使用Spring组件JDBC Template简化持久化操作

案例下载：git clone https://gitee.com/chenxiaonian/selection_course.git

JDBC Template概念

Sprint JDBC Template

• 为了简化持久化操作，Spring在JDBC API之上提供了JDBC Template组件
• JDBC Template提供统一的模板方法，在保留代码灵活性的基础上，尽量减少持久化代码

[使用JDBC Template之前]

[使用JDBC Template之后]

环境配置

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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>org.example</groupId>
    <artifactId>selection_course</artifactId>
    <version>1.0-SNAPSHOT</version>
    <properties>
        <spring.version>4.0.2.RELEASE</spring.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.44</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-beans</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
        </dependency>
    </dependencies>
</project>

src/main/resources/spring.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"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context.xsd
    http://www.springframework.org/schema/aop
    http://www.springframework.org/schema/aop/spring-aop.xsd
    http://www.springframework.org/schema/tx
    http://www.springframework.org/schema/tx/spring-tx.xsd">
    <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/selection_course?useUnicode=true&amp;characterEncoding=utf-8"/>
        <property name="username" value="root"/>
        <property name="password" value="root"/>
    </bean>
    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="dataSource"/>
    </bean>
    <context:component-scan base-package="com.song.sc"/>
</beans>

execute方法

一般用户创建表和修改表结构

src/test/java/Test.java

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.jdbc.core.JdbcTemplate;

public class Test {
    @org.junit.Test
    public void testExecute(){
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring.xml");
        JdbcTemplate jdbcTemplate = (JdbcTemplate) applicationContext.getBean("jdbcTemplate");
        jdbcTemplate.execute("create table user1(id int,name varchar(20))");
    }
}

运行结果：创建表user1

updata方法

对数据进行增删改操作

src/test/java/Test.java

    @org.junit.Test
    public void testUpdate1(){
        String sql = "insert into student(name,sex) values(?,?)";
        jdbcTemplate.update(sql,new Object[]{"张三","男"});
    }

    @org.junit.Test
    public void testUpdate2(){
        String sql = "update student set sex=? where id=?";
        jdbcTemplate.update(sql,new Object[]{"女",1});
    }

batchUpdate方法

批量增删改操作

src/test/java/Test.java

    @org.junit.Test
    public void testBatchUpdate1(){
        String[] sqls = {
                "insert into Student(name,sex) values('李四','男')",
                "insert into Student(name,sex) values('王五','男')",
                "update Student set sex = '女' where id=1"
        };
        jdbcTemplate.batchUpdate(sqls);
    }

    @org.junit.Test
    public void testBatchUpdate2(){
        String sql = "insert into selection(student,course) values(?,?)";
        List<Object[]> list = new ArrayList<Object[]>();
        list.add(new Object[]{1,1001});
        list.add(new Object[]{1,1003});
        jdbcTemplate.batchUpdate(sql,list);
    }

query方法和queryXXX方法

查询简单数据项 - 获取一个

    @org.junit.Test
    public void testQuerySimple1(){
        String sql = "select count(*) from student";
        int count = jdbcTemplate.queryForObject(sql,Integer.class);
        System.out.println(count);
    }

查询简单数据项 - 获取多个

    @org.junit.Test
    public void testQuerySimple2(){
        String sql = "select name from student where sex=?";
        List<String> names = jdbcTemplate.queryForList(sql,String.class,"男");
        System.out.println(names);
    }

查询复杂对象（封装为Map）- 获取一个

    @org.junit.Test
    public void testQueryMap1(){
        String sql = "select * from student where id=?";
        Map<String,Object> student = jdbcTemplate.queryForMap(sql,1);
        System.out.println(student);
    }

查询复杂对象（封装为Map）- 获取多个

    @org.junit.Test
    public void testQueryMap2(){
        String sql = "select * from student";
        List<Map<String,Object>> students = jdbcTemplate.queryForList(sql);
        System.out.println(students);
    }

查询复杂对象（封装为实体对象）- 获取一个

    @org.junit.Test
    public void testQueryEntity1(){
        String sql = "select * from student where id=?";
        Student student = jdbcTemplate.queryForObject(sql, new RowMapper<Student>() {
            @Override
            public Student mapRow(ResultSet resultSet, int i) throws SQLException {
                Student stu = new Student();
                stu.setId(resultSet.getInt("id"));
                stu.setName(resultSet.getString("name"));
                stu.setSex(resultSet.getString("sex"));
                stu.setBorn(resultSet.getDate("born"));
                return stu;
            }
        }, 1);
        System.out.println(student);
    }

Student{id=1, name=’张三’, sex=’女’, born=null}

查询复杂对象（封装为实体对象）- 获取多个

    @org.junit.Test
    public void testQueryEntity2(){
        String sql = "select * from student";
        List<Student> students = jdbcTemplate.query(sql, new RowMapper<Student>() {
            @Override
            public Student mapRow(ResultSet resultSet, int i) throws SQLException {
                Student stu = new Student();
                stu.setId(resultSet.getInt("id"));
                stu.setName(resultSet.getString("name"));
                stu.setSex(resultSet.getString("sex"));
                stu.setBorn(resultSet.getDate("born"));
                return stu;
            }
        });
        System.out.println(students);
    }

[Student{id=1, name=’张三’, sex=’女’, born=null}, Student{id=2, name=’李四’, sex=’男’, born=null}, Student{id=3, name=’王五’, sex=’男’, born=null}]

以上查询复杂对象（封装为实体对象），new RowMapper处理每次要写，有点冗余，可以采用内部类的方式改善

    @org.junit.Test
    public void testQueryEntity1(){
        String sql = "select * from student where id=?";
        Student student = jdbcTemplate.queryForObject(sql, new StudentRowMapper(), 1);
        System.out.println(student);
    }

    @org.junit.Test
    public void testQueryEntity2(){
        String sql = "select * from student";
        List<Student> students = jdbcTemplate.query(sql, new StudentRowMapper());
        System.out.println(students);
    }

    private class StudentRowMapper implements RowMapper<Student>{
        @Override
        public Student mapRow(ResultSet resultSet, int i) throws SQLException {
            Student stu = new Student();
            stu.setId(resultSet.getInt("id"));
            stu.setName(resultSet.getString("name"));
            stu.setSex(resultSet.getString("sex"));
            stu.setBorn(resultSet.getDate("born"));
            return stu;
        }
    }

持久层实现

实现实体类

src/main/java/com/song/sc/entity/Student.java

package com.song.sc.entity;

import java.util.Date;

public class Student {
    private int id;
    private String name;
    private String sex;
    private Date born;

    public int getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public Date getBorn() {
        return born;
    }

    public void setBorn(Date born) {
        this.born = born;
    }

    @Override
    public String toString() {
        return "Student{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", sex='" + sex + '\'' +
                ", born=" + born +
                '}';
    }
}

src/main/java/com/song/sc/entity/Course.java

package com.song.sc.entity;

public class Course {
    private int id;
    private String name;
    private int score;

    public int getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    public int getScore() {
        return score;
    }

    public void setScore(int score) {
        this.score = score;
    }
}

src/main/java/com/song/sc/entity/Selection.java

package com.song.sc.entity;

import java.util.Date;

public class Selection {
    private int sid;
    private int cid;
    private Date selTime;
    private int score;

    public int getSid() {
        return sid;
    }

    public void setSid(int sid) {
        this.sid = sid;
    }

    public int getCid() {
        return cid;
    }

    public void setCid(int cid) {
        this.cid = cid;
    }

    public Date getSelTime() {
        return selTime;
    }

    public void setSelTime(Date selTime) {
        this.selTime = selTime;
    }

    public int getScore() {
        return score;
    }

    public void setScore(int score) {
        this.score = score;
    }
}

实现DAO

src/main/java/com/song/sc/dao/StudentDao.java

package com.song.sc.dao;

import com.song.sc.entity.Student;

import java.util.List;

public interface StudentDao {
    void insert(Student student);

    void update(Student student);

    void delete(int id);

    Student select(int id);

    List<Student> selectAll();
}

src/main/java/com/song/sc/dao/impl/StudentDaoImpl.java

package com.song.sc.dao.impl;

import com.song.sc.dao.StudentDao;
import com.song.sc.entity.Student;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.stereotype.Repository;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;

@Repository
public class StudentDaoImpl implements StudentDao {
    @Autowired
    private JdbcTemplate jdbcTemplate;

    @Override
    public void insert(Student student) {
        String sql = "insert into student(name,sex,born) values(?,?,?)";
        jdbcTemplate.update(sql, student.getName(), student.getSex(), student.getBorn());
    }

    @Override
    public void update(Student student) {
        String sql = "update student set name=?,sex=?,born=? where id=?";
        jdbcTemplate.update(sql, student.getName(), student.getSex(), student.getBorn(), student.getId());
    }

    @Override
    public void delete(int id) {
        String sql = "delete from student where id=?";
        jdbcTemplate.update(sql, id);
    }

    @Override
    public Student select(int id) {
        String sql = "select * from student where id=?";
        return jdbcTemplate.queryForObject(sql, new StudentRowMapper(), id);
    }

    @Override
    public List<Student> selectAll() {
        String sql = "select * from student";
        return jdbcTemplate.query(sql, new StudentRowMapper());
    }

    private class StudentRowMapper implements RowMapper<Student> {
        @Override
        public Student mapRow(ResultSet resultSet, int i) throws SQLException {
            Student stu = new Student();
            stu.setId(resultSet.getInt("id"));
            stu.setName(resultSet.getString("name"));
            stu.setSex(resultSet.getString("sex"));
            stu.setBorn(resultSet.getDate("born"));
            return stu;
        }
    }
}

src/main/java/com/song/sc/dao/CourseDao.java

package com.song.sc.dao;

import com.song.sc.entity.Course;

import java.util.List;

public interface CourseDao {
    void insert(Course course);

    void update(Course course);

    void delete(int id);

    Course select(int id);

    List<Course> selectAll();
}

src/main/java/com/song/sc/dao/impl/CourseDaoImpl.java

package com.song.sc.dao.impl;

import com.song.sc.dao.CourseDao;
import com.song.sc.entity.Course;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;

public class CourseDaoImpl implements CourseDao {
    @Autowired
    private JdbcTemplate jdbcTemplate;

    @Override
    public void insert(Course course) {
        String sql = "insert into course(name,score) values(?,?)";
        jdbcTemplate.update(sql, course.getName(), course.getScore());
    }

    @Override
    public void update(Course course) {
        String sql = "update course set name=?,score=? where id=?";
        jdbcTemplate.update(sql, course.getName(), course.getScore(), course.getId());
    }

    @Override
    public void delete(int id) {
        String sql = "delete from course where id=?";
        jdbcTemplate.update(sql, id);
    }

    @Override
    public Course select(int id) {
        String sql = "select * from course where id=?";
        return jdbcTemplate.queryForObject(sql, new CourseRowMapper(), id);
    }

    @Override
    public List<Course> selectAll() {
        String sql = "select * from course";
        return jdbcTemplate.query(sql, new CourseRowMapper());
    }

    private class CourseRowMapper implements RowMapper<Course> {
        @Override
        public Course mapRow(ResultSet resultSet, int i) throws SQLException {
            Course course = new Course();
            course.setId(resultSet.getInt("id"));
            course.setName(resultSet.getString("name"));
            course.setScore(resultSet.getInt("score"));
            return course;
        }
    }
}

src/main/java/com/song/sc/dao/SelectionDao.java

package com.song.sc.dao;

import com.song.sc.entity.Selection;

import java.util.List;
import java.util.Map;

public interface SelectionDao {
    void insert(List<Selection> selections);

    void delete(int sid, int cid);

    List<Map<String, Object>> selectByStudent(int sid);

    List<Map<String, Object>> selectByCourse(int cid);
}

src/main/java/com/song/sc/dao/impl/SelectionDaoImpl.java

package com.song.sc.dao.impl;

import com.song.sc.dao.SelectionDao;
import com.song.sc.entity.Selection;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

public class SelectionDaoImpl implements SelectionDao {
    @Autowired
    private JdbcTemplate jdbcTemplate;

    @Override
    public void insert(List<Selection> selections) {
        String sql = "insert into selection values(?,?,?,?)";
        List<Object[]> list = new ArrayList<Object[]>();
        for (Selection selection : selections) {
            Object[] args = new Object[4];
            args[0] = selection.getSid();
            args[1] = selection.getCid();
            args[2] = selection.getSelTime();
            args[3] = selection.getScore();
            list.add(args);
        }
        jdbcTemplate.batchUpdate(sql, list);
    }

    @Override
    public void delete(int sid, int cid) {
        String sql = "delete from selection where student=? and course=?";
        jdbcTemplate.update(sql, sid, cid);
    }

    @Override
    public List<Map<String, Object>> selectByStudent(int sid) {
        String sql = "select se.*, stu.name sname, cou.name cname from selection se" +
                "left join student stu on se.student = stu.id" +
                "left join course cou on se.course = cou.id" +
                "where student=?";
        return jdbcTemplate.queryForList(sql, sid);
    }

    @Override
    public List<Map<String, Object>> selectByCourse(int cid) {
        String sql = "select se.*, stu.name sname, cou.name cname from selection se" +
                "left join student stu on se.student = stu.id" +
                "left join course cou on se.course = cou.id" +
                "where course=?";
        return jdbcTemplate.queryForList(sql, cid);
    }
}

总结

JDBC Template是Spring框架点击JDBC操作的封装，简单，灵活但不够强大
实际应用中还需要和其他ORM框架混合使用

持久化操作的特点：必须，机械性 ORM：对象 - 关系