Spring Batch ItemProcessor组件-默认处理器

引言

概念

默认ItemProcessor

ValidatingItemProcessor：校验处理器

ItemProcessorAdapter：适配器处理器

ScriptItemProcessor：脚本处理器

CompositeItemProcessor：组合处理器

自定义ItemProcessor处理器

转视频版

引言

接着上篇：Spring Batch ItemReader组件-读数据库了解Spring Batch ItemReader读组件后，接下来一起学习一下Spring Batch 数据处理组件：ItemProcessor

概念

前面我们多次讲过，居于块的读与写，中间还夹着一个ItemProcessor 条目处理。当我们通过ItemReader 将数据读取出来之后，你面临2个选择：

1>直接将数据转向输出

2>对读入的数据进行再加工。

如果选择第一种，那ItemProcessor 可以不用出现，如果选择第二种，就需要引入ItemProcessor 条目处理组件啦。

Spring Batch 为ItemProcessor提供默认的处理器与自定义处理器2种模式以满足各种需求。

默认ItemProcessor

Spring Batch 提供现成的ItemProcessor 组件有4种：

ValidatingItemProcessor：校验处理器
ItemProcessorAdapter：适配器处理器
ScriptItemProcessor：脚本处理器
CompositeItemProcessor：组合处理器

ValidatingItemProcessor：校验处理器

这个好理解，很多时候ItemReader读出来的数据是相对原始的数据，并没有做过多的校验

数据文件users-validate.txt

1##18
2##16
3#laofei#20
4#zhongfei#19
5#feifei#15

比如上面文本数据，第一条，第二条name数值没有指定，在ItemReader 读取之后，必定将 "" 空串封装到User name属性中，语法上没有错，但逻辑上可以做文章，比如：用户名不为空。

解决上述问题，可以使用Spring Batch 提供ValidatingItemProcessor 校验器处理。

接下来我们看下ValidatingItemProcessor 怎么实现

1>导入校验依赖

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-validation</artifactId>
</dependency>

2>定义实体对象

@Getter
@Setter
@ToString
public class User {
    private Long id;
    @NotBlank(message = "用户名不能为null或空串")
    private String name;
    private int age;
}

3>实现

package com.langfeiyes.batch._26_itemprocessor_validate;

import org.springframework.batch.core.Job;
import org.springframework.batch.core.Step;
import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;
import org.springframework.batch.core.configuration.annotation.JobBuilderFactory;
import org.springframework.batch.core.configuration.annotation.StepBuilderFactory;
import org.springframework.batch.item.ItemWriter;
import org.springframework.batch.item.file.FlatFileItemReader;
import org.springframework.batch.item.file.builder.FlatFileItemReaderBuilder;
import org.springframework.batch.item.validator.BeanValidatingItemProcessor;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.core.io.ClassPathResource;
import org.springframework.util.StringUtils;

import java.util.List;

@SpringBootApplication
@EnableBatchProcessing
public class ValidationProcessorJob {
    @Autowired
    private JobBuilderFactory jobBuilderFactory;
    @Autowired
    private StepBuilderFactory stepBuilderFactory;


    @Bean
    public FlatFileItemReader<User> userItemReader(){
        return new FlatFileItemReaderBuilder<User>()
                .name("userItemReader")
                .resource(new ClassPathResource("users-validate.txt"))
                .delimited().delimiter("#")
                .names("id", "name", "age")
                .targetType(User.class)
                .build();
    }

    @Bean
    public ItemWriter<User> itemWriter(){
        return new ItemWriter<User>() {
            @Override
            public void write(List<? extends User> items) throws Exception {
                items.forEach(System.err::println);
            }
        };
    }


    @Bean
    public BeanValidatingItemProcessor<User> beanValidatingItemProcessor(){
        BeanValidatingItemProcessor<User> beanValidatingItemProcessor = new BeanValidatingItemProcessor<>();
        beanValidatingItemProcessor.setFilter(true);  //不满足条件丢弃数据

        return beanValidatingItemProcessor;
    }


    @Bean
    public Step step(){
        return stepBuilderFactory.get("step1")
                .<User, User>chunk(1)
                .reader(userItemReader())
                .processor(beanValidatingItemProcessor())
                .writer(itemWriter())
                .build();

    }

    @Bean
    public Job job(){
        return jobBuilderFactory.get("validate-processor-job4")
                .start(step())
                .build();
    }
    public static void main(String[] args) {
        SpringApplication.run(ValidationProcessorJob.class, args);
    }
}

解析：

1>核心是beanValidatingItemProcessor() 实例方法，核心BeanValidatingItemProcessor 类是Spring Batch 提供现成的Validator校验类，这里直接使用即可。BeanValidatingItemProcessor 是 ValidatingItemProcessor 子类

2> step()实例方法，多了.processor(beanValidatingItemProcessor()) 操作，引入ItemProcessor 组件。

ItemProcessorAdapter：适配器处理器

开发中，很多的校验逻辑已经有现成的啦，那做ItemProcessor处理时候，是否能使用现成逻辑呢？答案是：yes

比如：现有处理逻辑：将User对象中name转换成大写

public class UserServiceImpl{
    public User toUppeCase(User user){
        user.setName(user.getName().toUpperCase());
        return user;
    }
}

新建users-adapter.txt 文件，用于测试

1#dafei#18
2#xiaofei#16
3#laofei#20
4#zhongfei#19
5#feifei#15

完整的逻辑

package com.langfeiyes.batch._27_itemprocessor_adapter;

import org.springframework.batch.core.Job;
import org.springframework.batch.core.Step;
import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;
import org.springframework.batch.core.configuration.annotation.JobBuilderFactory;
import org.springframework.batch.core.configuration.annotation.StepBuilderFactory;
import org.springframework.batch.item.ItemWriter;
import org.springframework.batch.item.adapter.ItemProcessorAdapter;
import org.springframework.batch.item.file.FlatFileItemReader;
import org.springframework.batch.item.file.builder.FlatFileItemReaderBuilder;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.core.io.ClassPathResource;

import java.util.List;

@SpringBootApplication
@EnableBatchProcessing
public class AdapterProcessorJob {
    @Autowired
    private JobBuilderFactory jobBuilderFactory;
    @Autowired
    private StepBuilderFactory stepBuilderFactory;


    @Bean
    public FlatFileItemReader<User> userItemReader(){
        return new FlatFileItemReaderBuilder<User>()
                .name("userItemReader")
                .resource(new ClassPathResource("users-adapter.txt"))
                .delimited().delimiter("#")
                .names("id", "name", "age")
                .targetType(User.class)
                .build();
    }

    @Bean
    public ItemWriter<User> itemWriter(){
        return new ItemWriter<User>() {
            @Override
            public void write(List<? extends User> items) throws Exception {
                items.forEach(System.err::println);
            }
        };
    }
    @Bean
    public UserServiceImpl userService(){
        return new UserServiceImpl();
    }
    @Bean
    public ItemProcessorAdapter<User, User> itemProcessorAdapter(){
        ItemProcessorAdapter<User, User> adapter = new ItemProcessorAdapter<>();
        adapter.setTargetObject(userService());
        adapter.setTargetMethod("toUppeCase");

        return adapter;
    }

    @Bean
    public Step step(){
        return stepBuilderFactory.get("step1")
                .<User, User>chunk(1)
                .reader(userItemReader())
                .processor(itemProcessorAdapter())
                .writer(itemWriter())
                .build();

    }
    @Bean
    public Job job(){
        return jobBuilderFactory.get("adapter-processor-job")
                .start(step())
                .build();
    }
    public static void main(String[] args) {
        SpringApplication.run(AdapterProcessorJob.class, args);
    }
}

ScriptItemProcessor：脚本处理器

前面要实现User name 变大写，需要大费周折，又定义类，又是定义方法，能不能简化一点。答案也是yes， Spring Batch 提供js脚本的形式，将上面逻辑写到js文件中，加载这文件，就可以实现，省去定义类，定义方法的麻烦。

需求：使用js脚本方式实现用户名大写处理

userScript.js

item.setName(item.getName().toUpperCase());
item;

这里注意：

1>item是约定的单词，表示ItemReader读除来每个条目

2>userScript.js文件放置到resource资源文件中

完整代码

package com.langfeiyes.batch._28_itemprocessor_script;

import org.springframework.batch.core.Job;
import org.springframework.batch.core.Step;
import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;
import org.springframework.batch.core.configuration.annotation.JobBuilderFactory;
import org.springframework.batch.core.configuration.annotation.StepBuilderFactory;
import org.springframework.batch.item.ItemWriter;
import org.springframework.batch.item.file.FlatFileItemReader;
import org.springframework.batch.item.file.builder.FlatFileItemReaderBuilder;
import org.springframework.batch.item.support.ScriptItemProcessor;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.core.io.ClassPathResource;

import java.util.List;

@SpringBootApplication
@EnableBatchProcessing
public class ScriptProcessorJob {
    @Autowired
    private JobBuilderFactory jobBuilderFactory;
    @Autowired
    private StepBuilderFactory stepBuilderFactory;


    @Bean
    public FlatFileItemReader<User> userItemReader(){
        return new FlatFileItemReaderBuilder<User>()
                .name("userItemReader")
                .resource(new ClassPathResource("users-adapter.txt"))
                .delimited().delimiter("#")
                .names("id", "name", "age")
                .targetType(User.class)
                .build();
    }

    @Bean
    public ItemWriter<User> itemWriter(){
        return new ItemWriter<User>() {
            @Override
            public void write(List<? extends User> items) throws Exception {
                items.forEach(System.err::println);
            }
        };
    }


    @Bean
    public ScriptItemProcessor<User, User> scriptItemProcessor(){
        ScriptItemProcessor<User, User> scriptItemProcessor = new ScriptItemProcessor();
        scriptItemProcessor.setScript(new ClassPathResource("userScript.js"));
        return scriptItemProcessor;
    }

    @Bean
    public Step step(){
        return stepBuilderFactory.get("step1")
                .<User, User>chunk(1)
                .reader(userItemReader())
                .processor(scriptItemProcessor())
                .writer(itemWriter())
                .build();

    }

    @Bean
    public Job job(){
        return jobBuilderFactory.get("script-processor-job")
                .start(step())
                .build();
    }
    public static void main(String[] args) {
        SpringApplication.run(ScriptProcessorJob.class, args);
    }
}

解析：

核心还是scriptItemProcessor() 实例方法，ScriptItemProcessor 类用于加载js 脚本并处理js脚本。

CompositeItemProcessor：组合处理器

CompositeItemProcessor是一个ItemProcessor处理组合，类似于过滤器链，数据先经过第一个处理器，然后再经过第二个处理器，直到最后。前一个处理器处理的结果，是后一个处理器的输出。

需求：将解析出来用户name进行判空处理，并将name属性转换成大写

1>读取文件：users-validate.txt

1##18
2##16
3#laofei#20
4#zhongfei#19
5#feifei#15

2>封装的实体对象

@Getter
@Setter
@ToString
public class User {
    private Long id;
    @NotBlank(message = "用户名不能为null或空串")
    private String name;
    private int age;
}

3>用于转换大写工具类

public class UserServiceImpl {
    public User toUppeCase(User user){
        user.setName(user.getName().toUpperCase());
        return user;
    }
}

4>完整代码

package com.langfeiyes.batch._29_itemprocessor_composite;

import org.springframework.batch.core.Job;
import org.springframework.batch.core.Step;
import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;
import org.springframework.batch.core.configuration.annotation.JobBuilderFactory;
import org.springframework.batch.core.configuration.annotation.StepBuilderFactory;
import org.springframework.batch.item.ItemWriter;
import org.springframework.batch.item.adapter.ItemProcessorAdapter;
import org.springframework.batch.item.file.FlatFileItemReader;
import org.springframework.batch.item.file.builder.FlatFileItemReaderBuilder;
import org.springframework.batch.item.support.CompositeItemProcessor;
import org.springframework.batch.item.validator.BeanValidatingItemProcessor;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.core.io.ClassPathResource;

import java.util.Arrays;
import java.util.List;

@SpringBootApplication
@EnableBatchProcessing
public class CompositeProcessorJob {
    @Autowired
    private JobBuilderFactory jobBuilderFactory;
    @Autowired
    private StepBuilderFactory stepBuilderFactory;


    @Bean
    public FlatFileItemReader<User> userItemReader(){
        return new FlatFileItemReaderBuilder<User>()
                .name("userItemReader")
                .resource(new ClassPathResource("users-validate.txt"))
                .delimited().delimiter("#")
                .names("id", "name", "age")
                .targetType(User.class)
                .build();
    }

    @Bean
    public ItemWriter<User> itemWriter(){
        return new ItemWriter<User>() {
            @Override
            public void write(List<? extends User> items) throws Exception {
                items.forEach(System.err::println);
            }
        };
    }

    @Bean
    public UserServiceImpl userService(){
        return new UserServiceImpl();
    }
    @Bean
    public BeanValidatingItemProcessor<User> beanValidatingItemProcessor(){
        BeanValidatingItemProcessor<User> beanValidatingItemProcessor = new BeanValidatingItemProcessor<>();
        beanValidatingItemProcessor.setFilter(true);  //不满足条件丢弃数据
        return beanValidatingItemProcessor;
    }

    @Bean
    public ItemProcessorAdapter<User, User> itemProcessorAdapter(){
        ItemProcessorAdapter<User, User> adapter = new ItemProcessorAdapter<>();
        adapter.setTargetObject(userService());
        adapter.setTargetMethod("toUppeCase");

        return adapter;
    }

    @Bean
    public CompositeItemProcessor<User, User>  compositeItemProcessor(){
        CompositeItemProcessor<User, User> compositeItemProcessor = new CompositeItemProcessor<>();
        compositeItemProcessor.setDelegates(Arrays.asList(
                beanValidatingItemProcessor(), itemProcessorAdapter()
        ));
        return  compositeItemProcessor;
    }

    @Bean
    public Step step(){
        return stepBuilderFactory.get("step1")
                .<User, User>chunk(1)
                .reader(userItemReader())
                .processor(compositeItemProcessor())
                .writer(itemWriter())
                .build();

    }

    @Bean
    public Job job(){
        return jobBuilderFactory.get("composite-processor-job")
                .start(step())
                .build();
    }
    public static void main(String[] args) {
        SpringApplication.run(CompositeProcessorJob.class, args);
    }
}

解析：

核心代码：compositeItemProcessor() 实例方法，使用setDelegates 操作将其他ItemProcessor 处理合并成一个。

自定义ItemProcessor处理器

除去上面默认的几种处理器外，Spring Batch 也允许我们自定义，具体做法只需要实现ItemProcessor接口即可

需求：自定义处理器，筛选出id为偶数的用户

1>定义读取文件user.txt

1#dafei#18
2#xiaofei#16
3#laofei#20
4#zhongfei#19
5#feifei#15

2>定义实体对象

@Getter
@Setter
@ToString
public class User {
    private Long id;
    private String name;
    private int age;
}

3>自定义处理器

//自定义
public class CustomizeItemProcessor implements ItemProcessor<User,User> {
    @Override
    public User process(User item) throws Exception {
        //id 为偶数的用户放弃
        //返回null时候 读入的item会被放弃，不会进入itemwriter
        return item.getId() % 2 != 0 ? item : null;
    }
}

4>完整代码

package com.langfeiyes.batch._30_itemprocessor_customize;

import org.springframework.batch.core.Job;
import org.springframework.batch.core.Step;
import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;
import org.springframework.batch.core.configuration.annotation.JobBuilderFactory;
import org.springframework.batch.core.configuration.annotation.StepBuilderFactory;
import org.springframework.batch.item.ItemWriter;
import org.springframework.batch.item.file.FlatFileItemReader;
import org.springframework.batch.item.file.builder.FlatFileItemReaderBuilder;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.core.io.ClassPathResource;

import java.util.List;

@SpringBootApplication
@EnableBatchProcessing
public class CustomizeProcessorJob {
    @Autowired
    private JobBuilderFactory jobBuilderFactory;
    @Autowired
    private StepBuilderFactory stepBuilderFactory;


    @Bean
    public FlatFileItemReader<User> userItemReader(){
        return new FlatFileItemReaderBuilder<User>()
                .name("userItemReader")
                .resource(new ClassPathResource("users.txt"))
                .delimited().delimiter("#")
                .names("id", "name", "age")
                .targetType(User.class)
                .build();
    }

    @Bean
    public ItemWriter<User> itemWriter(){
        return new ItemWriter<User>() {
            @Override
            public void write(List<? extends User> items) throws Exception {
                items.forEach(System.err::println);
            }
        };
    }
    @Bean
    public CustomizeItemProcessor customizeItemProcessor(){
        return new CustomizeItemProcessor();
    }

    @Bean
    public Step step(){
        return stepBuilderFactory.get("step1")
                .<User, User>chunk(1)
                .reader(userItemReader())
                .processor(customizeItemProcessor())
                .writer(itemWriter())
                .build();

    }
    @Bean
    public Job job(){
        return jobBuilderFactory.get("customize-processor-job")
                .start(step())
                .build();
    }
    public static void main(String[] args) {
        SpringApplication.run(CustomizeProcessorJob.class, args);
    }
}

到这，本篇就结束了，欲知后事如何，请听下回分解~

转视频版

看文字不过瘾可以切换视频版：Spring Batch高效批处理框架实战