java 获取当然JDK版本信息

使用spring下的JdkVersion.java文件获取当然jdk版本信息。

JdkVersion.java代码：

package org.springframework.core;
/**
 * Internal helper class used to find the Java/JVM version
 * that Spring is operating on, to allow for automatically
 * adapting to the present platform's capabilities.
 *
 * <p>Note that Spring requires JVM 1.5 or higher, as of Spring 3.0.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @author Rick Evans
 */
public abstract class JdkVersion {
	/**
	 * Constant identifying the 1.3.x JVM (JDK 1.3).
	 */
	public static final int JAVA_13 = 0;
	/**
	 * Constant identifying the 1.4.x JVM (J2SE 1.4).
	 */
	public static final int JAVA_14 = 1;
	/**
	 * Constant identifying the 1.5 JVM (Java 5).
	 */
	public static final int JAVA_15 = 2;
	/**
	 * Constant identifying the 1.6 JVM (Java 6).
	 */
	public static final int JAVA_16 = 3;
	/**
	 * Constant identifying the 1.7 JVM (Java 7).
	 */
	public static final int JAVA_17 = 4;
	private static final String javaVersion;
	private static final int majorJavaVersion;
	static {
		javaVersion = System.getProperty("java.version");
		// version String should look like "1.4.2_10"
		if (javaVersion.contains("1.7.")) {
			majorJavaVersion = JAVA_17;
		}
		else if (javaVersion.contains("1.6.")) {
			majorJavaVersion = JAVA_16;
		}
		else {
			// else leave 1.5 as default (it's either 1.5 or unknown)
			majorJavaVersion = JAVA_15;
		}
	}
	/**
	 * Return the full Java version string, as returned by
	 * <code>System.getProperty("java.version")</code>.
	 * @return the full Java version string
	 * @see System#getProperty(String)
	 */
	public static String getJavaVersion() {
		return javaVersion;
	}
	/**
	 * Get the major version code. This means we can do things like
	 * <code>if (getMajorJavaVersion() < JAVA_14)</code>.
	 * @return a code comparable to the JAVA_XX codes in this class
	 * @see #JAVA_13
	 * @see #JAVA_14
	 * @see #JAVA_15
	 * @see #JAVA_16
	 * @see #JAVA_17
	 */
	public static int getMajorJavaVersion() {
		return majorJavaVersion;
	}
	/**
	 * Convenience method to determine if the current JVM is at least Java 1.4.
	 * @return <code>true</code> if the current JVM is at least Java 1.4
	 * @deprecated as of Spring 3.0 which requires Java 1.5+
	 * @see #getMajorJavaVersion()
	 * @see #JAVA_14
	 * @see #JAVA_15
	 * @see #JAVA_16
	 * @see #JAVA_17
	 */
	@Deprecated
	public static boolean isAtLeastJava14() {
		return true;
	}
	/**
	 * Convenience method to determine if the current JVM is at least
	 * Java 1.5 (Java 5).
	 * @return <code>true</code> if the current JVM is at least Java 1.5
	 * @deprecated as of Spring 3.0 which requires Java 1.5+
	 * @see #getMajorJavaVersion()
	 * @see #JAVA_15
	 * @see #JAVA_16
	 * @see #JAVA_17
	 */
	@Deprecated
	public static boolean isAtLeastJava15() {
		return true;
	}
	/**
	 * Convenience method to determine if the current JVM is at least
	 * Java 1.6 (Java 6).
	 * @return <code>true</code> if the current JVM is at least Java 1.6
	 * @deprecated as of Spring 3.0, in favor of reflective checks for
	 * the specific Java 1.6 classes of interest
	 * @see #getMajorJavaVersion()
	 * @see #JAVA_16
	 * @see #JAVA_17
	 */
	@Deprecated
	public static boolean isAtLeastJava16() {
		return (majorJavaVersion >= JAVA_16);
	}
}

GetJdkVersion.java代码：

public class GetJdkVersion {
	@SuppressWarnings("static-access")
	public static void main(String[] args) {
		JdkVersion jdkVersion = new JdkVersion() {
		};
		System.out.println(jdkVersion.getJavaVersion()); 
	}
}

测试信息：1.6.0_23