ASMSupport4.6 生成位运算符
在java中我们经常用到为运算符，我们假设有如下代码：
public static void main(String[] args){
String[] binary = { “0000”, “0001”, “0010”, “0011”,
“0100”, “0101”, “0110”, “0111”, “1000”,
“1001”, “1010”, “1011”, “1100”, “1101”, “1110”, “1111” };
int a = 3;
int b = 6;
int c = a | b;
int d = a & b;
int e = a b;
int f = (a 0xFFFFFFFF) & b | a & (b 0xFFFFFFFF);
int g = (a 0xFFFFFFFF) & 0xF;
System.out.println(” a = " + binary[a]);
System.out.println(” b = " + binary[b]);
System.out.println(” a|b = " + binary[c]);
System.out.println(” a&b = " + binary[d]);
System.out.println(” a^b = " + binary[e]);
System.out.println(“~a&b|a&~b = " + binary[f]);
System.out.println(” ~a = " + binary[g]);
}
那么我们用asmsupport生成上面的字节码的代码如下
package example.operators;
import org.objectweb.asm.Opcodes;
import jw.asmsupport.block.method.common.StaticMethodBody;
import jw.asmsupport.clazz.AClass;
import jw.asmsupport.clazz.AClassFactory;
import jw.asmsupport.creator.ClassCreator;
import jw.asmsupport.definition.value.Value;
import jw.asmsupport.definition.variable.LocalVariable;
import example.AbstractExample;
public class BitwiseOperatorGenerate extends AbstractExample {
/**
* @param args
*/
public static void main(String[] args) {
ClassCreator creator = new ClassCreator(Opcodes.V1_5, Opcodes.ACC_PUBLIC , "generated.operators.BitwiseOperatorGenerateExample", null, null);
/*
* 生成一个main方法，方法内容和main1内容相同
*/
creator.createStaticMethod("main", new AClass[]{AClassFactory.getProductClass(String[].class)}, new String[]{"args"}, null, null,
Opcodes.ACC_PUBLIC + Opcodes.ACC_STATIC, new StaticMethodBody(){
@Override
public void generateBody(LocalVariable... argus) {
/*String binary[] = {
"0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111",
"1000", "1001", "1010", "1011", "1100", "1101", "1110", "1111"
};*/
LocalVariable binary = createArrayVariable("binary", AClassFactory.getArrayClass(String[].class), false,
newArrayWithValue(AClassFactory.getArrayClass(String[].class), stringValueArray(new String[]{
"0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111",
"1000", "1001", "1010", "1011", "1100", "1101", "1110", "1111"})));
//int a = 3;
LocalVariable a = createVariable("a", AClass.INT_ACLASS, false, Value.value(3));
//int b = 6;
LocalVariable b = createVariable("b", AClass.INT_ACLASS, false, Value.value(6));
//int c = a | b;
LocalVariable c = createVariable("c", AClass.INT_ACLASS, false, this.bitOr(a, b));
//int d = a & b;
LocalVariable d = createVariable("d", AClass.INT_ACLASS, false, this.bitAnd(a, b));
//int e = a ^ b;
LocalVariable e = createVariable("e", AClass.INT_ACLASS, false, this.bitXor(a, b));
//int f = (~a & b) | (a & ~b);
LocalVariable f = createVariable("f", AClass.INT_ACLASS, false, bitOr(bitAnd(inverts(a), b), bitAnd(a, inverts(b))));
//int g = ~a & 0x0f;
LocalVariable g = createVariable("g", AClass.INT_ACLASS, false, this.bitAnd(inverts(a), Value.value(0x0f)));
//System.out.println(" a = " + binary[a]);
invoke(systemOut, "println", append(Value.value(" a = "), arrayLoad(binary, a)));
//System.out.println(" b = " + binary[b]);
invoke(systemOut, "println", append(Value.value(" b = "), arrayLoad(binary, b)));
//System.out.println(" a|b = " + binary[c]);
invoke(systemOut, "println", append(Value.value(" a|b = "), arrayLoad(binary, c)));
//System.out.println(" a&b = " + binary[d]);
invoke(systemOut, "println", append(Value.value(" a&b = "), arrayLoad(binary, d)));
//System.out.println(" a^b = " + binary[e]);
invoke(systemOut, "println", append(Value.value(" a^b = "), arrayLoad(binary, e)));
//System.out.println("~a&b|a&~b = " + binary[f]);
invoke(systemOut, "println", append(Value.value("~a&b|a&~b = "), arrayLoad(binary, f)));
//System.out.println(" ~a = " + binary[g]);
invoke(systemOut, "println", append(Value.value(" ~a = "), arrayLoad(binary, g)));
runReturn();
}
});
generate(creator);
}
public static Value[] stringValueArray(String[] strs){
Value[] vals = new Value[strs.length];
for(int i=0; i
这里我们主要关注下面这几行代码：
LocalVariable c = createVariable("c", AClass.INT_ACLASS, false, this.bitOr(a, b))
这段代码的作用是创建一个名为”c”的int类型的变量，并且将a和b做或(|)运算的结果保存到这个变量。
LocalVariable d = createVariable("d", AClass.INT_ACLASS, false, this.bitAnd(a, b));
这段代码的作用是创建一个名为”d”的int类型的变量，并且将a和b做与(&)运算的结果保存到这个变量。
LocalVariable e = createVariable("e", AClass.INT_ACLASS, false, this.bitXor(a, b));
这段代码的作用是创建一个名为”e”的int类型的变量，并且将a和b做异或(^)运算的结果保存到这个变量。
LocalVariable f = createVariable("f", AClass.INT_ACLASS, false, bitOr(bitAnd(inverts(a), b), bitAnd(a, inverts(b))));
这段代码的作用是创建一个名为”f”的int类型的变量，至于他的值，稍微复杂点，不过也是运算上多几个步骤，他是先将a取反(~),再和b做与(&)操作获得结果1；再将a和取反(~)后的b做与(&)操作得到结果2，然后再将结果1和结果2做或(^)操作将结果赋予f，对应的java代码就是~a&b|a&~b