java.lang.IllegalArgumentException: There is no PasswordEncoder mapped for the id "null"报错

出现问题的原因：

　　内存用户验证时，Spring boot 2.0.1引用的security 依赖是 spring security 5.X版本，此版本需要提供一个PasswordEncorder的实例，否则后台汇报错误：
java.lang.IllegalArgumentException: There is no PasswordEncoder mapped for the id "null"
并且页面毫无响应。

解决方法：

创建PasswordEncorder的实现类MyPasswordEncoder。

代码一：

 1 package com.mmall.demo;
 2
 3 import org.springframework.security.crypto.password.PasswordEncoder;
 4
 5 public class MyPasswordEncoder implements PasswordEncoder {
 6     @Override
 7     public String encode(CharSequence rawPassword) {
 8         return rawPassword.toString();
 9     }
10
11     @Override
12     public boolean matches(CharSequence rawPassword, String encodedPassword) {
13         return encodedPassword.equals(rawPassword);
14     }
15 }

代码二：

 1 package com.mmall.demo;
 2
 3 import org.springframework.context.annotation.Configuration;
 4 import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;
 5 import org.springframework.security.config.annotation.web.builders.HttpSecurity;
 6 import org.springframework.security.config.annotation.web.builders.WebSecurity;
 7 import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
 8 import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
 9
10 @Configuration
11 @EnableWebSecurity
12 public class SpringSecurityConfig extends WebSecurityConfigurerAdapter {
13
14     @Override
15     protected void configure(AuthenticationManagerBuilder auth) throws Exception {
16         auth.inMemoryAuthentication().
17                 passwordEncoder(new MyPasswordEncoder()).
18                 withUser("admin").password("123456").roles("ADMIN");
19     }
20
21     @Override
22     protected void configure(HttpSecurity http) throws Exception {
23        http.authorizeRequests()
24                .antMatchers("/").permitAll()
25                .anyRequest().authenticated()
26                .and()
27                .logout().permitAll()
28                .and()
29                .formLogin();
30        http.csrf().disable();
31     }
32
33     @Override
34     public void configure(WebSecurity web) throws Exception {
35         web.ignoring().antMatchers("/js/**","/css/**","/image/**");
36     }
37
38
39 }

原文地址：https://www.cnblogs.com/chenyanlong/p/10688662.html