我写了一个java类，它有很多getter ..现在我想得到所有的getter方法，并调用他们的时候..我知道有方法，如getMethods()或getMethod(字符串名称，类…parameterTypes)，但我只是想得到getter确实…，使用正则表达式?有人能告诉我吗?谢谢!
不要用正则表达式，用Introspector:
for(PropertyDescriptor propertyDescriptor :
Introspector.getBeanInfo(yourClass).getPropertyDescriptors()){
// propertyEditor.getReadMethod() exposes the getter
// btw, this may be null if you have a write-only property
System.out.println(propertyDescriptor.getReadMethod());
}
通常你不需要Object.class的属性，所以你会使用带有两个参数的方法:
Introspector.getBeanInfo(yourClass, stopClass)
// usually with Object.class as 2nd param
// the first class is inclusive, the second exclusive
顺便说一句:有框架可以为你做这些，并为你提供一个高级视图。如。Commons/beanutils有
方法Map<String, String> properties = BeanUtils.describe(yourObject);
(这里的docs)，它的作用是:查找并执行所有getter，并将结果存储在map中。不幸的是，BeanUtils.describe()在返回之前将所有属性值转换为string。WTF。由于@danw
更新:
这是一个基于对象bean属性返回Map<String, Object>的Java 8方法。
public static Map<String, Object> beanProperties(Object bean) {
try {
return Arrays.asList(
Introspector.getBeanInfo(bean.getClass(), Object.class)
.getPropertyDescriptors()
)
.stream()
// filter out properties with setters only
.filter(pd -> Objects.nonNull(pd.getReadMethod()))
.collect(Collectors.toMap(
// bean property name
PropertyDescriptor::getName,
pd -> { // invoke method to get value
try {
return pd.getReadMethod().invoke(bean);
} catch (Exception e) {
// replace this with better error handling
return null;
}
}));
} catch (IntrospectionException e) {
// and this, too
return Collections.emptyMap();
}
}
原来collections . tomap()讨厌空值。下面是上面代码的一个更命令式的版本:
public static Map<String, Object> beanProperties(Object bean) {
try {
Map<String, Object> map = new HashMap<>();
Arrays.asList(Introspector.getBeanInfo(bean.getClass(), Object.class)
.getPropertyDescriptors())
.stream()
// filter out properties with setters only
.filter(pd -> Objects.nonNull(pd.getReadMethod()))
.forEach(pd -> { // invoke method to get value
try {
Object value = pd.getReadMethod().invoke(bean);
if (value != null) {
map.put(pd.getName(), value);
}
} catch (Exception e) {
// add proper error handling here
}
});
return map;
} catch (IntrospectionException e) {
// and here, too
return Collections.emptyMap();
}
}
下面以更简洁的方式使用JavaSlang:
实现相同的功能public static Map<String, Object> javaSlangBeanProperties(Object bean) {
try {
return Stream.of(Introspector.getBeanInfo(bean.getClass(), Object.class)
.getPropertyDescriptors())
.filter(pd -> pd.getReadMethod() != null)
.toJavaMap(pd -> {
try {
return new Tuple2<>(
pd.getName(),
pd.getReadMethod().invoke(bean));
} catch (Exception e) {
throw new IllegalStateException();
}
});
} catch (IntrospectionException e) {
throw new IllegalStateException();
}
}
这是番石榴的版本:
public static Map<String, Object> guavaBeanProperties(Object bean) {
Object NULL = new Object();
try {
return Maps.transformValues(
Arrays.stream(
Introspector.getBeanInfo(bean.getClass(), Object.class)
.getPropertyDescriptors())
.filter(pd -> Objects.nonNull(pd.getReadMethod()))
.collect(ImmutableMap::<String, Object>builder,
(builder, pd) -> {
try {
Object result = pd.getReadMethod()
.invoke(bean);
builder.put(pd.getName(),
firstNonNull(result, NULL));
} catch (Exception e) {
throw propagate(e);
}
},
(left, right) -> left.putAll(right.build()))
.build(), v -> v == NULL ? null : v);
} catch (IntrospectionException e) {
throw propagate(e);
}
}
您可以使用Reflections框架来实现
import org.reflections.ReflectionUtils.*;
Set<Method> getters = ReflectionUtils.getAllMethods(someClass,
ReflectionUtils.withModifier(Modifier.PUBLIC), ReflectionUtils.withPrefix("get"));
Spring为Bean内省提供了一个简单的BeanUtil方法:
PropertyDescriptor pd = BeanUtils.getPropertyDescriptor(clazz, property);
Method getter = pd.getReadMethod();
// Get the Class object associated with this class.
MyClass myClass= new MyClass ();
Class objClass= myClass.getClass();
// Get the public methods associated with this class.
Method[] methods = objClass.getMethods();
for (Method method:methods)
{
System.out.println("Public method found: " + method.toString());
}
为什么不使用简单的Java呢?…
public static Map<String, Object> beanProperties(final Object bean) {
final Map<String, Object> result = new HashMap<String, Object>();
try {
final PropertyDescriptor[] propertyDescriptors = Introspector.getBeanInfo(bean.getClass(), Object.class).getPropertyDescriptors();
for (PropertyDescriptor propertyDescriptor : propertyDescriptors) {
final Method readMethod = propertyDescriptor.getReadMethod();
if (readMethod != null) {
result.put(propertyDescriptor.getName(), readMethod.invoke(bean, (Object[]) null));
}
}
} catch (Exception ex) {
// ignore
}
return result;
}
…
代码测试正常
private void callAllGetterMethodsInTestModel(TestModel testModelObject) {
try {
Class testModelClass = Class.forName("com.example.testreflectionapi.TestModel");
Method[] methods = testModelClass.getDeclaredMethods();
ArrayList<String> getterResults = new ArrayList<>();
for (Method method :
methods) {
if (method.getName().startsWith("get")){
getterResults.add((String) method.invoke(testModelObject));
}
}
Log.d("sayanReflextion", "==>: "+getterResults.toString());
} catch (ClassNotFoundException | IllegalAccessException | InvocationTargetException e) {
e.printStackTrace();
}
}
public static void retrieveAndExecuteBeanGetterMethods(Object bean) throws IntrospectionException {
List<PropertyDescriptor> beanGettersList = Arrays.asList(
Introspector.getBeanInfo(bean.getClass(), Object.class)
.getPropertyDescriptors());
beanGettersList.stream()
.filter(pd -> Objects.nonNull(pd.getReadMethod()))
.collect(Collectors.toMap(PropertyDescriptor::getName,
pd -> {
try {
return pd.getReadMethod().invoke(bean);
} catch (Exception e) {
return null;
}
}));
}