MyBatisPlus系列六：活动记录ActiveRecord

 Active Record(活动记录)，是一种领域模型模式，特点是一个模型类对应关系型数据库中的 一个表，而模型类的一个实例对应表中的一行记录。
 ActiveRecord 一直广受动态语言（ PHP 、 Ruby 等）的喜爱，而 Java 作为准静态语言， 对于 ActiveRecord 往往只能感叹其优雅，所以 MyBatisPlus也在 AR 道路上进行了一定的探索 。
1、需要让实体类继承 Model 类且实现主键指定方法

public class Employee extends Model {
	//..fields
	//..getter and setter

	/**
	 * 指定当前实体类的主键属性
	 */
	@Override
	protected Serializable pkVal() {
		return id;
	} 
}

测试新增：

@Test
public void  testARInsert() {
	Employee employee = new Employee();
	employee.setLastName("宋老师");
	employee.setEmail("[email protected]");
	employee.setGender(1);
	employee.setAge(35);
	boolean result = employee.insert();
	System.out.println("result:" +result );
}

控制台输出：

Preparing: INSERT INTO tbl_employee ( last_name, email, gender, age ) VALUES ( ?, ?, ?, ? )   
Parameters: 宋老师(String), [email protected](String), 1(Integer), 35(Integer)
Updates: 1
result:true

测试修改：

@Test
public void testARUpdate() {
	Employee employee = new Employee();
	employee.setId(2);
	employee.setLastName("宋老湿");
	employee.setEmail("[email protected]");
	employee.setGender(1);
	employee.setAge(36);
	boolean result = employee.updateById();
	System.out.println("result:" +result );
}

控制台输出：

Preparing: UPDATE tbl_employee SET last_name=?, email=?, gender=?, age=? WHERE id=?   
Parameters: 宋老湿(String), [email protected](String), 1(Integer), 36(Integer), 2(Integer)  
Updates: 1
result:true

测试查询：

@Test
public void testARSelect() {
	Employee employee = new Employee();
	Employee result = employee.selectById(14);
	System.out.println("result: " +result );
	
	employee.setId(14);
	Employee result1 = employee.selectById();
	System.out.println("result: " +result1 );
	
	List emps = employee.selectAll();
	System.out.println(emps);
	
	List emps1= 
			employee.selectList(new EntityWrapper().like("last_name", "老师"));
	System.out.println(emps1);
	
	Integer result2 = employee.selectCount(new EntityWrapper().eq("gender", 0));
	System.out.println("result: " +result2 );
}

控制台输出：

selectById(14)方法：
Preparing: SELECT id,last_name AS lastName,email,gender,age FROM tbl_employee WHERE id=?   
Parameters: 14(Integer) 
Total: 0
result: null
selectById()方法：
Preparing: SELECT id,last_name AS lastName,email,gender,age FROM tbl_employee WHERE id=?   
Parameters: 14(Integer)
Total: 0
result: null
selectAll()方法：
Preparing: SELECT id,last_name AS lastName,email,gender,age FROM tbl_employee   
Parameters:   
Total: 4
[Employee [id=2, lastName=宋老湿, [email protected], gender=1, age=36], Employee [id=7, lastName=王五, [email protected], gender=0, age=null], Employee [id=8, lastName=宋老师, [email protected], gender=1, age=35], Employee [id=9, lastName=宋老师, [email protected], gender=1, age=35]]
selectList方法：
Preparing: SELECT id,last_name AS lastName,email,gender,age FROM tbl_employee WHERE (last_name LIKE ?)   
Parameters: %老师%(String)
Total: 2
[Employee [id=8, lastName=宋老师, [email protected], gender=1, age=35], Employee [id=9, lastName=宋老师, [email protected], gender=1, age=35]]
selectCount方法：
Preparing: SELECT COUNT(1) FROM tbl_employee WHERE (gender = ?) 
Parameters: 0(Integer) 
Total: 1
result: 1

测试删除：

/**
 * 注意: 删除不存在的数据 逻辑上也是属于成功的. 
 */
@Test
public void testARDelete() {
	Employee employee = new Employee();
	boolean result = employee.deleteById(2);
	System.out.println("result:" +result );
	
	employee.setId(2);
	boolean result1 = employee.deleteById();
	System.out.println("result:" +result1 );
	
	boolean result3 = employee.delete(new EntityWrapper().like("last_name", "小"));
	System.out.println("result:" +result3 );
}

控制台输出：

deleteById(2)方法：
Preparing: DELETE FROM tbl_employee WHERE id=? 
Parameters: 2(Integer) 
result:true
deleteById()方法：
Preparing: DELETE FROM tbl_employee WHERE id=?
Parameters: 2(Integer) 
Updates: 0
result:true
delete方法：
Preparing: DELETE FROM tbl_employee WHERE (last_name LIKE ?) 
Parameters: %小%(String) 
Updates: 0
result:true

测试分页：

@Test
public void  testARPage() {
	Employee employee = new Employee();
	Page page = employee.selectPage(new Page<>(1, 1), 
			new EntityWrapper().like("last_name", "老"));
	List emps = page.getRecords();
	System.out.println(emps);
}

控制台输出：

Preparing: SELECT id,last_name AS lastName,email,gender,age FROM tbl_employee WHERE (last_name LIKE ?)  
Parameters: %老%(String)
[Employee [id=8, lastName=宋老师, [email protected], gender=1, age=35]]