[转]Spring Resource loader with GetResource() example

转载地址：http://www.mkyong.com/spring/spring-resource-loader-with-getresource-example/

Spring’s resource loader provides a very generic getResource() method to get the resources like (text file, media file, image file…) from file system , classpath or URL. You can get the getResource() method from the application context.

Here’s an example to show how to use getResource() to load a text file from

1. File system

Resource resource = appContext.getResource("file:c:\\testing.txt");

2. URL path

Resource resource = appContext.getResource("url:http://www.yourdomain.com/testing.txt");

3. Class path

Resource resource = appContext.getResource("classpath:com/mkyong/common/testing.txt");

You just need to specify the resource location, and the Spring will handle the rest and return you a Resource object.

Full example withgetResource() method.

package com.mkyong.common;
 
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
 
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.core.io.Resource;
public class App 
{
    public static void main( String[] args )
    {
    	ApplicationContext appContext = 
    	   new ClassPathXmlApplicationContext(new String[] {"If-you-have-any.xml"});
 
    	Resource resource = 
           appContext.getResource("classpath:com/mkyong/common/testing.txt");
 
    try{
     	  InputStream is = resource.getInputStream();
          BufferedReader br = new BufferedReader(new InputStreamReader(is));
 
          String line;
          while ((line = br.readLine()) != null) {
             System.out.println(line);
       	  } 
          br.close();
 
    	}catch(IOException e){
    		e.printStackTrace();
    	}
 
    }
}

Bean resource loader (ResourceLoaderAware)

Since bean does not have the application context access, how can a bean access a resources? The workaround is implement the ResourceLoaderAware interface and create setter method for ResourceLoader object. Spring will DI the resource loader into your bean.

package com.mkyong.customer.services;
 
import org.springframework.context.ResourceLoaderAware;
import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceLoader;
 
public class CustomerService implements ResourceLoaderAware
{
	private ResourceLoader resourceLoader;
 
	public void setResourceLoader(ResourceLoader resourceLoader) {
		this.resourceLoader = resourceLoader;
	}
 
	public Resource getResource(String location){
		return resourceLoader.getResource(location);
	}
}

Bean configuration file

<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">
 
   <bean id="customerService" 
           class="com.mkyong.customer.services.CustomerService" />
 
</beans>

Run it

package com.mkyong.common;
 
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
 
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.core.io.Resource;
 
import com.mkyong.customer.services.CustomerService;
public class App 
{
    public static void main( String[] args )
    {
    	ApplicationContext appContext = 
    	   new ClassPathXmlApplicationContext(new String[] {"Spring-Customer.xml"});
 
    	CustomerService cust = 
           (CustomerService)appContext.getBean("customerService");
 
    	Resource resource = 
            cust.getResource("classpath:com/mkyong/common/testing.txt");
 
    try{
          InputStream is = resource.getInputStream();
          BufferedReader br = new BufferedReader(new InputStreamReader(is));
 
          String line;
          while ((line = br.readLine()) != null) {
     	       System.out.println(line);
          } 
          br.close();
 
    	}catch(IOException e){
    		e.printStackTrace();
    	}
 
    }
}

Now you can get the resources from a bean.

Conclusion

Without this getResource() method, you will need to deal with different resources with different solution, like File object for file system resource, URL object for URL resource. Spring really did a good job with this super generic getResource()method, it really save our time to deal with resources.