public static final int M = 1024 * 1024;
public static void main(String[] args) {
    byte[] b1 = new byte[2 * M];
    byte[] b2 = new byte[2 * M];
    byte[] b3 = new byte[2 * M];
    byte[] b4 = new byte[4 * M];
    System.gc();
}

[GC (Allocation Failure) [PSYoungGen: 6914K->952K(9216K)] 6914K->5056K(19456K), 0.0045301 secs] [Times: user=0.05 sys=0.00, real=0.00 secs] 
[GC (System.gc()) --[PSYoungGen: 7252K->7252K(9216K)] 11356K->13412K(19456K), 0.0019800 secs] [Times: user=0.00 sys=0.00, real=0.00 secs] 
[Full GC (System.gc()) [PSYoungGen: 7252K->4840K(9216K)] [ParOldGen: 6160K->6145K(10240K)] 13412K->10986K(19456K), [Metaspace: 3494K->3494K(1056768K)], 0.0071106 secs] [Times: user=0.00 sys=0.00, real=0.01 secs] 
Heap
 PSYoungGen      total 9216K, used 5087K [0x00000000ff600000, 0x0000000100000000, 0x0000000100000000)
  eden space 8192K, 62% used [0x00000000ff600000,0x00000000ffaf7c38,0x00000000ffe00000)
  from space 1024K, 0% used [0x00000000ffe00000,0x00000000ffe00000,0x00000000fff00000)
  to   space 1024K, 0% used [0x00000000fff00000,0x00000000fff00000,0x0000000100000000)
 ParOldGen       total 10240K, used 6145K [0x00000000fec00000, 0x00000000ff600000, 0x00000000ff600000)
  object space 10240K, 60% used [0x00000000fec00000,0x00000000ff200518,0x00000000ff600000)
 Metaspace       used 3509K, capacity 4498K, committed 4864K, reserved 1056768K
  class space    used 387K, capacity 390K, committed 512K, reserved 1048576K

"Netty Builtin Server 1" #16 prio=5 os_prio=0 tid=0x0000000018f2b000 nid=0x2100 runnable [0x000000001bf3f000]
   java.lang.Thread.State: RUNNABLE
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll0(Native Method)
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll(WindowsSelectorImpl.java:296)
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.access$400(WindowsSelectorImpl.java:278)
        at sun.nio.ch.WindowsSelectorImpl.doSelect(WindowsSelectorImpl.java:159)
        at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
        - locked <0x00000000e155f760> (a io.netty.channel.nio.SelectedSelectionKeySet)
        - locked <0x00000000e155f790> (a java.util.Collections$UnmodifiableSet)
        - locked <0x00000000e29d20e8> (a sun.nio.ch.WindowsSelectorImpl)
        at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
        at io.netty.channel.nio.SelectedSelectionKeySetSelector.select(SelectedSelectionKeySetSelector.java:62)
        at io.netty.channel.nio.NioEventLoop.select(NioEventLoop.java:752)
        at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:408)
        at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:858)
        at java.lang.Thread.run(Thread.java:745)
   Locked ownable synchronizers:
        - None

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
public class Hello extends FileInputStream implements Runnable,ActionListener{
    private String name;
    public Hello(String name) throws FileNotFoundException {
        super(name);
    }
    @Override
    public void actionPerformed(ActionEvent e) {
    }
    @Override
    public void run() {
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
}

CA	FE	BA	BE	00	00	00	34	00	1F	0A	00	04	00	18	09
00	03	00	19	07	00	1A	07	00	1B	07	00	1C	07	00	1D
01	00	04	6E	61	6D	65	01	00	12	4C	6A	61	76	61	2F
6C	61	6E	67	2F	53	74	72	69	6E	67	3B	01	00	06	3C
69	6E	69	74	3E	01	00	15	28	4C	6A	61	76	61	2F	6C
61	6E	67	2F	53	74	72	69	6E	67	3B	29	56	01	00	04
43	6F	64	65	01	00	0F	4C	69	6E	65	4E	75	6D	62	65
72	54	61	62	6C	65	01	00	0A	45	78	63	65	70	74	69
6F	6E	73	07	00	1E	01	00	0F	61	63	74	69	6F	6E	50
65	72	66	6F	72	6D	65	64	01	00	1F	28	4C	6A	61	76
61	2F	61	77	74	2F	65	76	65	6E	74	2F	41	63	74	69
6F	6E	45	76	65	6E	74	3B	29	56	01	00	03	72	75	6E
01	00	03	28	29	56	01	00	07	67	65	74	4E	61	6D	65
01	00	14	28	29	4C	6A	61	76	61	2F	6C	61	6E	67	2F
53	74	72	69	6E	67	3B	01	00	07	73	65	74	4E	61	6D
65	01	00	0A	53	6F	75	72	63	65	46	69	6C	65	01	00
0A	48	65	6C	6C	6F	2E	6A	61	76	61	0C	00	09	00	0A
0C	00	07	00	08	01	00	05	48	65	6C	6C	6F	01	00	17
6A	61	76	61	2F	69	6F	2F	46	69	6C	65	49	6E	70	75
74	53	74	72	65	61	6D	01	00	12	6A	61	76	61	2F	6C
61	6E	67	2F	52	75	6E	6E	61	62	6C	65	01	00	1D	6A
61	76	61	2F	61	77	74	2F	65	76	65	6E	74	2F	41	63
74	69	6F	6E	4C	69	73	74	65	6E	65	72	01	00	1D	6A
61	76	61	2F	69	6F	2F	46	69	6C	65	4E	6F	74	46	6F
75	6E	64	45	78	63	65	70	74	69	6F	6E	00	21	00	03
00	04	00	02	00	05	00	06	00	01	00	02	00	07	00	08
00	00	00	05	00	01	00	09	00	0A	00	02	00	0B	00	00
00	22	00	02	00	02	00	00	00	06	2A	2B	B7	00	01	B1
00	00	00	01	00	0C	00	00	00	0A	00	02	00	00	00	0B
00	05	00	0C	00	0D	00	00	00	04	00	01	00	0E	00	01
00	0F	00	10	00	01	00	0B	00	00	00	19	00	00	00	02
00	00	00	01	B1	00	00	00	01	00	0C	00	00	00	06	00
01	00	00	00	11	00	01	00	11	00	12	00	01	00	0B	00
00	00	19	00	00	00	01	00	00	00	01	B1	00	00	00	01
00	0C	00	00	00	06	00	01	00	00	00	16	00	01	00	13
00	14	00	01	00	0B	00	00	00	1D	00	01	00	01	00	00
00	05	2A	B4	00	02	B0	00	00	00	01	00	0C	00	00	00
06	00	01	00	00	00	19	00	01	00	15	00	0A	00	01	00
0B	00	00	00	22	00	02	00	02	00	00	00	06	2A	2B	B5
00	02	B1	00	00	00	01	00	0C	00	00	00	0A	00	02	00
00	00	1D	00	05	00	1E	00	01	00	16	00	00	00	02	00
17

CONSTANT_Methodref_info {
    u1 tag;
    u2 class_index;
    u2 name_and_type_index;
}

CONSTANT_Fieldref_info {
    u1 tag;
    u2 class_index;
    u2 name_and_type_index;
}

CONSTANT_Utf8_info {
    u1 tag;
    u2 length;
    u1 bytes[length];
}

protected Class<?> loadClass(String var1, boolean var2) throws ClassNotFoundException {
        synchronized(this.getClassLoadingLock(var1)) {
            Class var4 = this.findLoadedClass(var1);                           // 检查这个类是否被加载过
            if (var4 == null) {
                long var5 = System.nanoTime();
                try {
                    if (this.parent != null) {
                        var4 = this.parent.loadClass(var1, false);             // 递归调用父类加载器去尝试加载( 应用程序类加载器 ---> 扩展类加载器  ----> 启动类加载器 )
                    } else {
                        var4 = this.findBootstrapClassOrNull(var1);
                    }
                } catch (ClassNotFoundException var10) {
                    ;
                }
                if (var4 == null) {                                           // 如果还是加载不成功，就自己去实现加载功能。
                    long var7 = System.nanoTime();
                    var4 = this.findClass(var1);
                    PerfCounter.getParentDelegationTime().addTime(var7 - var5);
                    PerfCounter.getFindClassTime().addElapsedTimeFrom(var7);
                    PerfCounter.getFindClasses().increment();
                }
            }
            if (var2) {
                this.resolveClass(var4);
            }
            return var4;
        }
    }

public Response<Map<String, Object>> login(String username,
                                               String password, HttpServletRequest request,
                                               HttpServletResponse response)
            throws HttpRequestMethodNotSupportedException {
        // 非空校验（前端也有部分校验）
        Asserts.notEmpty(username);
        Asserts.notEmpty(password);
        // Oauth2的 密码授权模式
        Map<String, String> map = Maps.newHashMap();
        // 获取数据库配置的 clientId
        String clientId = ${clientId};
        map.put("username", username);
        map.put("password", password);
        map.put("grant_type", "password");
        map.put("scope", "read write trust"); // 权限共有 read write trust 三种
        // 构建客户端的Authentication
        UsernamePasswordAuthenticationToken token = new UsernamePasswordAuthenticationToken(
                clientId, "", Lists.newArrayList());
        // 调用Spring security Oauth2 的postAccessToken 生成 Oauth2AccessToken
        ResponseEntity<OAuth2AccessToken> responseEntity = tokenEndpoint
                .postAccessToken(token, map);
        OAuth2AccessToken oAuth2AccessToken = responseEntity.getBody();
        JwtAuthenticationToken authenticationToken = null;
        if (oAuth2AccessToken != null) {
            // 对生成的token包装成Jwt的实现， tokenProvider是自己写的一个接口，共有两个方法，下文会分析
            authenticationToken = tokenProvider.createToken(request, response,
                    oAuth2AccessToken);
        }
        
        // 把一些不敏感的信息提取出来
        Map<String, Object> oauthInfo = extract(authenticationToken);
        // 存入redis
        tokenRedisService.putOauthInfo(authenticationToken.getAccessToken(),oauthInfo);
        return Response.ok(oauthInfo);
    }

@RequestMapping(value = "/oauth/token", method=RequestMethod.POST)
	public ResponseEntity<OAuth2AccessToken> postAccessToken(Principal principal, @RequestParam
	Map<String, String> parameters) throws HttpRequestMethodNotSupportedException {
		if (!(principal instanceof Authentication)) {
			throw new InsufficientAuthenticationException(
					"There is no client authentication. Try adding an appropriate authentication filter.");
		}
		String clientId = getClientId(principal);
		ClientDetails authenticatedClient = getClientDetailsService().loadClientByClientId(clientId);
		TokenRequest tokenRequest = getOAuth2RequestFactory().createTokenRequest(parameters, authenticatedClient);
		if (clientId != null && !clientId.equals("")) {
			// Only validate the client details if a client authenticated during this
			// request.
			if (!clientId.equals(tokenRequest.getClientId())) {
				// double check to make sure that the client ID in the token request is the same as that in the
				// authenticated client
				throw new InvalidClientException("Given client ID does not match authenticated client");
			}
		}
		if (authenticatedClient != null) {
			oAuth2RequestValidator.validateScope(tokenRequest, authenticatedClient);
		}
		if (!StringUtils.hasText(tokenRequest.getGrantType())) {
			throw new InvalidRequestException("Missing grant type");
		}
		if (tokenRequest.getGrantType().equals("implicit")) {
			throw new InvalidGrantException("Implicit grant type not supported from token endpoint");
		}
		if (isAuthCodeRequest(parameters)) {
			// The scope was requested or determined during the authorization step
			if (!tokenRequest.getScope().isEmpty()) {
				logger.debug("Clearing scope of incoming token request");
				tokenRequest.setScope(Collections.<String> emptySet());
			}
		}
		if (isRefreshTokenRequest(parameters)) {
			// A refresh token has its own default scopes, so we should ignore any added by the factory here.
			tokenRequest.setScope(OAuth2Utils.parseParameterList(parameters.get(OAuth2Utils.SCOPE)));
		}
        // 有五种类型的Granter，我司只实现了两种。
		OAuth2AccessToken token = getTokenGranter().grant(tokenRequest.getGrantType(), tokenRequest);
		if (token == null) {
			throw new UnsupportedGrantTypeException("Unsupported grant type: " + tokenRequest.getGrantType());
		}
		return getResponse(token);
	}

@Override
public void configure(ResourceServerSecurityConfigurer resources) throws Exception {
    resources.resourceId(RESOURCE_ID)
            .accessDeniedHandler(new ThrowAccessDeniedHandler(objectMapper))
            .authenticationEntryPoint(new ThrowEntryPoint(objectMapper))
            .stateless(true)
             // 重点是这个配置，通过这个来实现
            .tokenServices(new UAALoadBalancerUserInfoTokenServices(loadBalancerClient,resourceServerProperties.getServiceId(), resourceServerProperties.getUserInfoUri()));
}

    protected Response getMap(String path, String accessToken) {
        if (LOGGER.isDebugEnabled()) {
            LOGGER.debug("Getting user info from: " + path);
        }
        try {
            OAuth2RestOperations restTemplate = this.restTemplate;
            if (restTemplate == null) {
                BaseOAuth2ProtectedResourceDetails resource = new BaseOAuth2ProtectedResourceDetails();
                resource.setClientId(this.clientId);
                restTemplate = new OAuth2RestTemplate(resource);
            }
            OAuth2AccessToken existingToken = ((OAuth2RestOperations)restTemplate).getOAuth2ClientContext().getAccessToken();
            if (existingToken == null || !accessToken.equals(existingToken.getValue())) {
                DefaultOAuth2AccessToken token = new DefaultOAuth2AccessToken(accessToken);
                token.setTokenType(this.tokenType);
                ((OAuth2RestOperations)restTemplate).getOAuth2ClientContext().setAccessToken(token);
            }
            return (Response)((OAuth2RestOperations)restTemplate).getForEntity(path, Response.class, new Object[0]).getBody();
        } catch (Exception var6) {
            LOGGER.warn("Could not fetch user details: " + var6.getClass() + ", " + var6.getMessage());
            return null;
        }
    }
}

@RequestMapping(method = RequestMethod.GET, value ="/oauth/me")
   public Map<String, Object> me(
           @PathVariable(required = false) String service,
           OAuth2Authentication auth) {
       Map<String, Object> me = Collections.EMPTY_MAP;
       //往用户信息里面添加权限信息
       List<SimpleGrantedAuthorityImpl> authorities = new ArrayList<SimpleGrantedAuthorityImpl>();
       logger.info(
               "/oauth/me request... OAuth2Authentication[{}] service[{}]",
               auth, service);
       // 认证失败
       if (auth == null) {
           throw new OAuth2Exception("Authorization message is not null.");
       }
       OAuth2Request request = auth.getOAuth2Request();
       if (request == null) {
           me.clear();
           throw new OAuth2Exception("OAuth2Request message is not null.");
       }
       Authentication authentication = auth.getUserAuthentication();
       // 登录用户授权模式 password,authorization_code,refresh_token
       if (authentication instanceof UsernamePasswordAuthenticationToken) {
           UsernamePasswordAuthenticationToken usernamePasswordAuthenticationToken = (UsernamePasswordAuthenticationToken) authentication;
           UserDetails userInfo = userService
                   .selectByUserNameOrMobileOrEmail(usernamePasswordAuthenticationToken
                           .getName());
           // 将密码清空
           userInfo.setLoginPasswd("");
           me.clear();
           // 授权部分
           //...
           userInfo.setAuthorities(authorities);
           me.put("name", userInfo.getLoginName());
           // USERINFO_FIELDS_CACHE 常量是UserDetail的所有属性集合
           for (Field field : USERINFO_FIELDS_CACHE) {
               // 找寻所有的get方法
               Method m = ReflectionUtils.findMethod(userInfo.getClass(),
                       SecurityUtils.getMethodName(field.getName()));
               if (null != m) {
                   me.put(field.getName(),
                           ReflectionUtils.invokeMethod(m, userInfo));
               }
           }
           return Response.ok(me);
       }
       // 如果不是这几种授权类型，抛出异常
       me.clear();
       throw new OAuth2Exception("Bad request.");
   }