写简单的mvc框架实例讲解

import com.hebaibai.amvc.RequestType;
import java.lang.annotation.*;

/**
 * 表示这个类中的，添加了@Request注解的method被映射为一个http地址。
 *
 * @author hjx
 */
@Documented
@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface Request {

  /**
   * 请求类型
   * 支持GET，POST，DELETE，PUT
   *
   * @return
   */
  RequestType[] type() default {RequestType.GET, RequestType.POST, RequestType.DELETE, RequestType.PUT};

  /**
   * 请求地址
   * 添加在class上时，会将value中的值添加在其他方法上的@Request.value()的值前，作为基础地址。
   *
   * @return
   */
  String value() default "/";
}

{
 "annotationSupport": true,
 "annotationPackage": "com.hebaibai.demo.web",
// "mapping": [
//  {
//   "url": "/index",
//   "requestType": [
//    "get"
//   ],
//   "method": "index",
//   "objectClass": "com.hebaibai.demo.web.IndexController",
//   "paramTypes": [
//    "java.lang.String",
//    "int"
//   ]
//  }
// ]
}

/**
 * 从给定的报名中找出所有的class
 *
 * @param packageName
 * @param classes
 */
@SneakyThrows({IOException.class})
public static void getClassByPackage(String packageName, Set<Class> classes) {
  Assert.notNull(classes);
  String packagePath = packageName.replace(DOT, SLASH);
  Enumeration<URL> resources = ClassUtils.getClassLoader().getResources(packagePath);
  while (resources.hasMoreElements()) {
    URL url = resources.nextElement();
    //文件类型
    String protocol = url.getProtocol();
    String filePath = URLDecoder.decode(url.getFile(), CHARSET_UTF_8);
    if (TYPE_FILE.equals(protocol)) {
      getClassByFilePath(packageName, filePath, classes);
    }
    if (TYPE_JAR.equals(protocol)) {
      //截取文件的路径
      filePath = filePath.substring(filePath.indexOf(":") + 1, filePath.indexOf("!"));
      getClassByJarPath(packageName, filePath, classes);
    }
  }
}

/**
 * 在文件夹中递归找出该文件夹中在package中的class
 *
 * @param packageName
 * @param filePath
 * @param classes
 */
static void getClassByFilePath(
  String packageName,
  String filePath,
  Set<Class> classes
) {
  File targetFile = new File(filePath);
  if (!targetFile.exists()) {
    return;
  }
  if (targetFile.isDirectory()) {
    File[] files = targetFile.listFiles();
    for (File file : files) {
      String path = file.getPath();
      getClassByFilePath(packageName, path, classes);
    }
  } else {
    //如果是一个class文件
    boolean trueClass = filePath.endsWith(CLASS_MARK);
    if (trueClass) {
      //提取完整的类名
      filePath = filePath.replace(SLASH, DOT);
      int i = filePath.indexOf(packageName);
      String className = filePath.substring(i, filePath.length() - 6);
      //不是一个内部类
      boolean notInnerClass = className.indexOf("$") == -1;
      if (notInnerClass) {
        //根据类名加载class对象
        Class aClass = ClassUtils.forName(className);
        if (aClass != null) {
          classes.add(aClass);
        }
      }
    }
  }
}

/**
 * 在jar文件中找出该文件夹中在package中的class
 *
 * @param packageName
 * @param filePath
 * @param classes
 */
@SneakyThrows({IOException.class})
static void getClassByJarPath(
  String packageName,
  String filePath,
  Set<Class> classes
) {
  JarFile jarFile = new URLJarFile(new File(filePath));
  Enumeration<JarEntry> entries = jarFile.entries();
  while (entries.hasMoreElements()) {
    JarEntry jarEntry = entries.nextElement();
    String jarEntryName = jarEntry.getName().replace(SLASH, DOT);
    //在package下的class
    boolean trueClass = jarEntryName.endsWith(CLASS_MARK) && jarEntryName.startsWith(packageName);
    //不是一个内部类
    boolean notInnerClass = jarEntryName.indexOf("$") == -1;
    if (trueClass && notInnerClass) {
      String className = jarEntryName.substring(0, jarEntryName.length() - 6);
      System.out.println(className);
      //根据类名加载class对象
      Class aClass = ClassUtils.forName(className);
      if (aClass != null) {
        classes.add(aClass);
      }
    }
  }
}

/**
 * 通过解析Class 获取映射
 *
 * @param aClass
 * @return
 */
public List<UrlMethodMapping> getUrlMethodMappingListByClass(Class<Request> aClass) {
  List<UrlMethodMapping> mappings = new ArrayList<>();
  Request request = aClass.getDeclaredAnnotation(Request.class);
  if (request == null) {
    return mappings;
  }
  String basePath = request.value();
  for (Method classMethod : aClass.getDeclaredMethods()) {
    UrlMethodMapping urlMethodMapping = getUrlMethodMappingListByMethod(classMethod);
    if (urlMethodMapping == null) {
      continue;
    }
    //将添加在class上的Request中的path作为基础路径
    String url = UrlUtils.makeUrl(basePath + "/" + urlMethodMapping.getUrl());
    urlMethodMapping.setUrl(url);
    mappings.add(urlMethodMapping);
  }
  return mappings;
}

/**
 * 通过解析Method 获取映射
 * 注解Request不存在时跳出
 *
 * @param method
 * @return
 */
private UrlMethodMapping getUrlMethodMappingListByMethod(Method method) {
  Request request = method.getDeclaredAnnotation(Request.class);
  if (request == null) {
    return null;
  }
  Class<?> declaringClass = method.getDeclaringClass();
  String path = request.value();
  for (char c : path.toCharArray()) {
    Assert.isTrue(c != ' ', declaringClass + "." + method.getName() + "请求路径异常：" + path + " ！");
  }
  return getUrlMethodMapping(
      path,
      request.type(),
      declaringClass,
      method,
      method.getParameterTypes()
  );
}

private static final String SLASH = "/";

/**
 * 处理url
 * 1：去掉连接中相邻并重复的“/”,
 * 2：链接开头没有“/”,则添加。
 * 3：链接结尾有“/”，则去掉。
 *
 * @param url
 * @return
 */
public static String makeUrl(@NonNull String url) {
  char[] chars = url.toCharArray();
  StringBuilder newUrl = new StringBuilder();
  if (!url.startsWith(SLASH)) {
    newUrl.append(SLASH);
  }
  for (int i = 0; i < chars.length; i++) {
    if (i != 0 && chars[i] == chars[i - 1] && chars[i] == '/') {
      continue;
    }
    if (i == chars.length - 1 && chars[i] == '/') {
      continue;
    }
    newUrl.append(chars[i]);
  }
  return newUrl.toString();
}

/**
 * 使用注解来加载UrlMethodMapping
 *
 * @param configJson
 */
private void addApplicationUrlMappingByAnnotationConfig(JSONObject configJson) {
  String annotationPackage = configJson.getString(ANNOTATION_PACKAGE_NODE);
  Assert.notNull(annotationPackage, ANNOTATION_PACKAGE_NODE + NOT_FIND);
  //获取添加了@Request的类
  Set<Class> classes = new HashSet<>();
  ClassUtils.getClassByPackage(annotationPackage, classes);
  Iterator<Class> iterator = classes.iterator();
  while (iterator.hasNext()) {
    Class aClass = iterator.next();
    List<UrlMethodMapping> mappings = urlMethodMappingFactory.getUrlMethodMappingListByClass(aClass);
    if (mappings.size() == 0) {
      continue;
    }
    for (UrlMethodMapping mapping : mappings) {
      addApplicationUrlMapping(mapping);
    }
  }
}

/**
 * 使用文件配置来加载UrlMethodMapping
 * 配置中找不到的话不执行。
 *
 * @param configJson
 */
private void addApplicationUrlMappingByJsonConfig(JSONObject configJson) {
  JSONArray jsonArray = configJson.getJSONArray(MAPPING_NODE);
  if (jsonArray == null || jsonArray.size() == 0) {
    return;
  }
  for (int i = 0; i < jsonArray.size(); i++) {
    UrlMethodMapping mapping = urlMethodMappingFactory.getUrlMethodMappingByJson(jsonArray.getJSONObject(i));
    addApplicationUrlMapping(mapping);
  }
}

/**
 * 初始化配置
 */
@SneakyThrows(IOException.class)
protected void init() {
  String configFileName = applicationName + ".json";
  InputStream inputStream = ClassUtils.getClassLoader().getResourceAsStream(configFileName);
  byte[] bytes = new byte[inputStream.available()];
  inputStream.read(bytes);
  String config = new String(bytes, "utf-8");
  //应用配置
  JSONObject configJson = JSONObject.parseObject(config);

  //TODO:生成对象的工厂类（先默认为每次都new一个新的对象）
  this.objectFactory = new AlwaysNewObjectFactory();
  //TODO:不同的入参名称获取类（当前默认为asm）
  urlMethodMappingFactory.setParamNameGetter(new AsmParamNameGetter());
  //通过文件配置加载
  addApplicationUrlMappingByJsonConfig(configJson);
  //是否开启注解支持
  Boolean annotationSupport = configJson.getBoolean(ANNOTATION_SUPPORT_NODE);
  Assert.notNull(annotationSupport, ANNOTATION_SUPPORT_NODE + NOT_FIND);
  if (annotationSupport) {
    addApplicationUrlMappingByAnnotationConfig(configJson);
  }
}