【Spring】自定义标签

完成一个spring的自定义配置一般需要以下5个步骤：
1.设计配置属性和JavaBean
2.编写XSD文件 全称就是 XML Schema 它就是校验XML，定义了一些列的语法来规范XML
3.编写NamespaceHandler和BeanDefinitionParser完成解析工作
4.编写spring.handlers和spring.schemas串联起所有部件
5.在Bean文件中应用

接下来就按照以上五个步骤来自定义一个简单的标签

1. 设计属性和JavaBean

<school:people id="testPeople" name="Jack" age="11"></school:people>

package com.soa.other.spring.schema;

/**
 * Created by pengyunlong on 2018/5/27.
 */
public class People {
    private String id;
    private String name;
    private Integer age;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "People{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

2. 编写XSD文件

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<xsd:schema xmlns="http://www.springframework.org/schema/agan"
            xmlns:xsd="http://www.w3.org/2001/XMLSchema"
            xmlns:beans="http://www.springframework.org/schema/beans"
            targetNamespace="http://www.springframework.org/schema/school"
            elementFormDefault="qualified"
            attributeFormDefault="unqualified">
    <xsd:import namespace="http://www.w3.org/XML/1998/namespace"/>
    <xsd:element name="people">
        <xsd:complexType>
            <xsd:attribute name="id" type="xsd:string"></xsd:attribute>
            <xsd:attribute name="name" type="xsd:string"></xsd:attribute>
            <xsd:attribute name="age" type="xsd:int"></xsd:attribute>
            <!--<xsd:complexContent>
                <xsd:extension base="beans:identifiedType">
                    <xsd:attribute name="name" type="xsd:string"></xsd:attribute>
                    <xsd:attribute name="age" type="xsd:int"></xsd:attribute>
                </xsd:extension>
            </xsd:complexContent>-->
        </xsd:complexType>
    </xsd:element>
</xsd:schema>

3.编写NamespaceHandler和BeanDefinitionParser完成解析工作

package com.soa.other.spring.schema;

import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.BeanDefinitionHolder;
import org.springframework.beans.factory.xml.NamespaceHandler;
import org.springframework.beans.factory.xml.NamespaceHandlerSupport;
import org.springframework.beans.factory.xml.ParserContext;
import org.w3c.dom.Element;
import org.w3c.dom.Node;

/**
 * Created by pengyunlong on 2018/5/27.
 */
public class MyNameSpaceHandler extends NamespaceHandlerSupport{
    @Override
    public void init() {
        registerBeanDefinitionParser("people",new PeopleBeanDefinitionParser());
    }
}

package com.soa.other.spring.schema;

import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.xml.AbstractBeanDefinitionParser;
import org.springframework.beans.factory.xml.AbstractSingleBeanDefinitionParser;
import org.springframework.beans.factory.xml.BeanDefinitionParser;
import org.springframework.beans.factory.xml.ParserContext;
import org.springframework.util.StringUtils;
import org.w3c.dom.Element;

/**
 * Created by pengyunlong on 2018/5/27.
 */
public class PeopleBeanDefinitionParser extends AbstractSingleBeanDefinitionParser{
    @Override
    protected Class<?> getBeanClass(Element element) {
        return People.class;
    }

    @Override
    protected void doParse(Element element, BeanDefinitionBuilder builder) {
        String name = element.getAttribute("name");
        String age = element.getAttribute("age");
        String id = element.getAttribute("id");
        if (StringUtils.hasText(id)){
            builder.addPropertyValue("id",id);
        }
        if (StringUtils.hasText(name)){
            builder.addPropertyValue("name",name);
        }
        if (StringUtils.hasText(age)){
            builder.addPropertyValue("age",age);
        }
    }
}

4. 编写spring.handlers和spring.schemas串联起所有部件

META-INF/spring.handlers

http\://www.springframework.org/schema/school=com.soa.other.spring.schema.MyNameSpaceHandler

META-INF\spring.schemas

http\://www.springframework.org/schema/school/school.xsd=/META-INF/school.xsd

5. 在Bean文件中应用标签

MyName.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:school="http://www.springframework.org/schema/school"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/school
        http://www.springframework.org/schema/school/school.xsd ">
    <school:people id="testPeople" name="Jack" age="11"></school:people>
</beans>

测试

package com.soa;

import com.soa.other.spring.schema.People;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import java.awt.event.PaintEvent;

/**
 * Spring自定义标签
 *
 */
public class App 
{
    public static void main( String[] args )
    {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("MyName.xml");
        People people = (People) context.getBean("testPeople");
        System.out.println(people.toString());
    }
}

结果

People{id='testPeople', name='Jack', age=11}

附

目录结构
pom.xml

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>com.other.soa</groupId>
  <artifactId>spring-schema</artifactId>
  <version>1.0-SNAPSHOT</version>

  <name>spring-schema</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>
  <parent>
    <groupId>com.other.soa</groupId>
    <artifactId>parent</artifactId>
    <version>1.0-SNAPSHOT</version>
  </parent>
  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.7</maven.compiler.source>
    <maven.compiler.target>1.7</maven.compiler.target>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-beans</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
    </dependency>
  </dependencies>
</project>