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## Spring中引入MybatisPlus

### 准备工作

#### 创建maven工程

略

#### 准备数据表

```SQL
CREATE TABLE t_employee 
(
    emp_id int(10) not null auto_increment primary key,
    emp_name varchar(8) not null default '',
    sex tinyint(1) not null default 0,
    age tinyint(3) not null default 0,
    email varchar(64) not null default ''
);

INSERT INTO t_employee(emp_name, age, sex, email) VALUES
  ("paul", 36, 1, "pual@qq.com"),
  ("james", 36, 1, "james.com"),
  ("刘亦菲", 34, 2, "liu@qq.com"),
  ("郑爽", 30, 2, "zhengshuang@qq.com"),
  ("周杰伦", 42, 1, "jay@163.com"),
  ("谢霆锋", 40, 1, "xietingfeng@178.com"),
  ("索隆", 16, 1, "suolong@google.com"),
  ("乔巴", 6, 1, "qiaoba@zz.com")
```

#### JavaBean

```java
package com.mybatisplus.entity;

/**
 * @author monkeykingGWX
 * email 704835519@qq.com
 * created 2021-04-24 15:12
 */

public class Employee {
    private Integer empId;
    private Integer age;
    private String empName;
    private String email;
    private Integer sex;

public Employee(Integer empId, Integer age, String empName, String email, Integer sex) {
        this.empId = empId;
        this.age = age;
        this.empName = empName;
        this.email = email;
        this.sex = sex;
    }

public Employee() {
    }

public Integer getEmpId() {
        return empId;
    }

public void setEmpId(Integer empId) {
        this.empId = empId;
    }

public Integer getAge() {
        return age;
    }

public void setAge(Integer age) {
        this.age = age;
    }

public String getEmpName() {
        return empName;
    }

public void setEmpName(String empName) {
        this.empName = empName;
    }

public String getEmail() {
        return email;
    }

public void setEmail(String email) {
        this.email = email;
    }

public Integer getSex() {
        return sex;
    }

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

@Override
    public String toString() {
        return "Employee{" +
                "empId=" + empId +
                ", age=" + age +
                ", empName='" + empName + '\'' +
                ", email='" + email + '\'' +
                ", sex=" + sex +
                '}';
    }
}
```

#### 加入依赖

在 pom.xml 中加入对 MP、Spring、连接池、Junit、Mysql 驱动等依赖。注意，不需要添加Mybatis依赖以及mybatis-spring，MybatiPlus会帮我们自动引入这两个依赖。

![](http://img.1024phper.com/blog21042415302412263)

```xml
<dependency>
  <groupId>junit</groupId>
  <artifactId>junit</artifactId>
  <version>4.11</version>
  <scope>test</scope>
</dependency>

<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-context</artifactId>
  <version>5.2.5.RELEASE</version>
</dependency>
<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-orm</artifactId>
  <version>5.2.5.RELEASE</version>
</dependency>
<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-webmvc</artifactId>
  <version>5.2.5.RELEASE</version>
</dependency>

<dependency>
  <groupId>mysql</groupId>
  <artifactId>mysql-connector-java</artifactId>
  <version>5.1.9</version>
</dependency>

<dependency>
  <groupId>com.alibaba</groupId>
  <artifactId>druid</artifactId>
  <version>1.1.12</version>
</dependency>

<dependency>
  <groupId>com.baomidou</groupId>
  <artifactId>mybatis-plus</artifactId>
  <version>2.3</version>
</dependency>

<dependency>
  <groupId>log4j</groupId>
  <artifactId>log4j</artifactId>
  <version>1.2.17</version>
</dependency>
```

#### 创建Mybatis配置文件

resources/mybatis.xml

```xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    
</configuration>
```

#### 创建Spring配置文件

数据源jdbc.properties

```properties
jdbc.url=jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf8
jdbc.user=root
jdbc.pass=
jdbc.maxActive=10
```

![](http://img.1024phper.com/blog21042415515520169)

![](http://img.1024phper.com/blog21042415515546356)

可以看到，mybatisplus的整合方式几乎和Mybatis一模一样，除了上图用红线框出来的地方不一样外。

#### 创建EmployeeMapper

```java
public interface EmployeeMapper extends BaseMapper<Employee> {
}
```

![](http://img.1024phper.com/blog21042416074815995)

#### 设置注解

在实体类上需要做一些配置才可以正常使用mybatisplus

```java
@TableName(value = "t_employee")
public class Employee {
    @TableId(value = "emp_id", type = IdType.AUTO)
    private Integer empId;
    ……
}
```

#### 测试插入一条数据

```java
public class TestCurd {
    private ApplicationContext context = new ClassPathXmlApplicationContext("spring.xml");
    private EmployeeMapper mapper = context.getBean("employeeMapper", EmployeeMapper.class);

@Test
    public void testInsert1 ()
    {
        Employee employee = new Employee();
        employee.setAge(32);
        employee.setEmpName("curry");
        employee.setEmail("curry@qq.com");
        employee.setSex(1);

Integer affect = mapper.insert(employee);
        System.out.println(affect);
    }
}
```

### 全局配置

```java

<bean id="globalConfiguration" class="com.baomidou.mybatisplus.entity.GlobalConfiguration">
    
    <property name="tablePrefix" value="t_" />
    
    <property name="idType" value="0" />
</bean>
```

![](http://img.1024phper.com/blog21042416493724840)

配置好了后，实体类的注解就可以去掉了。（@TableId需要保留，告诉框架这个字段是主键）

至此，准备工作已就绪。

## SpringBoot中引入MybatisPlus

### 创建项目

略

### 引入依赖

```xml
<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
    </dependency>
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid</artifactId>
        <version>1.1.12</version>
    </dependency>
    
    <dependency>
        <groupId>com.baomidou</groupId>
        <artifactId>mybatis-plus-boot-starter</artifactId>
        <version>3.3.1</version>
    </dependency>
</dependencies>
```

### 实体类

```java
@Data
@AllArgsConstructor
@NoArgsConstructor
@ToString
public class Employee {
    private Integer empId;
    private Integer age;
    private String empName;
    private String email;
    private Integer sex;
}
```

### 配置MybatPlus

```yaml
spring:
  datasource:
    name: myDataSource
    type: com.alibaba.druid.pool.DruidDataSource
    url: jdbc:mysql://47.114.137.16:3306/test?useUnicode=true&characterEncoding=utf8&serverTimezone=UTC
    username: gwx
    password: 8425df6795cf
    driver-class-name: com.mysql.cj.jdbc.Driver

logging:
  level:
    com.boot.mp.mapper: debug
server:
  port: 8888
mybatis-plus:
  configuration:
    map-underscore-to-camel-case: true
  mapper-locations: classpath:mapper/*Mapper.xml
  global-config:
    db-config:
      table-prefix: t_ #表前缀
      id-type: auto # 主键类型
```

### 创建Mapper

```java
@Repository
public interface EmployeeMapper extends BaseMapper<Employee> {
}
```

### 启动类

```java
@MapperScan("com.boot.mp.mapper")
@SpringBootApplication
public class App {

public static void main(String[] args) {
        SpringApplication.run(App.class, args);
    }
}
```

### 测试

```java
@SpringBootTest
class MpTest {

@Autowired
    EmployeeMapper employeeMapper;

@Test
    void test1 ()
    {
        List<Employee> employees = employeeMapper.selectList(null);

employees.forEach(System.out::println);
    }

@Test
    void test2 ()
    {
        Employee employee = new Employee();
        employee.setEmpName("嘟嘟");
        employee.setAge(3);
        employeeMapper.insert(employee);
    }
}
```

## CURD

### insert

插入方法有两种：

* insert 只插入非null的字段
* insertAllColumn 插入所有字段，即使该字段为null值

```java
Employee employee = new Employee();
employee.setAge(32);
employee.setEmpName("curry");

Integer affect = mapper.insert(employee); // INSERT INTO t_employee ( age, emp_name ) VALUES ( ?, ? )

Integer affect = mapper.insertAllColumn(employee);
//==>  Preparing: INSERT INTO t_employee ( emp_id,age,emp_name,email,sex ) VALUES ( ?,?,?,?,? ) 
//==> Parameters: null, 32(Integer), curry(String), null, null
```

### update

* updateById
* updateAllColumnById

```java
Employee employee = new Employee();
employee.setEmpId(13);
employee.setEmail("curry@google.io");
employee.setSex(1);

mapper.updateById(employee);
```

### select

* selectById

```java
Employee employee = mapper.selectById(1);
System.out.println(employee);
```

* selectBatchIds

```java
HashSet<Integer> ids = new HashSet<>();
ids.add(1);
ids.add(2);
ids.add(3);

List<Employee> employees = mapper.selectBatchIds(ids);
employees.forEach(System.out::println);
```

* selectByMap

```java
HashMap<String, Object> map = new HashMap<>();
map.put("emp_name", "curry");
map.put("age", 32);

List<Employee> employees = mapper.selectByMap(map);
employees.forEach(System.out::println);
```

* selectOne

### delete

* deleteById

```java
mapper.deleteById(13);
```

* deleteByMap

```java
HashMap<String, Object> map = new HashMap<>();
map.put("emp_name", "curry");
map.put("age", 32);
mapper.deleteByMap(map);
```

* deleteBatchIds

```java
HashSet<Integer> ids = new HashSet<>();
ids.add(11);
ids.add(12);
ids.add(13);
mapper.deleteBatchIds(ids);
```

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