spring security用了也有一段时间了，弄过异步和多数据源登录，也看过一点源码，最近弄rest，然后顺便搭oauth2，前端用json来登录，没想到spring security默认居然不能获取request中的json数据，谷歌一波后只在stackoverflow找到一个回答比较靠谱，还是得要重写filter，于是在这里填一波坑。
准备工作
基本的spring security配置就不说了，网上一堆例子，只要弄到普通的表单登录和自定义UserDetailsService就可以。因为需要重写Filter，所以需要对spring security的工作流程有一定的了解，这里简单说一下spring security的原理。
spring security 是基于javax.servlet.Filter的，因此才能在spring mvc（DispatcherServlet基于Servlet）前起作用。
-
UsernamePasswordAuthenticationFilter:实现Filter接口，负责拦截登录处理的url，帐号和密码会在这里获取，然后封装成
Authentication交给AuthenticationManager进行认证工作 -
Authentication:贯穿整个认证过程，封装了认证的用户名，密码和权限角色等信息，接口有一个boolean isAuthenticated()方法来决定该
Authentication认证成功没; -
AuthenticationManager:认证管理器，但本身并不做认证工作，只是做个管理者的角色。例如默认实现
ProviderManager会持有一个AuthenticationProvider数组，把认证工作交给这些AuthenticationProvider，直到有一个AuthenticationProvider完成了认证工作。 -
AuthenticationProvider:认证提供者，默认实现，也是最常使用的是
DaoAuthenticationProvider。我们在配置时一般重写一个UserDetailsService来从数据库获取正确的用户名密码，其实就是配置了DaoAuthenticationProvider的UserDetailsService属性，DaoAuthenticationProvider会做帐号和密码的比对，如果正常就返回给AuthenticationManager一个验证成功的Authentication
看UsernamePasswordAuthenticationFilter源码里的obtainUsername和obtainPassword方法只是简单地调用request.getParameter方法，因此如果用json发送用户名和密码会导致DaoAuthenticationProvider检查密码时为空，抛出BadCredentialsException。
/**
* Enables subclasses to override the composition of the password, such as by
* including additional values and a separator.
* <p>
* This might be used for example if a postcode/zipcode was required in addition to
* the password. A delimiter such as a pipe (|) should be used to separate the
* password and extended value(s). The <code>AuthenticationDao</code> will need to
* generate the expected password in a corresponding manner.
* </p>
*
* @param request so that request attributes can be retrieved
*
* @return the password that will be presented in the <code>Authentication</code>
* request token to the <code>AuthenticationManager</code>
*/
protected String obtainPassword(HttpServletRequest request) {
return request.getParameter(passwordParameter);
}
/**
* Enables subclasses to override the composition of the username, such as by
* including additional values and a separator.
*
* @param request so that request attributes can be retrieved
*
* @return the username that will be presented in the <code>Authentication</code>
* request token to the <code>AuthenticationManager</code>
*/
protected String obtainUsername(HttpServletRequest request) {
return request.getParameter(usernameParameter);
}
重写UsernamePasswordAnthenticationFilter
上面UsernamePasswordAnthenticationFilter的obtainUsername和obtainPassword方法的注释已经说了，可以让子类来自定义用户名和密码的获取工作。但是我们不打算重写这两个方法，而是重写它们的调用者attemptAuthentication方法，因为json反序列化毕竟有一定消耗，不会反序列化两次，只需要在重写的attemptAuthentication方法中检查是否json登录，然后直接反序列化返回Authentication对象即可。这样我们没有破坏原有的获取流程，还是可以重用父类原有的attemptAuthentication方法来处理表单登录。
/**
* AuthenticationFilter that supports rest login(json login) and form login.
* @author chenhuanming
*/
public class CustomAuthenticationFilter extends UsernamePasswordAuthenticationFilter {
@Override
public Authentication attemptAuthentication(HttpServletRequest request, HttpServletResponse response) throws AuthenticationException {
//attempt Authentication when Content-Type is json
if(request.getContentType().equals(MediaType.APPLICATION_JSON_UTF8_VALUE)
||request.getContentType().equals(MediaType.APPLICATION_JSON_VALUE)){
//use jackson to deserialize json
ObjectMapper mapper = new ObjectMapper();
UsernamePasswordAuthenticationToken authRequest = null;
try (InputStream is = request.getInputStream()){
AuthenticationBean authenticationBean = mapper.readValue(is,AuthenticationBean.class);
authRequest = new UsernamePasswordAuthenticationToken(
authenticationBean.getUsername(), authenticationBean.getPassword());
}catch (IOException e) {
e.printStackTrace();
authRequest = new UsernamePasswordAuthenticationToken(
"", "");
}finally {
setDetails(request, authRequest);
return this.getAuthenticationManager().authenticate(authRequest);
}
}
//transmit it to UsernamePasswordAuthenticationFilter
else {
return super.attemptAuthentication(request, response);
}
}
}
封装的AuthenticationBean类，用了lombok简化代码（lombok帮我们写getter和setter方法而已）
@Getter
@Setter
public class AuthenticationBean {
private String username;
private String password;
}
WebSecurityConfigurerAdapter配置
重写Filter不是问题，主要是怎么把这个Filter加到spring security的众多filter里面。
@Override
protected void configure(HttpSecurity http) throws Exception {
http
.cors().and()
.antMatcher("/**").authorizeRequests()
.antMatchers("/", "/login**").permitAll()
.anyRequest().authenticated()
//这里必须要写formLogin()，不然原有的UsernamePasswordAuthenticationFilter不会出现，也就无法配置我们重新的UsernamePasswordAuthenticationFilter
.and().formLogin().loginPage("/")
.and().csrf().disable();
//用重写的Filter替换掉原有的UsernamePasswordAuthenticationFilter
http.addFilterAt(customAuthenticationFilter(),
UsernamePasswordAuthenticationFilter.class);
}
//注册自定义的UsernamePasswordAuthenticationFilter
@Bean
CustomAuthenticationFilter customAuthenticationFilter() throws Exception {
CustomAuthenticationFilter filter = new CustomAuthenticationFilter();
filter.setAuthenticationSuccessHandler(new SuccessHandler());
filter.setAuthenticationFailureHandler(new FailureHandler());
filter.setFilterProcessesUrl("/login/self");
//这句很关键，重用WebSecurityConfigurerAdapter配置的AuthenticationManager，不然要自己组装AuthenticationManager
filter.setAuthenticationManager(authenticationManagerBean());
return filter;
}
题外话，如果搭自己的oauth2的server，需要让spring security oauth2共享同一个AuthenticationManager（源码的解释是这样写可以暴露出这个AuthenticationManager，也就是注册到spring ioc）
@Override
@Bean // share AuthenticationManager for web and oauth
public AuthenticationManager authenticationManagerBean() throws Exception {
return super.authenticationManagerBean();
}
至此，spring security就支持表单登录和异步json登录了。
