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Topic: 如何根据一个class的文件名,动态的加载class

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1.如何根据一个class的文件名,动态的加载class

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Posted by: KevinTian
Posted on: 2004-12-24 09:53

Question

如何根据一个class的文件名,动态的加载class Question

我用java写的程序,在运行时刻会搜索
该程序所在文件夹下的extend文件夹
中的class文件.
假设extend文件中的所有class都是public的
而且都是Base的之类,但是不知道这些class所在的package

Question

问题是,我的程序如何载入这些class,生成实例,并调用实例的方法

各位大虾多多指教 Smile

2.Re:如何根据一个class的文件名,动态的加载class [Re: KevinTian]	Copy to clipboard
Posted by: KevinTian Posted on: 2004-12-24 09:54 Class.forName似乎可以,但是Class.forName的参数是一个class的全限定名,比如,com.kevintian.Sub 但是在我的程序中,程序知道的是完整的路径, 比如C:\myclass\com\kvintian\extend\sub1.class

3.Re:如何根据一个class的文件名,动态的加载class [Re: KevinTian]	Copy to clipboard
Posted by: Jove Posted on: 2004-12-24 10:22 根据目录猜出他的包名，因为c:\myclasss相当于classpath,每个目录都应该是package segment

4.Re:如何根据一个class的文件名,动态的加载class [Re: KevinTian]	Copy to clipboard
Posted by: KevinTian Posted on: 2004-12-24 11:28 是不是一个叫com.kevintian.MyClass的class必需放在类似...\com\kevintian的文件夹下才可以运行??

5.Re:如何根据一个class的文件名,动态的加载class [Re: KevinTian]	Copy to clipboard
Posted by: beike Posted on: 2004-12-28 19:28 KevinTian wrote: 是不是一个叫com.kevintian.MyClass的class必需放在类似...\com\kevintian的文件夹下才可以运行?? 我想应该是

6.Re:如何根据一个class的文件名,动态的加载class [Re: KevinTian]	Copy to clipboard
Posted by: sailor Posted on: 2005-01-04 16:47 KevinTian wrote: 是不是一个叫com.kevintian.MyClass的class必需放在类似...\com\kevintian的文件夹下才可以运行?? 从java资料中查到有关包与文件组织关系的表明确实如此呀

7.Re:如何根据一个class的文件名,动态的加载class [Re: KevinTian]

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Posted by: tool
Posted on: 2005-01-11 23:10


import java.io.*;
import java.util.Hashtable;
public class DirectClassLoader extends ClassLoader
{
    protected final ClassLoader parent;
    private final Hashtable definedClasses = new Hashtable();
    public DirectClassLoader()
    {
        this(DirectClassLoader.class.getClassLoader());
    }
    public DirectClassLoader(ClassLoader _parent)
    {
        parent = _parent;
    }
    protected synchronized Class loadClass(String name, boolean resolve) throws ClassNotFoundException
    {
        Class cls = findLoadedClass(name);
        if (cls == null && parent != null)
        {
            try
            {
                cls = parent.loadClass(name);
            }
            catch (ClassNotFoundException e)
            {

            }
        }
        if (cls == null)
            cls = findClass(name);
        if (resolve)
            resolveClass(cls);
        return cls;
    }
    public Class loadClass(File file)throws ClassNotFoundException,IOException
    {
        return loadClass(new FileInputStream(file));
    }
    public Class loadClass(InputStream in)throws ClassNotFoundException,IOException
    {
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        byte[] buf = new byte[1024];
        for(;;)
        {
            int l = in.read(buf);
            if (l <= 0)
                break;
            out.write(buf,0,l);
        }
        in.close();
        return loadClass(out.toByteArray());
    }
    public Class loadClass(byte[] b)throws ClassNotFoundException
    {
        return loadClass(b,0,b.length);
    }
    public Class loadClass(byte[] b,int off,int len) throws ClassNotFoundException
    {
        Class cls = defineClass(null,b,off,len);
        definedClasses.put(cls.getName(),cls);
        return loadClass(cls.getName());
    }
    protected Class findClass(String name) throws ClassNotFoundException
    {
        Class cls = (Class)definedClasses.get(name);
        if (cls == null)
            throw new ClassNotFoundException(name);
        else
            return cls;
    }
}

8.Re:如何根据一个class的文件名,动态的加载class [Re: KevinTian]

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Posted by: tool
Posted on: 2005-01-11 23:11


import java.io.*;
import java.util.Hashtable;

public class DirectClassLoader extends ClassLoader
{
    protected final ClassLoader parent;
    private final Hashtable definedClasses = new Hashtable();
    public DirectClassLoader()
    {
        this(DirectClassLoader.class.getClassLoader());
    }
    public DirectClassLoader(ClassLoader _parent)
    {
        parent = _parent;
    }
    protected synchronized Class loadClass(String name, boolean resolve) throws ClassNotFoundException
    {
        Class cls = findLoadedClass(name);
        if (cls == null && parent != null)
        {
            try
            {
                cls = parent.loadClass(name);
            }
            catch (ClassNotFoundException e)
            {

            }
        }
        if (cls == null)
            cls = findClass(name);
        if (resolve)
            resolveClass(cls);
        return cls;
    }
    public Class loadClass(File file)throws ClassNotFoundException,IOException
    {
        return loadClass(new FileInputStream(file));
    }
    public Class loadClass(InputStream in)throws ClassNotFoundException,IOException
    {
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        byte[] buf = new byte[1024];
        for( ; ; )
        {
            int l = in.read(buf);
            if (l <= 0)
                break;
            out.write(buf,0,l);
        }
        in.close();
        return loadClass(out.toByteArray());
    }
    public Class loadClass(byte[] b)throws ClassNotFoundException
    {
        return loadClass(b,0,b.length);
    }
    public Class loadClass(byte[] b,int off,int len) throws ClassNotFoundException
    {
        Class cls = defineClass(null,b,off,len);
        definedClasses.put(cls.getName(),cls);
        return loadClass(cls.getName());
    }
    protected Class findClass(String name) throws ClassNotFoundException
    {
        Class cls = (Class)definedClasses.get(name);
        if (cls == null)
            throw new ClassNotFoundException(name);
        else
            return cls;
    }
}

9.Re:如何根据一个class的文件名,动态的加载class [Re: KevinTian]	Copy to clipboard
Posted by: littledeer1974 Posted on: 2005-02-08 09:12 楼上的朋友要是能在给点说明就更好了