🔐 ImmutableMethodImplementation
ImmutableMethodImplementation 是 MethodImplementation 接口的不可变实现，将方法体的寄存器数量、指令列表、try-catch 块和调试信息全部冻结为不可修改的 ImmutableList。
| 属性 | 值 |
|---|---|
| 源码 | immutable/ImmutableMethodImplementation.java |
| 包名 | org.jf.dexlib2.immutable |
| 实现接口 | MethodImplementation |
🎯 职责
- 持有不可变的指令列表（
ImmutableList<? extends ImmutableInstruction>） - 持有不可变的 try-catch 块列表
- 持有不可变的调试信息列表（行号、局部变量开始/结束等）
- 提供
of()工厂方法从任意MethodImplementation快速创建 Immutable 副本
🧠 关键实现
java
public class ImmutableMethodImplementation implements MethodImplementation {
protected final int registerCount;
@Nonnull protected final ImmutableList<? extends ImmutableInstruction> instructions;
@Nonnull protected final ImmutableList<? extends ImmutableTryBlock> tryBlocks;
@Nonnull protected final ImmutableList<? extends ImmutableDebugItem> debugItems;
public ImmutableMethodImplementation(int registerCount,
@Nullable Iterable<? extends Instruction> instructions,
@Nullable List<? extends TryBlock<? extends ExceptionHandler>> tryBlocks,
@Nullable Iterable<? extends DebugItem> debugItems) {
this.registerCount = registerCount;
this.instructions = ImmutableInstruction.immutableListOf(instructions);
this.tryBlocks = ImmutableTryBlock.immutableListOf(tryBlocks);
this.debugItems = ImmutableDebugItem.immutableListOf(debugItems);
}
// 静态工厂：幂等转换
@Nullable
public static ImmutableMethodImplementation of(@Nullable MethodImplementation impl) {
if (impl == null) return null;
if (impl instanceof ImmutableMethodImplementation) return (ImmutableMethodImplementation) impl;
return new ImmutableMethodImplementation(
impl.getRegisterCount(),
impl.getInstructions(),
impl.getTryBlocks(),
impl.getDebugItems());
}
}📌 小结
ImmutableMethodImplementation 是从 DexBackedMethodImplementation（懒加载）转换到内存实体化方法体的桥梁。在 ZjDroid 脱壳管道中，先通过 dexbacked 层懒读取方法体字节码，再转为 ImmutableMethodImplementation 进行分析，最终传入 DexPool 写出。
与 MutableMethodImplementation 的选择
- 只读场景（分析、写出已有方法体）→
ImmutableMethodImplementation - 需要修改方法体（插桩、patch）→
new MutableMethodImplementation(impl)