No qualifying bean of type ‘java.lang.String‘ available: expected at least 1 bean ...】

 Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'student' defined in file [D:\WorkHome\idea\spring\springall\spring_004_annotation\target\classes\com\bjpowernode\s02\Student.class]: Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'java.lang.String' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {}

//    public Student() {
//        System.out.println("学生的无参构造方法执行");
//    }

    public Student(String name, int age, School school) {
        this.name = name;
        this.age = age;
        this.school = school;
    }

package com.bjpowernode.s02;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("student")
public class Student {
    @Value("zhangsan")
    private String name;
    @Value("22")
    private  int age;

    @Autowired
    private School school;

//    public Student() {
//        System.out.println("学生的无参构造方法执行");
//    }
//
//    public Student(String name, int age, School school) {
//        this.name = name;
//        this.age = age;
//        this.school = school;
//    }

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", school=" + school +
                '}';
    }
}

注解创建对象方式，需要有一个无参构造函数（类中没有写任何的构造函数，默认就是有一个构造函数，如果写了任何一个构造函数，需要手动创建无参构造方法），无需set方法。

import org.springframework.stereotype.Component;

@Component("student")

在idea首次使用该注解时候，有可能不会自动导包，会爆红，不用改其他设置，记得导上面的包。