Spring JDBC處理CLOB型別欄位


以下範例將演示使用spring jdbc更新CLOB型別的欄位值,即更新student表中的可用記錄。

student表的結構如下 -

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);

在上面語法中 -

  • SqlLobValue - 表示SQL BLOB / CLOB值引數的物件。
  • in - SqlParameterSource物件將引數傳遞給更新查詢。
  • jdbcTemplateObject - NamedParameterJdbcTemplate物件來更新資料庫中的學生物件。

建立專案

要了解上面提到的Spring JDBC相關的概念,這裡建立一個專案用來演示如何操作CLOB型別欄位。開啟Eclipse IDE,並按照以下步驟建立一個名稱為:HandlingCLOB 的Spring應用程式專案。

步驟說明

  1. 參考第一個Spring JDBC專案來建立一個Maven專案 - /20/235/8754.html
  2. 更新bean組態並執行應用程式。

完整的專案結構如下所示 -

檔案 : pom.xml 的內容 -

<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>

以下是資料存取物件介面檔案:StudentDAO.java的程式碼內容:

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);

}

以下是檔案:Student.java的程式碼內容:

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;
    }
}

以下是檔案:StudentMapper.java的程式碼內容:

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;
    }
}

以下是實現類檔案:StudentJDBCTemplate.java,它實現了介面StudentDAO.java
以下是檔案:StudentJDBCTemplate.java的程式碼內容:

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);
    }
}

以下是程式執行入口檔案:MainApp.java的程式碼內容:

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和資料庫組態檔案:application-beans.xml的程式碼內容:

<?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 檔案的位置是:{workspace}/fistapp/src/main/java 目錄,如果放置錯了,程式可能會因為找不到此組態檔案而出錯。

完成建立原始碼和bean和資料庫連線資訊的檔案組態後,執行應用程式。這裡先簡單說明一下執行的步驟,在專案名稱(HandlingCLOB)上點選右鍵,在彈出的選單中選擇:【Run As】-> 【Maven test】

在執行測試成功後,應該會輸出類似以下內容(含有 BUILD SUCCESS 的資訊) 。
接下來,點選類檔案:MainApp.java 選擇【Run As】->【Java Application】,如果應用程式一切正常,這將列印以下訊息:

Updated Record with ID = 1

資料庫中的student表中的資料被修改為:

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>