spring p 标签

需要引入命名空间

xmlns:p="http://www.springframework.org/schema/p"

p 是什么含义

p 是 property 的缩写，为了简化bean的配置

    <!-- 普通的bean配置 -->
    <bean id="xiaomingPerson" class="cn.zno.Person">
        <property name="age" value="1"></property>
        <property name="car" ref="benz"></property>
    </bean>
    <!-- 瘦身的bean配置 -->
    <bean id="xiaomingP" class="cn.zno.Person" p:age="1" p:car-ref="benz" />

    <bean id="benz" class="cn.zno.Car">
        <property name="brand" value="benz"></property>
    </bean>

完整项目

依赖

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>4.1.6.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>4.1.6.RELEASE</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>

Spring Bean Configuration File [test.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:p="http://www.springframework.org/schema/p"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.1.xsd">

    <context:annotation-config />

    <!-- 普通的bean配置 -->
    <bean id="xiaomingPerson" class="cn.zno.Person">
        <property name="age" value="1"></property>
        <property name="car" ref="benz"></property>
    </bean>
    <!-- 瘦身的bean配置 -->
    <bean id="xiaomingP" class="cn.zno.Person" p:age="1" p:car-ref="benz" />

    <bean id="benz" class="cn.zno.Car">
        <property name="brand" value="benz"></property>
    </bean>
</beans>

java bean 文件

package cn.zno;

public class Person {

    private int age;
    private Car car;

    public int getAge() {
        return age;
    }

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

    public Car getCar() {
        return car;
    }

    public void setCar(Car car) {
        this.car = car;
    }

    @Override
    public String toString() {
        return "Person [age=" + age + ", car=" + car + "]";
    }

}

class Car {
    private String brand;

    public String getBrand() {
        return brand;
    }

    public void setBrand(String brand) {
        this.brand = brand;
    }

    @Override
    public String toString() {
        return "Car [brand=" + brand + "]";
    }
}

测试类 TestP.java

package ehcache;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import cn.zno.Person;

@ContextConfiguration(locations = { "classpath:test.xml" })
@RunWith(SpringJUnit4ClassRunner.class)
public class TestP {

    @Autowired
    private Person xiaomingPerson;
    @Autowired
    private Person xiaomingP;

    @Test
    public void show() {
        System.out.println(xiaomingPerson);
        System.out.println(xiaomingP);
    }
}

疑问

p:car 和 p:car-ref 用哪个？

用p:car-ref  

用p:car 

错误原因：

Caused by: java.lang.IllegalStateException: Cannot convert value of type [java.lang.String] to required type [cn.zno.Car] for property ‘car‘: no matching editors or conversion strategy found
	at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:287)
	at org.springframework.beans.BeanWrapperImpl.convertIfNecessary(BeanWrapperImpl.java:461)
	... 45 more

不带-ref 的相当于value ，value不能转化bean类型