Spring Boot数据库操作之基本的JDBC访问和JDBCTemplate使用
作者：谭东
我们先看下最基础的JDBC的使用方式吧。我们这里使用MySQL。电脑里可以安装个mysql，便于本地测试使用。
Mysql下载地址：https://dev.mysql.com/downloads/
下载后，解压mysql压缩包到某一文件件，在根目录新建my.ini文件，写入配置：
[mysqld]
character-set-server=utf8
collation-server=utf8_general_ci
[mysql]
default-character-set = utf8
[mysql.server]
default-character-set = utf8
[mysqld_safe]
default-character-set = utf8
[client]
default-character-set = utf8管理员身份运行cmd命令窗口。切换到mysql的bin文件夹下。输入命令：mysqld --install。
安装完毕，然后初始化：mysqld --initialize。启动服务：net start mysql。
登录mysql：mysql -u root -p，首次登陆一般是没有密码的，如果你安装的是mysql 5.7及以上版本，默认是有个随机密码了。
需要手动在mysql目录下搜索*.err，以文本形式打开才能看到如下内容：
[Note] A temporary password is generated for root@localhost: ?g#4:Yju&1Kp
红色部分为密码。这样登录成功后再去修改密码即可：alter user root@localhost identified by 'Mysql123456'。新密码最好有大写字母，小写字母和数字。
最后我们创建个数据库：create database student。
然后在student数据库里创建student表：create table student(id int primary key auto_increment,name varchar(100),sex varchar(10),age int,tel varchar(60));
在之前的pom.xml里引入mysql库。
mysql
mysql-connector-java
8.0.9-rc
application.properties里加入mysql配置信息。
server.port=8082
spring.datasource.url=jdbc:mysql://localhost:3306/student?serverTimezone=GMT=&useUnicode=true&characterEncoding=utf-8&useSSL=true
spring.datasource.username=root
spring.datasource.password=Mysql123456
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver编写JDBC工具类。
package com.tandong.testjavaweb.utils;
import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;
public class JDBCUtils {
// mysql 连接参数
private static String jdbcDriver = null;
private static String url = null;
private static String user = null;
private static String password = null;
private static boolean isCfg = false; // 记录是否读取过jdbc.properties文件配置 、避免多次读取
// 线程安全的懒汉模式单例
private static JDBCUtils jdbcUtils = null;
public static synchronized JDBCUtils getInstance() {
if (jdbcUtils == null) {
if (!isCfg) {
initJDBCParameter();
}
return jdbcUtils = new JDBCUtils();
}
return jdbcUtils;
}
/**
* 读取属性文件中的mysql配置
*/
private static void initJDBCParameter() {
Properties properties = new Properties();
InputStream in = JDBCUtils.class.getResourceAsStream("/application.properties");//加载 application.properties资源文件，如果该文件在包内则加包名
try {
properties.load(in);
in.close();
} catch (IOException e) {
e.printStackTrace();
}
if (jdbcDriver == null || url == null || user == null || password == null) {
jdbcDriver = properties.getProperty("spring.datasource.driver-class-name");
url = properties.getProperty("spring.datasource.url");
user = properties.getProperty("spring.datasource.username");
password = properties.getProperty("spring.datasource.password");
isCfg = true;
}
}
/**
* 获取数据连接
*
* @return
* @throws Exception
*/
public Connection getConnection() throws Exception {
Class.forName(jdbcDriver);
return DriverManager.getConnection(url, user, password);
}
/**
* 释放数据库链接资源
*
* @param con // 数据库连接对象
* @param stmt // 执行sql操作对象
* @param rs // 查询结果集对象
*/
public void closeConnection(Connection con, Statement stmt, ResultSet rs) {
try {
if (rs != null) {
rs.close();
}
if (stmt != null) {
stmt.close();
}
if (con != null) {
con.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}编写个Student实体类。
package com.tandong.testjavaweb.entity;
public class Student {
public int id;
public String name;
public String sex;
public int age;
public String tel;
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 int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getTel() {
return tel;
}
public void setTel(String tel) {
this.tel = tel;
}
@Override
public String toString() {
return "Student{" +
"id=" + id +
", name='" + name + '\'' +
", sex='" + sex + '\'' +
", age=" + age +
", tel='" + tel + '\'' +
'}';
}
}
编写StudentDao类。
package com.tandong.testjavaweb.dao;
import com.tandong.testjavaweb.entity.Student;
import java.sql.SQLException;
import java.util.List;
public interface StudentsDao {
//添加方法
void add(Student s) throws SQLException;
//更新方法
void update(Student s) throws SQLException;
//删除方法
void delete(int id) throws SQLException;
//查找方法
Student findById(int id) throws SQLException;
//查找所有
List findAll()throws SQLException;
} 编写StudentDao的实现类，StudentDaoImpl。
package com.tandong.testjavaweb.dao;
import com.tandong.testjavaweb.entity.Student;
import com.tandong.testjavaweb.utils.JDBCUtils;
import org.springframework.stereotype.Service;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
@Service
public class StudentsDaoImpl implements StudentsDao {
@Override
public void add(Student s) throws SQLException {
Connection conn = null;
PreparedStatement ps = null;
String sql = "insert into student(id,name,sex,age,tel)values(?,?,?,?,?)";
try {
conn = JDBCUtils.getInstance().getConnection();
ps = conn.prepareStatement(sql);
ps.setInt(1, s.id);
ps.setString(2, s.name);
ps.setString(3, s.sex);
ps.setInt(4, s.age);
ps.setString(5, s.tel);
ps.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
throw new SQLException("添加数据失败！");
} finally {
JDBCUtils.getInstance().closeConnection(conn, ps, null);
}
System.out.println("数据添加成功！");
}
@Override
public void update(Student s) throws SQLException {
Connection conn = null;
PreparedStatement ps = null;
if (s == null) return;
// 根据对象属性 拼接 更新sql
String sql = "update student set ";
StringBuilder sb = new StringBuilder(sql);
sb.append("name=?");
sb.append(",sex=?");
sb.append(",tel=?");
if (s.age != 0) sb.append(",age=?");
if (s.id != 0) sb.append("where id=?");
// 如果sql语句和原始语句一样，或者 没有包含条件语句不允许执行
if (sb.toString().equals(sql) || sb.toString().contains("where")) return;
try {
conn = JDBCUtils.getInstance().getConnection();
ps = conn.prepareStatement(sql);
ps.setString(1, s.name);
ps.setInt(2, s.age);
ps.setString(3, s.sex);
ps.setString(4, s.tel);
ps.setInt(5, s.id);
ps.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
throw new SQLException("更新数据失败");
} finally {
JDBCUtils.getInstance().closeConnection(conn, ps, null);
}
System.out.println("数据更新成功！");
}
@Override
public void delete(int id) throws SQLException {
Connection conn = null;
PreparedStatement ps = null;
String sql = "delete from student where id=?";
try {
conn = JDBCUtils.getInstance().getConnection();
ps = conn.prepareStatement(sql);
ps.setInt(1, id);
ps.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
throw new SQLException(" 删除数据失败");
} finally {
JDBCUtils.getInstance().closeConnection(conn, ps, null);
}
System.out.println("数据删除成功！");
}
@Override
public Student findById(int id) throws SQLException {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
Student s = null;
String sql = "select * from student where id=?";
try {
conn = JDBCUtils.getInstance().getConnection();
ps = conn.prepareStatement(sql);
ps.setInt(1, id);
rs = ps.executeQuery();
if (rs.next()) {
s = new Student();
s.id = id;
s.name = rs.getString("name");
s.age = rs.getInt("age");
s.sex = rs.getString("sex");
s.tel = rs.getString("tel");
}
} catch (Exception e) {
e.printStackTrace();
throw new SQLException("根据ID查询数据失败");
} finally {
JDBCUtils.getInstance().closeConnection(conn, ps, rs);
}
System.out.println("数据查询成功！");
return s;
}
@Override
public List findAll() throws SQLException {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
Student s;
List students = new ArrayList();
String sql = "select * from student";
try {
conn = JDBCUtils.getInstance().getConnection();
ps = conn.prepareStatement(sql);
rs = ps.executeQuery();
while (rs.next()) {
s = new Student();
s.id = rs.getInt("id");
s.name = rs.getString("name");
s.age = rs.getInt("age");
s.sex = rs.getString("sex");
s.tel = rs.getString("tel");
students.add(s);
}
} catch (Exception e) {
e.printStackTrace();
throw new SQLException("查询所有数据失败");
} finally {
JDBCUtils.getInstance().closeConnection(conn, ps, rs);
}
System.out.println("数据查询成功！");
return students;
}
} 编写访问查询接口。
package com.tandong.testjavaweb.controller;
import com.tandong.testjavaweb.dao.StudentsDaoImpl;
import com.tandong.testjavaweb.entity.Student;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.*;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
/**
* 注意@RestController用于写接口
*
* @Controller 用于写页面跳转
*/
@RestController
//@Controller
@SpringBootApplication
@RequestMapping("/student")
public class StudentController {
@Autowired
StudentsDaoImpl studentsDao;
/**
* ResopnseBody如果返回的是Object，会把返回结果转为Json格式输出
*
* @param userName
* @return
*/
@ResponseBody
@RequestMapping(value = "/getUserName", method = RequestMethod.GET)
public Object getUserNameGet(@RequestParam(value = "name") String userName) {
return userName;
}
@RequestMapping(value = "/getName", method = RequestMethod.GET)
public String getName(@RequestParam(value = "name") String name) {
return "Hello " + name;
}
@RequestMapping(value = "/addStudent", method = RequestMethod.GET)
public String listUser() {
Student student = new Student();
student.setAge(12);
student.setName("学生");
student.setSex("女");
student.setTel("13333333333");
try {
studentsDao.add(student);
} catch (SQLException e) {
e.printStackTrace();
}
return "插入成功";
}
@RequestMapping(value = "/list", method = RequestMethod.GET)
public Object getLists() {
List userList = null;
try {
userList = studentsDao.findAll();
} catch (SQLException e) {
e.printStackTrace();
}
return userList;
}
} 其中@Autowired是自动装配的注解。
好了，我们运行下。
访问：http://localhost:8082/student/addStudent，插入一条数据。
多插入几条，我们再访问：http://localhost:8082/student/list，查询数据。
附带下mysql常用命令：
删除mysql服务命令：sc delete mysql，或mysqld --remove
接下来再看下Spring-Boot-jdbc使用方式，也就是JDBCTemplate。
pom.xml导包：
org.springframework.boot
spring-boot-starter-jdbc
基于原来的StudentImpl，我们修改下：
package com.tandong.testjavaweb.dao;
import com.tandong.testjavaweb.entity.Student;
import com.tandong.testjavaweb.utils.JDBCUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Service;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
@Service
public class StudentsDaoImpl implements StudentsDao {
@Autowired
JdbcTemplate jdbcTemplate;
@Override
public void add(Student s) throws SQLException {
jdbcTemplate.update("insert into student(id,name,sex,age,tel)values(?,?,?,?,?)", s.getId()
, s.getName(), s.getSex(), s.getAge(), s.getTel());
}
@Override
public void update(Student s) throws SQLException {
jdbcTemplate.update("UPDATE student SET name=? ,sex=?,age=?,tel=? WHERE id=?",
s.getName(), s.getSex(), s.getAge(), s.getTel(), s.getId());
}
@Override
public void delete(int id) throws SQLException {
jdbcTemplate.update("DELETE from TABLE student where id=?", id);
}
@Override
public Student findById(int id) throws SQLException {
List list = jdbcTemplate.query("select * from student where id = ?", new Object[]{id}, new BeanPropertyRowMapper(Student.class));
if (list != null && list.size() > 0) {
Student student = list.get(0);
return student;
} else {
return null;
}
}
@Override
public List findAll() throws SQLException {
List list = jdbcTemplate.query("select * from student", new Object[]{}, new BeanPropertyRowMapper(Student.class));
if (list != null && list.size() > 0) {
return list;
} else {
return null;
}
}
} StudentController不需要修改，重新编译运行，这样就可以达到一样的效果了。
完整项目Github地址：https://github.com/jaychou2012/Spring-Boot-Web