简化java代码：mapstruct + 策略模式

目的

准备

注意

相同类型-属性名不同

实体类

映射

使用

验证-查看实现类

测试

不同类型(策略模式)

实体类

映射

工具类

使用：对象拷贝

验证-查看实现类

测试

使用：集合拷贝

测试

策略模式说明

准备-依赖

目的

简化 BeanUtils.copyProperties 属性对拷代码，自动生成空判断，结合策略模式自定义转换

集合对拷：一行代码就能完成以前先new，再 for循环，再add的多行代码，而且也不用判空

准备

这里我将开发中经常用到的全部依赖都列举出来（若下载不下来依赖，将settings.xml替换成我博客存档的那一份），此处为了不影响观看，放在文章末尾处。

注意

写好转换之后，maven 记得 clean install，查看一下生成的实现类有没有问题

实现类在 target 里面，若target没有，执行下列操作

相同类型-属性名不同

将下面 Doctor 中的 i1 s1 分别转给 DoctorDto 中的 i2 s2

实体类

@Data
@NoArgsConstructor
@AllArgsConstructor
public class Doctor {private int id;private String name;String s1;int i1;
}

@Data
@AllArgsConstructor
@NoArgsConstructor
public class DoctorDto {private int id;private String name;private String s2;private int i2;
}

映射

@Mapper(componentModel = "spring")
public interface BeanConvert {BeanConvert INSTANCE = Mappers.getMapper(BeanConvert.class);/*** 不一致的属性映射*/@Mappings({@Mapping(target = "i2", source = "i1"),@Mapping(target = "s2", source = "s1")})DoctorDto toDto(Doctor doctor);
}

使用

    @GetMapping("/test")public DoctorDto get() {Doctor doctor = new Doctor();doctor.setId(1);doctor.setName("张三");doctor.setI1(1);doctor.setS1("1");return BeanConvert.INSTANCE.toDto(doctor);}

验证-查看实现类

clean install 重启

测试

可以看到 i1，s1中的值已经过来了

不同类型(策略模式)

实体类

将下面 Sku2 中的 Long date Integer code 分别转给 SkuDTO2 中的 Date date String value

一个是时间戳转换，一个是枚举转换

@Data
@NoArgsConstructor
@AllArgsConstructor
@FieldDefaults(level = AccessLevel.PRIVATE)
public class Sku2 {Long skuId;String skuCode;String skuPrice;List<String> nameList;Long date;Integer code;
}

@Data
@NoArgsConstructor
@AllArgsConstructor
@FieldDefaults(level = AccessLevel.PRIVATE)
public class SkuDTO2 {Long skuId;String skuCode;String skuPrice;List<String> nameList;Date date;String value;
}

映射

uses 定义了两个策略，一个负责转换时间戳，一个负责转换枚举

@Mapper(componentModel = "spring", uses = {TimeConvertStrategy.class, EnumConvertStrategy.class})
public interface BeanConvert {/*** 策略模式测试*/@Mapping(target = "value", source = "code")SkuDTO2 domain2Dto(Sku2 sku2);}

@Component
public class EnumConvertStrategy {public String convert(Integer code) {return MyEnum.getByCode(code);}}

@Component
public class TimeConvertStrategy {public Date date2TimeStamp(Long timeStamp) {if (timeStamp == null) {return null;}return new Date(timeStamp);}}

public enum MyEnum {A(1,"哈哈"),B(2,"呵呵");private final Integer code;private final String msg;MyEnum(int code, String msg) {this.code = code;this.msg = msg;}public Integer getCode() {return code;}public String getMsg() {return msg;}public static String getByCode(Integer code) {if (code == null) {return null;}for (MyEnum value : MyEnum.values()) {if (value.getCode().equals(code)) {return value.getMsg();}}return null;}}

工具类

这里使用工具类，主要是辅助容器中的bean初始化的，包括我们定义的策略的初始化

/*** ApplicationContextAware 接口可以让 Bean 获取到 ApplicationContext 对象* 通过这个对象，可以获取 Spring 容器中的其他 Bean实例 或一些组件*/
@Component
public class ConvertSupport implements ApplicationContextAware {private static BeanConvert beanConvert;/*** 启动的时候，直接获取到 beanConvert 的实例*/@Overridepublic void setApplicationContext(ApplicationContext context) throws BeansException {// 这里如果没有执行，说明没有注入容器，但是我有了@Component注解，说明其未生效，主启动类@ComponentScan指定一下if (beanConvert == null) {beanConvert = context.getBean(BeanConvert.class);System.out.println("执行过这里");}}/*** 列表转换*/public static <I, O> List<O> copyList(List<I> inputList, BiFunction<BeanConvert, I, O> function) {if (CollectionUtils.isEmpty(inputList)) {return Collections.emptyList();}List<O> resultList = new ArrayList<>(inputList.size());for (I input : inputList) {resultList.add(function.apply(beanConvert, input));}return resultList;}/*** bean to bean*/public static <I, O> O castBean(I input, BiFunction<BeanConvert, I, O> function) {return function.apply(beanConvert, input);}}

使用：对象拷贝

    @GetMapping("/test2")public SkuDTO2 get2() {Sku2 sku2 = new Sku2();sku2.setSkuId(1L);sku2.setSkuCode("2");sku2.setNameList(Lists.newArrayList("测", "试"));sku2.setDate(new Date().getTime());sku2.setCode(1);return ConvertSupport.castBean(sku2, BeanConvert::domain2Dto);}

验证-查看实现类

clean install 重启

测试

使用：集合拷贝

    @GetMapping("/test3")public List<DoctorDto> get3() {List<Doctor> list = Lists.newArrayList(new Doctor(1, "张三", "1", 1),new Doctor(2, "李四", "2", 2),new Doctor(3, "王五", "3", 3));return ConvertSupport.copyList(list, BeanConvert::toDto);}

此后，一行代码就能完成以前先new，再 for循环，再add的多行代码，而且也不用判空

测试

策略模式说明

上面使用的是用来处理不同类型，平常去除 if else 的使用方式：

先定义两个策略，和上面类似，spring管理后，通过策略内部判断决定怎么走，方法再抽象出一层

/*** 策略1*/
@Component
public class Situation1 implements Situation {private static final String value = "用户传过来的值为1";/*** 判断进入哪个策略(if)*/@Overridepublic Boolean judge(String val) {return value.equals(val);}/*** 逻辑处理*/@Overridepublic int logic(int a, int b) {return a + b;}
}

/*** 策略2*/
@Component
public class Situation2 implements Situation {private static final String value = "用户传过来的值为2";/*** 判断进入哪个策略(if)*/@Overridepublic Boolean judge(String val) {return value.equals(val);}/*** 逻辑处理*/@Overridepublic int logic(int a, int b) {return a - b;}
}

public interface Situation {/*** 判断进入哪个策略(if)*/Boolean judge(String val);/*** 逻辑处理*/int logic(int a, int b);
}

@RestController
public class StrategyTest {@Autowiredprivate ApplicationContext applicationContext;@GetMapping("/test/st")public void test() {String value = "用户传过来的值为2";Map<String, Situation> beans = applicationContext.getBeansOfType(Situation.class);beans.forEach((k, Strategy) -> {// 判断用户传过来的值，从而决定进入哪个策略if (Strategy.judge(value)) {int num = Strategy.logic(8, 2);System.out.println(num);}});}
}

准备-依赖

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.6.1</version><relativePath/> <!-- lookup parent from repository --></parent><groupId>com.mytest</groupId><artifactId>springboot-demo</artifactId><version>0.0.1-SNAPSHOT</version><name>springboot-demo</name><description>springboot-demo</description><properties><org.mapstruct.version>1.5.0.RC1</org.mapstruct.version><org.projectlombok.version>1.18.22</org.projectlombok.version><lombok-mapstruct-binding.version>0.2.0</lombok-mapstruct-binding.version><maven.compiler.source>1.8</maven.compiler.source><maven.compiler.target>1.8</maven.compiler.target></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><!--HuTool为我们提供的一些便捷工具。--><dependency><groupId>cn.hutool</groupId><artifactId>hutool-all</artifactId><version>4.1.14</version></dependency><!--Valid--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-validation</artifactId><version>2.3.2.RELEASE</version></dependency><!--自定义注解--><dependency><groupId>javax.validation</groupId><artifactId>validation-api</artifactId><version>2.0.1.Final</version></dependency><!-- 定时任务 --><dependency><groupId>org.quartz-scheduler</groupId><artifactId>quartz</artifactId><exclusions><exclusion><groupId>com.mchange</groupId><artifactId>c3p0</artifactId></exclusion></exclusions></dependency><!-- 解析客户端操作系统、浏览器等 --><dependency><groupId>eu.bitwalker</groupId><artifactId>UserAgentUtils</artifactId><version>1.21</version></dependency><!-- pagehelper 分页插件 注意 pagehelper 和 spring-boot-starter-parent 版本，容易出现循环依赖 一般通过加@Lazy解决，这里通过版本号解决--><dependency><groupId>com.github.pagehelper</groupId><artifactId>pagehelper-spring-boot-starter</artifactId><version>1.4.1</version></dependency><!--HttpUtils需要的所有依赖--><dependency><groupId>com.alibaba</groupId><artifactId>fastjson</artifactId><version>1.2.15</version></dependency><dependency><groupId>org.apache.httpcomponents</groupId><artifactId>httpclient</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-configuration-processor</artifactId><optional>true</optional></dependency><!--mybatisplus--><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId><version>3.4.1</version></dependency><!--DateTime 需要的依赖，由于没有版本号管理，如果不写version，上面有一处会爆红--><dependency><groupId>joda-time</groupId><artifactId>joda-time</artifactId><version>2.9.4</version></dependency><!--代码生成器--><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-generator</artifactId><version>3.4.1</version></dependency><!--velocity模板引擎--><dependency><groupId>org.apache.velocity</groupId><artifactId>velocity-engine-core</artifactId><version>2.3</version></dependency><!-- easyexcel依赖 --><dependency><groupId>com.alibaba</groupId><artifactId>easyexcel</artifactId><version>3.0.5</version></dependency><dependency><groupId>cn.afterturn</groupId><artifactId>easypoi-base</artifactId><version>4.3.0</version></dependency><dependency><groupId>cn.afterturn</groupId><artifactId>easypoi-web</artifactId><version>4.3.0</version></dependency><dependency><groupId>cn.afterturn</groupId><artifactId>easypoi-annotation</artifactId><version>4.3.0</version></dependency><dependency><groupId>com.alibaba</groupId><artifactId>druid</artifactId><version>1.1.16</version></dependency><!--Lists.partition 需要的依赖--><dependency><groupId>com.google.guava</groupId><artifactId>guava</artifactId><version>25.1-jre</version></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-redis</artifactId><exclusions><exclusion><groupId>io.lettuce</groupId><artifactId>lettuce-core</artifactId></exclusion></exclusions></dependency><!--        &lt;!&ndash;jedis，redis客户端&ndash;&gt;--><dependency><groupId>redis.clients</groupId><artifactId>jedis</artifactId></dependency><!--        &lt;!&ndash;使用redisson作为所有分布式锁，分布式对象等功能框架，也可以使用springboot的方式，就不用自己@Configuration了&ndash;&gt;--><dependency><groupId>org.redisson</groupId><artifactId>redisson</artifactId><version>3.13.3</version></dependency><!--mysql驱动--><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.17</version></dependency><dependency><groupId>org.mapstruct</groupId><artifactId>mapstruct</artifactId><version>${org.mapstruct.version}</version></dependency><!-- 特别注意 mapstruct 和 lombok 的顺序，顺序出问题，实现类就不映射了 --><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>${org.projectlombok.version}</version><scope>provided</scope></dependency><dependency><groupId>org.apache.commons</groupId><artifactId>commons-lang3</artifactId><version>3.10</version></dependency><!--CollectionUtils依赖--><dependency><groupId>commons-collections</groupId><artifactId>commons-collections</artifactId><version>3.2.2</version></dependency><dependency><groupId>com.google.code.google-collections</groupId><artifactId>google-collect</artifactId><version>snapshot-20080530</version></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-aop</artifactId></dependency><!-- https://mvnrepository.com/artifact/org.slf4j/slf4j-log4j12 -->
<!--        <dependency><groupId>org.slf4j</groupId><artifactId>slf4j-log4j12</artifactId></dependency>--><dependency><groupId>com.alibaba</groupId><artifactId>transmittable-thread-local</artifactId><version>2.11.5</version></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>com.google.guava</groupId><artifactId>guava</artifactId><version>21.0</version></dependency><dependency><groupId>javax.persistence</groupId><artifactId>persistence-api</artifactId><version>1.0</version></dependency><!--注意：3.0.0 版本   http://localhost:8081/swagger-ui.html   页面可能登陆不上去--><dependency><groupId>io.springfox</groupId><artifactId>springfox-swagger2</artifactId><version>2.9.2</version></dependency><dependency><groupId>io.springfox</groupId><artifactId>springfox-swagger-ui</artifactId><version>2.9.2</version></dependency></dependencies><!-- 特别注意 mapstruct 和 lombok 的顺序，顺序出问题，实现类就不映射了 --><build><plugins><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId><version>3.8.1</version><configuration><source>1.8</source><target>1.8</target><annotationProcessorPaths><path><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>${org.projectlombok.version}</version></path><!-- This is needed when using Lombok 1.18.16 and above --><path><groupId>org.projectlombok</groupId><artifactId>lombok-mapstruct-binding</artifactId><version>${lombok-mapstruct-binding.version}</version></path><!-- Mapstruct should follow the lombok path(s) --><path><groupId>org.mapstruct</groupId><artifactId>mapstruct-processor</artifactId><version>${org.mapstruct.version}</version></path></annotationProcessorPaths></configuration></plugin></plugins><resources><resource><directory>src/main/java</directory><includes><include>**/*.properties</include><include>**/*.xml</include><include>**/*.yml</include></includes><filtering>false</filtering></resource><resource><directory>src/main/resources</directory><includes><include>**/*.properties</include><include>**/*.xml</include><include>**/*.yml</include></includes><filtering>false</filtering></resource></resources></build></project>