java.lang.IllegalArgumentException: There is no PasswordEncoder mapped for the id “null”

有些版本不要求这样子做,所以就不会有该问题的发生,
我现在用的是5.0版本,强制要求提供一个,所以我们就给一个PasswordEncoder给他.
我们也可以使用Spring自带的PasswordEncoder.为了方便起见,我们以明文形式存密码在后台,故使用自定义PasswordEncoder

public class MyPasswordEncoder implements PasswordEncoder {
 
    @Override
    public String encode(CharSequence arg0) {
        return arg0.toString();
    }
 
    @Override
    public boolean matches(CharSequence arg0, String arg1) {
        return arg1.equals(arg0.toString());
    }
 
}

@Configuration
@EnableWebSecurity
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {
 
    @Override
    protected void configure(AuthenticationManagerBuilder auth) throws Exception {
 
        auth
          .inMemoryAuthentication()
          .passwordEncoder(new MyPasswordEncoder())//在此处应用自定义PasswordEncoder
          .withUser("user")
          .password("password")
          .roles("USER");
    }
}

@Bean
    public PasswordEncoder passwordEncoder() {
        return new BCryptPasswordEncoder();
    }