Spring(十二)之JDBC框架

JDBC 框架概述

在使用普通的 JDBC 数据库时，就会很麻烦的写不必要的代码来处理异常，打开和关闭数据库连接等。但 Spring JDBC 框架负责所有的低层细节，从开始打开连接，准备和执行 SQL 语句，处理异常，处理事务，到最后关闭连接。

所以当从数据库中获取数据时，你所做的是定义连接参数，指定要执行的 SQL 语句，每次迭代完成所需的工作。

Spring JDBC 提供几种方法和数据库中相应的不同的类与接口。我将给出使用 JdbcTemplate 类框架的经典和最受欢迎的方法。这是管理所有数据库通信和异常处理的中央框架类。

JdbcTemplate 类

JdbcTemplate 类执行 SQL 查询、更新语句和存储过程调用，执行迭代结果集和提取返回参数值。它也捕获 JDBC 异常并转换它们到 org.springframework.dao 包中定义的通用类、更多的信息、异常层次结构。

JdbcTemplate 类的实例是线程安全配置的。所以你可以配置 JdbcTemplate 的单个实例，然后将这个共享的引用安全地注入到多个 DAOs 中。

使用 JdbcTemplate 类时常见的做法是在你的 Spring 配置文件中配置数据源，然后共享数据源 bean 依赖注入到 DAO 类中，并在数据源的设值函数中创建了 JdbcTemplate。

演示示例如下:

(1)建立mysql数据库，并导入该脚本，库名可任意命名，这里命名为test,sql脚本为:

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

(2)创建实体

package com.tutorialspoint;
public class Student {private Integer age;private String name;private Integer id;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;}
}

(3)创建DAO

package com.tutorialspoint;
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 create* a record in the Student table.*/public void create(String name, Integer age);/** * This is the method to be used to list down* a record from the Student table corresponding* to a passed student id.*/public Student getStudent(Integer id);/** * 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 delete* a record from the Student table corresponding* to a passed student id.*/public void delete(Integer id);/** * This is the method to be used to update* a record into the Student table.*/public void update(Integer id, Integer age);
}

(4)创建StudentMapper

package com.tutorialspoint;
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"));return student;}
}

(5)创建StudentJDBCTemplate

package com.tutorialspoint;
import java.util.List;
import javax.sql.DataSource;
import org.springframework.jdbc.core.JdbcTemplate;
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 void create(String name, Integer age) {String SQL = "insert into Student (name, age) values (?, ?)";     jdbcTemplateObject.update( SQL, name, age);System.out.println("Created Record Name = " + name + " Age = " + age);return;}public Student getStudent(Integer id) {String SQL = "select * from Student where id = ?";Student student = jdbcTemplateObject.queryForObject(SQL, new Object[]{id}, new StudentMapper());return student;}public List<Student> listStudents() {String SQL = "select * from Student";List <Student> students = jdbcTemplateObject.query(SQL, new StudentMapper());return students;}public void delete(Integer id){String SQL = "delete from Student where id = ?";jdbcTemplateObject.update(SQL, id);System.out.println("Deleted Record with ID = " + id );return;}public void update(Integer id, Integer age){String SQL = "update Student set age = ? where id = ?";jdbcTemplateObject.update(SQL, age, id);System.out.println("Updated Record with ID = " + id );return;}
}

(6)编写对应的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/beanshttp://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="1234"/></bean><!-- Definition for studentJDBCTemplate bean --><bean id="studentJDBCTemplate" class="com.tutorialspoint.StudentJDBCTemplate"><property name="dataSource"  ref="dataSource" />    </bean></beans>

(7)编写MainApp.java并运行

package com.tutorialspoint;
import java.util.List;import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class MainApp {public static void main(String[] args) {ApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml");StudentJDBCTemplate studentJDBCTemplate = (StudentJDBCTemplate)context.getBean("studentJDBCTemplate");    System.out.println("------Records Creation--------" );studentJDBCTemplate.create("Zara", 11);studentJDBCTemplate.create("Nuha", 2);studentJDBCTemplate.create("Ayan", 15);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("----Updating Record with ID = 2 -----" );studentJDBCTemplate.update(2, 20);System.out.println("----Listing Record with ID = 2 -----" );Student student = studentJDBCTemplate.getStudent(2);System.out.print("ID : " + student.getId() );System.out.print(", Name : " + student.getName() );System.out.println(", Age : " + student.getAge());      }
}

运行结果如下:

数据表数据由无变为有:

转载于:https://www.cnblogs.com/youcong/p/9460819.html