org.springframework.jdbc.core.NamedParameterJdbcTemplate
类是一个具有基本JDBC操作的模板类,允许使用命名参数而不是传统的’?
‘占位符。 这个类代表一个包装的JdbcTemplate
,在执行时完成从命名参数占位符替换为JDBC样式’?
‘ 占位符。它还允许将值列表扩展到适当数量的占位符。
使用到的 Student
表的结构如下 -
CREATE TABLE Student(
ID INT NOT NULL AUTO_INCREMENT,
NAME VARCHAR(20) NOT NULL,
AGE INT NOT NULL,
DESCRIPTION LONGTEXT DEFAULT NULL,
PRIMARY KEY (ID)
);
类的声明
以下是org.springframework.jdbc.core.NamedParameterJdbcTemplate
接口的声明 -
public class NamedParameterJdbcTemplate
extends Object
implements NamedParameterJdbcOperations
语法
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);
在上代码中,
- in -
SqlParameterSource
对象将参数传递给更新查询。 - SqlLobValue - 表示SQL
BLOB/CLOB
值参数的对象。 - jdbcTemplateObject -
NamedParameterJdbcTemplate
对象来更新数据库中的Student
对象。
实例项目
要了解上述与Spring JDBC相关的概念,下面我们编写一个使用NamedParameterJdbcTemplate
来更新Student
对象。打开Eclipse IDE,并按照以下步骤创建一个Spring应用程序,这里创建一个名称为:NamedParameterJdbcTemplate 的项目。
步骤说明
- 参考第一个Spring JDBC项目来创建一个Maven项目 - http://www.yiibai.com/springjdbc/first_application.html
- 更新bean配置并运行应用程序。
完整的项目结构如下所示 -
以下是Maven配置文件:pom.xml的代码内容:
<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>NamedParameterJdbcTemplate</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>NamedParameterJdbcTemplate</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>
以下是数据访问对象接口文件:StudentDAO.java的内容:
package com.yiibai;
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 list down all the records from the
* Student table.
*/
public List<Student> listStudents();
/**
* This is the method to be used to update a record into the Student table.
*/
public void updateDescription(Integer id, String description);
public void create(String name, Integer age);
}
以下是文件:Student.java的代码内容:
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的代码内容:
package com.yiibai;
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;
}
}
实现类StudentJDBCTemplate.java
实现了定义的DAO接口 - StudentDAO.java
,以下是文件:StudentJDBCTemplate.java的代码内容:
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;
this.jdbcTemplateObject = new JdbcTemplate(dataSource);
}
public List<Student> listStudents() {
String SQL = "select * from Student";
List<Student> students = jdbcTemplateObject.query(SQL, new StudentMapper());
return students;
}
public void create(String name, Integer age) {
// TODO Auto-generated method stub
String insertQuery = "insert into student (name, age, description) values (?, ?, NULL)";
jdbcTemplateObject.update(insertQuery, name, age);
System.out.println("Created Record Name = " + name + " Age = " + age);
return;
}
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);
}
}
以下是文件:MainApp.java的代码内容:
package com.yiibai;
import java.util.ArrayList;
import java.util.List;
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");
System.out.println("------Records Creation--------");
studentJDBCTemplate.create("Maxsu", 21);
studentJDBCTemplate.create("Curry", 22);
studentJDBCTemplate.create("Suzend", 23);
// 更新描述
studentJDBCTemplate.updateDescription(1, "This can be a very long text upto 4 GB of size.");
studentJDBCTemplate.updateDescription(2, "随便写一下描述内容......易百教程(www.yiibai.com) - 专注于IT教程和实例");
System.out.println("------Listing Multiple Records--------");
List<Student> students = studentJDBCTemplate.listStudents();
for (Student record : students) {
System.out.print("ID : " + record.getId());
System.out.print(", Name : " + record.getName());
System.out.println(", Age : " + record.getAge());
System.out.println(", Description : " + record.getDescription());
}
}
}
以下是文件:application-beans.xml的代码内容:
<?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 目录,如果放置错了,程序可能会因为找不到此配置文件而出错。
完成创建源代码和bean和数据库连接信息的文件配置后,运行应用程序。这里先简单说明一下运行的步骤,在项目名称(NamedParameterJdbcTemplate)上点击右键,在弹出的菜单中选择:【Run As】-> 【Maven test】
在运行测试成功后,应该会输出类似以下内容(含有 BUILD SUCCESS 的信息) 。
接下来,点击类文件:MainApp.java 选择【Run As】->【Java Application】,如果应用程序一切正常,这将打印以下结果:
------Records Creation--------
Created Record Name = Maxsu Age = 21
Created Record Name = Curry Age = 22
Created Record Name = Suzend Age = 23
Updated Record with ID = 1
Updated Record with ID = 2
------Listing Multiple Records--------
ID : 1, Name : Maxsu, Age : 21
, Description : This can be a very long text upto 4 GB of size.
ID : 2, Name : Curry, Age : 22
, Description : 随便写一下描述内容......易百教程(www.yiibai.com) - 专注于IT教程和实例
ID : 3, Name : Suzend, Age : 23
, Description : null