标签：str runnable list org tor java 添加 optional tps
函数可以作为变量、参数、返回值和数据类型
相关内容有@FunctionalInterface(Runnable、Comparator内部添加了)，Lambda和函数式接口
感觉上面这句话就说的很有道理，下面针对普通函数,lambda和具体内部实现来说下
Runnable runnable = new Runnable() {
@Override
public void run() {
System.out.println("do something");
}
};
从上面内部类和下面函数式接口可以看出，Lambda其实就是在函数式接口上进一步简化了代码
Runnable runnable = () -> System.out.println("do Something");
Optional<Integer> result = Stream.of("a", "be", "hello")
.map(s -> s.length())
.filter(l-> l <= 3)
.max((o1, o2) -> o1-o2);
System.out.println(result.get());
Optional<Integer> result = Stream.of("a", "be", "hello")
//功能性接口：类型转换
.map(new Function<String, Integer>() {
@Override
public Integer apply(String s) {
return s.length();
}
})
//谓语性接口：返回bool值
.filter(new Predicate<Integer>() {
@Override
public boolean test(Integer integer) {
return integer <= 3;
}
})
//comparator比较器(对象内部比较还可以实现Comparable接口)，o1-o2是升序,1,2输出2，若是o2-o1则是逆序，输出1
.max(new Comparator<Integer>() {
@Override
public int compare(Integer o1, Integer o2) {
return o1 - o2;
}
});
System.out.println(result.get());
package lambda;
import java.util.*;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.stream.Stream;
/**
* @ProjectName: Method
* @Package: lambda
* @Description:
* @Author: huyuqiao
* @CreateDate: 2020/9/22 9:17
*/
public class Method {
private static void oldFunction(){
Runnable runnable = new Runnable() {
@Override
public void run() {
System.out.println("do something");
}
};
}
private static void newFunction(){
Runnable runnable = () -> System.out.println("do Something");
}
private static void optionalFunction(){
Optional<Integer> result = Stream.of("a", "be", "hello")
.map(s -> s.length())
.filter(l-> l <= 3)
.max((o1, o2) -> o1-o2);
System.out.println(result.get());
}
/*这个函数是上面的全写，上面函数进行了简化*/
private static void optionalFunction_2(){
Optional<Integer> result = Stream.of("a", "be", "hello")
//功能性接口：类型转换
.map(new Function<String, Integer>() {
@Override
public Integer apply(String s) {
return s.length();
}
})
//谓语性接口：返回bool值
.filter(new Predicate<Integer>() {
@Override
public boolean test(Integer integer) {
return integer <= 3;
}
})
//comparator比较器(对象内部比较还可以实现Comparable接口)，o1-o2是升序,1,2输出2，若是o2-o1则是逆序，输出1
.max(new Comparator<Integer>() {
@Override
public int compare(Integer o1, Integer o2) {
return o1 - o2;
}
});
System.out.println(result.get());
}
private static void compareFunction(){
List<User> users = new ArrayList<>();
users.add(new User(2, "asdf", "sadf"));
users.add(new User(1, "asdf", "sadf"));
Collections.sort(users, new Comparator<User>() {
@Override
public int compare(User o1, User o2) {
return Integer.compare(o2.getId(), o1.getId());
}
});
users.stream().forEach(System.out::println);
}
private static void compareFunction_2(){
List<User> users = new ArrayList<>();
users.add(new User(2, "asdf", "sadf"));
users.add(new User(1, "asdf", "sadf"));
//定义比较器
Comparator<User> comparator = (u1, u2) -> Integer.compare(u1.getId(), u2.getId());
users.sort(comparator);
users.stream().forEach(System.out::println);
}
public static void main(String[] args){
/* oldFunction();
newFunction();
optionalFunction();
optionalFunction_2();*/
// compareFunction();
compareFunction_2();
}
}
之前写的四个函数式接口： https://www.cnblogs.com/meditation5201314/p/13693089.html
SpringMvc:@ControllerAdvice具备下面3个功能：
前面2个好理解，最后一个数据预处理在传递多个参数的时候，如果遇到变量名相同，后台就无法区分，所以需要配置进行区分（之前好像都没遇到过，记录一下）
给出两个相同类，Controller层里面就要进行区分(postman中就要使用u.userName,p.userName来进行区分，否则什么都不写的话原来默认就是全部覆盖.)
@PostMapping("/book")
public void addBook(@ModelAttribute("u") User user, @ModelAttribute("p")Person person, Model model){
System.out.println(user);
System.out.println(person);
Map<String, Object> map = model.asMap();
System.out.println(map);
}
package huyuqiao.exception;
import org.springframework.web.bind.WebDataBinder;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.InitBinder;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.servlet.ModelAndView;
import java.util.HashMap;
import java.util.Map;
/**
* @ProjectName: GloabalExceptionHandler
* @Package: huyuqiao.exception
* @Description:
* @Author: huyuqiao
* @CreateDate: 2020/9/22 19:01
*/
@ControllerAdvice
public class GloabalExceptionHandler {
/*全局异常处理---可以改成NullPointerException异常处理*/
@ExceptionHandler(Exception.class)
public ModelAndView customException(Exception e) {
ModelAndView mv = new ModelAndView();
mv.addObject("message", e.getMessage());
mv.setViewName("myerror");
return mv;
}
/*全局数据绑定*/
@ModelAttribute(name = "md")
public Map<String,Object> mydata() {
HashMap<String, Object> map = new HashMap<>();
map.put("age", 99);
map.put("gender", "男");
return map;
}
/*全局数据预处理*/
@InitBinder("u")
public void u(WebDataBinder binder) {
binder.setFieldDefaultPrefix("u.");
}
@InitBinder("p")
public void p(WebDataBinder binder) {
binder.setFieldDefaultPrefix("p.");
}
}
Java-学习日记(函数式编程与@ControllerAdvice)
标签：str runnable list org tor java 添加 optional tps
原文地址：https://www.cnblogs.com/meditation5201314/p/13714417.html
