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MyBatis Plus介紹
MyBatis Plus?（簡稱MP）是國內人員開發(fā)的 MyBatis 增強工具，在 MyBatis 的基礎上只做增強不做改變，為簡化開發(fā)、提高效率而生。
特征
無侵入：Mybatis-Plus 在 Mybatis 的基礎上進行擴展，只做增強不做改變，引入 Mybatis-Plus 不會對您現(xiàn)有的 Mybatis
構架產生任何影響，而且 MP 支持所有 Mybatis 原生的特性
依賴少：僅僅依賴 Mybatis 以及 Mybatis-Spring
損耗?。簡蛹磿詣幼⑷牖綜URD，性能基本無損耗，直接面向對象操作
預防Sql注入：內置Sql注入剝離器，有效預防Sql注入攻擊
通用CRUD操作：內置通用 Mapper、通用 Service，僅僅通過少量配置即可實現(xiàn)單表大部分 CRUD 操作，更有強大的條件構造器，滿足各類使用需求
多種主鍵策略：支持多達4種主鍵策略（內含分布式唯一ID生成器），可自由配置，完美解決主鍵問題
框架結構
Mybatis Plus使用
1.導入依賴
<dependency> <groupId>com.baomidou</groupId>
<artifactId>mybatis-plus</artifactId> <version>2.0.1</version> </dependency>
2.MP整合的配置
<!-- 0.連接池屬性設置讀取指定的properties文件 --> <context:property-placeholder
location="classpath:db.properties" ignore-unresolvable="true"/> <!--
1.將連接池放入spring容器 --> <bean name="dataSource"class
="com.mchange.v2.c3p0.ComboPooledDataSource"> <property name="jdbcUrl"
value="${jdbc.url}"></property> <property name="driverClass"
value="${jdbc.driver}"></property> <property name="user"
value="${jdbc.username}"></property> <property name="password"
value="${jdbc.password}"></property> </bean> <bean id="sqlSessionFactory"class
="com.baomidou.mybatisplus.spring.MybatisSqlSessionFactoryBean"> <property
name="dataSource" ref="dataSource"/> <!-- 配置實體掃描路徑，多個package可以用分號; 逗號, 分隔，
支持通配符*--> <!-- com.a.b.entity;com.a.c.entity;com.d.*.entity--> <property
name="typeAliasesPackage" value="cn.xm.jwxt.bean.*"/> <property
name="configuration" ref="mybatisConfig"/> <!-- MP 全局配置注入 --> <property
name="globalConfig" ref="globalConfig"/> <property name="plugins"> <array> <!--
分頁插件配置 --> <bean id="paginationInterceptor"class
="com.baomidou.mybatisplus.plugins.PaginationInterceptor"/> <!--
性能攔截器，兼打印sql，不建議生產環(huán)境配置--> <bean id="performanceInterceptor"class
="com.baomidou.mybatisplus.plugins.PerformanceInterceptor"/> </array>
</property> </bean> <bean id="mybatisConfig"class
="com.baomidou.mybatisplus.MybatisConfiguration"> <property
name="mapUnderscoreToCamelCase" value="true"/> </bean> <!-- 定義 MP 全局策略 -->
<bean id="globalConfig"class
="com.baomidou.mybatisplus.entity.GlobalConfiguration"> <property name="idType"
value="2"/> <property name="dbType" value="mysql"/> <!-- 全局表為下劃線命名設置true -->
<property name="dbColumnUnderline" value="true"/> </bean> <!-- 配置mybatis
掃描mapper接口的路徑,
相當于注解@MapperScan，@MapperScan("com.baomidou.mybatisplus.test.h2.entity.mapper")-->
<bean id="mapperScannerConfigurer"class
="org.mybatis.spring.mapper.MapperScannerConfigurer"> <property
name="basePackage" value="cn.xm.jwxt.mapper"/> </bean>
3.實體
@TableName(value="employee")
public class Employee { private Integer id ; private String lastName; private
String email ;private Integer gender; private Integer age ; public Integer
getId() {return id; } public void setId(Integer id) { this.id = id; } public
String getLastName() {return lastName; } public void setLastName(String
lastName) {this.lastName = lastName; } public String getEmail() { return email;
}public void setEmail(String email) { this.email = email; } public Integer
getGender() {return gender; } public void setGender(Integer gender) { this
.gender = gender; } public Integer getAge() { return age; } public void
setAge(Integer age) {this.age = age; } @Override public String toString() {
return "Employee [id=" + id + ", lastName=" + lastName + ", email=" + email +
", gender=" + gender + ", age=" + age + "]"; } }
4.mapper 接口
public interface EmployeeMapper extends BaseMapper<Employee> {}
5.新增
@Test public void testCommonInsert() { //初始化Employee對象 Employee employee = new
Employee(); employee.setLastName("MP"); employee.setEmail("[email protected]");
employee.setGender(1); //insert方法在插入時，會根據實體類的每個屬性進行非空判斷，只有非空的屬性對應的字段才會出現(xiàn)到SQL語句中
Integer result = employeeMapper.insert(employee); System.out.println("result: "
+ result ); //insertAllColumn方法在插入時，不管屬性是否非空， 屬性所對應的字段都會出現(xiàn)到SQL語句中. Integer
result1 = employeeMapper.insertAllColumn(employee); System.out.println("result:
" + result1 ); //獲取當前數據在數據庫中的主鍵值 Integer key = employee.getId();
System.out.println("key:" + key ); }
6.修改
@Test public void testCommonUpdate() { //初始化修改對象 Employee employee = new
Employee(); employee.setId(7); employee.setLastName("王五"); employee.setEmail(
"[email protected]"); employee.setGender(0); //
updateById方法在修改時，會根據實體類的每個屬性進行非空判斷，只有非空的屬性對應的字段才會出現(xiàn)到SQL語句中 Integer result =
employeeMapper.updateById(employee); System.out.println("result: " + result );
//updateAllColumnById方法在修改時，不管屬性是否非空， 屬性所對應的字段都會出現(xiàn)到SQL語句中. Integer result1 =
employeeMapper.updateAllColumnById(employee); System.out.println("result: " +
result1 ); }
7.查詢
@Test public void testCommonSelect() { //1. 通過id查詢 Employee employee =
employeeMapper.selectById(7); System.out.println(employee); //2.
通過多個列進行查詢。selectOne查詢結果只能是一條，否則報錯 Employee employee1 = new Employee();
employee.setLastName("王五"); employee.setGender(0); Employee result =
employeeMapper.selectOne(employee1); System.out.println("result: " +result ); //
3. 通過多個id進行查詢 List<Integer> idList = new ArrayList<>(); idList.add(4);
idList.add(5); idList.add(6); idList.add(7); List<Employee> emps =
employeeMapper.selectBatchIds(idList); System.out.println(emps);//4.
通過Map封裝條件查詢。map中的key是數據庫中字段名 Map<String,Object> columnMap = new HashMap<>();
columnMap.put("last_name", "Tom"); columnMap.put("gender", 1); List<Employee>
emps1 = employeeMapper.selectByMap(columnMap); System.out.println(emps1); //5.
分頁查詢 List<Employee> emps2 = employeeMapper.selectPage(new Page<>(3, 2), null);
System.out.println(emps2); }
8.刪除
@Test public void testCommonDelete() { //1 .根據id進行刪除 Integer result =
employeeMapper.deleteById(13); System.out.println("result: " + result ); //2.
根據條件進行刪除 Map<String,Object> columnMap = new HashMap<>(); columnMap.put(
"last_name", "MP"); columnMap.put("email", "[email protected]"); Integer result1 =
employeeMapper.deleteByMap(columnMap); System.out.println("result: " + result1
);//3. 批量刪除 List<Integer> idList = new ArrayList<>(); idList.add(3); idList.add(
4); idList.add(5); Integer result2 = employeeMapper.deleteBatchIds(idList);
System.out.println("result: " + result2 ); }
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