自訂類載入器-孫衛琴《Java物件導向編程》

package cn.edu.bnu.songjie.ch10.selfclassloader;import java.io.*;/** * 自訂的類載入器，只需要擴充ClassLoader，然後覆蓋它的findClass(Sring name)方法即可， * 該方法根據參數指定的類名，返回對應的Class對象的引用。 * @author songjie * */public class MyClassLoader extends ClassLoader{private String name;private String path = "d:\\";private final String fileType = ".class";public MyClassLoader(String name){this.name = name;}public MyClassLoader(ClassLoader parent, String name){super(parent);this.name = name;}public String toString(){return name;}public void setPath(String path){this.path = path;}public String getPath(){return path;}protected Class findClass(String name){byte[] data = loadClassData(name);return defineClass(name, data, 0, data.length);//此方法從ClassLoader繼承而來}/** * 把類的二級制資料讀入到記憶體 * @param name * @return */private byte[] loadClassData(String name){FileInputStream fis = null;byte[] data = null;ByteArrayOutputStream baos  = null;try{name = name.replaceAll("\\.", "\\\\");fis = new FileInputStream(new File(path+name+fileType));baos = new ByteArrayOutputStream();int ch = 0;while((ch = fis.read()) != -1){baos.write(ch);}data = baos.toByteArray();}catch(FileNotFoundException e1){System.out.println("檔案沒找到");}catch(IOException e2){System.out.println("檔案內容讀取異常");}finally{try{baos.close();fis.close();}catch(IOException e3){e3.printStackTrace();}}return data;}}