8. 成员变量/成员方法解析

成员变量和成员方法的数据结构是一样的，所以可以使用相同的解析逻辑。首先解析出变量/方法的总数量，然后遍历并解析field_info或method_info对象的所有信息。

成员变量/成员方法解析代码片段：

// u2 fields_count;
this.fieldsCount = dis.readUnsignedShort();
// field_info fields[fields_count];
for (int i = 0; i < this.fieldsCount; i++) {
    //        field_info {
    //          u2 access_flags;
    //          u2 name_index;
    //          u2 descriptor_index;
    //          u2 attributes_count;
    //          attribute_info attributes[attributes_count];
    //        }
    this.fieldList.add(readFieldOrMethod());
}
/**
 * 读取成员变量或者方法的公用属性
 *
 * @return 成员变量或方法属性信息
 * @throws IOException 读取异常
 */
private Map<String, Object> readFieldOrMethod() throws IOException {
    Map<String, Object> dataMap = new LinkedHashMap<>();
    // u2 access_flags;
    dataMap.put("access", dis.readUnsignedShort());
    // u2 name_index;
    dataMap.put("name", getConstantPoolValue(dis.readUnsignedShort()));
    // u2 descriptor_index;
    dataMap.put("desc", getConstantPoolValue(dis.readUnsignedShort()));
    // u2 attributes_count;
    int attributesCount = dis.readUnsignedShort();
    dataMap.put("attributesCount", attributesCount);
    // 读取成员变量属性信息
    dataMap.put("attributes", readAttributes(attributesCount));
    return dataMap;
}

成员变量解析结果：

{
    "fieldsCount": 4, 
    "fieldList": [
        {
            "access": 2, 
            "name": "password", 
            "desc": "Ljava/lang/String;", 
            "attributesCount": 0, 
            "attributes": { }
        }, 
        {
            "access": 2, 
            "name": "id", 
            "desc": "J", 
            "attributesCount": 0, 
            "attributes": { }
        }, 
        {
            "access": 26, 
            "name": "serialVersionUID", 
            "desc": "J", 
            "attributesCount": 1, 
            "attributes": {
                "attributeName": "ConstantValue", 
                "attributeLength": 2, 
                "ConstantValue": {
                    "constantValue": -7366591802115334000
                }
            }
        }, 
        {
            "access": 2, 
            "name": "username", 
            "desc": "Ljava/lang/String;", 
            "attributesCount": 0, 
            "attributes": { }
        }
    ]
}

成员方法解析结果（因结果过大，仅保留了一个getPassword方法）：

{
    "methodsCount": 10, 
    "methodList": [
        {
            "access": 1, 
            "name": "getPassword", 
            "desc": "()Ljava/lang/String;", 
            "attributesCount": 1, 
            "attributes": {
                "attributeName": "Code", 
                "attributeLength": 47, 
                "Code": {
                    "maxStack": 1, 
                    "maxLocals": 1, 
                    "codeLength": 5, 
                    "opcodes": [
                        "aload_0", 
                        "getfield #15 <com/anbai/sec/bytecode/TestHelloWorld.password>", 
                        "areturn"
                    ], 
                    "exceptionTable": {
                        "exceptionTableLength": 0, 
                        "exceptionTableList": [ ]
                    }, 
                    "attributeLength": 47, 
                    "attributes": {
                        "attributeName": "LocalVariableTable", 
                        "attributeLength": 12, 
                        "LineNumberTable": {
                            "lineNumberTableLength": 1, 
                            "lineNumberTableList": [
                                {
                                    "startPc": 0, 
                                    "lineNumber": 49
                                }
                            ]
                        }, 
                        "LocalVariableTable": {
                            "localVariableTableLength": 1, 
                            "localVariableTableList": [
                                {
                                    "startPc": 0, 
                                    "length": 5, 
                                    "name": "this", 
                                    "desc": "Lcom/anbai/sec/bytecode/TestHelloWorld;", 
                                    "index": 0
                                }
                            ]
                        }
                    }
                }
            }
        }
    ]
}