semver/README.md

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# Semantic Version Annotation Processor
An [annotation processor](https://docs.oracle.com/javase/8/docs/api/javax/annotation/processing/Processor.html) that automatically generates a `Version` class containing the [semantic version](http://semver.org/) (major, minor, patch, etc.) that is read from a `Properties` file or defined in the [annotation](https://docs.oracle.com/javase/tutorial/java/annotations/basics.html).
This processor was inspired by Cédric Beust's [version-processor](https://github.com/cbeust/version-processor).
## Examples
* Using annotation elements:
```java
@Version(major = 1, minor = 0, patch = 0, prerelease = "beta")
public class A {
// ...
```
* Or using a [properties](https://docs.oracle.com/javase/tutorial/essential/environment/properties.html) file:
```java
@Version(properties = "version.properties")
public class A {
// ...
```
```ini
# version.properties
version.major=1
version.minor=0
version.patch=0
version.prerelease=beta
```
## Template
Upon running the annotator processor, a source file `GeneratedVersion.java` is automatically generated with static methods to access the semantic version data. The source is based on a fully customizable [Velocity](http://velocity.apache.org/) template.
```java
@Version(template = "myversion.vm")
public class A {
// ...
```
### Default Template
The default template implements the following static methods:
Method | Description | Example
------------------|----------------------------------|------------------
`getProject` | The project name, if any. | `MyProject`
`getBuildDate` | The build date. | [`java.util.Date`](https://docs.oracle.com/javase/8/docs/api/java/util/Date.html)
`getVersion` | The full version string. | `1.0.0-alpha+001`
`getMajor` | The major version. | `1`
`getMinor` | The minor version. | `0`
`getPatch` | The patch version. | `0`
`getPreRelease` | The pre-release version, if any. | `alpha`
`getBuildMetadata`| The build metadata, if any. | `001`
### Custom Template
A very simple custom template might look something like:
```java
/* myversion.vm */
package ${packageName}
import java.util.Date;
public final class ${className} {
public final static String BUILDMETA = "${buildmeta}";
public final static Date DATE = new Date(${epoch}L);
public final static int MAJOR = ${major};
public final static int MINOR = ${minor};
public final static int PATCH = ${patch};
public final static String PRERELEASE = "${prerelease}";
public final static String PROJECT = "${project}";
}
```
The Velocity variables are automatically filled in by the processor.
## Elements & Properties
The following annotation elements and properties are available:
Element | Property | Description | Default
-------------|----------------------|----------------------------------|-------------
`project` | `version.project` | The project name. |
`major` | `version.major` | The major version number. | `1`
`minor` | `version.major` | The minor version number. | `0`
`patch` | `version.patch` | The patch version number. | `0`
`prerelease` | `version.prerelease` | The pre-release version. |
`buildmeta` | `version.buildmeta` | The build metadata version. |
`className` | | The name of the generated class. | `GeneratedVersion`
`properties` | | The properties file. |
`template` | | The template file. | `version.vm`
In order to easily incorporate with existing projects, the property keys may be assigned custom values:
```java
@Version(
properties = "example.properties",
majorKey = "example.major",
minorKey = "example.minor",
patchKey = "example.patch",
prereleaseKey = "example.prerelease",
buildmetaKey = "example.buildmeta",
projectKey = "example.project"
)
public class Example {
// ...
```
```ini
# example.properties
example.project=Example
example.major=1
example.minor=0
example.patch=0
...
```