如何为渐变自定义Java任务输入指定默认值

Question

我有一个用Java编写的自定义Gradle任务，作为Gradle插件的一部分，它看起来像这样：

public abstract class MyTask extends DefaultTask {
private static final String DEFAULT_SERVICE_VERSION = "NO VERSION";
private String serviceVersion;
@Option(option = "serviceVersion", description = "Configures the service version.")
public void setServiceVersion(String serviceVersion) {
this.serviceVersion = serviceVersion;
}
@Input
public String getServiceVersion() {
return serviceVersion;
}

@TaskAction
public void myTask() {
String serviceVersionCurrent = getServiceVersion() != null ? getServiceVersion() : DEFAULT_SERVICE_VERSION;

这允许我调用以serviceVersion为参数的任务，如下所示：

gradle myTask --serviceVersion="0.1"

我想让serviceVersion在某种程度上是可选的，如果没有指定值，那么默认为DEFAULT_SERVICE_VERSION

现在，它失败了：

> gradle myTask
> Task :myTask FAILED
FAILURE: Build failed with an exception.
* What went wrong:
Some problems were found with the configuration of task ':myTask' (type 'MyTask').
> No value has been specified for property 'serviceVersion'.

如果没有指定任何值，我应该如何注释我的属性以使其默认为某个值？

Answer 1

只需在变量初始化时指定默认值：

public class GreetingTask extends DefaultTask {
private String serviceVersion = "v1.0";
@Option(option = "serviceVersion", description = "Configure service version")
public void setServiceVersion(String serviceVersion) {
this.serviceVersion = serviceVersion;
}
@Input
public String getServiceVersion() {
return this.serviceVersion;
}
@TaskAction
public void task() {
System.out.println(this.serviceVersion);
}
}

输出为：

$ ./gradlew greeting
> Task :greeting
v1.0
BUILD SUCCESSFUL in 2s
3 actionable tasks: 3 executed
$ ./gradlew greeting --serviceVersion=v2.0
> Task :greeting
v2.0
BUILD SUCCESSFUL in 1s
3 actionable tasks: 1 executed, 2 up-to-date