public V compute(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction)
  
  对于指定key做remappingFunction函数调用，remappingFunction函数返回值即为新的value，如果返回值为null，则从map中删除对应的key。compute返回key更新后的值（remappingFunction函数返回值）

public V computeIfAbsent(K key, Function<? super K, ? extends V> mappingFunction)

  如果指定的key不存在，对该key做mappingFunction函数操作，mappingFunction函数返回值不为null，则将对应的k-v放到map中，否则不操作。如果key不存在computeIfAbsent返回值同mappingFunction，如果key存在返回key对应的value（此时mappingFunction不会调用）。

public V computeIfPresent(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction)

类似与computeIfAbsent，仅对已经存在的key才计算新value。同样，如果remappingFunction返回值为null，会删除对应的k-v。

public interface CrudRepository<T> {

    Iterable<T> findAll();

}

public class BaseImpl <T> implements CrudRepository<T> {

    @Override
    public Iterable<T> findAll() {
        Class<T> c = getTClass();
        System.out.println(c);
        common(c);
        return null;
    }

    /**
     * 通用的方法使用泛型的class去干一些事情。
     *
     * @param c 泛型类
     */
    private void common(Class<T> c) {

    }

    /**
     * 获取 T.class
     */
    public Class<T> getTClass() {
        return (Class<T>) ((ParameterizedType) getClass().getGenericSuperclass()).getActualTypeArguments()[0];
    }
}

public class PhoneRepository extends BaseImpl<Phone> {

    public static class Phone {
        private static final long serialVersionUID = 1L;
        private String name;
        private Long price;
        private Long updateDate;

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public Long getPrice() {
            return price;
        }

        public void setPrice(Long price) {
            this.price = price;
        }

        public Long getUpdateDate() {
            return updateDate;
        }

        public void setUpdateDate(Long updateDate) {
            this.updateDate = updateDate;
        }
    }
}

public class Test {

    public static void main(String[] args) {
        PhoneRepository phoneRepository = new PhoneRepository();
        Iterable<Phone> phones = phoneRepository.findAll();
    }
}

结果：
class cn.zero.reflect.PhoneRepository$Phone

public class GenericsUtils {

    /**
     * 通过反射,获得定义Class时声明的父类的范型参数的类型.
     *
     * 如public BookManager extends Manager<Book>
     */
    public static Class getSuperClassGenericType(Class clazz) {
        return getSuperClassGenericType(clazz, 0);
    }

    /**
     * 通过反射,获得定义Class时声明的父类的范型参数的类型.
     *
     * 如public BookManager extends Manager<Book>, 返回Book
     */
    public static Class getSuperClassGenericType(Class clazz, int index) throws IndexOutOfBoundsException {
        Type genType = clazz.getGenericSuperclass();
        if (!(genType instanceof ParameterizedType)) {
            return Object.class;
        }
        Type[] params = ((ParameterizedType) genType).getActualTypeArguments();
        if (index >= params.length || index < 0) {
            return Object.class;
        }
        if (!(params[index] instanceof Class)) {
            return Object.class;
        }
        return (Class) params[index];
    }
}

Process process = Runtime.getRuntime().exec(shPath);
int exitCode = process.waitFor();

//padEnd 尾填充
String a = "12345";
String b = Strings.padEnd(a, 7, 'x');
System.out.println(b); // 12345xx

//padStart 头填充
String a="12345";
String b=Strings.padStart(a, 7, 'x');
System.out.println(b); // xx12345

//Strings.isNullOrEmpty  空校验
String a = "";
boolean b = Strings.isNullOrEmpty(a);
System.out.println(b);

//Strings.nullToEmpty  如果为null 转为""
String a = null;
String b = Strings.nullToEmpty(a);
System.out.println(b);

//Strings.emptyToNull  如果为"" 转为null
String a = "";
String b = Strings.emptyToNull(a);
System.out.println(b); // null

//Strings.repeat  重复字符串
String a = "123";
String b = Strings.repeat(a, 3);
System.out.println(b); // 123123123

//Strings.commonPrefix 获取a,b左公共部分字符串
String a = "abcdsfsfs";
String b = "abc3sfsd";
String c = Strings.commonPrefix(a, b);
System.out.println(c); // abc

//Strings.commonSuffix 获取a,b右公共部分字符串
String a = "faaxyz";
String b = "fwefxyz";
String c = Strings.commonSuffix(a, b);
System.out.println(c); // xyz