以下示例將演示使用spring jdbc更新CLOB類型的字段值，即更新student表中的可用記錄。

student表的結(jié)構(gòu)如下 -

CREATE TABLE student(
   ID   INT NOT NULL AUTO_INCREMENT,
   NAME VARCHAR(20) NOT NULL,
   AGE  INT NOT NULL,
   DESCRIPTION LONGTEXT,
   PRIMARY KEY (ID)
);

INSERT INTO student(ID,NAME,AGE,DESCRIPTION) VALUES(1,'Maxsu', 23, NULL);

語(yǔ)法：

MapSqlParameterSource in = new MapSqlParameterSource();
in.addValue("id", id);
in.addValue("description",  new SqlLobValue(description, new DefaultLobHandler()), Types.CLOB);

String SQL = "update Student set description = :description where id = :id";
NamedParameterJdbcTemplate jdbcTemplateObject = new NamedParameterJdbcTemplate(dataSource);
jdbcTemplateObject.update(SQL, in);

在上面語(yǔ)法中 -

• SqlLobValue - 表示SQL BLOB / CLOB值參數(shù)的對(duì)象。
• in - SqlParameterSource對(duì)象將參數(shù)傳遞給更新查詢。
• jdbcTemplateObject - NamedParameterJdbcTemplate對(duì)象來更新數(shù)據(jù)庫(kù)中的學(xué)生對(duì)象。

創(chuàng)建項(xiàng)目

要了解上面提到的Spring JDBC相關(guān)的概念，這里創(chuàng)建一個(gè)項(xiàng)目用來演示如何操作CLOB類型字段。打開Eclipse IDE，并按照以下步驟創(chuàng)建一個(gè)名稱為：HandlingCLOB 的Spring應(yīng)用程序項(xiàng)目。

步驟說明

1. 參考第一個(gè)Spring JDBC項(xiàng)目來創(chuàng)建一個(gè)Maven項(xiàng)目 - http://www.yiibai.com/springjdbc/first_application.html
2. 更新bean配置并運(yùn)行應(yīng)用程序。

完整的項(xiàng)目結(jié)構(gòu)如下所示 -

文件 : pom.xml 的內(nèi)容 -

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.yiibai</groupId>
    <artifactId>HandlingCLOB</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>
    <name>HandlingCLOB</name>
    <url>http://maven.apache.org</url>
    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.40</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>4.1.0.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>4.1.4.RELEASE</version>
        </dependency>
    </dependencies>
</project>

以下是數(shù)據(jù)訪問對(duì)象接口文件：StudentDAO.java的代碼內(nèi)容：

package com.yiibai;

import java.util.List;
import javax.sql.DataSource;

import java.util.List;
import javax.sql.DataSource;

public interface StudentDAO {
    /**
     * This is the method to be used to initialize database resources ie.
     * connection.
     */
    public void setDataSource(DataSource ds);

    /**
     * This is the method to be used to update a record into the Student table.
     */
    public void updateDescription(Integer id, String description);

}

以下是文件：Student.java的代碼內(nèi)容：

package com.yiibai;

public class Student {
    private Integer age;
    private String name;
    private Integer id;
    private String description;

    public void setAge(Integer age) {
        this.age = age;
    }

    public Integer getAge() {
        return age;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public Integer getId() {
        return id;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }
}

以下是文件：StudentMapper.java的代碼內(nèi)容：

package com.yiibai;

import java.sql.ResultSet;
import java.sql.SQLException;
import org.springframework.jdbc.core.RowMapper;

import java.sql.ResultSet;
import java.sql.SQLException;
import org.springframework.jdbc.core.RowMapper;

public class StudentMapper implements RowMapper<Student> {
    public Student mapRow(ResultSet rs, int rowNum) throws SQLException {
        Student student = new Student();
        student.setId(rs.getInt("id"));
        student.setName(rs.getString("name"));
        student.setAge(rs.getInt("age"));
        student.setDescription(rs.getString("description"));
        return student;
    }
}

以下是實(shí)現(xiàn)類文件:StudentJDBCTemplate.java，它實(shí)現(xiàn)了接口StudentDAO.java：
以下是文件：StudentJDBCTemplate.java的代碼內(nèi)容：

package com.yiibai;

import java.util.List;
import javax.sql.DataSource;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.namedparam.MapSqlParameterSource;
import org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate;
import org.springframework.jdbc.core.namedparam.SqlParameterSource;
import org.springframework.jdbc.core.simple.SimpleJdbcCall;
import org.springframework.jdbc.core.support.SqlLobValue;
import org.springframework.jdbc.support.lob.DefaultLobHandler;
import java.io.ByteArrayInputStream;
import java.sql.Types;

public class StudentJDBCTemplate implements StudentDAO {
    private DataSource dataSource;
    private JdbcTemplate jdbcTemplateObject;

    public void setDataSource(DataSource dataSource) {
        this.dataSource = dataSource;
    }

    public void updateDescription(Integer id, String description) {

        MapSqlParameterSource in = new MapSqlParameterSource();
        in.addValue("id", id);
        in.addValue("description", new SqlLobValue(description, new DefaultLobHandler()), Types.CLOB);

        String SQL = "update Student set description = :description where id = :id";
        NamedParameterJdbcTemplate jdbcTemplateObject = new NamedParameterJdbcTemplate(dataSource);
        jdbcTemplateObject.update(SQL, in);
        System.out.println("Updated Record with ID = " + id);
    }
}

以下是程序執(zhí)行入口文件：MainApp.java的代碼內(nèi)容：

package com.yiibai;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.yiibai.StudentJDBCTemplate;

public class MainApp {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("application-beans.xml");

        StudentJDBCTemplate studentJDBCTemplate = (StudentJDBCTemplate) context.getBean("studentJDBCTemplate");

        studentJDBCTemplate.updateDescription(1, "This can be a very long text upto 4 GB of size.");
    }
}

以下是Bean和數(shù)據(jù)庫(kù)配置文件：application-beans.xml的代碼內(nèi)容：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd ">

    <!-- Initialization for data source -->
    <bean id="dataSource"
        class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="com.mysql.jdbc.Driver" />
        <property name="url" value="jdbc:mysql://localhost:3306/test?characterEncoding=utf8&useSSL=true" />
        <property name="username" value="root" />
        <property name="password" value="123456" />
    </bean>

    <!-- Definition for studentJDBCTemplate bean -->
    <bean id="studentJDBCTemplate" class="com.yiibai.StudentJDBCTemplate">
        <property name="dataSource" ref="dataSource" />
    </bean>

</beans>

注意： application-beans.xml 文件的位置是：{workspace}/fistapp/src/main/java 目錄，如果放置錯(cuò)了，程序可能會(huì)因?yàn)檎也坏酱伺渲梦募鲥e(cuò)。

完成創(chuàng)建源代碼和bean和數(shù)據(jù)庫(kù)連接信息的文件配置后，運(yùn)行應(yīng)用程序。這里先簡(jiǎn)單說明一下運(yùn)行的步驟，在項(xiàng)目名稱(HandlingCLOB)上點(diǎn)擊右鍵，在彈出的菜單中選擇：【Run As】-> 【Maven test】

在運(yùn)行測(cè)試成功后，應(yīng)該會(huì)輸出類似以下內(nèi)容(含有 BUILD SUCCESS 的信息) 。
接下來，點(diǎn)擊類文件：MainApp.java 選擇【Run As】->【Java Application】，如果應(yīng)用程序一切正常，這將打印以下消息：

Updated Record with ID = 1

數(shù)據(jù)庫(kù)中的student表中的數(shù)據(jù)被修改為：

mysql> select * from student;
+----+-------+-----+-------------------------------------------------+
| ID | NAME  | AGE | DESCRIPTION                                     |
+----+-------+-----+-------------------------------------------------+
|  1 | Maxsu |  23 | This can be a very long text upto 4 GB of size. |
+----+-------+-----+-------------------------------------------------+
1 row in set

mysql>