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[英]How to Parse only a portion of a web JSON in Java using RestTemplate?
[英]How to parse only selected portion of XML using spring batch and convert it into java POJO
我试图解析XML文件并从中转换java POJO。 我的示例XML看起来像
students.xml
<?xml version="1.0" encoding="ISO-8859-1" standalone="no"?>
<group>
<college>
<name>Hogwards</name>
<city>Unknown</city>
</college>
<student>
<name>Tony Tester</name>
<rollNo>1</rollNo>
<enrollmentDate>2016-10-31</enrollmentDate>
<sampleTimeStamp>2016-11-07T05:50:45</sampleTimeStamp>
<salary>16.57</salary>
</student>
<student>
<name>Nick Newbie</name>
<rollNo>2</rollNo>
<enrollmentDate>2017-10-31</enrollmentDate>
<sampleTimeStamp>2016-11-07T05:50:45</sampleTimeStamp>
<salary>29.68</salary>
</student>
<student>
<name>Ian Intermediate</name>
<rollNo>3</rollNo>
<enrollmentDate>2018-10-31</enrollmentDate>
<sampleTimeStamp>2016-11-07T05:50:45</sampleTimeStamp>
<salary>789.62</salary>
</student>
</group>
在这里,我的目标是解析文件,并使用spring批处理将学生信息填充到数据库中,为了我的目的,大学信息对我来说是一种完全没用的标题,所以在我的批处理阅读器中我想忽略它而只是我想要以块的形式解析学生信息。 截至目前,我的代码正在使用GroupDTO类来一次解析整个记录,并且一次创建对象,因此我无法提供spring批处理的功能。 我的要求是学生信息应该以块的形式进行解析,假设大小为300左右。 但截至目前,我的代码一次解析整个XML文件并从中填充java对象。 请帮助我忽略大学部分部分,只是使用spring批量解析学生部分的部分或建议一些适当的链接,这可以帮助我找到我的问题的一些解决方案。 提前致谢...
XmlConfiguration.java
@Configuration
public class XmlConfiguration
{
@Autowired
JobBuilderFactory jobBuilderFactory;
@Autowired
StepBuilderFactory stepBuilderFactory;
@StepScope
@Bean(name="xmlReader")
public SynchronizedItemStreamReader<GroupDTO> reader()
{
StaxEventItemReader<GroupDTO> xmlFileReader = new StaxEventItemReader<>();
xmlFileReader.setResource(new ClassPathResource("students.xml"));
xmlFileReader.setFragmentRootElementName("group");
Map<String, Class<?>> aliases = new HashMap<>();
aliases.put("group", GroupDTO.class);
aliases.put("college", CollegeDTO.class);
aliases.put("student", StudentDTO.class);
XStreamMarshaller xStreamMarshaller = new XStreamMarshaller();
xStreamMarshaller.setAliases(aliases);
String dateFormat = "yyyy-MM-dd";
String timeFormat = "HHmmss";
String[] acceptableFormats = {timeFormat};
xStreamMarshaller.getXStream().autodetectAnnotations(true);
xStreamMarshaller.getXStream().registerConverter(new DateConverter(dateFormat, acceptableFormats));
xStreamMarshaller.getXStream().addPermission(NoTypePermission.NONE);
xStreamMarshaller.getXStream().addPermission(NullPermission.NULL);
xStreamMarshaller.getXStream().addPermission(PrimitiveTypePermission.PRIMITIVES);
xStreamMarshaller.getXStream().allowTypeHierarchy(Collection.class);
xStreamMarshaller.getXStream().allowTypesByWildcard(new String[] {"com.example.demo.**"});
xStreamMarshaller.getXStream().addImplicitCollection(GroupDTO.class, "list");
xmlFileReader.setUnmarshaller(xStreamMarshaller);
SynchronizedItemStreamReader<GroupDTO> synchronizedItemStreamReader = new SynchronizedItemStreamReader<>();
synchronizedItemStreamReader.setDelegate(xmlFileReader);
return synchronizedItemStreamReader;
}
@Bean(name="xmlProcessor")
public ItemProcessor<GroupDTO, GroupDTO> processor()
{
return new Processor();
}
@Bean(name="xmlWriter")
public ItemWriter<GroupDTO> writer()
{
return new Writer();
}
@Bean(name="xmljobListener")
public JobExecutionListenerSupport jobListener()
{
return new JobListener();
}
@JobScope
@Bean(name="xmltaskExecutor")
public ThreadPoolTaskExecutor taskExecutor()
{
ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
executor.setCorePoolSize(50);
executor.setMaxPoolSize(100);
return executor;
}
@Bean(name="xmlStep")
public Step xmlFileToDatabaseStep()
{
return stepBuilderFactory.get("xmlStep")
.<GroupDTO, GroupDTO>chunk(2)
.reader(this.reader())
.processor(this.processor())
.writer(this.writer())
.taskExecutor(this.taskExecutor())
.build();
}
@Bean(name="xmlJob")
public Job xmlFileToDatabaseJob(@Autowired @Qualifier("xmlStep") Step step)
{
return jobBuilderFactory
.get("xmlJob"+new Date())
.incrementer(new RunIdIncrementer())
.listener(this.jobListener())
.flow(step)
.end()
.build();
}
}
GroupDTO.java
@XStreamAlias("group")
public class GroupDTO
{
@XStreamAlias("college")
private CollegeDTO college;
@XStreamAlias("student")
private List<StudentDTO> list;
...... getter,setter, constructors
}
CollegeDTO.java
public class CollegeDTO
{
private String name;
private String city;
...... getter,setter and constructor
}
StudentDTO.java
public class StudentDTO
{
private String name;
private Integer rollNo;
private Date enrollmentDate;
private Date sampleTimeStamp;
private BigDecimal salary;
... getter, setter and constructor
}
在作业内部,您可以使用可以使用块标记的tasklet。 它将具有reader和writer属性,并且可以具有处理器属性。 “处理器”是可选的。
<batch:job id="helloWorldJob">
<batch:step id="step1">
<batch:tasklet>
<batch:chunk reader="itemReader" writer="itemWriter"
processor="itemProcessor" commit-interval="10">
</batch:chunk>
</batch:tasklet>
</batch:step>
</batch:job>
然后,当您声明阅读器标签时,您将定义映射器。
<!-- READER -->
<bean id = "itemReader"
class = "org.springframework.batch.item.file.FlatFileItemReader">
...
<property name = "lineMapper">
<bean class = "org.springframework.batch.item.file.mapping.DefaultLineMapper">
...
<property name = "fieldSetMapper">
<bean class = "tudy.batch.Mapper" />
</property>
</bean>
</property>
</bean>
这个Mapper类是一个很好的选择,可以做你想要的。 此映射器将读取输入文件。 我想你需要做的就是忽略大学标签。
public class Mapper implements FieldSetMapper<Student>{
public Student mapFieldSet(FieldSet fieldSet) throws BindException {
// Instantiating the report object
Student student = new Student();
// Setting the fields
student.setName(fieldSet.readInt(0));
student.setRollNo(fieldSet.readString(1));
student.setEnrollmentDate(fieldSet.readString(2));
student.setSampleTimeStamp(fieldSet.readString(3));
student.setSalary(fieldSet.readString(4));
return Student;
}
}
您可以使用索引或名称。 你应该调试你的代码并确认大学将如何忽略它的位置或名称。
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