对反射的封装

--摘自《android插件化开发指南》

前面是基本封装，后面是进一步的封装

一。基本封装

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;

public class RefInvoke {

    //构造函数
    public static Object createObject(String className, Class[] pareTyples, Object[] pareVaules) {
        try {
            Class r = Class.forName(className);
            Constructor ctor = r.getDeclaredConstructor(pareTyples);
            ctor.setAccessible(true);
            return ctor.newInstance(pareVaules);
        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }

    //调用实例方法
    public static Object invokeInstanceMethod(Object obj, String methodName, Class[] pareTyples, Object[] pareVaules) {
        if (obj == null)
            return null;

        try {
            //调用一个private方法
            Method method = obj.getClass().getDeclaredMethod(methodName, pareTyples); //在指定类中获取指定的方法
            method.setAccessible(true);
            return method.invoke(obj, pareVaules);

        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }

    //调用静态方法
    public static Object invokeStaticMethod(String className, String method_name, Class[] pareTyples, Object[] pareVaules) {
        try {
            Class obj_class = Class.forName(className);
            Method method = obj_class.getDeclaredMethod(method_name, pareTyples);
            method.setAccessible(true);
            return method.invoke(null, pareVaules);
        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }

    //获取字段值
    public static Object getFieldObject(String className, Object obj, String filedName) {
        try {
            Class obj_class = Class.forName(className);
            Field field = obj_class.getDeclaredField(filedName);
            field.setAccessible(true);
            return field.get(obj);
        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }

    //设置字段值
    public static void setFieldObject(String classname, Object obj, String filedName, Object filedVaule) {
        try {
            Class obj_class = Class.forName(classname);
            Field field = obj_class.getDeclaredField(filedName);
            field.setAccessible(true);
            field.set(obj, filedVaule);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

No1:

构造函数

public class TestClassCtor {
    private String name;

    public TestClassCtor() {
        name = "baobao";
    }

    public TestClassCtor(int a) {

    }

    public TestClassCtor(int a, String b) {
        name = b;
    }

    private TestClassCtor(int a, double c) {

    }

    @Override
    public String toString() {
        return name;
    }
}

try {
            String className = "com.example.reflectiontest.TestClassCtor";
            Class r = Class.forName(className);

            //含参
            Class[] p3 = {int.class, String.class};
            Object[] v3 = {1, "bjq"};
            Object obj = RefInvoke.createObject(className, p3, v3);
            System.out.println(obj.toString());

            //无参
            Object obj2 = RefInvoke.createObject(className, null, null);
            System.out.println(obj2.toString());

        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
-------------------
bjq
baobao

No2：

实例方法

public class TestClassCtor {
    private String name;

    public TestClassCtor() {
        name = "baobao";
    }

    public TestClassCtor(int a) {

    }

    public TestClassCtor(int a, String b) {
        name = b;
    }

    private TestClassCtor(int a, double c) {

    }

    private String doSomething(String d) {
        System.out.println("TestClassCtor,doSomething");
        return "123" + d;
    }
}

try {
    String className = "com.example.reflectiontest.TestClassCtor";
    Class r = Class.forName(className);

    Class[] p3 = {int.class, String.class};
    Object[] v3 = {1, "bjq"};
    Object obj = RefInvoke.createObject(className, p3, v3);
    //含参
    Class[] p4 = {String.class};
    Object[] v4 = {"jianqiang"};
    Object result = RefInvoke.invokeInstanceMethod(obj, "doSomething", p4, v4);
    System.out.println(result.toString());

} catch (ClassNotFoundException e) {
    e.printStackTrace();
}
-------------------------
TestClassCtor,doSomething
123jianqiang

No3：

调用静态方法

public class TestClassCtor {
    private String name;

    public TestClassCtor() {
        name = "baobao";
    }

    public TestClassCtor(int a) {

    }

    public TestClassCtor(int a, String b) {
        name = b;
    }

    private TestClassCtor(int a, double c) {

    }

    private static void work() {
        System.out.println("TestClassCtor,work");
    }
}

try {
    String className = "com.example.reflectiontest.TestClassCtor";
    Class r = Class.forName(className);

    //含参
    Class[] p5 = {};
    Object[] v5 = {};
    RefInvoke.invokeStaticMethod(className, "work", p5, v5);

} catch (ClassNotFoundException e) {
    e.printStackTrace();
}
-----------------------
TestClassCtor,work

No4：

设置字段的值

public class TestClassCtor {
    private String name;
    private static String address;

    public TestClassCtor() {
        name = "baobao";
    }

    public TestClassCtor(int a) {

    }

    public TestClassCtor(int a, String b) {
        name = b;
    }

    private TestClassCtor(int a, double c) {

    }
}

try {
    String className = "com.example.reflectiontest.TestClassCtor";
    Class r = Class.forName(className);

    Class[] p3 = {int.class, String.class};
    Object[] v3 = {1, "bjq"};
    Object obj = RefInvoke.createObject(className, p3, v3);

    RefInvoke.setFieldObject(className, obj, "name", "jianqiang1982");
    Object fieldObject = RefInvoke.getFieldObject(className, obj, "name");
    System.out.println(fieldObject.toString());

    RefInvoke.setFieldObject(className, null, "address", "ABCD");
    Object fieldObject2 = RefInvoke.getFieldObject(className, null, "address");
    System.out.println(fieldObject2.toString());

} catch (ClassNotFoundException e) {
    e.printStackTrace();
}
---------------------
jianqiang1982
ABCD

二。进一步封装

其实就是重构了一下

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;

public class RefInvoke {

    //无参
    public static Object createObject(String className) {
        Class[] pareTyples = new Class[]{};
        Object[] pareVaules = new Object[]{};

        try {
            Class r = Class.forName(className);
            return createObject(r, pareTyples, pareVaules);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }

        return null;
    }

    //无参
    public static Object createObject(Class clazz) {
        Class[] pareTyple = new Class[]{};
        Object[] pareVaules = new Object[]{};

        return createObject(clazz, pareTyple, pareVaules);
    }

    //一个参数
    public static Object createObject(String className, Class pareTyple, Object pareVaule) {
        Class[] pareTyples = new Class[]{pareTyple};
        Object[] pareVaules = new Object[]{pareVaule};

        try {
            Class r = Class.forName(className);
            return createObject(r, pareTyples, pareVaules);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }

        return null;
    }

    //一个参数
    public static Object createObject(Class clazz, Class pareTyple, Object pareVaule) {
        Class[] pareTyples = new Class[]{pareTyple};
        Object[] pareVaules = new Object[]{pareVaule};

        return createObject(clazz, pareTyples, pareVaules);
    }

    //多个参数
    public static Object createObject(String className, Class[] pareTyples, Object[] pareVaules) {
        try {
            Class r = Class.forName(className);
            return createObject(r, pareTyples, pareVaules);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }

        return null;
    }

    //多个参数
    public static Object createObject(Class clazz, Class[] pareTyples, Object[] pareVaules) {
        try {
            Constructor ctor = clazz.getDeclaredConstructor(pareTyples);
            ctor.setAccessible(true);
            return ctor.newInstance(pareVaules);
        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }


    //多个参数
    public static Object invokeInstanceMethod(Object obj, String methodName, Class[] pareTyples, Object[] pareVaules) {
        if (obj == null)
            return null;

        try {
            //调用一个private方法
            Method method = obj.getClass().getDeclaredMethod(methodName, pareTyples); //在指定类中获取指定的方法
            method.setAccessible(true);
            return method.invoke(obj, pareVaules);

        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }

    //一个参数
    public static Object invokeInstanceMethod(Object obj, String methodName, Class pareTyple, Object pareVaule) {
        Class[] pareTyples = {pareTyple};
        Object[] pareVaules = {pareVaule};

        return invokeInstanceMethod(obj, methodName, pareTyples, pareVaules);
    }

    //无参
    public static Object invokeInstanceMethod(Object obj, String methodName) {
        Class[] pareTyples = new Class[]{};
        Object[] pareVaules = new Object[]{};

        return invokeInstanceMethod(obj, methodName, pareTyples, pareVaules);
    }


    //无参
    public static Object invokeStaticMethod(String className, String method_name) {
        Class[] pareTyples = new Class[]{};
        Object[] pareVaules = new Object[]{};

        return invokeStaticMethod(className, method_name, pareTyples, pareVaules);
    }

    //一个参数
    public static Object invokeStaticMethod(String className, String method_name, Class pareTyple, Object pareVaule) {
        Class[] pareTyples = new Class[]{pareTyple};
        Object[] pareVaules = new Object[]{pareVaule};

        return invokeStaticMethod(className, method_name, pareTyples, pareVaules);
    }

    //多个参数
    public static Object invokeStaticMethod(String className, String method_name, Class[] pareTyples, Object[] pareVaules) {
        try {
            Class obj_class = Class.forName(className);
            return invokeStaticMethod(obj_class, method_name, pareTyples, pareVaules);
        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }

    //无参
    public static Object invokeStaticMethod(Class clazz, String method_name) {
        Class[] pareTyples = new Class[]{};
        Object[] pareVaules = new Object[]{};

        return invokeStaticMethod(clazz, method_name, pareTyples, pareVaules);
    }

    //一个参数
    public static Object invokeStaticMethod(Class clazz, String method_name, Class classType, Object pareVaule) {
        Class[] classTypes = new Class[]{classType};
        Object[] pareVaules = new Object[]{pareVaule};

        return invokeStaticMethod(clazz, method_name, classTypes, pareVaules);
    }

    //多个参数
    public static Object invokeStaticMethod(Class clazz, String method_name, Class[] pareTyples, Object[] pareVaules) {
        try {
            Method method = clazz.getDeclaredMethod(method_name, pareTyples);
            method.setAccessible(true);
            return method.invoke(null, pareVaules);
        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }


    //简写版本
    public static Object getFieldObject(Object obj, String filedName) {
        return getFieldObject(obj.getClass(), obj, filedName);
    }

    public static Object getFieldObject(String className, Object obj, String filedName) {
        try {
            Class obj_class = Class.forName(className);
            return getFieldObject(obj_class, obj, filedName);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        return null;
    }

    public static Object getFieldObject(Class clazz, Object obj, String filedName) {
        try {
            Field field = clazz.getDeclaredField(filedName);
            field.setAccessible(true);
            return field.get(obj);
        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }

    //简写版本
    public static void setFieldObject(Object obj, String filedName, Object filedVaule) {
        setFieldObject(obj.getClass(), obj, filedName, filedVaule);
    }

    public static void setFieldObject(Class clazz, Object obj, String filedName, Object filedVaule) {
        try {
            Field field = clazz.getDeclaredField(filedName);
            field.setAccessible(true);
            field.set(obj, filedVaule);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static void setFieldObject(String className, Object obj, String filedName, Object filedVaule) {
        try {
            Class obj_class = Class.forName(className);
            setFieldObject(obj_class, obj, filedName, filedVaule);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }


    public static Object getStaticFieldObject(String className, String filedName) {
        return getFieldObject(className, null, filedName);
    }

    public static Object getStaticFieldObject(Class clazz, String filedName) {
        return getFieldObject(clazz, null, filedName);
    }

    public static void setStaticFieldObject(String classname, String filedName, Object filedVaule) {
        setFieldObject(classname, null, filedName, filedVaule);
    }

    public static void setStaticFieldObject(Class clazz, String filedName, Object filedVaule) {
        setFieldObject(clazz, null, filedName, filedVaule);
    }
}

只要掌握了基本的java反射，就能够封装出来

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