Four ways to obtain the contents of the Properties file in Java

This article mainly introduces several ways to read properties configuration files in Java. The editor thinks it is quite good. Now I will share it with you and give it as a reference. Let’s follow the editor and take a look.

I believe that a JAVA developer must be familiar with the properties file. For example, the configuration:

1. config.properties It often stores some system constants, version numbers, paths, etc.

2. database.properties stores database connection parameters

3. log4j.properties log Some basic configurations

4. redis.properties Some configurations of the cache database
   

Of course, the prefix is ​​defined by the user, generally For example, the content of the file is in the "key=value" format. The text Comment information can be commented with "#". Let's talk about how to read and write the properties configuration file during development.

Java reads Properties file

Properties class reads

Properties classInheritedfrom# The ##Hashtable class implements the Map interface, and also uses a key-value pair form to save the attribute set. However, there is something special about Properties, that is, its keys and values ​​are both of string type.

//方式一
InputStream in = new BufferedInputStream(new FileInputStream("文件路径名"));
Properties p = new Properties();
p.load(in);
System.out.println(p.getProperty("version"));
//方式二
InputStream ins = PropertiesUtil.class.getResourceAsStream("文件路径名");
Properties ps = new Properties();
ps.load(ins);
System.out.println(ps.getProperty("version"));
//方式三
InputStream inss = PropertiesUtil.class.getClassLoader().getResourceAsStream("文件名");
Properties pss = new Properties();
pss.load(inss);
System.out.println(pss.getProperty("version"));
//方式四
InputStream insss = ClassLoader.getSystemResourceAsStream("文件名");
Properties psss = new Properties();
psss.load(insss);
System.out.println(pss.getProperty("version"));

ResourceBundle reading method

This class provides a shortcut for software internationalization. This class allows the programs you write to:

1. Easily localize or translate into different languages

2. Process multiple items at once Each language environment

3. can be easily modified later to support more language environments

To put it simply, the function of this class is Read the resource properties file (properties), and then match the national language information of the current system (can also be specified by the program) based on the name information (localization information) of the .properties file, and then obtain the contents of the corresponding properties file.

When using this class, one thing to note is that the name of this properties file is standardized: the general naming convention is: Custom name language code country code.properties, if it is the default, write directly For: Custom name.properties

For example:

1. myres_en_US.properties

2. myres_zh_CN.properties

3. myres.properties

//方式五
ResourceBundle rb = ResourceBundle.getBundle("文件名前缀", Locale.getDefault());
System.out.println(rb.getObject("version"));
//方式六
InputStream is = new BufferedInputStream(new FileInputStream("文件名前缀"));
ResourceBundle rbs = new PropertyResourceBundle(is);
System.out.println(rbs.getObject("version"));

ResourceBundle reading method is relatively convenient, but if you look at the source code carefully, ResourceBundle will be read once by the system. cache.
In a production environment, if we want to dynamically modify some parameters of properties, we must restart the server if we use the ResourceBundle reading method.
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