Java讀取Properties配置文件的6種方式匯總

更新時間：2023年07月22日 08:54:35 作者：怡人蝶夢

這篇文章主要給大家介紹了關(guān)于Java讀取Properties配置文件的6種方式,java中的properties文件是一種配置文件,主要用于表達(dá)配置信息,文中通過示例代碼介紹的非常詳細(xì),需要的朋友可以參考下

Java讀取Properties的方式
1. this.getClass().getResourceAsStream()
2.當(dāng)前類的加載器進(jìn)行讀取this.getClass().getClassLoader().getResourceAsStream()
3. ClassLoader類的static方法 getSystemResourceAsStream()
4. Spring中的 ClassPathResource讀取
5. PropertyResourceBundle讀取InputStream流
6.ResourceBundle.getBundle()
總結(jié)

Java讀取Properties的方式

項目結(jié)構(gòu)：經(jīng)典的maven項目結(jié)構(gòu)

配置文件1和2內(nèi)容一致：

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=mysql://localhost:3306/database?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai
jdbc.username=root
jdbc.password=123456

1. this.getClass().getResourceAsStream()

//讀取配置文件1
public void readProperties1() throws IOException {
    //不加/會從當(dāng)前包進(jìn)行尋找，加上/會從src開始找
    InputStream inputStream = this.getClass().getResourceAsStream("/jdbc.properties");
    Properties properties=new Properties();
    properties.load(inputStream);
    System.out.println("jdbc.driver="+properties.getProperty("jdbc.driver"));
    System.out.println("jdbc.url="+properties.getProperty("jdbc.url"));
    System.out.println("jdbc.username="+properties.getProperty("jdbc.username"));
    System.out.println("jdbc.password="+properties.getProperty("jdbc.password"));
}
//讀取配置文件2        
 public void readProperties1() throws IOException {
        InputStream inputStream = this.getClass().getResourceAsStream("/config/jdbc2.properties");
        Properties properties=new Properties();
        properties.load(inputStream);
        System.out.println("jdbc.driver="+properties.getProperty("jdbc.driver"));
        System.out.println("jdbc.url="+properties.getProperty("jdbc.url"));
        System.out.println("jdbc.username="+properties.getProperty("jdbc.username"));
        System.out.println("jdbc.password="+properties.getProperty("jdbc.password"));
}

2.當(dāng)前類的加載器進(jìn)行讀取this.getClass().getClassLoader().getResourceAsStream()

//讀取配置文件1
public void readProperties2() throws IOException {
    //不加/，若加了會為null
    InputStream inputStream = this.getClass().getClassLoader().getResourceAsStream("jdbc.properties");
    Properties properties=new Properties();
    properties.load(inputStream);
    System.out.println("jdbc.driver="+properties.getProperty("jdbc.driver"));
    System.out.println("jdbc.url="+properties.getProperty("jdbc.url"));
    System.out.println("jdbc.username="+properties.getProperty("jdbc.username"));
    System.out.println("jdbc.password="+properties.getProperty("jdbc.password"));
}
//讀取配置文件2
public void readProperties2() throws IOException {
        InputStream inputStream = this.getClass().getClassLoader().getResourceAsStream("config/jdbc2.properties");
        Properties properties=new Properties();
        properties.load(inputStream);
        System.out.println("jdbc.driver="+properties.getProperty("jdbc.driver"));
        System.out.println("jdbc.url="+properties.getProperty("jdbc.url"));
        System.out.println("jdbc.username="+properties.getProperty("jdbc.username"));
        System.out.println("jdbc.password="+properties.getProperty("jdbc.password"));
}

方法1和2區(qū)別：（classpath即為target/classes 這個目錄）

Class.getResourceAsStream() 從當(dāng)前類所在的位置開始查找配置文件位置。要找到j(luò)dbc.properties和jdbc2.properties必須加/從classpath下開始查找

Class.getClassLoader().getResourceAsStream() 默認(rèn)就從classpath路徑下開始查找，加上/會報空指針

十分有必要知道java中類的加載過程?。?！

3. ClassLoader類的static方法 getSystemResourceAsStream()

public void readProperties3() throws IOException {
        //InputStream inputStream = ClassLoader.getSystemResourceAsStream("config/jdbc2.properties");
        InputStream inputStream = ClassLoader.getSystemResourceAsStream("jdbc.properties");
        Properties properties=new Properties();
        properties.load(inputStream);
        System.out.println("jdbc.driver="+properties.getProperty("jdbc.driver"));
        System.out.println("jdbc.url="+properties.getProperty("jdbc.url"));
        System.out.println("jdbc.username="+properties.getProperty("jdbc.username"));
        System.out.println("jdbc.password="+properties.getProperty("jdbc.password"));
    }

4. Spring中的 ClassPathResource讀取

public void readProperties4() throws IOException {
        //ClassPathResource resource = new ClassPathResource("jdbc.properties");
        ClassPathResource resource = new ClassPathResource("config/jdbc2.properties");
        Properties properties= PropertiesLoaderUtils.loadProperties(resource);
        System.out.println("jdbc.driver="+properties.getProperty("jdbc.driver"));
        System.out.println("jdbc.url="+properties.getProperty("jdbc.url"));
        System.out.println("jdbc.username="+properties.getProperty("jdbc.username"));
        System.out.println("jdbc.password="+properties.getProperty("jdbc.password"));
}

5. PropertyResourceBundle讀取InputStream流

public void readProperties5() throws IOException {
        //InputStream inputStream = ClassLoader.getSystemResourceAsStream("jdbc.properties");
    	InputStream inputStream = ClassLoader.getSystemResourceAsStream("config/jdbc2.properties");
        PropertyResourceBundle bundle = new PropertyResourceBundle(inputStream);
        System.out.println(bundle.getString("jdbc.driver"));
        System.out.println(bundle.getString("jdbc.url"));
        System.out.println(bundle.getString("jdbc.username"));
        System.out.println(bundle.getString("jdbc.password"));
    }

6.ResourceBundle.getBundle()

//不用輸入后綴
public void readProperties6()  {
        //ResourceBundle bundle=ResourceBundle.getBundle("jdbc");
        ResourceBundle bundle=ResourceBundle.getBundle("config/jdbc2");
        System.out.println(bundle.getString("jdbc.driver"));
        System.out.println(bundle.getString("jdbc.url"));
        System.out.println(bundle.getString("jdbc.username"));
        System.out.println(bundle.getString("jdbc.password"));
    }