我如何知道编译了.class文件的Java版本？
我试图找出如何通过查看其二进制数据来确定.class文件的版本。 我知道使用javap会告诉我版本 – 但不幸的是我并不总是在我需要检查的机器上安装JDK 。 但我可以访问普通的旧HEX编辑器……
我尝试从经过认证的来源找到相关文档 – 我能够得到的就是这个： http ： //fredericktang.wordpress.com/2007/09/28/java-class-file-version/
虽然这篇博文非常精彩 – 但它并没有真正备份官方Java文档。
任何提示？
编辑：没关系 – 抱歉 – 我找到了规范： 这里
JVM规范与您将获得的权威一样具有权威性。 第4章可能就是你所追求的。
您引用的文档实际上是JVM类文件规范的逐字转换（更简单的英语）。
我保持方便的一些hitoric值
Major Major(hex) Minor Java platform version 45 2d 3 1.0 45 2d 3 1.1 46 2e 0 1.2 47 2f 0 1.3 48 30 0 1.4 49 31 0 1.5 50 32 0 1.6
—编辑回应尼尔的观察，即1.0和1.1使用相同的主要次要数字—
从类头中，无法确定该类是否针对1.0或1.1版本的Java进行编译。 也就是说，有许多其他技术可以帮助确定是否针对1.0或1.1编译了一个类。
首先，如果该类是针对1.1编译的，那么它可能包含一个仅1.1的库类。 一旦在其中一个类中找到其中一个，就可以安全地得出结论，它是针对Java 1.1编译的类。
请注意，可以在类的开头搜索常量池，以确定类文件需要哪些类才能完全解析所有外部引用。
单独搜索类可能很麻烦，幸运的是还添加了很多包。 以下包特定于Java 1.1，即它们未包含在Java 1.0中
+ java.awt.datatransfer + java.awt.event + java.beans + java.lang.reflect + java.math + java.rmi.dgc + java.rmi + java.rmi.registry + java.rmi.server + java.security.acl + java.security + java.security.interfaces + java.sql + java.text + java.util.zip
在围栏的另一侧，对以下方法的大量调用建议（但不是实际certificate）代码是针对Java 1.0编写的，因为它们在Java 1.1中由于新的awt事件重构而被弃用。
Deprecated Classes java.io.LineNumberInputStream: LineNumberInputStream is deprecated. java.io.StringBufferInputStream: StringBufferInputStream is deprecated. Deprecated Methods java.awt.BorderLayout: addLayoutComponent() is deprecated. java.awt.CardLayout: addLayoutComponent() is deprecated. java.awt.CheckboxGroup: getCurrent() is deprecated. java.awt.CheckboxGroup: setCurrent() is deprecated. java.awt.Choice: countItems() is deprecated. java.awt.Component: getPeer() is deprecated. java.awt.Component: enable() is deprecated. java.awt.Component: enable() is deprecated. java.awt.Component: disable() is deprecated. java.awt.Component: show() is deprecated. java.awt.Component: show() is deprecated. java.awt.Component: hide() is deprecated. java.awt.Component: location() is deprecated. java.awt.Component: move() is deprecated. java.awt.Component: size() is deprecated. java.awt.Component: resize() is deprecated. java.awt.Component: resize() is deprecated. java.awt.Component: bounds() is deprecated. java.awt.Component: reshape() is deprecated. java.awt.Component: preferredSize() is deprecated. java.awt.Component: minimumSize() is deprecated. java.awt.Component: layout() is deprecated. java.awt.Component: inside() is deprecated. java.awt.Component: locate() is deprecated. java.awt.Component: deliverEvent() is deprecated. java.awt.Component: postEvent() is deprecated. java.awt.Component: handleEvent() is deprecated. java.awt.Component: mouseDown() is deprecated. java.awt.Component: mouseDrag() is deprecated. java.awt.Component: mouseUp() is deprecated. java.awt.Component: mouseMove() is deprecated. java.awt.Component: mouseEnter() is deprecated. java.awt.Component: mouseExit() is deprecated. java.awt.Component: keyDown() is deprecated. java.awt.Component: keyUp() is deprecated. java.awt.Component: action() is deprecated. java.awt.Component: gotFocus() is deprecated. java.awt.Component: lostFocus() is deprecated. java.awt.Component: nextFocus() is deprecated. java.awt.Container: countComponents() is deprecated. java.awt.Container: insets() is deprecated. java.awt.Container: layout() is deprecated. java.awt.Container: preferredSize() is deprecated. java.awt.Container: minimumSize() is deprecated. java.awt.Container: deliverEvent() is deprecated. java.awt.Container: locate() is deprecated. java.awt.FontMetrics: getMaxDecent() is deprecated. java.awt.Frame: setCursor() is deprecated. java.awt.Frame: getCursorType() is deprecated. java.awt.Graphics: getClipRect() is deprecated. java.awt.List: countItems() is deprecated. java.awt.List: clear() is deprecated. java.awt.List: isSelected() is deprecated. java.awt.List: allowsMultipleSelections() is deprecated. java.awt.List: setMultipleSelections() is deprecated. java.awt.List: preferredSize() is deprecated. java.awt.List: preferredSize() is deprecated. java.awt.List: minimumSize() is deprecated. java.awt.List: minimumSize() is deprecated. java.awt.List: delItems() is deprecated. java.awt.Menu: countItems() is deprecated. java.awt.MenuBar: countMenus() is deprecated. java.awt.MenuComponent: getPeer() is deprecated. java.awt.MenuComponent: postEvent() is deprecated. java.awt.MenuContainer: postEvent() is deprecated. java.awt.MenuItem: enable() is deprecated. java.awt.MenuItem: enable() is deprecated. java.awt.MenuItem: disable() is deprecated. java.awt.Polygon: getBoundingBox() is deprecated. java.awt.Polygon: inside() is deprecated. java.awt.Rectangle: reshape() is deprecated. java.awt.Rectangle: move() is deprecated. java.awt.Rectangle: resize() is deprecated. java.awt.Rectangle: inside() is deprecated. java.awt.ScrollPane: layout() is deprecated. java.awt.Scrollbar: getVisible() is deprecated. java.awt.Scrollbar: setLineIncrement() is deprecated. java.awt.Scrollbar: getLineIncrement() is deprecated. java.awt.Scrollbar: setPageIncrement() is deprecated. java.awt.Scrollbar: getPageIncrement() is deprecated. java.awt.TextArea: insertText() is deprecated. java.awt.TextArea: appendText() is deprecated. java.awt.TextArea: replaceText() is deprecated. java.awt.TextArea: preferredSize() is deprecated. java.awt.TextArea: preferredSize() is deprecated. java.awt.TextArea: minimumSize() is deprecated. java.awt.TextArea: minimumSize() is deprecated. java.awt.TextField: setEchoCharacter() is deprecated. java.awt.TextField: preferredSize() is deprecated. java.awt.TextField: preferredSize() is deprecated. java.awt.TextField: minimumSize() is deprecated. java.awt.TextField: minimumSize() is deprecated. java.awt.Window: postEvent() is deprecated. java.io.ByteArrayOutputStream: toString() is deprecated. java.io.DataInputStream: readLine() is deprecated. java.io.PrintStream: PrintStream() is deprecated. java.io.PrintStream: PrintStream() is deprecated. java.io.StreamTokenizer: StreamTokenizer() is deprecated. java.lang.Character: isJavaLetter() is deprecated. java.lang.Character: isJavaLetterOrDigit() is deprecated. java.lang.Character: isSpace() is deprecated. java.lang.ClassLoader: defineClass() is deprecated. java.lang.Runtime: getLocalizedInputStream() is deprecated. java.lang.Runtime: getLocalizedOutputStream() is deprecated. java.lang.String: String() is deprecated. java.lang.String: String() is deprecated. java.lang.String: getBytes() is deprecated. java.lang.System: getenv() is deprecated. java.net.Socket: Socket() is deprecated. java.net.Socket: Socket() is deprecated. java.util.Date: Date() is deprecated. java.util.Date: Date() is deprecated. java.util.Date: Date() is deprecated. java.util.Date: Date() is deprecated. java.util.Date: UTC() is deprecated. java.util.Date: parse() is deprecated. java.util.Date: getYear() is deprecated. java.util.Date: setYear() is deprecated. java.util.Date: getMonth() is deprecated. java.util.Date: setMonth() is deprecated. java.util.Date: getDate() is deprecated. java.util.Date: setDate() is deprecated. java.util.Date: getDay() is deprecated. java.util.Date: getHours() is deprecated. java.util.Date: setHours() is deprecated. java.util.Date: getMinutes() is deprecated. java.util.Date: setMinutes() is deprecated. java.util.Date: getSeconds() is deprecated. java.util.Date: setSeconds() is deprecated. java.util.Date: toLocaleString() is deprecated. java.util.Date: toGMTString() is deprecated. java.util.Date: getTimezoneOffset() is deprecated.
可以certificateJava代码是1.1版，但仅在某些情况下（如果代码使用新添加的1.1function）。 通常不可能certificateJava代码是1.0，但是没有使用Java 1.1特性，并且大量使用Java已弃用的function暗示了针对Java 1.0环境的类。
我不知道任何可能能够区分这两者的类内标记（行号表的差异等），主要是因为我没有必要在hex编辑器中挖掘1.0和1.1类。