JAVA 配置管理库 typesafe.config

      Typesafe的Config库，纯Java写成、零外部依赖、代码精简、功能灵活、API友好。支持Java properties、JSON、JSON超集格式HOCON以及环境变量。它也是Akka的配置管理库。

    特性：

• 纯java实现，无任何依赖
• 充分的测试
• 支持: Java properties, JSON
• 可以合并各种格式的配置文件
• 可以通过文件、urls、classpath加载配置
• 支持多层嵌套的配置方式
• 识别Java system properties, 如java -Dmyapp.foo.bar=10
• 可以转换长短，大小等单位。如配置文件中timeout=10s，则可以转换成任意的毫秒或者类型转换，比如yes可以转换为boolean类型的true:
  comments
  includes
  substitutions (“foo” : bar,"foo":Hello{who})
  properties-like notation (a.b=c)
  less noisy, more lenient syntax
  substitute environment variables (logdir=${HOME}/logs)

    目前config只支持配置文件，如果想从数据库获取配置文件，需要自己定义。 config库很擅长合并配置。

Example

    默认加载classpath下的application.conf,application.json和application.properties文件。通过ConfigFactory.load()加载。

application.conf：

conf.foo="This value comes from simple-app's application.conf"conf.whatever = "This value comes from simple-app's application.conf"

application.properties:

properties.foo="This value comes from simple-app's application.properties"properties.whatever = "This value comes from simple-app's application.properties"

application.json:

{    "id":1,    "label":"person",    "outE":{        "uses":[            {                "id":16,                "inV":11,                "properties":{                    "skill":5                }            },            {                "id":15,                "inV":10,                "properties":{                    "skill":4                }            }        ],        "develops":[            {                "id":13,                "inV":10,                "properties":{                    "since":2009                }            },            {                "id":14,                "inV":11,                "properties":{                    "since":2010                }            }        ]    },    "properties":{        "name":[            {                "id":0,                "value":"marko"            }        ],        "location":[            {                "id":6,                "value":"san diego",                "properties":{                    "startTime":1997,                    "endTime":2001                }            },            {                "id":7,                "value":"santa cruz",                "properties":{                    "startTime":2001,                    "endTime":2004                }            },            {                "id":8,                "value":"brussels",                "properties":{                    "startTime":2004,                    "endTime":2005                }            },            {                "id":9,                "value":"santa fe",                "properties":{                    "startTime":2005                }            }        ]    }}

public class SimpleTypesafeConfig {    private Config config;    public SimpleTypesafeConfig(Config config) {        this.config = config;        config.checkValid(ConfigFactory.defaultReference(), "conf");    }    public SimpleTypesafeConfig() {        this(ConfigFactory.load());    }    public void printSetting(String path) {        System.out.println("The setting '" + path + "' is: " + config.getString(path));    }    public static void main(String[] args) {        SimpleTypesafeConfig s = new SimpleTypesafeConfig();        s.printSetting("properties.whatever");//application.properties        //output: The setting 'properties.whatever' is: "This value comes from simple-app's application.properties"        s.printSetting("conf.whatever");//application.conf        //output:The setting 'conf.whatever' is: This value comes from simple-app's application.conf        s.printSetting("label");//application.conf        //output: person    }}

其中核心加载代码：

config.checkValid(ConfigFactory.defaultReference(), "conf");

底层调用：

    private static ClassLoader checkedContextClassLoader(String methodName) {        ClassLoader loader = Thread.currentThread().getContextClassLoader();        if(loader == null) {            throw new BugOrBroken("Context class loader is not set for the current thread; if Thread.currentThread().getContextClassLoader() returns null, you must pass a ClassLoader explicitly to ConfigFactory." + methodName);        } else {            return loader;        }    }