Geronimo XBean

    1 Overview

    XBean是Apache Geronimo的子项目，目标是像Eclipse IDE那样，用于创建基于插件的服务器（跟Geronimo GBean的目标有些重合）。从现状来看，XBean更多地被用于简化Spring 配置。例如，Apache ActiveMQ的配置基于XBean。2 Custom namespace

    最简单的custom namespace是java://加上全路径包名的形式，以下是个简单的例子：
package com.versus.misc.xbean;

import java.math.BigDecimal;

import org.apache.commons.lang.builder.ToStringBuilder;
import org.apache.commons.lang.builder.ToStringStyle;

public class Product {
private String name;
private BigDecimal price;

public String toString() {
return new ToStringBuilder(this, ToStringStyle.SHORT_PREFIX_STYLE)
.append("name", name)
.append("price", price).toString();
}

public String getName() {
return name;
}

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

public BigDecimal getPrice() {
return price;
}

public void setPrice(BigDecimal price) {
this.price = price;
}
}
    以下是配置文件xbean.xml的内容：
<beans xmlns:p="java://com.versus.misc.xbean">
  <p:Product id="product" name="USD/JPY" price="100.00"/>
</beans>
    以下是测试用的test case：
package com.versus.misc.xbean;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotNull;

import java.math.BigDecimal;

import org.apache.xbean.spring.context.ClassPathXmlApplicationContext;
import org.junit.Test;

public class XBeanTest {

@Test
public void test() {
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("classpath:com/versus/misc/xbean/xbean.xml");
Product product = (Product)context.getBean("product");
assertNotNull(product);
assertEquals("USD/JPY", product.getName());
assertEquals(new BigDecimal("100.00"), product.getPrice());
}
}
    以上的例子中，custom namespace是java://com.versus.misc.xbean；Product是定义在com.versus.misc.xbean包中的一个类；Product类的成员变量都被映射成XML的属性。需要注意的是，必须使用org.xbean.spring.context.ClassPathXmlApplicationContext，而不是Spring自带的ApplicationContext。
 
3 Custom mapping

    在之前的例子中，如果给Product类增加一个名为id的int型成员变量，那么为了避免和标准Spring属性的冲突，应该使用custom mapping。首先要在META-INF/services/org/apache/xbean/spring/目录下建立一个名为$namespace的属性文件。例如，如果namespace是http://xbean.versus.com/product，那么需要建立META-INF/services/org/apache/xbean/spring/http/xbean.versus.com/product文件，其内容如下：
package = com.versus.misc.xbean
product = com.versus.misc.xbean.Product
product.alias.productId = id #将id成员变量映射为productId属性
    以下是配置文件xbean.xml的内容：
<beans xmlns:p="http://xbean.versus.com/product" >
  <p:product id="product" productId="1" name="USD/JPY" price="100.00"/>
</beans>
    以下是测试用的test case：
package com.versus.misc.xbean;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotNull;

import java.math.BigDecimal;

import org.apache.xbean.spring.context.ClassPathXmlApplicationContext;
import org.junit.Test;

public class XBeanTest {

@Test
public void test() {
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("classpath:com/versus/misc/xbean/xbean.xml");
Product product = (Product)context.getBean("product");
assertNotNull(product);
assertEquals(1, product.getId());
assertEquals("USD/JPY", product.getName());
assertEquals(new BigDecimal("100.00"), product.getPrice());
}
}
 
4 Constructor injection

    除了setter注入之外，XBean也支持constructor注入，以下是个简单的例子：
package com.versus.misc.xbean;

import java.math.BigDecimal;

import org.apache.commons.lang.builder.ToStringBuilder;
import org.apache.commons.lang.builder.ToStringStyle;

public class Product {
private int id;
private String name;
private BigDecimal price;
private Leverage leverage;

public String toString() {
return new ToStringBuilder(this, ToStringStyle.SHORT_PREFIX_STYLE)
.append("id", id)
.append("name", name)
.append("price", price)
.append("leverage", leverage).toString();
}

public int getId() {
return id;
}

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

public String getName() {
return name;
}

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

public BigDecimal getPrice() {
return price;
}

public void setPrice(BigDecimal price) {
this.price = price;
}

public Leverage getLeverage() {
return leverage;
}

public void setLeverage(Leverage leverage) {
this.leverage = leverage;
}
}
 
package com.versus.misc.xbean;

import java.math.BigDecimal;

public class Leverage {
private int value;
private BigDecimal margin;

public Leverage(int value, BigDecimal margin) {
this.value = value;
this.margin = margin;
}

public int getValue() {
return value;
}

public BigDecimal getMargin() {
return margin;
}
}
    META-INF/services/org/apache/xbean/spring/http/xbean.versus.com/product文件的内容如下:
package = com.versus.misc.xbean
product = com.versus.misc.xbean.Product
leverage = com.versus.misc.xbean.Leverage
product.alias.productId = id
com.versus.misc.xbean.Leverage(int,java.math.BigDecimal).parameterNames=value margin
    以下是配置文件xbean.xml的内容：
<beans xmlns:p="http://xbean.versus.com/product">
  <p:product id="product" productId="1" name="##USD/JPY" price="100.00" leverage="#leverage"/>
  <p:leverage id="leverage" value="50" margin="12345"/>
</beans>
    以下是测试用的test case：
package com.versus.misc.xbean;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotNull;

import java.math.BigDecimal;

import org.apache.xbean.spring.context.ClassPathXmlApplicationContext;
import org.junit.Test;

public class XBeanTest {

@Test
public void test() {
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("classpath:com/versus/misc/xbean/xbean.xml");

Product product = (Product)context.getBean("product");
assertNotNull(product);
assertEquals(1, product.getId());
assertEquals("#USD/JPY", product.getName());
assertEquals(new BigDecimal("100.00"), product.getPrice());

Leverage leverage = (Leverage)context.getBean("leverage");
assertNotNull(leverage);
assertEquals(50, leverage.getValue());
assertEquals(new BigDecimal("12345"), leverage.getMargin());

assertEquals(leverage, product.getLeverage());
}
}
    需要注意的是，以上例子中p:product的leverage属性通过#引用了leverage。如果你期望配置一个以#开头的字符串，那么字符串的需要以##开头（例如以上例子中，product中name成员变量的值是#USD/JPY）。
 
5 Assembling collections

    跟Spring一样，XBean也支持装配集合类型。以上的例子中，假设每种FX交易的商品可以有多个杠杆，那么需要进行以下的修改：
package com.versus.misc.xbean;

import java.math.BigDecimal;
import java.util.List;

import org.apache.commons.lang.builder.ToStringBuilder;
import org.apache.commons.lang.builder.ToStringStyle;

public class Product {
private int id;
private String name;
private BigDecimal price;
private List<Leverage> leverages;

public String toString() {
return new ToStringBuilder(this, ToStringStyle.SHORT_PREFIX_STYLE)
.append("id", id)
.append("name", name)
.append("price", price)
.append("leverages", leverages).toString();
}

public int getId() {
return id;
}

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

public String getName() {
return name;
}

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

public BigDecimal getPrice() {
return price;
}

public void setPrice(BigDecimal price) {
this.price = price;
}

public List<Leverage> getLeverages() {
return leverages;
}

public void setLeverages(List<Leverage> leverages) {
this.leverages = leverages;
}
}
    META-INF/services/org/apache/xbean/spring/http/xbean.versus.com/product文件的内容如下:
package = com.versus.misc.xbean
product = com.versus.misc.xbean.Product
leverage = com.versus.misc.xbean.Leverage
product.alias.productId = id
product.alias.leverages.list = leverages
com.versus.misc.xbean.Leverage(int,java.math.BigDecimal).parameterNames=value margin

    以下是配置文件xbean.xml的内容：
<beans xmlns:p="http://xbean.versus.com/product">
  <p:product id="product" productId="1" name="USD/JPY" price="100.00">
      <leverages>
          <p:leverage id="leverage1" value="50" margin="12345"/>
          <p:leverage id="leverage2" value="100" margin="24690"/>
      </leverages>
  </p:product>
</beans>
    以下是测试用的test case：
package com.versus.misc.xbean;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotNull;

import java.math.BigDecimal;

import org.apache.xbean.spring.context.ClassPathXmlApplicationContext;
import org.junit.Test;

public class XBeanTest {

@Test
public void test() {
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("classpath:com/versus/misc/xbean/xbean.xml");

Product product = (Product)context.getBean("product");
assertNotNull(product);
assertEquals(1, product.getId());
assertEquals("USD/JPY", product.getName());
assertEquals(new BigDecimal("100.00"), product.getPrice());
assertEquals(2, product.getLeverages().size());

Leverage leverage1 = product.getLeverages().get(0);
assertNotNull(leverage1);
assertEquals(50, leverage1.getValue());
assertEquals(new BigDecimal("12345"), leverage1.getMargin());

Leverage leverage2 = product.getLeverages().get(1);
assertNotNull(leverage2);
assertEquals(100, leverage2.getValue());
assertEquals(new BigDecimal("24690"), leverage2.getMargin());
}
}