Spring資源加載程式的getResource()示例

1. 檔系統

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

2. URL路徑

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

3. 類路徑

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

package com.xuhuhu.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/zaixian/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資源加載器(ResourceLoaderAware)

因為 bean 沒有應用程式上下文的訪問，一個bean如何訪問資源？解決方法是實現 ResourceLoaderAware 介面，並為資源加載對象 setter 方法. Spring將盡的資源加載到bean。

package com.zaixian.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配置檔

<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.zaixian.customer.services.CustomerService" />

</beans>

執行它

package com.xuhuhu.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.zaixian.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/zaixian/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();
    	}

    }
}

總結

如果沒有這個 getResource()方法，將需要處理不同的解決方案，如檔對象的檔系統資源，對URL資源的URL對象不同的資源。Spring真的很好地與這個超級通用的getResource()方法工作，它確實可以幫我們節省處理資源的時間。