springboot整合mybatis实现数据的持久化
我们依然通过做一个实例来学习,始终相信先看着做出来,再加强理论,搞清原理的学习方法比较快。
下图是项目整体结构:
新建一个MySQL数据库,这里数据库名为springboot,建立user_t数据表,作为我们示例操作的表对象。
user_t信息如下:
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SET FOREIGN_KEY_CHECKS=0; -- ---------------------------- -- Table structure for user_t -- ---------------------------- DROP TABLE IF EXISTS `user_t`; CREATE TABLE `user_t` ( `id` int(11) NOT NULL AUTO_INCREMENT, `user_name` varchar(255) NOT NULL, `password` varchar(255) NOT NULL, `age` int(11) DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8; |
-- ----------------------------
-- Table structure for user_t
-- ----------------------------
DROP TABLE IF EXISTS `user_t`;
CREATE TABLE `user_t` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`user_name` varchar(255) NOT NULL,
`password` varchar(255) NOT NULL,
`age` int(11) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8;
数据库及表创建成功后,回到我们的工程中
第零步,我们这里集成druid,使用连接池,引入mybatis及druid的依赖包:
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<dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>1.3.2</version> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>druid</artifactId> <version>1.1.0</version> </dependency> </dependencies> |
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.1.0</version>
</dependency>
</dependencies>
第一步,在yml配置文件中配置数据源、Mybatis的实体和配置文件路径:
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mybatis: typeAliasesPackage: com.javazhiyin.entity mapperLocations: classpath:mapper/*.xml spring: datasource: driver-class-name: com.mysql.jdbc.Driver url: jdbc:mysql://localhost:3306/springboot?useUnicode=true&characterEncoding=UTF-8&useSSL=false username: root password: 1011 |
spring:
datasource:
driver-class-name: com.mysql.jdbc.Driver
url: jdbc:mysql://localhost:3306/springboot?useUnicode=true&characterEncoding=UTF-8&useSSL=false
username: root
password: 1011
第二步,创建一个实体类,对应数据表实体映射:
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package com.javazhiyin.entity; /** * Created by 57783 on 2018/7/6. */ public class User { private Integer id; private String userName; private String password; private Integer age; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getUserName() { return userName; } public void setUserName(String userName) { this.userName = userName == null ? null : userName.trim(); } public String getPassword() { return password; } public void setPassword(String password) { this.password = password == null ? null : password.trim(); } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } } |
/**
* Created by 57783 on 2018/7/6.
*/
public class User {
private Integer id;
private String userName;
private String password;
private Integer age;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName == null ? null : userName.trim();
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password == null ? null : password.trim();
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
}
第三步,写DAO接口(增删改查):
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package com.javazhiyin.dao; import com.javazhiyin.entity.User; import java.util.List; /** * Created by 57783 on 2018/7/6. */ public interface UserDao { List<User> findAll(); void addUser(User user); void updUser(User user); int delUser(Integer id); } |
import com.javazhiyin.entity.User;
import java.util.List;
/**
* Created by 57783 on 2018/7/6.
*/
public interface UserDao {
List<User> findAll();
void addUser(User user);
void updUser(User user);
int delUser(Integer id);
}
第四步,编写xml映射文件:
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<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" > <mapper namespace="com.javazhiyin.dao.UserDao" > <resultMap id="BaseResultMap" type="com.javazhiyin.entity.User" > <id column="id" property="id" jdbcType="INTEGER" /> <result column="user_name" property="userName" jdbcType="VARCHAR" /> <result column="password" property="password" jdbcType="VARCHAR" /> <result column="age" property="age" jdbcType="INTEGER" /> </resultMap> <sql id="Base_Column_List" > id, user_name, password, age </sql> <select id="findAll" resultMap="BaseResultMap"> select <include refid="Base_Column_List" /> from user_t </select> <insert id="addUser" parameterType="com.javazhiyin.entity.User"> insert into user_t (user_name, password, age) values (#{userName,jdbcType=VARCHAR}, #{password,jdbcType=VARCHAR}, #{age,jdbcType=INTEGER}) </insert> <update id="updUser" parameterType="com.javazhiyin.entity.User" > update user_t set user_name = #{userName,jdbcType=VARCHAR}, password = #{password,jdbcType=VARCHAR}, age = #{age,jdbcType=INTEGER} where id = #{id,jdbcType=INTEGER} </update> <delete id="delUser" parameterType="java.lang.Integer" > delete from user_t where id = #{id,jdbcType=INTEGER} </delete> </mapper> |
<resultMap id="BaseResultMap" type="com.javazhiyin.entity.User" >
<id column="id" property="id" jdbcType="INTEGER" />
<result column="user_name" property="userName" jdbcType="VARCHAR" />
<result column="password" property="password" jdbcType="VARCHAR" />
<result column="age" property="age" jdbcType="INTEGER" />
</resultMap>
<sql id="Base_Column_List" >
id, user_name, password, age
</sql>
<select id="findAll" resultMap="BaseResultMap">
select
<include refid="Base_Column_List" />
from user_t
</select>
<insert id="addUser" parameterType="com.javazhiyin.entity.User">
insert into user_t (user_name, password, age)
values (#{userName,jdbcType=VARCHAR}, #{password,jdbcType=VARCHAR},
#{age,jdbcType=INTEGER})
</insert>
<update id="updUser" parameterType="com.javazhiyin.entity.User" >
update user_t
set user_name = #{userName,jdbcType=VARCHAR},
password = #{password,jdbcType=VARCHAR},
age = #{age,jdbcType=INTEGER}
where id = #{id,jdbcType=INTEGER}
</update>
<delete id="delUser" parameterType="java.lang.Integer" >
delete from user_t
where id = #{id,jdbcType=INTEGER}
</delete>
</mapper>
第五步,编写Service接口:
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package com.javazhiyin.service; import com.javazhiyin.entity.User; import java.util.List; /** * Created by 57783 on 2018/7/6. */ public interface UserService { List<User> getUser(); void addUser(User user); void updUser(User user); int delUser(Integer id); } |
import com.javazhiyin.entity.User;
import java.util.List;
/**
* Created by 57783 on 2018/7/6.
*/
public interface UserService {
List<User> getUser();
void addUser(User user);
void updUser(User user);
int delUser(Integer id);
}
第六步,Service接口的实现类:
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package com.javazhiyin.service.impl; import com.javazhiyin.dao.UserDao; import com.javazhiyin.entity.User; import com.javazhiyin.service.UserService; import org.springframework.stereotype.Service; import javax.annotation.Resource; import java.util.List; /** * Created by 57783 on 2018/7/6. */ @Service("userService") public class UserServiceImpl implements UserService { @Resource private UserDao userDao; public List<User> getUser() { return userDao.findAll(); } public void addUser(User user){ userDao.addUser(user); } public void updUser(User user){ userDao.updUser(user); } public int delUser(Integer id){ return userDao.delUser(id); } } |
import com.javazhiyin.dao.UserDao;
import com.javazhiyin.entity.User;
import com.javazhiyin.service.UserService;
import org.springframework.stereotype.Service;
import javax.annotation.Resource;
import java.util.List;
/**
* Created by 57783 on 2018/7/6.
*/
@Service("userService")
public class UserServiceImpl implements UserService {
@Resource
private UserDao userDao;
public List<User> getUser() {
return userDao.findAll();
}
public void addUser(User user){
userDao.addUser(user);
}
public void updUser(User user){
userDao.updUser(user);
}
public int delUser(Integer id){
return userDao.delUser(id);
}
}
第七步,新建一个Controller类,实现增删改查操作接口:
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package com.javazhiyin.controller; import com.javazhiyin.entity.User; import com.javazhiyin.service.UserService; import org.springframework.web.bind.annotation.*; import javax.annotation.Resource; import java.util.List; /** * Created by 57783 on 2018/7/6. */ @RestController public class UserController { @Resource private UserService userService; @GetMapping("/showUser") public List<User> getUser(){ List<User> user = this.userService.getUser(); return user; } @PostMapping(value = "/addUser") public void addUser(@RequestParam("username") String username, @RequestParam("password") String password, @RequestParam("age") Integer age){ User user = new User(); user.setUserName(username); user.setPassword(password); user.setAge(age); userService.addUser(user); } @PutMapping(value = "updUser/{id}") public void updUser(@PathVariable("id") Integer id, @RequestParam("username") String username, @RequestParam("password") String password, @RequestParam("age") Integer age){ User user = new User(); user.setId(id); user.setUserName(username); user.setPassword(password); user.setAge(age); userService.updUser(user); } @DeleteMapping(value = "delUser/{id}") public void delUser(@PathVariable("id") Integer id){ userService.delUser(id); } } |
import com.javazhiyin.entity.User;
import com.javazhiyin.service.UserService;
import org.springframework.web.bind.annotation.*;
import javax.annotation.Resource;
import java.util.List;
/**
* Created by 57783 on 2018/7/6.
*/
@RestController
public class UserController {
@Resource
private UserService userService;
@GetMapping("/showUser")
public List<User> getUser(){
List<User> user = this.userService.getUser();
return user;
}
@PostMapping(value = "/addUser")
public void addUser(@RequestParam("username") String username,
@RequestParam("password") String password,
@RequestParam("age") Integer age){
User user = new User();
user.setUserName(username);
user.setPassword(password);
user.setAge(age);
userService.addUser(user);
}
@PutMapping(value = "updUser/{id}")
public void updUser(@PathVariable("id") Integer id,
@RequestParam("username") String username,
@RequestParam("password") String password,
@RequestParam("age") Integer age){
User user = new User();
user.setId(id);
user.setUserName(username);
user.setPassword(password);
user.setAge(age);
userService.updUser(user);
}
@DeleteMapping(value = "delUser/{id}")
public void delUser(@PathVariable("id") Integer id){
userService.delUser(id);
}
}
最后,我们修改Bootdemo03Application启动类,添加@MapperScan注解,使其可以扫描DAO层接口:
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package com.javazhiyin; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.mybatis.spring.annotation.MapperScan; import org.springframework.boot.web.servlet.support.SpringBootServletInitializer; @SpringBootApplication @MapperScan("com.javazhiyin.dao") public class Bootdemo03Application extends SpringBootServletInitializer { public static void main(String[] args) { SpringApplication.run(Bootdemo03Application.class, args); } } |
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;
@SpringBootApplication
@MapperScan("com.javazhiyin.dao")
public class Bootdemo03Application extends SpringBootServletInitializer {
public static void main(String[] args) {
SpringApplication.run(Bootdemo03Application.class, args);
}
}
这样,我们就实现了springboot整合mybatis完成对数据简单的增删改查的demo,我们测试一下所写的程序是否可以正常工作:
查询测试:
新增测试:
修改测试:
删除测试:
我们可以看到可以全部测试通过。
几个问题:
1、@Resource注解的理解?
@Resource的作用相当于@Autowired,只不过@Autowired按byType自动注入,而@Resource默认按 byName自动注入罢了。@Resource有两个属性是比较重要的,分是name和type,Spring将@Resource注解的name属性解析为bean的名字,而type属性则解析为bean的类型。所以如果使用name属性,则使用byName的自动注入策略,而使用type属性时则使用byType自动注入策略。如果既不指定name也不指定type属性,这时将通过反射机制使用byName自动注入策略。
@Resource装配顺序
1. 如果同时指定了name和type,则从Spring上下文中找到唯一匹配的bean进行装配,找不到则抛出异常
2. 如果指定了name,则从上下文中查找名称(id)匹配的bean进行装配,找不到则抛出异常
3. 如果指定了type,则从上下文中找到类型匹配的唯一bean进行装配,找不到或者找到多个,都会抛出异常
4. 如果既没有指定name,又没有指定type,则自动按照byName方式进行装配;如果没有匹配,则回退为一个原始类型进行匹配,如果匹配则自动装配;
2、@Autowired 与@Resource的区别:
1、 @Autowired与@Resource都可以用来装配bean. 都可以写在字段上,或写在setter方法上。
2、 @Autowired默认按类型装配,默认情况下必须要求依赖对象必须存在,如果要允许null值,可以设置它的required属性为false,如:@Autowired(required=false) 。
3、@Resource,默认安装名称进行装配,名称可以通过name属性进行指定,如果没有指定name属性,当注解写在字段上时,默认取字段名进行安装名称查找,如果注解写在setter方法上默认取属性名进行装配。当找不到与名称匹配的bean时才按照类型进行装配。但是需要注意的是,如果name属性一旦指定,就只会按照名称进行装配。