一个读取Class文件的示例程序

package bytecodeResearch;
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import java.io.BufferedInputStream;
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import java.io.BufferedWriter;
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import java.io.FileInputStream;
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import java.io.FileWriter;
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import java.io.IOException;
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public class ReadAndWriteClass {
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//16进制数字字符集
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private static String hexString = "0123456789ABCDEF";
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/**
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* 将字节数组的指定长度部分编码成16进制数字字符串
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* @param buffer 待编码的字节数组
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* @param length 指定的长度
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* @return 编码后连接而成的字符串
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*/
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public static String encode(byte[] buffer,int length)
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{
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StringBuilder sbr = new StringBuilder();
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//将字节数组中每个字节拆解成2位16进制整数
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for(int i=0;i<length;i++)
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{
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sbr.append(hexString.charAt((buffer[i]&0xf0)>>4));
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sbr.append(hexString.charAt(buffer[i]&0x0f));
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sbr.append(" ");
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}
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return sbr.toString();
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}
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/**
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* 读取一个Class文件，将其所有字节转换为16进制整数，并以字符形式输出
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* @param inputPath 输入文件的完整路径
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* @param outputPath 输出文件的完整路径
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* @throws IOException 读写过程中可能抛出的异常
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*/
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public static void rwclass(String inputPath, String outputPath) throws IOException
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{
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//读取Class文件要用字节输入流
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BufferedInputStream bis = new BufferedInputStream(
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new FileInputStream(inputPath));
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//输出转换后的文件要用字符输出流
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BufferedWriter bw = new BufferedWriter(
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new FileWriter(outputPath));
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int readSize = 16;
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byte[] buffer_read = new byte[readSize];
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String line;
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String lineNumber = "0000000";
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String strReplace;
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int i = 0;
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while ((readSize = bis.read(buffer_read,0,readSize))!= -1)
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{
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line = encode(buffer_read,readSize);
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strReplace = Integer.toHexString(i);
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lineNumber = lineNumber.substring(0, 7-strReplace.length());
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lineNumber = lineNumber+strReplace;
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line = lineNumber+"0h: "+line;
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bw.write(line);
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bw.newLine();
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i++;
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}
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bis.close();
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bw.close();
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}
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/**
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* 程序的入口方法
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* @param args
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* @throws IOException
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*/
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public static void main(String[] args)
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{
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//指定输入、输出文件的完整路径
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String inputPath = "L:/HelloWorld/HelloWorld.class";
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String outputPath = "L:/HelloWorld/HelloWorld_ByteCode.txt";
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try {
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rwclass(inputPath, outputPath);
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System.out.println("Successfully !");
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} catch (IOException ioe) {
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System.err.println("Something wrong with reading or writing

!");
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ioe.printStackTrace();
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}
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}
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}
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posted on 2008-02-01 04:11 独孤求败阅读(1746) 评论(4) 编辑收藏所属分类: Java ByteCode

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