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什么是 MyBatis ？
mybatis是一款优秀的持久层框架，它支持定制化SQL、存储过程以及高级映射。Mybatis避免了几乎所有的JDBC代码和手动设置参数以及获取结果集。Mybatis可以使用简单的XML或注解来配置和映射原生信息，将接口和Java的pojo object映射成数据库中的记录。
创建一个新工程，引入的pom如下：
<?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>com.wujie</groupId>
<artifactId>springboot-mybatis</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>springboot-mybatis</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.3.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<!-- https://mvnrepository.com/artifact/com.alibaba/druid -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.1.10</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
配置数据源：
#数据库访问配置
#主数据源，默认的
spring:
datasource:
url: jdbc:mysql://localhost:3306/my?useUnicode=true&characterEncoding=utf8&useSSL=false
type: com.alibaba.druid.pool.DruidDataSource
driver-class-name: com.mysql.jdbc.Driver
username: root
password: root
#下面为连接池补充设置，应用到上面所有的数据源中
#初始化大小
tomcat:
initial-size: 5
min-idle: 5
max-active: 20
max-wait: 60000 #设置超时时间
time-between-eviction-runs-millis: 60000 #配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒
min-evictable-idle-time-millis: 30000 #配置一个链接在池中的最小生存时间
validation-query: select 'X'
test-while-idle: true
test-on-borrow: false
test-on-return: false
server:
port: 80
mybatis:
mapper-locations: classpath:com/wujie/springbootmybatis/mapper/*.xml然后使用逆向生成工具帮助我们生成pojo、dao、mapper文件，为我们大大的节约了我们的开发时间。（工具在后面）
创建service
public interface StudentService {
int deleteByPrimaryKey(Integer id);
int insertSelective(StudentEntity record);
StudentEntity selectByPrimaryKey(Integer id);
List<StudentEntity> findALl();
int updateByPrimaryKeySelective(StudentEntity record);
}创建service的实现
@Service
public class StudentServiceImpl implements StudentService {
@Autowired
private StudentDao studentDao;
@Override
public int deleteByPrimaryKey(Integer id) {
return studentDao.deleteByPrimaryKey(id);
}
@Override
public int insertSelective(StudentEntity record) {
return studentDao.insertSelective(record);
}
@Override
public StudentEntity selectByPrimaryKey(Integer id) {
return studentDao.selectByPrimaryKey(id);
}
@Override
public List<StudentEntity> findALl() {
return studentDao.findAll();
}
@Override
public int updateByPrimaryKeySelective(StudentEntity record) {
return studentDao.updateByPrimaryKeySelective(record);
}
}创建controller
@RestController
@RequestMapping("student")
public class StudentController {
@Autowired
private StudentService studentService;
@RequestMapping("add")
public String add(StudentEntity studentEntity){
Integer i = studentService.insertSelective(studentEntity);
if (i != 1) {
return "add fail";
}else{
return "add success";
}
}
@RequestMapping("update")
public String update(StudentEntity studentEntity){
Integer i = studentService.updateByPrimaryKeySelective(studentEntity);
if (i != 1) {
return "update fail";
}else{
return "update success";
}
}
@RequestMapping("list")
public Object list(Integer id){
if(id != null){
StudentEntity studentEntity = studentService.selectByPrimaryKey(id);
if(studentEntity != null){
return studentEntity;
}else {
return " this id is not data";
}
}else {
List<StudentEntity> aLl = studentService.findALl();
if (aLl != null && aLl.size() > 0) {
return aLl;
}else {
return "data is null";
}
}
}
@RequestMapping("delete")
public String delete(Integer id){
Integer i = studentService.deleteByPrimaryKey(id);
if (i != 1) {
return "delete fail";
}else {
return "delete success";
}
}
}注意：
我在运行的时候报错了Invalid bound statement (not found): com.wujie.springbootmybatis.dao.StudentDao.findALl，找不到对应的方法，我们可以按照以下步骤一一排除：
- 查看我们的对应dao以及mapper是否有错
- 查看mapper文件位置是否配置
- 查看启动类上是否加了@MapperScan（"mapper地址"）注解
- 查看target中是否有xml文件，如果没有请在pom中添加
<resources>
<resource>
<directory>${basedir}/src/main/java</directory>
<includes>
<include>**/*.xml</include>
</includes>
</resource>
</resources>经过以上步骤，基本上就能够解决，如果还不能解决，请联系我！
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