MyBatis-Plus具体实战应用

约定不等于承诺〃 2023-10-15 22:48 40阅读 0赞

## 一、逻辑删除 ##

> 曾经我们写的删除代码都是物理删除。
> 
> 逻辑删除：删除转变为更新
> 
> update user set deleted=1 where id = 1 and deleted=0
> 
> 查找: 追加 where 条件过**滤掉已删除数据**,如果使用 wrapper.entity 生成的 where 条件也会自动追加该字段
> 
> 查找: `select id,name,deleted from user where deleted=0`

### 1.修改表结构 ###

*  给 user 表增加 deleted 字段（1代表删除0代表未删除）
    
        CREATE TABLE `user` (
          `id` bigint NOT NULL AUTO_INCREMENT COMMENT '主键ID',
          `name` varchar(30) DEFAULT NULL COMMENT '姓名',
          `age` int DEFAULT NULL COMMENT '年龄',
          `uemail` varchar(128) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci DEFAULT NULL COMMENT '邮箱',
          `deleted` int DEFAULT '0' COMMENT '删除与否',
          PRIMARY KEY (`id`)
        ) ENGINE=InnoDB AUTO_INCREMENT=8 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;
 *  修改字段的方式
    
        ALTER TABLE user ADD column `deleted` int DEFAULT '0' COMMENT '删除与否';

### 2.开启配置支持 ###

*  配置`com.baomidou.mybatisplus.core.config.GlobalConfig$DbConfig`
    
        mybatis-plus:
          global-config:
            db-config:
              logic-delete-value: 1 # 逻辑已删除值(默认为 1)
              logic-not-delete-value: 0 # 逻辑未删除值(默认为 0)

### 3.`@TableLogic` ###

*  实体类字段上加上`@TableLogic`注解
    
        @Data
        public class User {
              
            @TableId(type = IdType.AUTO)
            private Long id;
            private String name;
            @TableField(select = false)
            private Integer age;
            @TableField(value = "uemail")
            private String email;
            @TableLogic
            private Integer deleted;
        }

### 4.测试 ###

*  测试删除
    
        @Test
        public void testLogicDeleted(){
              
            int ret = userMapper.deleteById(3L);
            System.out.println("删除受影响行数为："+ret);
        }
 *  结果
    
        ==>  Preparing: UPDATE user SET deleted=1 WHERE id=? AND deleted=0
        ==> Parameters: 3(Long)
        <==    Updates: 1
 *  测试查询
    
        @Test
        public void testLogicDeletedSelect(){
              
            QueryWrapper<User> wrapper = new QueryWrapper<>();
            List<User> user = userMapper.selectList(wrapper);
            System.out.println(user);
        }
 *  结果
    
        ==>  Preparing: SELECT id,name,uemail AS email,deleted FROM user WHERE deleted=0
        ==> Parameters: 
        <==      Total: 3
 *  数据库结果
    
    ![image-20221203104225946][]

## 二、通用枚举 ##

> 解决了繁琐的配置，让 mybatis 优雅的使用枚举属性！ 从 3.5.2 版本开始只需完成 `步骤1: 声明通用枚举属性` 即可使用

### 1.修改表结构 ###

*  添加性别字段
    
        ALTER TABLE user ADD column `sex` int DEFAULT '1' COMMENT '1-男 0-女';

### 2.声明通用枚举属性 ###

*  枚举
    
        public enum SexEnum implements IEnum<Integer> {
              
            MAN(1, "男"),
            WOMAN(0, "女");
        
            private int value;
            private String desc;
        
            SexEnum(int value,String desc){
              
                this.value = value;
                this.desc = desc;
            }
        
            @Override
            public Integer getValue() {
              
                return this.value;
            }
        
            @Override
            public String toString() {
              
                return this.desc;
            }
        }

### 3.实体属性使用枚举类型 ###

*  实体属性添加枚举类型
    
        @Data
        public class User {
              
            @TableId(type = IdType.AUTO)
            private Long id;
            private String name;
            @TableField(select = false)
            private Integer age;
            @TableField(value = "uemail")
            private String email;
            @TableLogic
            private Integer deleted;
            private SexEnum sex;
        }

### 4.额外补充 ###

> 如果是3.5.2版本之后的不需要配置了

*  之前版本的按如下配置
    
        mybatis-plus:
            # 支持统配符 * 或者 ; 分割
            typeEnumsPackage: com.baomidou.springboot.entity.enums
 *  序列化给前端按如下两种方式都可以实现

#### 4.1Fastjson ####

*  添加如下注解
    
        @JSONField(serialzeFeatures= SerializerFeature.WriteEnumUsingToString)
        private UserStatus status;

#### 4.2 jackson ####

*  添加如下注解
    
        @JsonValue	//标记响应json值
        private final int code;

### 5.测试 ###

*  测试
    
        @Test
        public void testEnum(){
              
            User entity = new User();
            entity.setEmail("erew");
            entity.setAge(19);
            entity.setName("小红");
            entity.setSex(SexEnum.MAN);
            int insert = userMapper.insert(entity);
            System.out.println("受影响行数为："+insert);
        }
 *  结果
    
        ==>  Preparing: INSERT INTO user ( name, age, uemail, sex ) VALUES ( ?, ?, ?, ? )
        ==> Parameters: 小红(String), 19(Integer), erew(String), 1(Integer)
        <==    Updates: 1
 *  数据库结果
    
    ![image-20221203110746879][]

## 三、自动填充功能 ##

> 开发中，比如
> 
>  *  插入数据的时候需要插入创建时间
>  *  更新数据的时候需要添加更新时间

### 1.修改表结构 ###

*  修改表结构
    
        CREATE TABLE `user` (
          `id` bigint NOT NULL AUTO_INCREMENT COMMENT '主键ID',
          `name` varchar(30) DEFAULT NULL COMMENT '姓名',
          `age` int DEFAULT NULL COMMENT '年龄',
          `uemail` varchar(128) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci DEFAULT NULL COMMENT '邮箱',
          `deleted` int DEFAULT '0' COMMENT '删除与否',
          `sex` int DEFAULT '1' COMMENT '性别',
          `create_time` datetime DEFAULT NULL COMMENT '创建时间',
          `update_time` datetime DEFAULT NULL COMMENT '更新时间',
          PRIMARY KEY (`id`)
        ) ENGINE=InnoDB AUTO_INCREMENT=11 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

### 2.@TableField ###

*  FieldFill
    
        public enum FieldFill {
              
            DEFAULT,//不处理
            INSERT,//插入查出
            UPDATE,//更新处理
            INSERT_UPDATE;//插入和更新处理
        }
 *  添加字段
    
        @TableField(value = "create_time",fill = FieldFill.INSERT)
        private Date createTime;
        @TableField(value = "update_time",fill = FieldFill.UPDATE)
        private Date updateTime;

### 3.自定义实现类 MyMetaObjectHandler ###

*  自定义实现类 MyMetaObjectHandler
    
        @Slf4j
        @Component
        public class MyMetaObjectHandler implements MetaObjectHandler {
            @Override
            public void insertFill(MetaObject metaObject) {
                log.info("start insert fill ....");
                setFieldValByName("createTime",new Date(),metaObject);
            }
        
            @Override
            public void updateFill(MetaObject metaObject) {
                log.info("start update fill ....");
                setFieldValByName("updateTime",new Date(),metaObject);
            }
        }

### 4.测试 ###

*  测试插入操作
    
        @Test
        public void testFillInsert(){
              
            User entity = new User();
            entity.setEmail("erew");
            entity.setAge(19);
            entity.setName("小红");
            entity.setSex(SexEnum.MAN);
            int insert = userMapper.insert(entity);
            System.out.println("受影响行数为："+insert);
        }
 *  测试结果
    
        ==>  Preparing: INSERT INTO user ( name, age, uemail, sex, create_time ) VALUES ( ?, ?, ?, ?, ? )
        ==> Parameters: 小红(String), 19(Integer), erew(String), 1(Integer), 2022-12-03 11:34:41.169(Timestamp)
        <==    Updates: 1
 *  测试更新操作
    
        @Test
        public void testFillUpdate(){
              
            User entity = new User();
            entity.setId(15L);
            entity.setEmail("erew");
            entity.setAge(19);
            entity.setName("小红");
            entity.setSex(SexEnum.MAN);
            int insert = userMapper.updateById(entity);
            System.out.println("受影响行数为："+insert);
        }
 *  测试结果
    
        ==>  Preparing: UPDATE user SET name=?, age=?, uemail=?, sex=?, update_time=? WHERE id=? AND deleted=0
        ==> Parameters: 小红(String), 19(Integer), erew(String), 1(Integer), 2022-12-03 11:37:10.716(Timestamp), 15(Long)
        <==    Updates: 1
 *  数据库结果
    
    ![image-20221203113830320][]·

## 四、SQL注入器 ##

### 1.SQL注入的原理分析 ###

> MyBatisPlus 是使用 ISqlInjector 接口负责SQL注入工作

![image-20221203161601088][]

*  具体实现注入
    
        public void inspectInject(MapperBuilderAssistant builderAssistant, Class<?> mapperClass) {
              
                Class<?> modelClass = ReflectionKit.getSuperClassGenericType(mapperClass, Mapper.class, 0);
                if (modelClass != null) {
              
                    String className = mapperClass.toString();
                    Set<String> mapperRegistryCache = GlobalConfigUtils.getMapperRegistryCache(builderAssistant.getConfiguration());
                    if (!mapperRegistryCache.contains(className)) {
              
                        TableInfo tableInfo = TableInfoHelper.initTableInfo(builderAssistant, modelClass);
                        List<AbstractMethod> methodList = this.getMethodList(mapperClass, tableInfo);
                        if (CollectionUtils.isNotEmpty(methodList)) {
              
                            methodList.forEach((m) -> {
              
                                m.inject(builderAssistant, mapperClass, modelClass, tableInfo);
                            });
                        } else {
              
                            this.logger.debug(mapperClass.toString() + ", No effective injection method was found.");
                        }
        
                        mapperRegistryCache.add(className);
                    }
                }
        
            }
 *  实际的实现代码
    
        methodList.forEach((m) -> {
              
                                m.inject(builderAssistant, mapperClass, modelClass, tableInfo);
                            });
 *  m.inject 调用具体方法
    
        this.injectMappedStatement(mapperClass, modelClass, tableInfo);
 *  最终具体的执行就是自己定义的类
    
    ![image-20221203162803951][]

### 2.扩充BaseMapper中方法 ###

#### 2.1编写自己的BaseMapper ####

*  编写MyBaseMapper
    
        public interface MyBaseMapper<T> extends BaseMapper<T> {
              
            List<T> listAll();
        }
 *  需要用到的mapper 直接继承即可
    
        @Repository
        public interface UserMapper extends MyBaseMapper<User> {
              
            
        }

#### 2.2编写MySqlInjector ####

*  MySqlInjector
    
        @Component	
        public class MySqlInjector extends DefaultSqlInjector {
              
            @Override
            public List<AbstractMethod> getMethodList(Class<?> mapperClass, TableInfo tableInfo) {
              
                //默认的mybatis-plus 的注入方法
                List<AbstractMethod> methodList = super.getMethodList(mapperClass, tableInfo);
                //添加自己的 listAll 类
                methodList.add(new ListAll());
                return methodList;
            }
        }

#### 2.3编写ListAll类 ####

*  创建ListAll 类
    
        public class ListAll extends AbstractMethod {
              
            @Override
            public MappedStatement injectMappedStatement(Class<?> mapperClass, Class<?> modelClass, TableInfo tableInfo) {
              
                String sqlMethod = "listAll";
                String sql = "select * from "+tableInfo.getTableName();
                SqlSource sqlSource = this.languageDriver.createSqlSource(this.configuration, sql, modelClass);
                return this.addSelectMappedStatementForTable(mapperClass,sqlMethod,sqlSource,tableInfo);
            }
        }

#### 2.4测试 ####

*  测试
    
        @Test
        public void testInjector(){
              
            List<User> users = userMapper.listAll();
            System.out.println(users);
        }
 *  结果
    
        ==>  Preparing: select * from user
        ==> Parameters: 
        <==      Total: 13

## 五、插件 ##

### 1.拦截器核心代码 ###

> ### MybatisPlusInterceptor ###
> 
> 该插件是核心插件,目前代理了 `Executor#query` 和 `Executor#update` 和 `StatementHandler#prepare` 方法

*  拦截器核心代码
    
        @Intercepts({
              
                @Signature(type = StatementHandler.class, method = "prepare", args = {
              Connection.class, Integer.class}),
        })
        @Component
        public class MyInterceptor implements Interceptor {
              
            @Override
            public Object intercept(Invocation invocation) throws Throwable {
              
                System.out.println("拦截前操作");
                //做拦截操作
                return invocation.proceed();
            }
        
            @Override
            public Object plugin(Object target) {
              
                System.out.println("装配插件");
                //装配插件
                return Plugin.wrap(target, this);
            }
        
            @Override
            public void setProperties(Properties properties) {
              
                System.out.println("设置属性");
                //属性设置
            }
        }
 *  交给容器管理即可实现拦截操作

### 2.分页插件 ###

*  使用
    
        @Configuration
        @MapperScan("cn.sycoder.mapper")
        public class MybatisPlusConfig {
              
            @Bean
            public MybatisPlusInterceptor mybatisPlusInterceptor() {
              
                MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
                interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
                return interceptor;
            }
        }

### 3.乐观锁插件 ###

> ### OptimisticLockerInnerInterceptor ###
> 
> > 当要更新一条记录的时候，希望这条记录没有被别人更新  
> > 乐观锁实现方式：
> > 
> > >  *  取出记录时，获取当前 version
> > >  *  更新时，带上这个 version
> > >  *  执行更新时， set version = newVersion where version = oldVersion
> > >  *  如果 version 不对，就更新失败

#### 3.1乐观锁补充 ####

*  在数据库增加一个 version 字段来管理数据，假设没有其它人操作过这条数据，先读取本条数据的version,然后再修改的时候，判断之前拿出来的version 和现在的version是否一致，如果不一致，则表示被人操作过，不能够正常实现更新
 *  sql 演示
    
        update user set age = 123123,version = version+1  where id = 16 and version = 0;
    
    ![image-20221203173656602][]

#### 3.2添加乐观锁配置 ####

*  添加配置
    
        @Configuration
        @MapperScan("cn.sycoder.mapper")
        public class MybatisPlusConfig {
              
            @Bean
            public MybatisPlusInterceptor mybatisPlusInterceptor() {
              
                MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
                interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
                interceptor.addInnerInterceptor(new OptimisticLockerInnerInterceptor());
                return interceptor;
            }
        }

#### 3.3修改表结构 ####

*  表结构
    
        CREATE TABLE `user` (
          `id` bigint NOT NULL AUTO_INCREMENT COMMENT '主键ID',
          `name` varchar(30) DEFAULT NULL COMMENT '姓名',
          `age` int DEFAULT NULL COMMENT '年龄',
          `uemail` varchar(128) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci DEFAULT NULL COMMENT '邮箱',
          `deleted` int DEFAULT '0' COMMENT '删除与否',
          `sex` int DEFAULT '1' COMMENT '性别',
          `create_time` datetime DEFAULT NULL COMMENT '创建时间',
          `update_time` datetime DEFAULT NULL COMMENT '更新时间',
          `version` int DEFAULT NULL COMMENT '乐观锁控制',
          PRIMARY KEY (`id`)
        ) ENGINE=InnoDB AUTO_INCREMENT=17 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

#### 3.4添加 version 字段 ####

*  实体添加字段
    
        @Version
        private Integer version;

#### 3.5测试 ####

*  测试乐观锁
    
        @Test
        public void testVersion(){
              
            User user = userMapper.selectById(16L);
            user.setName("云哥666");
            int count = userMapper.updateById(user);
            System.out.println("受影响行数："+count);
        }
 *  结果
    
        ==>  Preparing: UPDATE user SET name=?, uemail=?, sex=?, create_time=?, update_time=?, version=? WHERE id=? AND version=? AND deleted=0
        ==> Parameters: 云哥666(String), sy@qq.com(String), 1(Integer), 2022-12-03 11:34:41.0(Timestamp), 2022-12-03 17:44:05.425(Timestamp), 3(Integer), 16(Long), 2(Integer)
        <==    Updates: 1

### 4.防全表更新与删除插件 ###

> ### BlockAttackInnerInterceptor ###
> 
> 针对 update 和 delete 语句 作用: 阻止恶意的全表更新删除

#### 4.1配置拦截器 ####

*  配置
    
        @Configuration
        @MapperScan("cn.sycoder.mapper")
        public class MybatisPlusConfig {
              
            @Bean
            public MybatisPlusInterceptor mybatisPlusInterceptor() {
              
                MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
                interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
                interceptor.addInnerInterceptor(new OptimisticLockerInnerInterceptor());
                interceptor.addInnerInterceptor(new BlockAttackInnerInterceptor());
                return interceptor;
            }
        }

#### 4.2测试 ####

*  测试全表删除
    
        @Test
        public void testDeleteAll(){
              
            QueryWrapper<User> wrapper = new QueryWrapper<>();
            int count = userMapper.delete(wrapper);
            System.out.println("受影响行数："+count);
        }

## 六、代码生成器 ##

*  简化开发流程，提高开发效率，让程序写很少的代码就能实现开发

### 1.创建 mybatis-plus-02 模块 ###

*  任选创建方式创建

### 2.添加依赖 ###

*  依赖
    
        <parent>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-parent</artifactId>
                <version>2.7.5</version>
            </parent>
        
            <dependencies>
                <dependency>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter</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.baomidou</groupId>
                    <artifactId>mybatis-plus-boot-starter</artifactId>
                    <version>3.5.2</version>
                </dependency>
                <dependency>
                    <groupId>com.baomidou</groupId>
                    <artifactId>mybatis-plus-generator</artifactId>
                    <version>3.5.2</version>
                </dependency>
                <dependency>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-freemarker</artifactId>
                </dependency>
                <dependency>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-web</artifactId>
                </dependency>
                <dependency>
                    <groupId>org.freemarker</groupId>
                    <artifactId>freemarker</artifactId>
                    <version>2.3.31</version>
                </dependency>
                <dependency>
                    <groupId>io.springfox</groupId>
                    <artifactId>springfox-swagger-ui</artifactId>
                    <version>2.10.1</version>
                </dependency>
                <dependency>
                    <groupId>io.springfox</groupId>
                    <artifactId>springfox-swagger2</artifactId>
                    <version>2.10.1</version>
                </dependency>
            </dependencies>

### 3.使用 ###

*  使用
    
        public static void main(String[] args) {
              
                FastAutoGenerator.create("jdbc:mysql://localhost:3306/mybatis-plus", "root", "123456")
                        .globalConfig(builder -> {
              
                            builder.author("sy") // 设置作者
                                    .enableSwagger() // 开启 swagger 模式
                                    .fileOverride() // 覆盖已生成文件
                                    .outputDir("F:\\03-Spring\\MyBatisPlus\\homework\\mybatis-plus-02\\src\\main\\java\\"); // 指定输出目录
                        })
                        .packageConfig(builder -> {
              
                            builder.parent("cn") // 设置父包名
                                    .moduleName("sycoder") // 设置父包模块名
                                    .pathInfo(Collections.singletonMap(OutputFile.xml, "F:\\03-Spring\\MyBatisPlus\\homework\\mybatis-plus-02\\src\\main\\resources\\cn\\sycoder")); // 设置mapperXml生成路径
                        })
                        .strategyConfig(builder -> {
              
                            builder.addInclude("user"); // 设置需要生成的表名
        //                            .addTablePrefix("t_", "c_"); // 设置过滤表前缀
                        })
                        .templateEngine(new FreemarkerTemplateEngine()) // 使用Freemarker引擎模板，默认的是Velocity引擎模板
                        .execute();
        
            }

s-plus-02\\src\\main\\java\\"); // 指定输出目录  
\})  
.packageConfig(builder -> \{  
builder.parent(“cn”) // 设置父包名  
.moduleName(“sycoder”) // 设置父包模块名  
.pathInfo(Collections.singletonMap(OutputFile.xml, “F:\\03-Spring\\MyBatisPlus\\homework\\mybatis-plus-02\\src\\main\\resources\\cn\\sycoder”)); // 设置mapperXml生成路径  
\})  
.strategyConfig(builder -> \{  
builder.addInclude(“user”); // 设置需要生成的表名  
// .addTablePrefix(“t\_”, “c\_”); // 设置过滤表前缀  
\})  
.templateEngine(new FreemarkerTemplateEngine()) // 使用Freemarker引擎模板，默认的是Velocity引擎模板  
.execute();

}

[image-20221203104225946]: https://img-blog.csdnimg.cn/img_convert/a81ae5c8dace63f3c4cc97f21c000dbf.png
[image-20221203110746879]: https://img-blog.csdnimg.cn/img_convert/4c199480d90d628308630f6c46612579.png
[image-20221203113830320]: https://img-blog.csdnimg.cn/img_convert/655bfddce1a31601a774f1d520d0b2b5.png
[image-20221203161601088]: https://img-blog.csdnimg.cn/img_convert/aac0360d3c116d99af9bae1a5008e7be.png
[image-20221203162803951]: https://img-blog.csdnimg.cn/img_convert/033b0b0741b299da6193409d6d1a22b2.png
[image-20221203173656602]: https://img-blog.csdnimg.cn/img_convert/cc17cd864267112e1235b2f0786cda1d.png