;

import  org.apache.ibatis.type.JdbcType;
import  org.apache.ibatis.type.TypeHandler;

public  class  OracleClobTypeHandler  implements  TypeHandler {            public  Object valueOf(String param) {          return  null ;      }        @Override      public  Object getResult(ResultSet arg0, String arg1)  throws  SQLException {          CLOB clob = (CLOB) arg0.getClob(arg1);          return  (clob ==  null  || clob.length() ==  0 ) ?  null  : clob.getSubString(( long )  1 , ( int ) clob.length());      }        @Override      public  Object getResult(ResultSet arg0,  int  arg1)  throws  SQLException {          return  null ;      }        @Override      public  Object getResult(CallableStatement arg0,  int  arg1)  throws  SQLException {          return  null ;      }        @Override      public  void  setParameter(PreparedStatement arg0,  int  arg1, Object arg2, JdbcType arg3)  throws  SQLException {          CLOB clob = CLOB.empty_lob();          clob.setString( 1 , (String) arg2);          arg0.setClob(arg1, clob);      } }

    public  Object valueOf(String param) {
        return  null ;
    }

    @Override
    public  Object getResult(ResultSet arg0, String arg1)  throws  SQLException {
        CLOB clob = (CLOB) arg0.getClob(arg1);
        return  (clob ==  null  || clob.length() ==  0 ) ?  null  : clob.getSubString(( long )  1 , ( int ) clob.length());
    }

    @Override
    public  Object getResult(ResultSet arg0,  int  arg1)  throws  SQLException {
        return  null ;
    }

    @Override
    public  Object getResult(CallableStatement arg0,  int  arg1)  throws  SQLException {
        return  null ;
    }

    @Override
    public  void  setParameter(PreparedStatement arg0,  int  arg1, Object arg2, JdbcType arg3)  throws  SQLException {
        CLOB clob = CLOB.empty_lob();
        clob.setString( 1 , (String) arg2);
        arg0.setClob(arg1, clob);
    }
}

Spring配置文件

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

    xmlns:xsi="

    xmlns:mvc="
    xmlns:tx="
    xsi:schemaLocation="
    default-autowire = "byType" >


    < bean  id = "dataSource"  class = "org.springframework.jdbc.datasource.DriverManagerDataSource" >
         < property  name = "driverClassName" >< value >oracle.jdbc.driver.OracleDriver value > property >
         < property  name = "url" >< value >jdbc:oracle:thin:@127.0.0.1:1521:pms value > property >
         < property  name = "username" >< value >pms value > property >
         < property  name = "password" >< value >pms value > property >
    bean >



    < bean  id = "sqlSessionFactory"  class = "org.mybatis.spring.SqlSessionFactoryBean" >
        < property  name = "dataSource"  ref = "dataSource"  />
        < property  name = "mapperLocations" >
            < list >
                < value >classpath:examples/mybatis/oracle/UsersMapper.xml value >
            list >
        property >
    bean >


    < bean  id = "dao"  class = "org.mybatis.spring.mapper.MapperFactoryBean" >

        < property  name = "mapperInterface"  value = "examples.mapper.UsersMapper"  />
        < property  name = "sqlSessionFactory"  ref = "sqlSessionFactory"  />
    bean >
beans >

测试类

package  examples.service;

import  java.text.ParseException;
import  java.text.SimpleDateFormat;
import  java.util.List;

import  org.springframework.context.ApplicationContext;
import  org.springframework.context.support.ClassPathXmlApplicationContext;

import  examples.bean.Users;
import  examples.mapper.UsersMapper;

public  class  TestUsersService {

    @SuppressWarnings ( "unchecked" )
    public  static  void  main(String[] args)  throws  ParseException {
            ApplicationContext ac =
            new  ClassPathXmlApplicationContext( "classpath:/examples/service/spring.xml" );
            UsersMapper dao = (UsersMapper)ac.getBean( "dao" );

            //查询
             Users nullBean =  new  Users();
            List list = dao.queryByList(nullBean);
            if (list !=  null ) {
                for (Users user : list) {
                    System.out.println(user);
                }
            }

    }

}