判断jar包中class文件的java编译版本

  

import java.io.BufferedReader;

import java.io.DataInputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.util.zip.ZipEntry;

import java.util.zip.ZipFile;

import java.util.zip.ZipInputStream;

//The first 4 bytes are a magic number, 0xCAFEBABe, to identify a valid class file then the next 2 bytes identify the class format version (major and minor).

//Possible major/minor value :

//create table m2_lib ( library1 varchar2(100)) ;

//select '"'||replace(library1,'/','/')||'",' from m2_lib   ;

//

//select * from    m2_lib  for update;

//major  minor Java platform version

//45       3           1.0

//45       3           1.1

//46       0           1.2

//47       0           1.3

//48       0           1.4

//49       0           1.5

//50       0           1.6

public class ClassVersionChecker {

 public static void main(String[] args) throws IOException {

  // for (int i = 0; i < args.length; i++)

  // checkClassVersion(args[i]);

 

  String path = "d://aaa/";

  File file = new File(path);

 

  File [] jarsStrings =  file.listFiles();

  for (int i = 0; i < jarsStrings.length; i++)

   scanJarFileJDK1_5_Version(jarsStrings[i].getAbsolutePath());

 }

 private static void checkClassVersion(String filename) throws IOException {

  DataInputStream in = new DataInputStream(new FileInputStream(filename));

  int magic = in.readInt();

  if (magic != 0xcafebabe) {

   System.out.println(filename + " is not a valid class!");

   ;

  }

  int minor = in.readUnsignedShort();

  int major = in.readUnsignedShort();

  System.out.println(filename + ": " + major + " . " + minor);

  in.close();

 }

 private static void checkClassVersion(InputStream in1) throws IOException {

  DataInputStream in = new DataInputStream(in1);

  int magic = in.readInt();

  if (magic != 0xcafebabe) {

   System.out.println(in + " is not a valid class!");

   ;

  }

  int minor = in.readUnsignedShort();

  int major = in.readUnsignedShort();

 

  System.out.println(": " + major + " . " + minor);

  in.close();

 }

 

 private static void checkClassJDK1_5_Version(String jar,InputStream in1) throws IOException {

  DataInputStream in = new DataInputStream(in1);

  int magic = in.readInt();

  if (magic != 0xcafebabe) {

   System.out.println(in + " is not a valid class!");

   ;

  }

  int minor = in.readUnsignedShort();

  int major = in.readUnsignedShort();

  if (major >49)

  System.out.println(jar+": " + major + " . " + minor);

  in.close();

 }

 

 

 public static void scanJarFileJDK1_5_Version(String zipname) {

  try {

   ZipInputStream zin = new ZipInputStream(

     new FileInputStream(zipname));

   ZipEntry entry;

   while ((entry = zin.getNextEntry()) != null) {

    if (entry.getName().endsWith(".class")) {

     ZipFile file = new ZipFile(zipname);

     InputStream in = file.getInputStream(entry);

     checkClassJDK1_5_Version(zipname,in);

     break;

    }

   }

   zin.close();

  } catch (IOException e) {

  }

 }

 

 public static void scanZipFile(String zipname) {

  try {

   ZipInputStream zin = new ZipInputStream(

     new FileInputStream(zipname));

   ZipEntry entry;

   while ((entry = zin.getNextEntry()) != null) {

    System.out.println(entry.getName());

    zin.closeEntry();

   }

   zin.close();

  } catch (IOException e) {

  }

 }

 public static void scanClassFile(String zipname) {

  try {

   ZipInputStream zin = new ZipInputStream(

     new FileInputStream(zipname));

   ZipEntry entry;

   while ((entry = zin.getNextEntry()) != null) {

    if (entry.getName().endsWith(".class")) {

     System.out.println(entry.getName());

     ZipFile file = new ZipFile(zipname);

     InputStream in = file.getInputStream(entry);

     System.out.println(in);

     checkClassVersion(in);

     break;

    }

   }

   zin.close();

  } catch (IOException e) {

  }

 }

 public static void loadZipFile(String zipname, String name) {

  try {

   ZipInputStream zin = new ZipInputStream(

     new FileInputStream(zipname));

   ZipEntry entry;

   System.out.println("");

   while ((entry = zin.getNextEntry()) != null) {

    if (entry.getName().equals(name)) {

     BufferedReader in = new BufferedReader(

       new InputStreamReader(zin));

     String s;

     while ((s = in.readLine()) != null)

      System.out.println(s + "/n");

    }

    zin.closeEntry();

   }

   zin.close();

  } catch (IOException e) {

  }

 }

}