JDK

• Intro(JDK) #

  • 下载JDK #

    • reference #

      special：macosx[Sonoma]安装特殊版本 1.6.0_65，oracle没有提供 。
      上面的没有源码， 参考 改用 Java for OS X 2013-005 Developer Package，对应的JAVA版本为 1.6.0_65-b14-462.jdk 。

      Please be aware that IntelliJ IDEA 2022.3 won’t support running and testing Java applications that use Java 6. Java 6 reached “end of life” status several years ago
      对于JDK1.6，可以使用 IDEA 2022.2， 参考

      • https://mirrors.huaweicloud.com/java/jdk/
      • https://mirrors.huaweicloud.com/openjdk/
      • https://jdk.java.net/
      • https://www.oracle.com/java/technologies/downloads/archive/

  • 查看JDK详细信息包括版本，厂商 #

    java -XshowSettings:properties -version

  • 查看native 对应的C/C++代码 #

    // The theory behind this is that all native methods should start with "Java_" and continue by the rest of package name.
    // 形如：
    Java_com_foobar_main_test(...);
    // rapresents a method "test()" in packagename "com.foobar" and classfile "main". Overloaded methods could have their signature after the method name like:
    Java_com_foobar_main_test__Ljava_lang_String_I(..., jstring text, jint integer);
    
    // JDK native 方法位置(不同jdk方法名可能不一样，比如: (java.io.FileInputStream#open | open0)
    // for example
    // JDK 1.7 -> 
    
            |: https://github.com/openjdk/jdk/blob/jdk7-b80/jdk/src/share/classes/java/io/FileInputStream.java#L186
            /**
            * Opens the specified file for reading.
            * @param name the name of the file
            */
            private native void open(String name) throws FileNotFoundException;
        ==> 
            |: https://github.com/openjdk/jdk/blob/jdk7-b80/jdk/src/share/native/java/io/FileInputStream.c#L60C1-L60C34
            JNIEXPORT void JNICALL
            Java_java_io_FileInputStream_open(JNIEnv *env, jobject this, jstring path) {
                fileOpen(env, this, path, fis_fd, O_RDONLY);
            }
    
    // JDK 23  -> 
    
            |: https://github.com/openjdk/jdk/blob/jdk-23%2B6/src/java.base/share/classes/java/io/FileInputStream.java#L203
            /**
            * Opens the specified file for reading.
            * @param name the name of the file
            */
            private native void open0(String name) throws FileNotFoundException;
        ==>
            |: https://github.com/openjdk/jdk/blob/jdk-23%2B6/src/java.base/share/native/libjava/FileInputStream.c#L60C1-L60C35
            JNIEXPORT void JNICALL
            Java_java_io_FileInputStream_open0(JNIEnv *env, jobject this, jstring path) {
                fileOpen(env, this, path, fis_fd, O_RDONLY);
            }
    

Reference #

• https://stackoverflow.com/questions/65513492/how-to-find-the-native-c-function-who-called-a-java-method-in-a-android-app-an
• https://hackernoon.com/oracle-ibm-or-open-jdk-how-to-know-java-vendor-details