读取资源文件方法

package cn.gs.ly;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
import java.util.ResourceBundle;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * 读取资源文件
 *    1.ServletContext.getRealPath() 可读取应用中的任何文件，但只能在web中使用。
 *    2.ResourceBundle 可以在非web中使用，但是只能读取类路径(src)中的properties文件。
 *    3.利用类加载器ClassLoader 可以在非web环境中使用，可以读取类路径下任何文件。
 *  a.properties:E:WorkspaceWeb017WebContentWEB-INFa.properties
 *  b.properties:E:WorkspaceWeb017src.properties
 *  c.properties:E:WorkspaceWeb017srccngslyc.properties
 * */
public class ServletPro extends HttpServlet{    
    @Override
    public void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //测试方法
        test1();
//        test2();
//        test3();
//        test4();
//        test5();
//        test6();
//        test7();
    }
    @Override
    public void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doGet(req, resp);
    }
//========================== 使用getRealPath() ===============================================================    
    //使用getRealPath()读取a.properties
    private void test1() throws FileNotFoundException, IOException{
        ServletContext sc = this.getServletContext();
        String path = sc.getRealPath("/WEB-INF/a.properties");
        Properties pro = new Properties();        
            pro.load(new FileInputStream(path));
            String value = pro.getProperty("username");
            System.out.println(value);        
    }
    //使用getRealPath()读取b.properties
    private void test2() throws FileNotFoundException, IOException{
        ServletContext sc = this.getServletContext();
        String path = sc.getRealPath("/WEB-INF/classes/b.properties");
        Properties pro = new Properties();        
            pro.load(new FileInputStream(path));
            String value = pro.getProperty("username");
            System.out.println(value);        
    }
    //使用getRealPath()读取c.properties
    private void test3() throws FileNotFoundException, IOException{
        ServletContext sc = this.getServletContext();
        String path = sc.getRealPath("/WEB-INF/classes/cn/gs/ly/c.properties");
        Properties pro = new Properties();        
            pro.load(new FileInputStream(path));
            String value = pro.getProperty("username");
            System.out.println(value);        
    }
    
//======================== 使用ResourceBundle对象 =================================================================        
    //使用ResourceBundle对象读取b.properties
    private void test4(){
        ResourceBundle rb = ResourceBundle.getBundle("b");  // 基名
        String value = rb.getString("username");
        System.out.println(value);
    }
    //使用ResourceBundle对象读取c.properties
    private void test5(){
        ResourceBundle rb = ResourceBundle.getBundle("cn.gs.ly.c");  // 基名
        String value = rb.getString("username");
        System.out.println(value);
    }        
    
//======================= 利用类加载器ClassLoader ==================================================================        
    //利用类加载器ClassLoader  读取b.properties文件
    private void test6() throws IOException{
        //Class c = ServletPro.class;
        //c.getClassLoader();
        ClassLoader c = ServletPro.class.getClassLoader();
        InputStream in = c.getResourceAsStream("b.properties");
        Properties pro = new Properties();
        pro.load(in);
        String value = pro.getProperty("username");
        System.out.println(value);            
    }
    //利用类加载器ClassLoader  读取c.properties文件
    private void test7() throws IOException{
        //Class c = ServletPro.class;
        //c.getClassLoader();
        ClassLoader c = ServletPro.class.getClassLoader();
        InputStream in = c.getResourceAsStream("cn/gs/ly/c.properties");
        Properties pro = new Properties();
        pro.load(in);
        String value = pro.getProperty("username");
        System.out.println(value);            
    }
    
}