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typesafe.config与HOCON

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typesafe.config

Typesafe Config介绍

Why Typesafe Config

THE config library 非常好用的API，用过之后不会再想使用其他配置工具

  • 纯java实现，无任何依赖
  • 支持各种格式配置的融合: Java properties, JSON, and a human-friendly JSON superset
  • 可以通过文件、urls、classpath加载配置
  • 支持多层嵌套的配置方式：树形配置
  • 识别Java system properties, 如java -Dmyapp.foo.bar=10
  • 可以转换时间，大小等单位。如 “512k”、”10 seconds”
  • 类型转换，比如yes可以转换为true，数字之间也可以在内部做转换
  • JSON superset features:
    • 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)
  • 基于不可变对象，不用担心多线程问题

获取

使用gradle

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compile 'com.typesafe:config:1.2.1'

HOCON (Human-Optimized Config Object Notation)

config使用的是HOCON的文件格式，这种文件格式类似于json，很灵活但没有歧义，能引用，能替换，能注释，能兼容老的properties等格式

The following features are desirable, to support human usage:

  • less noisy / less pedantic syntax
  • ability to refer to another part of the configuration (set a value to another value)
  • import/include another configuration file into the current file
  • a mapping to a flat properties list such as Java’s system properties
  • ability to get values from environment variables
  • ability to write comments

约束：utf8编码

注释

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# 单行注释
a = 1 // 单行注释
b = 2 # 单行注释
c = [3, # 行内注释 # 4]

赋值与嵌套

普通赋值
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a : 1
a = 1

（对象）嵌套赋值
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{
    "foo" : { "a" : 42 },
    "foo" : { "b" : 43 }
}

{
    "foo" : { "a" : 42, "b" : 43 }
}

foo.bar : 42
foo { bar : 42 }

foo.bar.baz : 42
foo { bar { baz : 42 } }

a.x : 42, a.y : 43
a { x : 42, y : 43 }

多种格式
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{
    "foo" : {
        "bar" : 10,
        "baz" : 12
    }
}

foo : {
    bar : 10,
    baz : 12
}

foo {
    bar = 10
    baz = 12
}

foo.bar=10
foo.baz=12

foo.bar=10, foo.baz=12

多行赋值
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logo = """hello
world"""

数组与对象合并
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// one object
a : { b : 1, c : 2 }
// two objects that are merged via concatenation rules
a : { b : 1 } { c : 2 }
// two fields that are merged
a : { b : 1 }
a : { c : 2 }

// one array
a : [ 1, 2, 3, 4 ]
// two arrays that are concatenated
a : [ 1, 2 ] [ 3, 4 ]
// a later definition referring to an earlier
// (see "self-referential substitutions" below)
a : [ 1, 2 ]
a : ${a} [ 3, 4 ]

path = [ /bin ]
path = ${path} [ /usr/bin ]

对象的继承
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data-center-generic = { cluster-size = 6 }
data-center-east = ${data-center-generic} { name = "east" }

合并还是覆盖
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{ a : { x : 1 } } (first priority)
{ a : 42 } (fallback)
{ a : { y : 2 } } (another fallback)
# result in { a : { x : 1 } }

{ a : { x : 1 } } (first priority)
{ a : { y : 2 } } (fallback)
{ a : 42 } (another fallback)
# result in { a : { x : 1, y : 2 } }

替换

使用这样的语法 ${pathexpression} or ${?pathexpression}

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animal.favorite = dog
key : ${animal.favorite} is my favorite animal

pathexpression是绝对路径，替换是config对象构建的最后一步。

Include

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include "foo"

include "foo.properties"
include "foo.json"
include "foo.conf"

内置转换API

自动转换，时间单位（ns、ms、s、m、h etc），文件大小（kB、MB etc）

文件载入顺序

依次载入合并

  • 引用 jar 包中的 reference.conf 库引用配置
  • 引用 jar 包中的 application.{conf,json,properties} 应用配置
  • 本地 reference.conf 库引用配置
  • 本地 application.{conf,json,properties} 应用配置
  • system properties

在java代码中使用

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# 配置内容
foo=42
dev.foo=57
prod.foo=10

import com.typesafe.config.ConfigFactory

// 载入根配置
Config conf = ConfigFactory.load();
int foo1 = conf.getInt("dev.foo");

// 载入某个对象
Config prod = conf.getConfig("prod");
int foo2 = foo.getInt("foo");

Config devConfig = conf
                     .getConfig("dev")
                     .withFallback(originalConfig)

// handle default
// boolean getBoolean(String path, boolean fallback)

调试

使用下面的方法，会把最终所有的配置信息打印出来

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logger.debug(myConfig.root().render())

输出结果中包含所有载入的配置，如果使用了conf文件，会将对应文件的行信息也打印出来：

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{
    # system properties
    "awt" : {
        # system properties
        "toolkit" : "sun.awt.windows.WToolkit"
    },
    # complex1.conf: 2
    # these are our own config values defined by the app
    "complex-app" : {
        # complex1.conf: 3
        "something" : "This value comes from complex-app's complex1.conf"
    },
    ...
}

源代码