OSGI blueprint Converter的使用

怼烎@ 2022-08-18 15:18 128阅读 0赞

在我上一篇（http://blog.csdn.net/mn960mn/article/details/47316685）文章中讲到 Blueprint Container 规范定义了 4 种环境管理器

Bundle， BundleContext，BlueprintContainer，Converter

使用的时候，可以直接在blueprint.xml中配置和使用

前三个，想必大家都非常清楚了，也会用了，那么第四个org.osgi.service.blueprint.container.Converter是用来干什么的呢？

见名知意，这个是用来做转换的，那么怎么用呢？

下面来举一个例子说明如何使用Converter

首先，加入相关的依赖

<dependency>
    	<groupId>org.osgi</groupId>
    	<artifactId>org.osgi.core</artifactId>
    	<version>5.0.0</version>
    </dependency>
    <dependency>
    	<groupId>org.osgi</groupId>
    	<artifactId>org.osgi.compendium</artifactId>
    	<version>5.0.0</version>
    </dependency>

二：示例如下

package com.lala.bean;
    
    public class User 
    {
    	private Integer id;
    	private String name;
    	public Integer getId() {
    		return id;
    	}
    	public void setId(Integer id) {
    		this.id = id;
    	}
    	public String getName() {
    		return name;
    	}
    	public void setName(String name) {
    		this.name = name;
    	}
    	public String toString() {
    		return "User [id=" + id + ", name=" + name + "]";
    	}
    }

package com.lala.bean;
    
    public class Official 
    {
    	//职位
    	private String position;
    	private User user;
    	
    	public void display()
    	{
    		System.out.println(this);
    	}
    	
    	public String getPosition() {
    		return position;
    	}
    	public void setPosition(String position) {
    		this.position = position;
    	}
    	public User getUser() {
    		return user;
    	}
    	public void setUser(User user) {
    		this.user = user;
    	}
    
    	public String toString() {
    		return "Official [position=" + position + ", user=" + user + "]";
    	}
    }

package com.lala.convert;
    
    import org.osgi.service.blueprint.container.Converter;
    import org.osgi.service.blueprint.container.ReifiedType;
    
    import com.lala.bean.User;
    
    /**
     *	把字符串转换成User对象的转换器
     */
    public class UserConvert implements Converter 
    {
    	private static Integer id = 1;
    	/**
    	 * 如果需求是把字符串转换成User对象，则返回true,否则返回false
    	 */
    	public boolean canConvert(Object sourceObject, ReifiedType targetType)
    	{
    		if(sourceObject instanceof String)
    		{
    			return targetType.getRawClass().isAssignableFrom(User.class);
    		}
    		return false;
    	}
    	
    	/**
    	 * 把字符串转换成User
    	 */
    	public Object convert(Object sourceObject, ReifiedType targetType) throws Exception
    	{
    		User user = new User();
    		user.setId(id++);
    		user.setName(sourceObject.toString());
    		return user;
    	}
    }

package com.lala.convert;
    
    import org.osgi.service.blueprint.container.Converter;
    import org.osgi.service.blueprint.container.ReifiedType;
    
    import com.lala.bean.User;
    
    /**
     * 手动调用转换器转换
     */
    public class ConvertDemo 
    {
    	private Converter converter;
    	
    	public void display() throws Exception
    	{
    		System.out.println("-------------手动转换-------------");
    		System.out.println(converter.convert("吴佩孚", new ReifiedType(User.class)));
    		System.out.println(converter.convert("段祺瑞", new ReifiedType(User.class)));
    	}
    	
    	public void setConverter(Converter converter) 
    	{
    		this.converter = converter;
    	}
    }

<?xml version="1.0" encoding="UTF-8"?>
    <blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0"
               xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
               xsi:schemaLocation="
                 http://www.osgi.org/xmlns/blueprint/v1.0.0 http://www.osgi.org/xmlns/blueprint/v1.0.0/blueprint.xsd">
    
    	<type-converters>
    		
    		<bean class="com.lala.convert.UserConvert"/>
    	</type-converters>
    
    	
    	<bean class="com.lala.bean.User" id="lihongzhang">
    		<property name="id" value="1001"/>
    		<property name="name" value="李鸿章"/>
    	</bean>
    	<bean class="com.lala.bean.Official" init-method="display">
    		
    		<property name="user" ref="lihongzhang"/>
    		<property name="position" value="直隶总督"/>
    	</bean>
    	
    	
    	<bean class="com.lala.bean.Official" init-method="display">
    		
    		<property name="user" value="袁世凯"/>
    		<property name="position" value="北洋军阀"/>
    	</bean>
    	
    	
    	<bean class="com.lala.convert.ConvertDemo" init-method="display">
    		<property name="converter" ref="blueprintConverter" /> 
    	</bean>
    	
    </blueprint>

最后运行，即可看到输出

karaf@root>

Official \[position=直隶总督, user=User \[id=1001, name=李鸿章\]\]  
Official \[position=北洋军阀, user=User \[id=1, name=袁世凯\]\]  
\-------------手动转换-------------  
User \[id=2, name=吴佩孚\]  
User \[id=3, name=段祺瑞\]