Spring自定义标签解析

整体流程：

自定义一个<msb:user   username email age>,完成整个标签的处理工作
流程：1，需要解析的实体类User;
     2,自定义标签解析器UserBeanDefinitionParser,继承于AbstractSingleBeanDefinitionParser，重写两个方法getBeanClass()和doParse();
     3,解析器的处理类UserNamespaceHandler,继承于NamespaceHandlerSupport，重写方法init();
     4,解析器的配置文件和处理类的配置文件，放在META-INF下面，分别为spring.schemas,spring.handlers
     5,编写配置文件selftag.xml;
     6,编写测试类TestSelfTag

1、创建实体类

User.java

package com.mashibing.selftag;

public class User {

    private String username;
    private String email;
    private String password;

    public User() {
    }

    public User(String username, String email, String password) {
        this.username = username;
        this.email = email;
        this.password = password;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}
2、自定义解析器，继承AbstractSingleBeanDefinitionParser
UserBeanDefinitionParser.java

package com.mashibing.selftag;

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

public class UserBeanDefinitionParser extends AbstractSingleBeanDefinitionParser {

    //返回属性值所对应的现象
    @Override
    protected Class<?> getBeanClass(Element element) {
        return User.class;
    }

    @Override
    protected void doParse(Element element, BeanDefinitionBuilder builder) {
        // 获取标签具体的属性值
       String userName=element.getAttribute("userName");
       String email=element.getAttribute("email");
       String password=element.getAttribute("password");
       
       if(StringUtils.hasText(userName)){
           builder.addPropertyValue("username",userName);
       }
       
       if(StringUtils.hasText(email)){
           builder.addPropertyValue("email",email);
       }
       
       if(StringUtils.hasText(password)){
           builder.addPropertyValue("password",password);
       }
    }
3、自定义解析器的处理器，继承NamespaceHandlerSupport

UserNamespaceHandler.java

package com.mashibing.selftag;

import org.springframework.beans.factory.xml.NamespaceHandlerSupport;

public class UserNamespaceHandler extends NamespaceHandlerSupport {
    @Override
    public void init() {
        registerBeanDefinitionParser("user",new UserBeanDefinitionParser());
    }
}
4、自定义配置文件spring.handlers、spring.schemas
spring.handlers

http\://www.mashibing.com/schema/user=com.mashibing.selftag.UserNamespaceHandler
spring.schemas

http\://www.mashibing.com/schema/user.xsd=META-INF/user.xsd

5、配置applicationContext.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:msb="http://www.mashibing.com/schema/user"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.mashibing.com/schema/user
       http://www.mashibing.com/schema/user.xsd
">
    <msb:user id="msb" userName="qiangShan" email="1059931090@qq.com" password="root123456"></msb:user>

</beans>
6、编写测试类TestSelfTag.java
TestSelfTag.java

import com.mashibing.selftag.User;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class TestSelfTag {

    @Test
    public void test(){
        ApplicationContext context=new ClassPathXmlApplicationContext("applicationContext.xml");
        User user =(User) context.getBean("msb");
        System.out.println("username"+user.getUsername()+" "+"email"+user.getEmail());
    }
}