JAVA读写资源文件

灰太狼 2022-08-25 02:10 184阅读 0赞

#### 1. 写入 properties 文件 ####

设置属性值，然后把值写入属性文件：  `config.`

import java.io.FileOutputStream;
    import java.io.IOException;
    import java.io.OutputStream;
    import java.util.Properties;
     
    public class App {
      public static void main(String[] args) {
     
    	Properties prop = new Properties();
    	OutputStream output = null;
     
    	try {
     
    		output = new FileOutputStream("config.properties");
     
    		// 设置属性值
    		prop.setProperty("database", "localhost");
    		prop.setProperty("dbuser", "mkyong");
    		prop.setProperty("dbpassword", "password");
     
    		// 保存属性值
    		prop.store(output, null);
     
    	} catch (IOException io) {
    		io.printStackTrace();
    	} finally {
    		if (output != null) {
    			try {
    				output.close();
    			} catch (IOException e) {
    				e.printStackTrace();
    			}
    		}
     
    	}
      }
    }

#### 2. 读入 properties 文件 ####

从属性文件中把值载入系统

import java.io.FileInputStream;
    import java.io.IOException;
    import java.io.InputStream;
    import java.util.Properties;
     
    public class App {
      public static void main(String[] args) {
     
    	Properties prop = new Properties();
    	InputStream input = null;
     
    	try {
     
    		input = new FileInputStream("config.properties");
     
    		// 载入属性文件
    		prop.load(input);
     
    		// 获取属性值打印
    		System.out.println(prop.getProperty("database"));
    		System.out.println(prop.getProperty("dbuser"));
    		System.out.println(prop.getProperty("dbpassword"));
     
    	} catch (IOException ex) {
    		ex.printStackTrace();
    	} finally {
    		if (input != null) {
    			try {
    				input.close();
    			} catch (IOException e) {
    				e.printStackTrace();
    			}
    		}
    	}
     
      }
    }

3. 从项目类路径中载入属性文件

import java.io.IOException;
    import java.io.InputStream;
    import java.util.Properties;
     
    public class App {
     
      public static void main( String[] args ){
     
        	Properties prop = new Properties();
        	InputStream input = null;
     
        	try {
     
        		String filename = "config.properties";
        		input = App3.class.getClassLoader().getResourceAsStream(filename);
        		if(input==null){
        	            System.out.println("Sorry, unable to find " + filename);
        		    return;
        		}
     
        		//从类路径中载入属性文件
        		prop.load(input);
     
                    //获取属性值打印
                    System.out.println(prop.getProperty("database"));
        	        System.out.println(prop.getProperty("dbuser"));
        	        System.out.println(prop.getProperty("dbpassword"));
     
        	} catch (IOException ex) {
        		ex.printStackTrace();
            } finally{
            	if(input!=null){
            		try {
    				input.close();
    			} catch (IOException e) {
    				e.printStackTrace();
    			}
            	}
            }
     
        }
    }

#### 4. 打印 properties 文件的所有内容 ####

import java.io.IOException;
    import java.io.InputStream;
    import java.util.Enumeration;
    import java.util.Properties;
     
    public class App {
     
      public static void main(String[] args) {
    	App app = new App();
    	app.printThemAll();
      }
     
      private void printThemAll() {
     
    	Properties prop = new Properties();
    	InputStream input = null;
     
    	try {
     
    		String filename = "config.properties";
    		input = getClass().getClassLoader().getResourceAsStream(filename);
    		if (input == null) {
    			System.out.println("Sorry, unable to find " + filename);
    			return;
    		}
     
    		prop.load(input);
     
    		Enumeration<?> e = prop.propertyNames();
    		while (e.hasMoreElements()) {
    			String key = (String) e.nextElement();
    			String value = prop.getProperty(key);
    			System.out.println("Key : " + key + ", Value : " + value);
    		}
     
    	} catch (IOException ex) {
    		ex.printStackTrace();
    	} finally {
    		if (input != null) {
    			try {
    				input.close();
    			} catch (IOException e) {
    				e.printStackTrace();
    			}
    		}
    	}
     
      }
     
    }

源自：http://www.mkyong.com/java/java-properties-file-examples/