前言

前面写了两篇关于Xposed的一些基本使用，现在我们就把关注点集中到它的一些api上。

目录

Xposed Hook 构造方法
Xposed修改类属性
Xposed方法主动调用

Xposed Hook 构造方法

我们先看一下我们要hook的类

public class SharkUtils {
    public String name;
    private int age;

    public SharkUtils(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
}

Hook其构造方法的代码如下

public class HookTest implements IXposedHookLoadPackage {
    public void handleLoadPackage(XC_LoadPackage.LoadPackageParam loadPackageParam) throws Throwable {
        if (loadPackageParam.packageName.equals("com.shark.constructiontarget")) {
            XposedBridge.log(" has Hooked!");
            Class clazz = loadPackageParam.classLoader.loadClass(
                    "com.shark.uitls.SharkUtils");
            XposedHelpers.findAndHookConstructor(clazz, String.class, int.class, new XC_MethodHook() {
                @Override
                protected void beforeHookedMethod(MethodHookParam param) throws Throwable {
                    super.beforeHookedMethod(param);
                    XposedBridge.log("SharkUtils() is called!!beforeHookedMethod");
                    //得到参数
                    java.lang.Object[] params = param.args;

                    String name = (String) params[0];
                    int age = (int) params[1];

                    XposedBridge.log("name is:" + name);
                    XposedBridge.log("age is:" + age);
                }

                @Override
                protected void afterHookedMethod(MethodHookParam param) throws Throwable {
                    super.afterHookedMethod(param);
                    XposedBridge.log("SharkUtils() is called!!beforeHookedMethod");
                }
            });
        }
    }
}

Hook 构造方法使用findAndHookConstructor方法，param.args是参数数组他是Object[]类型，所以使用的时候记得转换一下。

---

Xposed修改类属性

这里可以使用反射去修改，但是Xposed已经提供了一套api供我们使用。它的核心也是反射。

需要hook的类如下

public class Student {
    public static String name = "fj";
    private int age;

    public Student(int age) {
        this.age = age;
    }

    public static String getName() {
        return name;
    }

    public static void setName(String name) {
        Student.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
}

修改静态属性

public class HookTest implements IXposedHookLoadPackage {
    public void handleLoadPackage(XC_LoadPackage.LoadPackageParam loadPackageParam) throws Throwable {
        if (loadPackageParam.packageName.equals("com.shark.constructiontarget")) {
            XposedBridge.log(" has Hooked!");
            //得到Class
            Class clazz = loadPackageParam.classLoader.loadClass(
                    "com.shark.uitls.Student");
            XposedBridge.log("Student Class->"+clazz);

            //修改静态属性
            XposedHelpers.setStaticObjectField(clazz, "name","shark");

            //获取静态属性
            String name= (String) XposedHelpers.getStaticObjectField(clazz,"name");

            XposedBridge.log("name is :"+name);
        }
    }
}

只要调用XposedHelpers.setStaticObjectField方法就可以完成修改了。对应的属性还有setStaticByteField、setStaticBooleanField等。

修改普通属性

public class HookTest implements IXposedHookLoadPackage {
    public void handleLoadPackage(XC_LoadPackage.LoadPackageParam loadPackageParam) throws Throwable {
        if (loadPackageParam.packageName.equals("com.shark.constructiontarget")) {
            XposedBridge.log(" has Hooked!");
            //得到Class
            Class clazz = loadPackageParam.classLoader.loadClass(
                    "com.shark.uitls.Student");
            //hook构造方法
            XposedHelpers.findAndHookConstructor(clazz, int.class, new XC_MethodHook() {
                @Override
                protected void beforeHookedMethod(MethodHookParam param) throws Throwable {
                    super.beforeHookedMethod(param);
                }

                @Override
                protected void afterHookedMethod(MethodHookParam param) throws Throwable {
                    super.afterHookedMethod(param);
                    //得到构造的对象
                    Object thisobj = param.thisObject;
                    //修改普通属性
                    XposedHelpers.setIntField(thisobj, "age", 24);
                }
            });
        }
    }
}

修改普通属性我们客户已hook其构造方法，使用param.thisObject得到对象，再调用 XposedHelpers.setIntField修改属性值。

---

Xposed方法主动调用

主动调用静态方法

public class HookTest implements IXposedHookLoadPackage {
    public void handleLoadPackage(XC_LoadPackage.LoadPackageParam loadPackageParam) throws Throwable {
        if (loadPackageParam.packageName.equals("com.shark.constructiontarget")) {
            XposedBridge.log(" has Hooked!");
            //得到Class
            Class clazz = loadPackageParam.classLoader.loadClass(
                    "com.shark.uitls.Student");
            //反射调用
//            Method getName = clazz.getDeclaredMethod("getName");
//            String invoke = (String) getName.invoke(null);
//            XposedBridge.log(invoke);

            //Xposed 提供的方式 设置name
            java.lang.Class<?>[] parameterTypes = {String.class};
            XposedHelpers.callStaticMethod(clazz,"setName",parameterTypes,"shark");
            //Xposed 提供的方式 获得name
            String getName1 = (String)XposedHelpers.callStaticMethod(clazz, "getName");
            XposedBridge.log(getName1);
        }
    }
}

同样你可以使用反射（在注释中已给出），Xposed也提供了XposedHelpers.callStaticMethod直接调用类的静态方法。

主动调用普通方法

public class HookTest implements IXposedHookLoadPackage {
    public void handleLoadPackage(XC_LoadPackage.LoadPackageParam loadPackageParam) throws Throwable {
        if (loadPackageParam.packageName.equals("com.shark.constructiontarget")) {
            XposedBridge.log(" has Hooked!");
            //得到Class
            Class clazz = loadPackageParam.classLoader.loadClass(
                    "com.shark.uitls.Student");

            //直接创建对象
//            Object student = XposedHelpers.newInstance(clazz, 30);
            //的到构造方法 创建对象
            Constructor declaredConstructor = clazz.getDeclaredConstructor(int.class);
            Object student = declaredConstructor.newInstance(33);
            //调用方法
            int getAge = (int) XposedHelpers.callMethod(student, "getAge");
            XposedBridge.log("age is:" + getAge);
        }
    }
}

Xposed提供了XposedHelpers.newInstance直接构造出对象，以此在调用XposedHelpers.callMethod就可以调用普通方法了。你也可以得到构造方法来new出对象。

但很多时候我们需要的是已经new出来的对象，而不是自己去new因为这个对象里面可能有我们需要用到的上下文。其实我们在Hook这个类的任意普通方法都可以通过param.thisObject得到该对象并保存到成员属性中，这样就能够去调用其对应的方法了

给个例子

public class HookTest implements IXposedHookLoadPackage {
    //主动调用的对象
    public Object studentObj;

    public void handleLoadPackage(XC_LoadPackage.LoadPackageParam loadPackageParam) throws Throwable {
        if (loadPackageParam.packageName.equals("com.shark.constructiontarget")) {
            XposedBridge.log(" has Hooked!");
            //得到Class
            Class Student = loadPackageParam.classLoader.loadClass(
                    "com.shark.uitls.Student");

            Class SharkUtils = loadPackageParam.classLoader.loadClass(
                    "com.shark.uitls.SharkUtils");

            //Hook Student的构造方法
            XposedHelpers.findAndHookConstructor(Student, int.class, new XC_MethodHook() {
                @Override
                protected void beforeHookedMethod(MethodHookParam param) throws Throwable {
                    super.beforeHookedMethod(param);
                }

                @Override
                protected void afterHookedMethod(MethodHookParam param) throws Throwable {
                    super.afterHookedMethod(param);
                    studentObj = param.thisObject;
                }
            });

            //Hook getName 在调用Student.getAge之前修改它
            XposedHelpers.findAndHookMethod(SharkUtils, "getName", new XC_MethodHook() {
                @Override
                protected void beforeHookedMethod(MethodHookParam param) throws Throwable {
                    super.beforeHookedMethod(param);
                    XposedHelpers.callMethod(studentObj,"setAge",80);
                }

                @Override
                protected void afterHookedMethod(MethodHookParam param) throws Throwable {
                    super.afterHookedMethod(param);
                }
            });
        }
    }
}