以下示例将演示如何在Spring JDBC的帮助下使用Update Query更新CLOB.我们将更新学生表中的可用记录.
CREATE TABLE Student( ID INT NOT NULL AUTO_INCREMENT, NAME VARCHAR(20) NOT NULL, AGE INT NOT NULL, DESCRIPTION LONGTEXT, PRIMARY KEY (ID) );
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);
其中,
in : SqlParameterSource对象,用于传递参数以更新查询.
SqlLobValue : 用于表示SQL BLOB/CLOB值参数的对象.
jdbcTemplateObject : NamedParameterJdbcTemplate对象,用于更新数据库中的student对象.
为了理解上述与Spring JDBC相关的概念,让我们编写一个例子,这将更新查询.要编写我们的示例,让我们使用一个可用的Eclipse IDE并使用以下步骤创建一个Spring应用程序.
Step | 描述 |
---|---|
1 | 更新在章节下创建的项目学生 Spring JDBC - First Application . |
2 | 更新bean配置并运行应用程序,如下所述. |
以下是数据访问对象接口文件的内容 StudentDAO.java .
package com.it1352; 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 Student.java 文件的内容.
package com.it1352; 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 StudentMapper.java 文件的内容.
package com.it1352; 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; } }
以下是定义的DAO接口StudentDAO的实现类文件 StudentJDBCTemplate.java .
package com.it1352; 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 MainApp.java 文件的内容.
package com.it1352; import java.util.List; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; import com.IT屋.StudentJDBCTemplate; public class MainApp { public static void main(String[] args) { ApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml"); StudentJDBCTemplate studentJDBCTemplate = (StudentJDBCTemplate)context.getBean("studentJDBCTemplate"); studentJDBCTemplate.updateDescription(1, "This can be a very long text upto 4 GB of size."); } }
以下是配置文件 Beans.xml .
<?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"/> <property name = "username" value = "root"/> <property name = "password" value = "admin"/> </bean> <!-- Definition for studentJDBCTemplate bean --> <bean id = "studentJDBCTemplate" class = "com.it1352.StudentJDBCTemplate"> <property name = "dataSource" ref = "dataSource" /> </bean> </beans>
完成源和bean配置文件的创建后,让我们运行应用程序.如果您的应用程序一切正常,它将打印以下消息.
Updated Record with ID = 1
您可以通过查询数据库来检查存储的描述.