Java CodeAttribute.getCodeLength方法代码示例

import javassist.bytecode.CodeAttribute; //导入方法依赖的package包/类
public Subroutine[] scan(MethodInfo method) throws BadBytecode {
    CodeAttribute code = method.getCodeAttribute();
    CodeIterator iter = code.iterator();

    subroutines = new Subroutine[code.getCodeLength()];
    subTable.clear();
    done.clear();

    scan(0, iter, null);

    ExceptionTable exceptions = code.getExceptionTable();
    for (int i = 0; i < exceptions.size(); i++) {
        int handler = exceptions.handlerPc(i);
        // If an exception is thrown in subroutine, the handler
        // is part of the same subroutine.
        scan(handler, iter, subroutines[exceptions.startPc(i)]);
    }

    return subroutines;
}
 

import javassist.bytecode.CodeAttribute; //导入方法依赖的package包/类
/**
 * Performs data-flow analysis on a method and returns an array, indexed by
 * instruction position, containing the starting frame state of all reachable
 * instructions. Non-reachable code, and illegal code offsets are represented
 * as a null in the frame state array. This can be used to detect dead code.
 *
 * If the method does not contain code (it is either native or abstract), null
 * is returned.
 *
 * @param clazz the declaring class of the method
 * @param method the method to analyze
 * @return an array, indexed by instruction position, of the starting frame state,
 *         or null if this method doesn't have code
 * @throws BadBytecode if the bytecode does not comply with the JVM specification
 */
public Frame[] analyze(CtClass clazz, MethodInfo method) throws BadBytecode {
    this.clazz = clazz;
    CodeAttribute codeAttribute = method.getCodeAttribute();
    // Native or Abstract
    if (codeAttribute == null)
        return null;

    int maxLocals = codeAttribute.getMaxLocals();
    int maxStack = codeAttribute.getMaxStack();
    int codeLength = codeAttribute.getCodeLength();

    CodeIterator iter = codeAttribute.iterator();
    IntQueue queue = new IntQueue();

    exceptions = buildExceptionInfo(method);
    subroutines = scanner.scan(method);

    Executor executor = new Executor(clazz.getClassPool(), method.getConstPool());
    frames = new Frame[codeLength];
    frames[iter.lookAhead()] = firstFrame(method, maxLocals, maxStack);
    queue.add(iter.next());
    while (!queue.isEmpty()) {
        analyzeNextEntry(method, iter, queue, executor);
    }

    return frames;
}
 

import javassist.bytecode.CodeAttribute; //导入方法依赖的package包/类
protected byte[] byteCodeAt(CodeAttribute ca, List<Integer> opCodeIndexList, int index) {
    int borne;
    int byteCodeIndex = opCodeIndexList.get(index);
    if(index + 1 == opCodeIndexList.size())
        borne = ca.getCodeLength();
    else
        borne = opCodeIndexList.get(index+1);
    CodeIterator iter = ca.iterator();
    byte[] bytecode = new  byte[borne - byteCodeIndex];
    for(int i = 0; i < borne - byteCodeIndex; i++) {
        bytecode[i] = (byte) iter.byteAt(i);
    }
    return bytecode;
}