package com.example.test;


import androidx.appcompat.app.AppCompatActivity;


import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;


import java.util.Random;


public class MainActivity extends AppCompatActivity {
    private static final String TAG = "xposedText";
    private TextView tv_hook;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tv_hook = (TextView) findViewById(R.id.tv_hook);
        tv_hook.setText("快来hook我");
        Log("init", new Random().nextInt(100));
    }


    public void Log(String msg, int code) {
        Log.i(TAG, "Log: " + msg + code);
    }
}

创建xposed模块

新增默认带Empty Activity的Module

在Module下的build.gradle文件添加依赖包

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])


    implementation 'androidx.appcompat:appcompat:1.1.0'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'androidx.test.ext:junit:1.1.1'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
    //xposed依赖包

    compileOnly 'de.robv.android.xposed:api:82'
}

然后sync，如果比较慢建议科学·上网。

在Module下的AndroidManifest.xml文件添加xposed相关meta标签，用于框架识别

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.xposed">


    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">

        <!--模块申明，true表示申明为xposed模块-->
        <meta-data
            android:name="xposedmodule"
            android:value="true" />


        <!--模块说明，一般为模块的功能描述-->
        <meta-data
            android:name="xposeddescription"
            android:value="这个模块是用来劫持登录的" />


        <!--模块兼容版本-->
        <meta-data
            android:name="xposedminversion"
            android:value="54" />

        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />


                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>


</manifest>

添加hook类，继承IXposedHookLoadPackage实现hook方法

package com.example.xposed;


import android.content.Context;
import android.util.Log;
import android.widget.TextView;
import android.widget.Toast;


import de.robv.android.xposed.IXposedHookLoadPackage;
import de.robv.android.xposed.XC_MethodHook;
import de.robv.android.xposed.XposedHelpers;
import de.robv.android.xposed.callbacks.XC_LoadPackage;


public class HookLog implements IXposedHookLoadPackage {
    private static final String TAG = "XposedHook";
    private Context hookContext = null;


    public void handleLoadPackage(XC_LoadPackage.LoadPackageParam lpparam) {


        //过滤非目标包
        if (lpparam == null) {
            return;
        }
        Log.e(TAG, "Load app packageName:" + lpparam.packageName);
        //目标app的包名，既目标apk的AndroidManifest.xml文件manifest标签中的package属性值
        if (!"com.example.test".equals(lpparam.packageName)) {
            return;
        }


        //获取context，用于Toast提示
        XposedHelpers.findAndHookMethod(
                //填写目标方法所在的完整类名
                "android.content.ContextWrapper",
                //默认classLoader
                lpparam.classLoader,
                //目标方法
                "getApplicationContext",
                // Hook回调
                new XC_MethodHook() {
                    protected void afterHookedMethod(MethodHookParam param) {
                        if (hookContext != null)
                            return;
                        hookContext = (Context) param.getResult();
                        Log.i(TAG + "hookContext", hookContext.getPackageCodePath());
                    }
                }
        );


        //进行hook
        XposedHelpers.findAndHookMethod(
                //填写目标方法所在的完整类名
                "com.example.test.MainActivity",
                //默认classLoader
                lpparam.classLoader,
                //目标方法
                "Log",
                //方法参数，有几个写几个
                String.class,
                // 注意，要做到与目标方法参数对应，这里不能用Integer.class。
                int.class,
                // Hook回调
                new XC_MethodHook() {


                    @Override
                    protected void beforeHookedMethod(MethodHookParam param) throws Exception {
                        Log.i(TAG, "劫持开始");
                        String msg = (String) param.args[0];
                        int code = (int) param.args[1];
                        Log.i(TAG, "原code：" + code);
                        Toast.makeText(hookContext, "原code：" + code, Toast.LENGTH_LONG).show();
                        //修改方法参数，设为54，这样就不随机了。
                        param.args[1] = 54;
                        TextView tv = (TextView) XposedHelpers.findField(param.thisObject.getClass(), "tv_hook").get(param.thisObject);
                        tv.setText("随机数被我固定为54了");
                    }


                    protected void afterHookedMethod(MethodHookParam param) {
                        Log.i(TAG, "劫持结束");
                    }
                }
        );


    }
}

在模块下的src/assets/xposed_init（没有则新建）文件添加完整的hook类名

com.example.xposed.HookLog
用于提示XposedBridge加载哪一个类。

安装xposed模块

安装完成之后，Xposed Installer下就会出现我们开发的模块了

打勾启用，然后软重启手机

hook测试app

接着我们直接运行测试app，xposed将启用我们写好的模块进行hook

最终我们拦截了参数，使其固定为54，并且改写了tv_hook的值

对于加壳的情况

若需目标app加壳，我们就不能直接findAndHookMethod了，因为真正app代码是在壳内动态加载的，所以要经过两次hook。
我们以360的壳为例

第一次hook

需要分析壳代码实际加载app的方法，然后注入获取到真正的ClassLoader

        XposedHelpers.findAndHookMethod(
                "com.stub.StubApp",
                lpparam.classLoader,
                "attachBaseContext",
                Context.class,
                // Hook回调
                new XC_MethodHook() {


                    @Override
                    protected void beforeHookedMethod(MethodHookParam param) throws Exception {
                        Log.e(TAG, "劫持开始");
                    }


                    protected void afterHookedMethod(MethodHookParam param) {
                        //获取到Context对象，通过这个对象来获取classloader
                        Context context = (Context) param.args[0];
                        //获取classloader，之后hook加固后的就使用这个classloader
                        ClassLoader realClassLoader = context.getClassLoader();
                        //下面就是将classloader修改成壳的classloader就可以成功的hook了
                        realXposedHook(realClassLoader);
                        Log.e(TAG, "劫持结束");
                    }
                }
        );

第二次hook

取到真正的ClassLoader，我们就可以愉快的hook了

    private void realXposedHook(final ClassLoader classLoader) {
        //固定格式
        XposedHelpers.findAndHookMethod(
                "com.target.class",
                classLoader,
                "targetMethod",
                // Hook回调
                new XC_MethodHook() {


                    @Override
                    protected void beforeHookedMethod(MethodHookParam param) throws Exception {
                        Log.e(TAG, "real劫持开始");
                    }


                    protected void afterHookedMethod(MethodHookParam param) {
                        Log.e(TAG, "real劫持结束");
                    }
                }
        );
    }

其他示例

目标代码

abstract class Animal{
    int anonymoutInt = 500;
    public abstract void eatFunc(String value);
}


public class HookDemo {
    private String Tag = "HookDemo";
    private static  int staticInt = 100;
    public  int publicInt = 200;
    private int privateInt = 300;


    public HookDemo(){
        this("NOHook");
        Log.d(Tag, "HookDemo() was called|||");
    }


    private HookDemo(String str){
        Log.d(Tag, "HookDemo(String str) was called|||" + str);
    }


    public void hookDemoTest(){
        Log.d(Tag, "staticInt = " + staticInt);
        Log.d(Tag, "PublicInt = " + publicInt);
        Log.d(Tag, "privateInt = " + privateInt);
        publicFunc("NOHook");
        Log.d(Tag, "PublicInt = " + publicInt);
        Log.d(Tag, "privateInt = " + privateInt);
        privateFunc("NOHook");
        staticPrivateFunc("NOHook");


        String[][] str = new String[1][2];
        Map map = new HashMap<String, String>();
        map.put("key", "value");
        ArrayList arrayList = new ArrayList();
        arrayList.add("listValue");
        complexParameterFunc("NOHook", str, map, arrayList);


        repleaceFunc();
        anonymousInner(new Animal() {
            @Override
            public void eatFunc(String value) {
                Log.d(Tag, "eatFunc(String value)  was called|||" + value);
                Log.d(Tag, "anonymoutInt =  " + anonymoutInt);
            }
        }, "NOHook");


        InnerClass innerClass = new InnerClass();
        innerClass.InnerFunc("NOHook");
    }


    public void publicFunc(String value){
        Log.d(Tag, "publicFunc(String value) was called|||" + value);
    }


    private void privateFunc(String value){
        Log.d(Tag, "privateFunc(String value) was called|||" + value);
    }


    static private void staticPrivateFunc(String value){
        Log.d("HookDemo", "staticPrivateFunc(Strin value) was called|||" + value);
    }


    private void complexParameterFunc(String value, String[][] str, Map<String,String> map, ArrayList arrayList)
    {
        Log.d("HookDemo", "complexParameter(Strin value) was called|||" + value);
    }


    private void repleaceFunc(){
        Log.d(Tag, "repleaceFunc will be replace|||");
    }


    public void anonymousInner(Animal dog, String value){
        Log.d(Tag, "anonymousInner was called|||" + value);
        dog.eatFunc("NOHook");
    }


    private void hideFunc(String value){
        Log.d(Tag, "hideFunc was called|||" + value);
    }


    class InnerClass{
        public int innerPublicInt = 10;
        private int innerPrivateInt = 20;
        public InnerClass(){
            Log.d(Tag, "InnerClass constructed func was called");
        }
        public void InnerFunc(String value){
            Log.d(Tag, "InnerFunc(String value) was called|||" + value);
            Log.d(Tag, "innerPublicInt = " + innerPublicInt);
            Log.d(Tag, "innerPrivateInt = " + innerPrivateInt);
        }
    }
}

hook模块

public class XposedHook implements IXposedHookLoadPackage {


    @Override
    public void handleLoadPackage(XC_LoadPackage.LoadPackageParam loadPackageParam) throws Throwable {
        if (loadPackageParam.packageName.equals("com.example.xposedhooktarget")) {
            final Class<?> clazz = XposedHelpers.findClass("com.example.xposedhooktarget.HookDemo", loadPackageParam.classLoader);
            //getClassInfo(clazz);


            //不需要获取类对象，即可直接修改类中的私有静态变量staticInt
            XposedHelpers.setStaticIntField(clazz, "staticInt", 99);


            //Hook无参构造函数，啥也不干。。。。
            XposedHelpers.findAndHookConstructor(clazz, new XC_MethodHook() {
                @Override
                protected void beforeHookedMethod(MethodHookParam param) throws Throwable {
                    XposedBridge.log("Haha, HookDemo constructed was hooked" );
                    //大坑，此时对象还没有建立，即不能获取对象，也不能修改非静态变量的值
                    //XposedHelpers.setIntField(param.thisObject, "publicInt", 199);
                    //XposedHelpers.setIntField(param.thisObject, "privateInt", 299);
                }
            });


            //Hook有参构造函数，修改参数
            XposedHelpers.findAndHookConstructor(clazz, String.class,  new XC_MethodHook() {
                @Override
                protected void beforeHookedMethod(MethodHookParam param) throws Throwable {
                    param.args[0] = "Haha, HookDemo(str) are hooked";
                }
            });


            //Hook有参构造函数，修改参数------不能使用XC_MethodReplacement()替换构造函数内容，
            //XposedHelpers.findAndHookConstructor(clazz, String.class, new XC_MethodReplacement() {
            //    @Override
            //    protected Object replaceHookedMethod(MethodHookParam methodHookParam) throws Throwable {
            //        Log.d("HookDemo" , "HookDemo(str) was replace");
            //    }
            //});


            //Hook公有方法publicFunc，
            // 1、修改参数
            // 2、修改下publicInt和privateInt的值
            // 3、再顺便调用一下隐藏函数hideFunc
            //XposedHelpers.findAndHookMethod("com.example.xposedhooktarget.HookDemo", clazz.getClassLoader(), "publicFunc", String.class, new XC_MethodHook()
            XposedHelpers.findAndHookMethod(clazz, "publicFunc", String.class, new XC_MethodHook() {
                @Override
                protected void beforeHookedMethod(MethodHookParam param) throws Throwable {
                    param.args[0] = "Haha, publicFunc are hooked";
                    XposedHelpers.setIntField(param.thisObject, "publicInt", 199);
                    XposedHelpers.setIntField(param.thisObject, "privateInt", 299);
                    // 让hook的对象本身去执行流程
                    Method md = clazz.getDeclaredMethod("hideFunc", String.class);
                    md.setAccessible(true);
                    //md.invoke(param.thisObject, "Haha, hideFunc was hooked");
                    XposedHelpers.callMethod(param.thisObject, "hideFunc", "Haha, hideFunc was hooked");


                    //实例化对象，然后再调用HideFunc方法
                    //Constructor constructor = clazz.getConstructor();
                    //XposedHelpers.callMethod(constructor.newInstance(), "hideFunc", "Haha, hideFunc was hooked");
                }
            });


            //Hook私有方法privateFunc，修改参数
            //XposedHelpers.findAndHookMethod("com.example.xposedhooktarget.HookDemo", clazz.getClassLoader(), "privateFunc", String.class, new XC_MethodHook()
            XposedHelpers.findAndHookMethod(clazz, "privateFunc", String.class, new XC_MethodHook() {
                @Override
                protected void beforeHookedMethod(MethodHookParam param) throws Throwable {
                    param.args[0] = "Haha, privateFunc are hooked";
                }
            });


            //Hook私有静态方法staticPrivateFunc, 修改参数
            XposedHelpers.findAndHookMethod(clazz, "staticPrivateFunc", String.class, new XC_MethodHook() {
                @Override
                protected void beforeHookedMethod(MethodHookParam param) throws Throwable {
                    param.args[0] = "Haha, staticPrivateFunc are hooked";
                }
            });


            //Hook复杂参数函数complexParameterFunc
            Class fclass1 = XposedHelpers.findClass("java.util.Map", loadPackageParam.classLoader);
            Class fclass2 = XposedHelpers.findClass("java.util.ArrayList", loadPackageParam.classLoader);
            XposedHelpers.findAndHookMethod(clazz, "complexParameterFunc", String.class,
                    "[[Ljava.lang.String;", fclass1, fclass2, new XC_MethodHook() {
                        @Override
                        protected void beforeHookedMethod(MethodHookParam param) throws Throwable {
                            param.args[0] = "Haha, complexParameterFunc are hooked";
                        }
                    });


            //Hook私有方法repleaceFunc, 替换打印内容
            XposedHelpers.findAndHookMethod(clazz, "repleaceFunc", new XC_MethodReplacement() {
                @Override
                protected Object replaceHookedMethod(MethodHookParam methodHookParam) throws Throwable {
                    Log.d("HookDemo", "Haha, repleaceFunc are replaced");
                    return null;
                }
            });
            //Hook方法, anonymousInner， 参数是抽象类，先加载所需要的类即可
            Class animalClazz  = loadPackageParam.classLoader.loadClass("com.example.xposedhooktarget.Animal");
            XposedHelpers.findAndHookMethod(clazz, "anonymousInner", animalClazz, String.class, new XC_MethodHook() {
                @Override
                protected void beforeHookedMethod(MethodHookParam param) throws Throwable {
                    XposedBridge.log("HookDemo This is test");
                    param.args[1] = "Haha, anonymousInner are hooked";
                }
            });


            //Hook匿名类的eatFunc方法，修改参数，顺便修改类中的anonymoutInt变量
            XposedHelpers.findAndHookMethod("com.example.xposedhooktarget.HookDemo$1", clazz.getClassLoader(),
                    "eatFunc", String.class, new XC_MethodHook() {
                        @Override
                        protected void beforeHookedMethod(MethodHookParam param) throws Throwable {
                            param.args[0] = "Haha, eatFunc are hooked";
                            XposedHelpers.setIntField(param.thisObject, "anonymoutInt", 499);
                        }
                    });


            //hook内部类的构造方法失败，且会导致hook内部类的InnerFunc方法也失败，原因不明
//            XposedHelpers.findAndHookConstructor(clazz1, new XC_MethodHook() {
//                        @Override
//                        protected void beforeHookedMethod(MethodHookParam param) throws Throwable {
//                            XposedBridge.log("Haha, InnerClass constructed was hooked" );
//                        }
//                    });


            //Hook内部类InnerClass的InnerFunc方法，修改参数，顺便修改类中的innerPublicInt和innerPrivateInt变量
            final Class<?> clazz1 = XposedHelpers.findClass("com.example.xposedhooktarget.HookDemo$InnerClass", loadPackageParam.classLoader);
            XposedHelpers.findAndHookMethod(clazz1, "InnerFunc", String.class, new XC_MethodHook() {
                        @Override
                        protected void beforeHookedMethod(MethodHookParam param) throws Throwable {
                            param.args[0] = "Haha, InnerFunc was hooked";
                            XposedHelpers.setIntField(param.thisObject, "innerPublicInt", 9);
                            XposedHelpers.setIntField(param.thisObject, "innerPrivateInt", 19);
                        }
                    });
        }
    }


    private void getClassInfo(Class clazz) {
        //getFields()与getDeclaredFields()区别:getFields()只能访问类中声明为公有的字段,私有的字段它无法访问，
        //能访问从其它类继承来的公有方法.getDeclaredFields()能访问类中所有的字段,与public,private,protect无关，
        //不能访问从其它类继承来的方法
        //getMethods()与getDeclaredMethods()区别:getMethods()只能访问类中声明为公有的方法,私有的方法它无法访问,
        //能访问从其它类继承来的公有方法.getDeclaredFields()能访问类中所有的字段,与public,private,protect无关,
        //不能访问从其它类继承来的方法
        //getConstructors()与getDeclaredConstructors()区别:getConstructors()只能访问类中声明为public的构造函数
        //getDeclaredConstructors()能访问类中所有的构造函数,与public,private,protect无关


        //XposedHelpers.setStaticObjectField(clazz,"sMoney",110);
        //Field sMoney = clazz.getDeclaredField("sMoney");
        //sMoney.setAccessible(true);
        Field[] fs;
        Method[] md;
        Constructor[] cl;
        fs = clazz.getFields();
        for (int i = 0; i < fs.length; i++) {
            XposedBridge.log("HookDemo getFiled: " + Modifier.toString(fs[i].getModifiers()) + " " +
                    fs[i].getType().getName() + " " + fs[i].getName());
        }
        fs = clazz.getDeclaredFields();
        for (int i = 0; i < fs.length; i++) {
            XposedBridge.log("HookDemo getDeclaredFields: " + Modifier.toString(fs[i].getModifiers()) + " " +
                    fs[i].getType().getName() + " " + fs[i].getName());
        }
        md = clazz.getMethods();
        for (int i = 0; i < md.length; i++) {
            Class<?> returnType = md[i].getReturnType();
            XposedBridge.log("HookDemo getMethods: " + Modifier.toString(md[i].getModifiers()) + " " +
                    returnType.getName() + " " + md[i].getName());
            //获取参数
            //Class<?> para[] = md[i].getParameterTypes();
            //for (int j = 0; j < para.length; ++j) {
            //System.out.print(para[j].getName() + " " + "arg" + j);
            //if (j < para.length - 1) {
            //    System.out.print(",");
            //}
            //}
        }
        md = clazz.getDeclaredMethods();
        for (int i = 0; i < md.length; i++) {
            Class<?> returnType = md[i].getReturnType();
            XposedBridge.log("HookDemo getDeclaredMethods: " + Modifier.toString(md[i].getModifiers()) + " " +
                    returnType.getName() + " " + md[i].getName());
        }
        cl = clazz.getConstructors();
        for (int i = 0; i < cl.length; i++) {
            XposedBridge.log("HookDemo getConstructors: " + Modifier.toString(cl[i].getModifiers()) + " " +
                    md[i].getName());
        }
        cl = clazz.getDeclaredConstructors();
        for (int i = 0; i < cl.length; i++) {
            XposedBridge.log("HookDemo getDeclaredConstructors: " + Modifier.toString(cl[i].getModifiers()) + " " +
                    md[i].getName());
        }
    }
}

总结

1、hook的难点在于逆向分析，花的时间比较多。
2、理论上可以基于xposed做任何事。
3、若目标app改版升级什么的，需要重新适配，很麻烦。

demo地址：
链接:百度网盘请输入提取码密码:bvww

参考

https://github.com/rovo89/XposedBridge/wiki/Development-tutorial
Android Studio Xposed模块编写（二） - Gordon0918 - 博客园

我不怕千万人阻挡，只怕自己投降。