spring schema自定义扩展

ゞ浴缸里的玫瑰 2022-09-27 12:29 174阅读 0赞

## spring schema自定义扩展 ##

> Spring 2.5在2.0的基于Schema的Bean配置的基础之上，再增加了扩展XML配置的机制。通过该机制，我们可以编写自己的Schema，并根据自定义的Schema用自定的标签配置Bean。要使用的Spring的扩展XML配置机制，也比较简单，有以下4个步骤：
> 
> 1.  编写自定义Schema文件；
> 2.  编写自定义NamespaceHandler；
> 3.  编写解析BeanDefinition的parser
> 4.  在Spring中注册上述组建

### Maven依赖 ###

<dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-core</artifactId>
        <version>3.2.4.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-beans</artifactId>
        <version>3.2.4.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-aop</artifactId>
        <version>3.2.4.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>3.2.4.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context-support</artifactId>
        <version>3.2.4.RELEASE</version>
    </dependency>

#### 一、编写schema文件 ####

参考：[http://www.w3school.com.cn/schema/schema\_elements\_ref.asp][http_www.w3school.com.cn_schema_schema_elements_ref.asp] , 如下`people.xsd`文件:

<?xml version="1.0" encoding="UTF-8"?>
    <xsd:schema xmlns="http://www.pomelo.com/schema/people" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:beans="http://www.springframework.org/schema/beans" targetNamespace="http://www.pomelo.com/schema/people" elementFormDefault="qualified" attributeFormDefault="unqualified">
        <xsd:import namespace="http://www.springframework.org/schema/beans"/>
    
        <xsd:element name="student">
            <xsd:complexType>
                <xsd:complexContent>
                    <xsd:extension base="beans:identifiedType">
    
                        <xsd:attribute name="name" type="xsd:string">
                            <xsd:annotation>
                                <xsd:documentation>姓名</xsd:documentation>
                            </xsd:annotation>
                        </xsd:attribute>
    
                        <xsd:attribute name="age" type="xsd:string">
                            <xsd:annotation>
                                <xsd:documentation>年龄</xsd:documentation>
                            </xsd:annotation>
                        </xsd:attribute>
    
                    </xsd:extension>
                </xsd:complexContent>
            </xsd:complexType>
        </xsd:element>
    </xsd:schema>

#### 二、编写自定义NamespaceHandler ####

package schema;
    
    import org.springframework.beans.factory.xml.NamespaceHandlerSupport;
    
    public class StudentNamespaceHandler extends NamespaceHandlerSupport { 
    
        @Override
        public void init() {
            registerBeanDefinitionParser("student", new StudentBeanDefinitionParser());
        }
    
    }

#### 三、编写BeanDefinition ####

package schema;
    
    import org.springframework.beans.factory.support.BeanDefinitionBuilder;
    import org.springframework.beans.factory.xml.AbstractSingleBeanDefinitionParser;
    import org.springframework.util.StringUtils;
    import org.w3c.dom.Element;
    
    public class StudentBeanDefinitionParser extends AbstractSingleBeanDefinitionParser { 
    
        protected Class getBeanClass(Element element) {
            return Student.class;
        }
    
        protected void doParse(Element element, BeanDefinitionBuilder bean) {
            String name = element.getAttribute("name");
            bean.addPropertyValue("name", name);
    
            String age = element.getAttribute("age");
            if (StringUtils.hasText(age)) {
                bean.addPropertyValue("age", Integer.valueOf(age));
            }
        }
    }

实体类：

package schema;
    
    public class Student {
    
        private String name;  
    
        private int age;  
    
        public String getName() {  
            return name;  
        }  
    
        public void setName(String name) {  
            this.name = name;  
        }  
    
        public int getAge() {  
            return age;  
        }  
    
        public void setAge(int age) {  
            this.age = age;  
        }  
    
    }

#### 四、注册schema组件 ####

最后在META-INF目录下添加两个配置文件(`spring.handler`和`spring.schema`):

`spring.handler`配置如下：

http\://www.pomelo.com/schema/people=schema.StudentNamespaceHandler

`spring.schema`配置如下：

http\://www.pomelo.com/schema/people.xsd=META-INF/people.xsd

#### 五、测试 ####

新建`applicationContext.xml`放在clasapath下面：

<?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:people="http://www.pomelo.com/schema/people" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.pomelo.com/schema/people http://www.pomelo.com/schema/people.xsd">
    
        <people:student id="student1" name="student1" age="18"/>
    
        <people:student id="student2" name="student2" age="20" />
    
    
        <bean id="student3" class="schema.Student">
            <property name="name" value="student3"/>
            <property name="age" value="23"/>
        </bean>
    
    </beans>

java调用：

package schema;
    
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    
    /** * Created by zhengyong on 17/3/3. */
    public class SchemaTest { 
    
        public static void main(String[] args) {
    
            ApplicationContext ctx = new ClassPathXmlApplicationContext("/applicationContext.xml");
            Student student1 = (Student) ctx.getBean("student1");
            Student student2 = (Student) ctx.getBean("student2");
            Student student3 = (Student) ctx.getBean("student3");
    
            System.out.println("name: " + student1.getName() + " age :" + student1.getAge());
            System.out.println("name: " + student2.getName() + " age :" + student2.getAge());
            System.out.println("name: " + student3.getName() + " age :" + student3.getAge());
        }
    }

具体代码详见：[https://github.com/zyongjava/pomelo/blob/master/src/main/resources/META-INF/people.xsd][https_github.com_zyongjava_pomelo_blob_master_src_main_resources_META-INF_people.xsd]

[http_www.w3school.com.cn_schema_schema_elements_ref.asp]: http://www.w3school.com.cn/schema/schema_elements_ref.asp
[https_github.com_zyongjava_pomelo_blob_master_src_main_resources_META-INF_people.xsd]: https://github.com/zyongjava/pomelo/blob/master/src/main/resources/META-INF/people.xsd