无法使用context：property-placeholder获得属性（春季）

Question

I am trying to read properties from "file" but not able to achive same.

web.xml

<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>classpath:ApplicationContext.xml</param-value>
</context-param>
<listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>

ApplicationContext.xml

<context:annotation-config />
<context:component-scan base-package="com.jodo.image.*"></context:component-scan>

<context:property-placeholder location="file:/usr/local/jodo/opt/cms-image/db.properties"/>
<context:property-placeholder location="file:/usr/local/jodo/opt/cms-image/service.properties"/>

<util:properties id="systemPropertiesHolder" location="file:/usr/local/jodo/opt/cms-image/service.properties">
</util:properties>

1st try

Class ThreadFileImageUpload

public class ThreadFileImageUpload extends Thread {
    private String rawImagePath;

    @Value("#{systemPropertiesHolder.rawImagePath}")
    public void setRawImagePath(String property){
        rawImagePath = property;
    }...

Result : rawImagePath is null

2nd try

Class ThreadFileImageUpload

@Configuration
@ImportResource("classpath:properties-config.xml")
public class ThreadFileImageUpload extends Thread {
    private @Value("${rawImagePath}") String rawImagePath;

properties-config.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:context="http://www.springframework.org/schema/context"
    xmlns:p="http://www.springframework.org/schema/p" 
    xmlns:util="http://www.springframework.org/schema/util"
    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-2.5.xsd
                http://www.springframework.org/schema/util 
                http://www.springframework.org/schema/util/spring-util-3.0.xsd">
  <context:property-placeholder location="file:/usr/local/jodo/opt/cms-image/service.properties"/>
</beans>

Result : rawImagePath is null

3rd try

Class ThreadFileImageUpload

@Configuration
@PropertySource("file:/usr/local/jodo/opt/cms-image/service.properties")
public class ThreadFileImageUpload extends Thread {
    @Autowired 
    Environment environment;
    private String rawImagePath;
    public void run() {
        if(environment == null){
                logger.info("environment is NULL");
            }
            rawImagePath = this.environment.getProperty("rawImagePath");
        ...

Give java.lang.NullPointerException (environment itself is null)

4th try

Class ThreadFileImageUpload

public class ThreadFileImageUpload extends Thread { 
    @Value("${rawImagePath}")
    private String rawImagePath;

Result : rawImagePath is null

5th try

ApplicationContext.xml (now placed all file in one property-placeholder)

<context:property-placeholder location="file:/usr/local/jodo/opt/cms-image/db.properties, file:/usr/local/jodo/opt/cms-image/service.properties"/>

Class ThreadFileImageUpload

public class ThreadFileImageUpload extends Thread { 
    @Value("${rawImagePath}")
    private String rawImagePath;

Result : rawImagePath is null

6th try

class ThreadFileImageUpload

package com.jodo.image.util;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
@Component
public class ThreadFileImageUpload extends Thread { 
    @Value("#{systemPropertiesHolder.rawImagePath}")
    private String rawImagePath;

AppliactionContext.xml

<context:annotation-config />
<context:component-scan base-package="com.jodo.image.*"></context:component-scan>
<util:properties id="systemPropertiesHolder" location="file:/usr/local/jodo/opt/cms-image/service.properties">
</util:properties>

Still getting it null

I am sure that property file has required field

[root@localhost /]# cat /usr/local/jodo/opt/cms-image/service.properties 
rawImagePath=/var/jodo-images/raw/

I am still stuck in same place.

Answer 1

Whevever you inject properties using @Value, the class your are injecting into needs to be a Spring bean. To make that happen you need to either annotate ThreadFileImageUpload with @Component and make sure that the class in a package that is within the component scan, or you need to add that bean manually (in this case into ApplicationContext.xml)

Answer 2

I think you're missing the name(root) of the properties. See this http://forum.spring.io/forum/spring-projects/container/61645-value-and-propertyplaceholderconfigurer

If the file is service.properties and you have

`<util:properties id="service" location="classpath:com/acme/app/service.properties"/>`

then try @Value("#{service.rawImagePath}")

Answer 3

To make @Value work, ThreadFileImageUpload instance must be a Spring managed component. Please note that instances created using "new" are not managed by Spring. The reference manual here and here may help you to understand Spring beans and component scanning.