add yaml support to apollo-client

[nobodyiam]

Fixes #653, #1113, #1321, #1488, #1585, #1698,

1. support yaml config file transform to properties
2. support yaml config file injection to Spring

Usage

Suppose you have a yml format namespace called 'application.yaml' as the following screenshot, then we could retrieve or inject the config just as the properties format in several ways.

1. API Usage

Config config = ConfigService.getConfig("application.yaml");

2. Spring Injection Usage

2.1 XML Config

<apollo:config namespaces="application.yaml" />

2.2 Java Config

@Configuration
@EnableApolloConfig({"application.yaml"})
public class AppConfig {}

3. Spring Boot Injection Usage

application.properties/bootstrap.properties content:

apollo.bootstrap.enabled = true
apollo.bootstrap.namespaces = application.yaml

[codecov-io]

Codecov Report

Merging #1944 into master will increase coverage by 0.6%.
The diff coverage is 94.24%.

@@             Coverage Diff             @@
##             master    #1944     +/-   ##
===========================================
+ Coverage     50.26%   50.86%   +0.6%     
- Complexity     1927     1979     +52     
===========================================
  Files           396      398      +2     
  Lines         12040    12175    +135     
  Branches       1224     1249     +25     
===========================================
+ Hits           6052     6193    +141     
+ Misses         5534     5524     -10     
- Partials        454      458      +4

Impacted Files	Coverage Δ	Complexity Δ
...trip/framework/apollo/internals/YmlConfigFile.java	66.66% <ø> (ø)	1 <0> (ø)	⬇️
...amework/apollo/internals/PropertiesConfigFile.java	65% <ø> (-1.67%)	9 <0> (-1)
.../framework/apollo/core/enums/ConfigFileFormat.java	0% <0%> (ø)	0 <0> (ø)	⬇️
...ip/framework/apollo/internals/DefaultInjector.java	68% <100%> (+1.33%)	3 <0> (ø)	⬇️
...apollo/spring/config/PropertySourcesProcessor.java	92.45% <100%> (+0.45%)	17 <1> (+1)	⬆️
...rip/framework/apollo/spi/DefaultConfigFactory.java	94.11% <100%> (+4.11%)	18 <8> (+7)	⬆️
...nals/PropertiesCompatibleFileConfigRepository.java	88.88% <88.88%> (ø)	7 <7> (?)
...m/ctrip/framework/apollo/util/yaml/YamlParser.java	94.73% <94.73%> (ø)	24 <24> (?)
...rip/framework/apollo/internals/YamlConfigFile.java	92.3% <95.65%> (+25.64%)	9 <8> (+8)	⬆️
... and 4 more

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[coveralls]

Coverage increased (+0.6%) to 54.628% when pulling b1ca961 on nobodyiam:yml-support into c8f84a6 on ctripcorp:master.

[kezhenxu94]

LGTM and I left a comment for your information

[kezhenxu94]

Is it really good to return an empty properties (instead of throwing) in case of the content is invalid? Then how do we tell that whether the content is empty or invalid. Isn't there such a situation that we need to do that?

[nobodyiam]

This is really a good question!

I think we need to give some thoughts into this...

[kezhenxu94]

My thought was throwing some exceptions like MalformedYamlException in case where the YAML document is invalid and returning empty properties in case where the YAML document is empty

[nobodyiam]

I think you are right, so asProperties will now throw a runtime exception if the content cannot be transformed to properties