Mybatis反射核心类Reflector的实现

public class Reflector {
  // 要被反射解析的类
  private final Class<?> type;
  // 可读属性列表即有get方法的属性列表
  private final String[] readablePropertyNames;
  // 可写属性列表即有set方法的属性列表
  private final String[] writeablePropertyNames;
  // set方法映射表。键为属性名,值为对应的set方法
  private final Map<String, Invoker> setMethods = new HashMap<String, Invoker>();
  // get方法映射表。键为属性名,值为对应的get方法
  private final Map<String, Invoker> getMethods = new HashMap<String, Invoker>();
  // set方法输入参数类型映射表。键为属性名,值为对应set方法输入参数类型的Class
  private final Map<String, Class<?>> setTypes = new HashMap<String, Class<?>>();
  // get方法返回值类型映射表。键为属性名,值为对应get方法返回值类型的Class
  private final Map<String, Class<?>> getTypes = new HashMap<String, Class<?>>();
  // 默认构造器
  private Constructor<?> defaultConstructor;
  // 忽略大小写的属性映射表。键为属性名全大写值，值为属性名
  private Map<String, String> caseInsensitivePropertyMap = new HashMap<String, String>();
  // Reflector类反射解析一个类的过程是由构造函数触发的
  public Reflector(Class<?> clazz) {
    // 记录被反射解析的类
    type = clazz;
    // 解析默认造方法
    addDefaultConstructor(clazz);
    // 解析所有的getter
    addGetMethods(clazz);
    // 解析所有的setter
    addSetMethods(clazz);
    // 解析所有属性
    addFields(clazz);
    // 获取可读属性列表
    readablePropertyNames = getMethods.keySet().toArray(new String[getMethods.keySet().size()]);
    // 获取可写属性列表
    writeablePropertyNames = setMethods.keySet().toArray(new String[setMethods.keySet().size()]);
    // 获取忽略大小写的属性列表
    for (String propName : readablePropertyNames) {
      caseInsensitivePropertyMap.put(propName.toUpperCase(Locale.ENGLISH), propName);
    }
    for (String propName : writeablePropertyNames) {
      caseInsensitivePropertyMap.put(propName.toUpperCase(Locale.ENGLISH), propName);
    }
  }
  .....
}

1、直接new
Reflector reflector = new Reflector(User.class);
2、工厂创建
ReflectorFactory reflectorFactory = new DefaultReflectorFactory();
Reflector reflector = reflectorFactory.findForClass(User.class);

Reflector reflector = new Reflector(User.class);
// 获取被解析反射的类
Class<?> type = reflector.getType();
// 根据属性名获取对应的set方法
Invoker setInvoker = reflector.getSetInvoker("name");
// 根据属性名获取对应的get方法
Invoker getInvoker = reflector.getGetInvoker("name");
// 获取所有可读属性列表
String[] getablePropertyNames = reflector.getGetablePropertyNames();
// 获取所有可写属性列表
String[] setablePropertyNames = reflector.getSetablePropertyNames();
// 获取默认构造器
Constructor<?> defaultConstructor = reflector.getDefaultConstructor();
// 根据属性名获取对应get方法返回值类型
Class<?> getterType = reflector.getGetterType("name");
// 根据属性名获取对应set方法参数类型
Class<?> setterType = reflector.getSetterType("name");
// 根据属性名不区分大小写获取属性名
String name = reflector.findPropertyName("name");
// 判断属性是否存在getter方法
boolean hasGetter = reflector.hasGetter("name");
// 判断属性是否存在getter方法
boolean hasSetter = reflector.hasSetter("name");

    @Test
    public void test1()throws Exception{
        Reflector reflector = new Reflector(User.class);
        Class<?> type = reflector.getType();
        System.out.println("要被反射解析的类:"+type);
        Constructor<?> defaultConstructor = reflector.getDefaultConstructor();
        System.out.println(defaultConstructor);
        String[] getablePropertyNames = reflector.getGetablePropertyNames();
        for (String propertyName : getablePropertyNames) {
            System.out.println("可读属性:"+propertyName);
        }
        System.out.println("----------------------------------------------------------");
        String[] setablePropertyNames = reflector.getSetablePropertyNames();
        for (String propertyName : setablePropertyNames) {
            System.out.println("可写属性:"+propertyName);
        }
        System.out.println("--------------------------------------------------");
        for (String propertyName : reflector.getGetablePropertyNames()) {
            Invoker name = reflector.getGetInvoker(propertyName);
            Object invoke = name.invoke(new User(), null);
            System.out.println("执行属性"+propertyName+"的get方法："+invoke);
        }
    }

  private String getSignature(Method method) {
    StringBuilder sb = new StringBuilder();
    Class<?> returnType = method.getReturnType();
    if (returnType != null) {
      sb.append(returnType.getName()).append('#');
    }
    sb.append(method.getName());
    Class<?>[] parameters = method.getParameterTypes();
    for (int i = 0; i < parameters.length; i++) {
      if (i == 0) {
        sb.append(':');
      } else {
        sb.append(',');
      }
      sb.append(parameters[i].getName());
    }
    return sb.toString();
  }