java读取配置文件的几种方法

在java web开发中，常常需要在启动服务器的时候就需要读取一些配置文件的信息，以初始化上下文和一些项目用到的配置常量，下面介绍几种读取配置文件的方法：

 

方法一：

 

public class PropUtil {

	public static Properties getProUtil() {
		Properties config = new Properties();
		InputStream is = null;
		try {
			System.out.println(PropUtil.class.getClassLoader().getResource("").toString()
);
			System.out.println(PropUtil.class.getResource("/").toString()
);
			is = PropUtil.class.getClassLoader().getResourceAsStream(
					"quartz.properties
");
			config.load(is);
		} catch (IOException ex) {
			//
		} finally {
			if (is != null) {
				try {
					is.close();
				} catch (IOException ex) {
					// ignore
				}
			}
		}
		return config;
	}

	public static void main(String[] args) {
		System.out.println(getProUtil().toString());
	}
}

 输入结果：

file:/D:/all_project/tee_7.6/tee-biz/target/test-classes/
file:/D:/all_project/tee_7.6/tee-biz/target/test-classes/
{org.quartz.threadPool.class=org.quartz.simpl.SimpleThreadPool, org.quartz.jobStore.class=org.quartz.simpl.RAMJobStore, org.quartz.scheduler.instanceId=one, org.quartz.threadPool.threadPriority=4, org.quartz.scheduler.instanceName=myScheduler, org.quartz.threadPool.threadCount=30}

    注意： 在工程项目中，PropUtil源文件所在的路径和编译后的字节码所在的路径不是在一个地方，具体是在pom.xml中配置的，根据输出结果，PropUtil生成的class文件在D:\all_project\tee_7.6\tee-biz\target\test-classes\com\taobao\tee\readResouceFiles目录下，它能读取的资源文件必须放在 D:/all_project/tee_7.6/tee-biz/target/test-classes/   目录下，所以只有把quartz.properties放在这个目录下才能读取到这个资源文件。

    另外，其中最好的写法是：InputStream input = Thread.currentThread().getContextClassLoader().getResourceAsStream("quartz.properties");

 

方法二：通过文件操作的方式

public class PropUtil {

	 public static Properties getProUtil() {
	 Properties config = new Properties();
	 InputStream is = null;
	 try {
		File file =new File("D:\\all_project\\riskm9.19\\riskm-web\\src\\main\\resources\\quartz.properties");
	    is=new FileInputStream(file);
	   config.load(is);
	 } catch (IOException ex) {
	 //
	 } finally {
	 if (is != null) {
	 try {
	 is.close();
	 } catch (IOException ex) {
	 // ignore
	 }
	 }
	 }
	 return config;
	 }

	public static void main(String[] args) {
		System.out.println(getProUtil().toString());
	}
}

 

方法三：通过资源捆绑的形式：ResourceBundle 。

 

方法四：其实跟之前差不多：

    public void initialize() throws SchedulerException {
        // short-circuit if already initialized
        if (cfg != null) {
            return;
        }
        if (initException != null) {
            throw initException;
        }

        String requestedFile = System.getProperty(PROPERTIES_FILE);
        String propFileName = requestedFile != null ? requestedFile
                : "quartz.properties";
        File propFile = new File(propFileName);

        Properties props = new Properties();

        InputStream in = null;

        try {
            if (propFile.exists()) {
                try {
                    if (requestedFile != null) {
                        propSrc = "specified file: '" + requestedFile + "'";
                    } else {
                        propSrc = "default file in current working dir: 'quartz.properties'";
                    }

                    in = new BufferedInputStream(new FileInputStream(propFileName));
                    props.load(in);

                } catch (IOException ioe) {
                    initException = new SchedulerException("Properties file: '"
                            + propFileName + "' could not be read.", ioe);
                    throw initException;
                }
            } else if (requestedFile != null) {
                in =
                    Thread.currentThread().getContextClassLoader().getResourceAsStream(requestedFile);

                if(in == null) {
                    initException = new SchedulerException("Properties file: '"
                        + requestedFile + "' could not be found.");
                    throw initException;
                }

                propSrc = "specified file: '" + requestedFile + "' in the class resource path.";

                in = new BufferedInputStream(in);
                try {
                    props.load(in);
                } catch (IOException ioe) {
                    initException = new SchedulerException("Properties file: '"
                            + requestedFile + "' could not be read.", ioe);
                    throw initException;
                }

            } else {
                propSrc = "default resource file in Quartz package: 'quartz.properties'";

                ClassLoader cl = getClass().getClassLoader();
                if(cl == null)
                    cl = findClassloader();
                if(cl == null)
                    throw new SchedulerConfigException("Unable to find a class loader on the current thread or class.");

                in = cl.getResourceAsStream(
                        "quartz.properties");

                if (in == null) {
                    in = cl.getResourceAsStream(
                            "/quartz.properties");
                }
                if (in == null) {
                    in = cl.getResourceAsStream(
                            "org/quartz/quartz.properties");
                }
                if (in == null) {
                    initException = new SchedulerException(
                            "Default quartz.properties not found in class path");
                    throw initException;
                }
                try {
                    props.load(in);
                } catch (IOException ioe) {
                    initException = new SchedulerException(
                            "Resource properties file: 'org/quartz/quartz.properties' "
                                    + "could not be read from the classpath.", ioe);
                    throw initException;
                }
            }
        } finally {
            if(in != null) {
                try { in.close(); } catch(IOException ignore) { /* ignore */ }
            }
        }

  
    }