java读取配置文件内容

利用com.typesafe.config包实现

<dependency>
            <groupId>com.typesafe</groupId>
            <artifactId>config</artifactId>
            <version>1.0.2</version>
        </dependency>

被读取的配置文件config.properties：

patrol.interval=5
push.interval=30
data = [{ controlNum : 1, loopNum : 1, pointNum : 1, status : 110 },
        { controlNum : 1, loopNum : 1, pointNum : 1, status = 111 }]

java 工具类：

import com.typesafe.config.Config;
import com.typesafe.config.ConfigFactory;


public class ServerConfig {

    private final static Config config;

    static {
        config = ConfigFactory.load("config.properties");
    }

    public static Config load() {
        return config;
    }
}

调用方式：

Config serverConfig = ServerConfig.load();
 int  PATROL_INTERVAL = serverConfig.getInt("patrol.interval");

或者使用Java IO实现

public class PropertiesReader {

    private static final String PROPERTIES_FILE_NAME = "aa.properties";
    
    private static Properties config = null;
    
    static {
        config = readProperties(PROPERTIES_FILE_NAME);
    }
    
    public static String getProperty(String key){
        return config.getProperty(key);
    }
    
    private static Properties readProperties(String fileName){
        InputStream inputStream = WsPropertiesReader.class.getClassLoader().getResourceAsStream(fileName);
        Properties config = new Properties();
          try {
              config.load(inputStream);
          } catch(IOException e){
              e.printStackTrace();
          } finally{
              if (inputStream != null){
                  try {
                     inputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
              }
          }
          
          return config;
    }
    
    public static Properties readProperties(InputStream inputStream){
        Properties config = new Properties();
          try {
              config.load(inputStream);
          } catch(IOException e){
              e.printStackTrace();
          } finally{
              if (inputStream != null){
                  try {
                      inputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
              }
          }
          
          return config;
    }
}

对于配置文件中有嵌套的配置内容，一种方法是，在Spring环境中

使用EmbeddedValueResolverAware读取配置文件内容

另外可以自己解析${}的形式

public class PropertiesReader {

    private static final String COMMON_PROPERTIES_FILE_NAME = "common-constants.properties";
    private static final String WEB_PROPERTIES_FILE_NAME = "application.properties";

    private static Properties commonConfig = null;
    private static Properties webConfig = null;

    static {
        commonConfig = readProperties(COMMON_PROPERTIES_FILE_NAME);
        webConfig = readProperties(WEB_PROPERTIES_FILE_NAME);
    }

    public static String getProperty(String key) {
        return commonConfig.getProperty(key);
    }

    /**
     * 支持复杂el表达式递归调用
     * @param key
     * @return
     */
    public static String getWebProperty(String key) {
        String value = webConfig.getProperty(key);
        String regex = "\$\{(.*?)\}"; //正则表达式
        Pattern pattern = Pattern.compile(regex);
        Matcher matcher = pattern.matcher(value);
        while(matcher.find()){
            String subProperty = getWebProperty(matcher.group(1));
            value = value.replace("${"+matcher.group(1)+"}",subProperty);
        }
        return value;
    }

    private static Properties readProperties(String fileName) {
        InputStream inputStream = PropertiesReader.class.getClassLoader().getResourceAsStream(fileName);

        Properties config = new Properties();
        try {
            config.load(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (inputStream != null) {
                try {
                    inputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

        return config;
    }
}