JDK8 Access to Parameter Names at Runtime
JDK 8的新特性之一, 运行时获取方法参数的名称
JDK8之前, Eclipse自带的ECJ编译器,同本地变量表,把方法参数的名字,放在最前面,使其编译出来的class的名字看推测.
而 JDK8把这种行为规范化(终于…) http://openjdk.java.net/jeps/118
参考文章 Java 8 parameter name at runtime
演示代码
package nutz_jdk8;
import java.lang.reflect.Constructor;
import java.lang.reflect.Parameter;
public class Bot {
private final String name;
private final String author;
private final int rating;
private final int score;
public Bot(String name, String author, int rating, int score) {
this.rating = rating; // 注意这里的顺序,并非按参数顺序逐一调用
this.score = score;
this.name = name;
this.author = author;
}
public static void main(String[] args) throws NoSuchMethodException, SecurityException {
Class<Bot> clazz = Bot.class;
Constructor ctor = clazz.getConstructor(String.class, String.class, int.class, int.class);
Parameter[] ctorParameters =ctor.getParameters();
for (Parameter param: ctorParameters) {
System.out.println(param.isNamePresent() + ":" + param.getName());
}
}
}
输出的结果是:
true:name
true:author
true:rating
true:score
然后, 这个特性并未默认启用,javac需要额外的参数”-parameters”
javac -parameters nutz_jdk8\Bot.java
java -cp nutz_jdk8.Bot
如果是Eclipse 4.4 (正式支持JDK8的初始版本), 则需要手动在”Java Compiler”中启用之
如果是maven,则需要这段
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
<compilerArgument>-parameters</compilerArgument>
</configuration>
</plugin>
JDK8 , 开始学习啦
开始学习新特性啦,哇哈哈
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