一个java实现代码(服务)编排的思路(未完)

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内容图文

创建模板java文件

使用freemaker创建一个java代码运行的模板，整体设计类似于模板方法设计模式，在模板内规定了程序运行的主体步骤，细节实现放在模板中的key中

前端配置模块

每个模块的背后都是一段提前写好的代码，这段代码是可以嵌入到之前准备好的模板的

用户通过拖拽模块来实现自己的逻辑

用户拖拽好模块并保存，后端基于模板及用户的配置信息，生成java文件

编译java文件

编辑java文件，加载相关的类，加入到spring容器中

后端提前准备好一个通用接口

这个接口的核心逻辑就是根据不同的java类名来调用spring容器中的类来完成逻辑。

已经写的demo类

@RestController
public class TestController {


    @Autowired
    private UserService userService;

    @GetMapping("/test")
    public String test01() throws Exception {
        String hello = userService.sayHello("hello");
        return hello;
    }
}

@Service
public class UserService {

    public String sayHello(String name) throws Exception {
        ReflectObj reflectObj = LoadClassUtil.map.get(name);
        return reflectObj.invoke();
    }
}

public class LoadClassUtil {


    public static Map<String, ReflectObj> map = new HashMap<>();
    static {
        try {
            loadClass("com.example.javasou.Hello");
        } catch (Exception exception) {
            exception.printStackTrace();
        }
    }

    //加载class对象
    public static void loadClass(String className) throws Exception {
        javac("E:\\learn\\java\\Hello.java");
        Thread.sleep(2000);
        MyClassLoader myClassLoader = new MyClassLoader();
        myClassLoader.setClassPath("E:\\learn\\java\\Hello.class");
        Class clazz = myClassLoader.loadClass(className);
        DynamicLoadUtils.addBean(clazz,"hello111",SpringContextUtil.getApplicationContext());
        Object obj = clazz.newInstance();
        map.put("hello",new ReflectObj(clazz, obj));
    }

    public static void javac(String packageAndClass) throws IOException {
        Runtime.getRuntime().exec("javac  " + packageAndClass);
    }
}

public class MyClassLoader extends ClassLoader {
    //需要加载类的路径
    private String classPath;

    public MyClassLoader() {
    }

    public MyClassLoader(String classPath) {
        super();
        this.classPath = classPath;
    }
    @Override
    protected Class<?> findClass(String name) throws ClassNotFoundException {
        Class<?> clazz = null;
        // 获取class文件字节码数组
        byte[] clazzByteArr = getData();

        if (clazzByteArr != null) {
            // 将class的字节码数组转换成class类的实例
            clazz = defineClass(name, clazzByteArr, 0, clazzByteArr.length);
        }
        return clazz;
    }

    private byte[] getData() {
        File file = new File(this.classPath);
        if (file.exists()) {
            FileInputStream in = null;
            ByteArrayOutputStream out = null;
            try {
                in = new FileInputStream(file);
                out = new ByteArrayOutputStream();

                byte[] buffer = new byte[1024];
                int size = 0;
                while ((size = in.read(buffer)) != -1) {
                    out.write(buffer, 0, size);
                }

            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return out.toByteArray();
        } else {
            return null;
        }
    }
    public String getClassPath() {
        return classPath;
    }
    public void setClassPath(String classPath) {
        this.classPath = classPath;
    }
}

public class ReflectObj {

    public ReflectObj(Class aClass, Object object) {
        this.aClass = aClass;
        this.object = object;
    }

    private Class aClass;
    private Object object;

    public String invoke() throws Exception {
        Method method = aClass.getMethod("sayHello", String.class);
        return (String) method.invoke(object, "123");
    }
}

@Component
public class SpringContextUtil implements ApplicationContextAware {

    private static ApplicationContext applicationContext;

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        SpringContextUtil.applicationContext = applicationContext;
    }

    //获取applicationContext
    public static ApplicationContext getApplicationContext() {
        return applicationContext;
    }

    //通过name获取 Bean.
    public static Object getBean(String name) {
        return getApplicationContext().getBean(name);
    }

    //通过class获取Bean.
    public static <T> T getBean(Class<T> clazz) {
        return getApplicationContext().getBean(clazz);
    }

    //通过name,以及Clazz返回指定的Bean
    public static <T> T getBean(String name, Class<T> clazz) {
        return getApplicationContext().getBean(name, clazz);
    }

}

public class DynamicLoadUtils {
    
    public static void registerController(String controllerBeanName) throws Exception {
        final RequestMappingHandlerMapping requestMappingHandlerMapping = (RequestMappingHandlerMapping)
                SpringContextUtil.getBean("requestMappingHandlerMapping");

        if (requestMappingHandlerMapping != null) {
            String handler = controllerBeanName;
            Object controller = SpringContextUtil.getBean(handler);
            if (controller == null) {
                return;
            }
            unregisterController(controllerBeanName);
            //注册Controller
            Method method = requestMappingHandlerMapping.getClass().getSuperclass().getSuperclass().
                    getDeclaredMethod("detectHandlerMethods", Object.class);
            method.setAccessible(true);
            method.invoke(requestMappingHandlerMapping, handler);
        }
    }

    public static void unregisterController(String controllerBeanName) {
        final RequestMappingHandlerMapping requestMappingHandlerMapping = (RequestMappingHandlerMapping)
                SpringContextUtil.getBean("requestMappingHandlerMapping");
        if (requestMappingHandlerMapping != null) {
            String handler = controllerBeanName;
            Object controller = SpringContextUtil.getBean(handler);
            if (controller == null) {
                return;
            }
            final Class<?> targetClass = controller.getClass();
            ReflectionUtils.doWithMethods(targetClass, new ReflectionUtils.MethodCallback() {
                @Override
                public void doWith(Method method) {
                    Method specificMethod = ClassUtils.getMostSpecificMethod(method, targetClass);
                    try {
                        Method createMappingMethod = RequestMappingHandlerMapping.class.
                                getDeclaredMethod("getMappingForMethod", Method.class, Class.class);
                        createMappingMethod.setAccessible(true);
                        RequestMappingInfo requestMappingInfo = (RequestMappingInfo)
                                createMappingMethod.invoke(requestMappingHandlerMapping, specificMethod, targetClass);
                        if (requestMappingInfo != null) {
                            requestMappingHandlerMapping.unregisterMapping(requestMappingInfo);
                        }
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }, ReflectionUtils.USER_DECLARED_METHODS);
        }
    }

    public static void addBean(String className, String serviceName, ApplicationContext app) {
        try {
            Class<?> clazz = Thread.currentThread().getContextClassLoader().loadClass(className);
            BeanDefinitionBuilder beanDefinitionBuilder = BeanDefinitionBuilder.genericBeanDefinition(clazz);
            registerBean(serviceName, beanDefinitionBuilder.getRawBeanDefinition(), app);
        } catch (ClassNotFoundException e) {
            System.out.println(className + ",主动注册失败.");
        }
    }

    public static void addBean(Class clazz, String serviceName, ApplicationContext app) {
        BeanDefinitionBuilder beanDefinitionBuilder = BeanDefinitionBuilder.genericBeanDefinition(clazz);
        registerBean(serviceName, beanDefinitionBuilder.getRawBeanDefinition(), app);
    }

    private static void registerBean(String beanName, BeanDefinition beanDefinition, ApplicationContext context) {
        ConfigurableApplicationContext configurableApplicationContext = (ConfigurableApplicationContext) context;
        BeanDefinitionRegistry beanDefinitonRegistry = (BeanDefinitionRegistry) configurableApplicationContext
                .getBeanFactory();
        beanDefinitonRegistry.registerBeanDefinition(beanName, beanDefinition);
    }

}

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