Beanio framework technical principle explanation
The Beanio framework is a Java open source data exchange and mapping framework. The bottom layer is based on JavaBeans and annotations.It aims to simplify the processing of data input and output, providing a flexible and easy -to -use method to read and write various data formats, such as CSV, XML, JSON, etc.
The technical principles of Beanio mainly include the following aspects:
1. Data mapping: Beanio uses JavaBeans to represent the data object and associate the data object with the data format by defining the mapping file.The mapping file is written in XML format, specifically the mapping relationship between the data object attribute and the data format field.In this way, Beanio can convert the data format into a Java object according to the mapping file and convert the Java object to the specified data format.
The following is an example of a simple mapping file. It is used to map the data in CSV format to the Java object:
<beanio xmlns="http://www.beanio.org/2012/03"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.beanio.org/2012/03 http://www.beanio.org/2012/03/mapping.xsd">
<stream name="csvStream" format="csv">
<record name="person" class="com.example.Person">
<field name="firstName" />
<field name="lastName" />
<field name="age" type="int" />
</record>
</stream>
</beanio>
2. Data reading and writing: Beanio provides a stream processing method to read and write data.By configured mapping files and input output streams, data read and write operations can be easily performed.For example, read the data source in CSV format for reading:
InputStream input = new FileInputStream("input.csv");
StreamFactory factory = StreamFactory.newInstance();
StreamDefinition streamDefinition = factory.loadStreamDefinition("mapping.xml");
BeanReader reader = factory.createReader("csvStream", input);
Person person;
while ((person = (Person) reader.read()) != null) {
/ Third
}
reader.close();
Similarly:
OutputStream output = new FileOutputStream("output.csv");
StreamFactory factory = StreamFactory.newInstance();
StreamDefinition streamDefinition = factory.loadStreamDefinition("mapping.xml");
BeanWriter writer = factory.createWriter("csvStream", output);
Person person = new Person();
person.setFirstName("John");
person.setLastName("Doe");
person.setAge(30);
writer.write(person);
writer.flush();
writer.close();
3. Data verification and conversion: Beanio provides rich data verification and conversion functions.By defining verification rules and converters in the mapping file, the verification and conversion of data can be realized in the process of reading and writing.For example, a verification rule can be defined to verify that the age must be greater than or equal to 18:
<field name="age" type="int">
<validator ref="minimumAgeValidator" />
</field>
<beanio:bindings xmlns:beanio="http://www.beanio.org/2012/03">
<beanio:rule>
<beanio:constant name="minimumAgeValidator" class="com.example.MinimumAgeValidator">
<beanio:property name="minimumAge" value="18" />
</beanio:constant>
</beanio:rule>
</beanio:bindings>
4. Advanced features: Beanio provides many high -level features, such as separators configuration, head/tail record processing, nested records, paging and repeated record processing.These features make Beanio apply to process complex data formats and data structures.
In summary, the Beanio framework associates the data object and data format by mapping files, provides convenient data input and output processing methods, and supports data verification and conversion functions.Its flexibility and ease of use enable developers to quickly process various data formats and realize the needs of data exchange and mapping.
