public class Dao {

    private MysqlConnection connection;

    public Dao(MysqlConnection connection) {
        this.connection = connection;
    }

    public void findAll() {
        connection.executeQuery("SELECT * FROM test");
    }

}

public class MysqlConnection {

    public void executeQuery(String sql) {
        System.out.println(sql);
    }

}

public class Dao {

    private Connection connection;

    public Dao(Connection connection) {
        this.connection = connection;
    }

    public void findAll() {
        connection.executeQuery("SELECT * FROM test");
    }

}

public interface Connection {

    void executeQuery(String sql);

}

public class MysqlConnection implements Connection {

    @Override
    public void executeQuery(String sql) {
        System.out.println(sql);
    }

}

/**
 * @author Yuicon
 */
@Slf4j
public class VersionRule extends PredicateBasedRule {

    private final CompositePredicate predicate;

    public VersionRule() {
        super();
        this.predicate = createCompositePredicate(new VersionPredicate(),
                new AvailabilityPredicate(this, null));
    }

    @Override
    public AbstractServerPredicate getPredicate() {
        return this.predicate;
    }

    private CompositePredicate createCompositePredicate(VersionPredicate versionPredicate,
                                                        AvailabilityPredicate availabilityPredicate) {
        return CompositePredicate.withPredicates(versionPredicate, availabilityPredicate)
                .build();
    }

    private static class VersionPredicate extends AbstractServerPredicate {

        private static final String VERSION_KEY = "version";

        @Override
        public boolean apply(@NullableDecl PredicateKey predicateKey) {
            if (predicateKey == null) {
                return true;
            }
            RequestContext ctx = RequestContext.getCurrentContext();
            HttpServletRequest request = ctx.getRequest();
            String version = request.getHeader(VERSION_KEY);
            if (version == null) {
                return true;
            }
            ConsulServer consulServer = (ConsulServer) predicateKey.getServer();
            if (!consulServer.getMetadata().containsKey(VERSION_KEY)) {
                return true;
            }
            log.info("id is {}, header is {}, metadata is {}, result is {}",
                    consulServer.getMetaInfo().getInstanceId(),
                    version, consulServer.getMetadata().get(VERSION_KEY),
                    consulServer.getMetadata().get(VERSION_KEY).equals(version));
            return consulServer.getMetadata().get(VERSION_KEY).equals(version);
        }
    }

}

@RibbonClients(defaultConfiguration = RibbonGatewayConfig.class)
@Configuration
public class RibbonGatewayConfig {

    @Bean
    public IRule versionRule() {
        return new VersionRule();
    }

}

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-security</artifactId>
		</dependency>

public interface UserDetails extends Serializable {

    //返回分配给用户的角色列表
    Collection<? extends GrantedAuthority> getAuthorities();
    
    //返回密码
    String getPassword();

    //返回帐号
    String getUsername();

    // 账户是否未过期
    boolean isAccountNonExpired();

    // 账户是否未锁定
    boolean isAccountNonLocked();

    // 密码是否未过期
    boolean isCredentialsNonExpired();

    // 账户是否激活
    boolean isEnabled();
}

public interface UserDetailsService {
    UserDetails loadUserByUsername(String var1) throws UsernameNotFoundException;
}

/**
 * Created by Yuicon on 2017/5/14.
 * https://segmentfault.com/u/yuicon
 */
public class User implements UserDetails {

    private final String id;
    //帐号,这里是我数据库里的字段
    private final String account;
    //密码
    private final String password;
    //角色集合
    private final Collection<? extends GrantedAuthority> authorities;

    User(String id, String account, String password, Collection<? extends GrantedAuthority> authorities) {
        this.id = id;
        this.account = account;
        this.password = password;
        this.authorities = authorities;
    }

    //返回分配给用户的角色列表
    @Override
    public Collection<? extends GrantedAuthority> getAuthorities() {
        return authorities;
    }

    @JsonIgnore
    public String getId() {
        return id;
    }

    @JsonIgnore
    @Override
    public String getPassword() {
        return password;
    }
    
    //虽然我数据库里的字段是 `account`  ,这里还是要写成 `getUsername()`,因为是继承的接口
    @Override
    public String getUsername() {
        return account;
    }
    // 账户是否未过期
    @JsonIgnore
    @Override
    public boolean isAccountNonExpired() {
        return true;
    }
    // 账户是否未锁定
    @JsonIgnore
    @Override
    public boolean isAccountNonLocked() {
        return true;
    }
    // 密码是否未过期
    @JsonIgnore
    @Override
    public boolean isCredentialsNonExpired() {
        return true;
    }
    // 账户是否激活
    @JsonIgnore
    @Override
    public boolean isEnabled() {
        return true;
    }
}

/**
 * Created by Yuicon on 2017/5/14.
 * https://segmentfault.com/u/yuicon
 */
@Service
public class UserDetailsServiceImpl implements UserDetailsService {
    
    // jpa
    @Autowired
    private UserRepository userRepository;

    /**
     * 提供一种从用户名可以查到用户并返回的方法
     * @param account 帐号
     * @return UserDetails
     * @throws UsernameNotFoundException
     */
    @Override
    public UserDetails loadUserByUsername(String account) throws UsernameNotFoundException {
        // 这里是数据库里的用户类
        User user = userRepository.findByAccount(account);

        if (user == null) {
            throw new UsernameNotFoundException(String.format("没有该用户 '%s'.", account));
        } else {
            //这里返回上面继承了 UserDetails  接口的用户类,为了简单我们写个工厂类
            return UserFactory.create(user);
        }
    }
}

/**
 * Created by Yuicon on 2017/5/14.
 * https://segmentfault.com/u/yuicon
 */
final class UserFactory {

    private UserFactory() {
    }

    static User create(User user) {
        return new User(
                user.getId(),
                user.getAccount(),
                user.getPassword(),
            mapToGrantedAuthorities(user.getRoles().stream().map(Role::getName).collect(Collectors.toList()))
        );
    }
    
    //将与用户类多对多的角色类的名称集合转换为 GrantedAuthority 集合
    private static List<GrantedAuthority> mapToGrantedAuthorities(List<String> authorities) {
        return authorities.stream()
                .map(SimpleGrantedAuthority::new)
                .collect(Collectors.toList());
    }
}

/**
 * Created by Yuicon on 2017/5/14.
 * https://segmentfault.com/u/yuicon
 */
@Configuration
@EnableWebSecurity
@EnableGlobalMethodSecurity(prePostEnabled = true)
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {

    // Spring会自动寻找实现接口的类注入,会找到我们的 UserDetailsServiceImpl  类
    @Autowired
    private UserDetailsService userDetailsService;

    @Autowired
    public void configureAuthentication(AuthenticationManagerBuilder authenticationManagerBuilder) throws Exception {
        authenticationManagerBuilder
                // 设置UserDetailsService
                .userDetailsService(this.userDetailsService)
                // 使用BCrypt进行密码的hash
                .passwordEncoder(passwordEncoder());
    }

    // 装载BCrypt密码编码器
    @Bean
    public PasswordEncoder passwordEncoder() {
        return new BCryptPasswordEncoder();
    }

    //允许跨域
    @Bean
    public WebMvcConfigurer corsConfigurer() {
        return new WebMvcConfigurerAdapter() {
            @Override
            public void addCorsMappings(CorsRegistry registry) {
                registry.addMapping("/**").allowedOrigins("*")
                        .allowedMethods("GET", "HEAD", "POST","PUT", "DELETE", "OPTIONS")
                        .allowCredentials(false).maxAge(3600);
            }
        };
    }

    @Override
    protected void configure(HttpSecurity httpSecurity) throws Exception {
        httpSecurity
                // 取消csrf
                .csrf().disable()
                // 基于token，所以不需要session
                .sessionManagement().sessionCreationPolicy(SessionCreationPolicy.STATELESS).and()
                .authorizeRequests()
                .antMatchers(HttpMethod.OPTIONS, "/**").permitAll()
                // 允许对于网站静态资源的无授权访问
                .antMatchers(
                        HttpMethod.GET,
                        "/",
                        "/*.html",
                        "/favicon.ico",
                        "/**/*.html",
                        "/**/*.css",
                        "/**/*.js",
                        "/webjars/**",
                        "/swagger-resources/**",
                        "/*/api-docs"
                ).permitAll()
                // 对于获取token的rest api要允许匿名访问
                .antMatchers("/auth/**").permitAll()
                // 除上面外的所有请求全部需要鉴权认证
                .anyRequest().authenticated();
        // 禁用缓存
        httpSecurity.headers().cacheControl();
    }
}

/**
 * 在 @PreAuthorize 中我们可以利用内建的 SPEL 表达式：比如 'hasRole()' 来决定哪些用户有权访问。
 * 需注意的一点是 hasRole 表达式认为每个角色名字前都有一个前缀 'ROLE_'。所以这里的 'ADMIN' 其实在
 * 数据库中存储的是 'ROLE_ADMIN' 。这个 @PreAuthorize 可以修饰Controller也可修饰Controller中的方法。
 **/
@RestController
@RequestMapping("/users")
@PreAuthorize("hasRole('USER')") //有ROLE_USER权限的用户可以访问
public class UserController {

   @Autowired
    private UserRepository repository;

    @PreAuthorize("hasRole('ADMIN')")//有ROLE_ADMIN权限的用户可以访问
    @RequestMapping(method = RequestMethod.GET)
    public List<User> getUsers() {
        return repository.findAll();
    }
}

        <dependency>
            <groupId>io.springfox</groupId>
	    <artifactId>springfox-swagger2</artifactId>
	    <version>2.7.0</version>
        </dependency>
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger-ui</artifactId>
            <version>2.7.0</version>
        </dependency>

/**
 * Created by Yuicon on 2017/5/20.
 * https://github.com/Yuicon
 */
@Configuration
@EnableSwagger2
public class Swagger2 {

    @Bean
    public Docket createRestApi() {
        return new Docket(DocumentationType.SWAGGER_2)
                .apiInfo(apiInfo())
                .select()
                // 指定controller存放的目录路径
                .apis(RequestHandlerSelectors.basePackage("com.digag.web"))
                .paths(PathSelectors.any())
                .build();
    }

    private ApiInfo apiInfo() {
        return new ApiInfoBuilder()
                 // 文档标题
                .title("DigAg")
                // 文档描述
                .description("https://github.com/Yuicon")
                .termsOfServiceUrl("https://github.com/Yuicon")
                .version("v1")
                .build();
    }

}

    @ApiOperation(value="创建条目")
    @RequestMapping(method = RequestMethod.POST)
    public JsonResult<Entry> saveEntry(@RequestBody @ApiParam(value = "条目对象", required = true) Entry entry, HttpServletRequest request) {
        return entryService.create(entry, request);
    }

public class Main {

    public static void main(String[] args) {
        OrderService service = new OrderService();
        service.test();
    }

}

public class OrderService {

    private OrderDao dao = new OrderDao();

    public void test() {
        dao.doSomeThing();
    }

}

public class OrderDao {

    public void doSomeThing() {
        System.out.println("test");
    }

}

public class Main {

    public static void main(String[] args) {
        Dao dao = new OrderDao();
        OrderService service = new OrderService(dao);
        service.test();
    }

}

public interface Dao {

    void doSomeThing();

}

public class OrderDao implements Dao {

    @Override
    public void doSomeThing() {
        System.out.println("test");
    }

}

public class OrderService {

    private Dao dao;

    public OrderService(Dao dao) {
        this.dao = dao;
    }

    public void test() {
        dao.doSomeThing();
    }

}

// 引导类要放在项目根目录下，也就是在 src 下面
public class Main {

    public static void main(String[] args) {
        // 生成容器
        Container container = new Container(Main.class);
        // 获取Bean
        OrderService service = container.getBean(OrderService.class);
        // 调用
        service.test();
    }

}

@Component
public class OrderService {

    @Autowired
    private Dao dao;

    public void test() {
        dao.doSomeThing();
    }

    public Dao getDao() {
        return dao;
    }

    public void setDao(Dao dao) {
        this.dao = dao;
    }
}

@Component
public class OrderDao implements Dao {

    @Override
    public void doSomeThing() {
        System.out.println("test");
    }

}

public interface Dao {

    void doSomeThing();

}

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE})
public @interface Component {
}

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.FIELD,ElementType.METHOD})
public @interface Autowired {
}

public class Container {

    private List<String> classPaths = new ArrayList<>();

    private String separator;

    private Map<Class, Object> components = new HashMap<>();

    public Container(Class cls) {
        File file = new File(cls.getResource("").getFile());
        separator = file.getName();
        renderClassPaths(new File(this.getClass().getResource("").getFile()));
        make();
        di();
    }

    private void make() {
        classPaths.forEach(classPath -> {
            try {
                Class c = Class.forName(classPath);
                // 找到有 @ioc.Component 注解的类并实例化
                if (c.isAnnotationPresent(Component.class)) {
                    components.put(c, c.newInstance());
                }
            } catch (ClassNotFoundException | InstantiationException | IllegalAccessException e) {
                e.printStackTrace();
            }
        });
    }

    /**
     * 注入依赖
     */
    private void di() {
        components.forEach((aClass, o) -> Arrays.stream(aClass.getDeclaredFields()).forEach(field -> {
            if (field.isAnnotationPresent(Autowired.class)) {
                try {
                    String methodName = "set" + field.getType().getName().substring(field.getType().getName().lastIndexOf(".") + 1);
                    Method method = aClass.getMethod(methodName, field.getType());
                    if (field.getType().isInterface()) {
                        components.keySet().forEach(aClass1 -> {
                            if (Arrays.stream(aClass1.getInterfaces()).anyMatch(aClass2 -> aClass2.equals(field.getType()))) {
                                try {
                                    method.invoke(o, components.get(aClass1));
                                } catch (IllegalAccessException | InvocationTargetException e) {
                                    e.printStackTrace();
                                }
                            }
                        });
                    } else {
                        method.invoke(o, components.get(field.getType()));
                    }
                } catch (NoSuchMethodException | IllegalAccessException | InvocationTargetException e) {
                    e.printStackTrace();
                }
            }
        }));
    }

    /**
     * 该方法会得到所有的类，将类的全类名写入到classPaths中
     *
     * @param file 包
     */
    private void renderClassPaths(File file) {
        if (file.isDirectory()) {
            File[] files = file.listFiles();
            Arrays.stream(Objects.requireNonNull(files)).forEach(this::renderClassPaths);
        } else {
            if (file.getName().endsWith(".class")) {
                String classPath = file.getPath()
                        .substring(file.getPath().lastIndexOf(separator) + separator.length() + 1)
                        .replace('\\', '.')
                        .replace(".class", "");
                classPaths.add(classPath);
            }
        }
    }

    public <T> T getBean(Class c) {
        return (T) components.get(c);
    }

}

Result "jmh.Benchmark.testGetGoodsList":
  65.969 ±(99.9%) 10.683 ms/op [Average]
  (min, avg, max) = (63.087, 65.969, 69.996), stdev = 2.774
  CI (99.9%): [55.286, 76.652] (assumes normal distribution)


# Run complete. Total time: 00:02:48

REMEMBER: The numbers below are just data. To gain reusable insights, you need to follow up on
why the numbers are the way they are. Use profilers (see -prof, -lprof), design factorial
experiments, perform baseline and negative tests that provide experimental control, make sure
the benchmarking environment is safe on JVM/OS/HW level, ask for reviews from the domain experts.
Do not assume the numbers tell you what you want them to tell.

Benchmark                   Mode  Cnt   Score    Error  Units
Benchmark.testGetGoodsList  avgt    5  65.969 ± 10.683  ms/op

Process finished with exit code 0

Result "jmh.Benchmark.testGetGoodsList":
  102.419 ±(99.9%) 153.083 ms/op [Average]
  (min, avg, max) = (65.047, 102.419, 162.409), stdev = 39.755
  CI (99.9%): [≈ 0, 255.502] (assumes normal distribution)


# Run complete. Total time: 00:03:03

REMEMBER: The numbers below are just data. To gain reusable insights, you need to follow up on
why the numbers are the way they are. Use profilers (see -prof, -lprof), design factorial
experiments, perform baseline and negative tests that provide experimental control, make sure
the benchmarking environment is safe on JVM/OS/HW level, ask for reviews from the domain experts.
Do not assume the numbers tell you what you want them to tell.

Benchmark                   Mode  Cnt    Score     Error  Units
Benchmark.testGetGoodsList  avgt    5  102.419 ± 153.083  ms/op

Process finished with exit code 0

Result "jmh.Benchmark.testGetGoodsList":
  29.210 ±(99.9%) 2.947 ms/op [Average]
  (min, avg, max) = (28.479, 29.210, 30.380), stdev = 0.765
  CI (99.9%): [26.263, 32.157] (assumes normal distribution)


# Run complete. Total time: 00:02:49

REMEMBER: The numbers below are just data. To gain reusable insights, you need to follow up on
why the numbers are the way they are. Use profilers (see -prof, -lprof), design factorial
experiments, perform baseline and negative tests that provide experimental control, make sure
the benchmarking environment is safe on JVM/OS/HW level, ask for reviews from the domain experts.
Do not assume the numbers tell you what you want them to tell.

Benchmark                   Mode  Cnt   Score   Error  Units
Benchmark.testGetGoodsList  avgt    5  29.210 ± 2.947  ms/op

Process finished with exit code 0

bin/zookeeper-server-start.sh config/zookeeper.properties
需要后台运行的加 -daemon 参数
bin/zookeeper-server-start.sh -daemon config/zookeeper.properties
用netstat -ntlp命令可以看到
tcp        0      0 0.0.0.0:2181            0.0.0.0:*               LISTEN      {pid}/java
就是启动成功了。

定义。映射是一种用于存放键/值对的数据结构，主要支持两种操作：插入（put），即将一组新的键值对存入映射中；查找（get），即根据给定的键得到相应的值。

Runnable runnable = () -> System.out.println("我很简洁");

public class Generics <T> {

    private T value;

    public T getValue() {
        return value;
    }

    public void setValue(T value) {
        this.value = value;
    }
}

public class Generics  {

    private Object value;

    public Object getValue() {
        return value;
    }

    public void setValue(Object value) {
        this.value = value;
    }
}

类定义参考上文例子
使用形式
Generics<String> generics = new Generics<String>();
后面尖括号内的内容在Jdk7以后可以省略
Generics<String> generics = new Generics<>();

    private <U> void out(U u) {
        System.out.println(u);
    }
    
    调用形式,
    Test.<String>out("test");
    大部分情况下<String>都可以省略，编译器可以推断出来类型
    Test.out("test");
    

public class Generics <T extends List> {

    private T value;

    public T getValue() {
        return value;
    }

    public void setValue(T value) {
        this.value = value;
    }

    public void add(Object u) {
        value.add(u);
    }

    public static void main(String[] args) {
        Generics<List> generics = new Generics<>();
        generics.setValue(new ArrayList<>());
        generics.add("ss");
        System.out.println(generics.getValue());
    }
    
}

public class Generics {

    private Object value;

    public Object getValue() {
        return value;
    }

    public void setValue(Object value) {
        this.value = value;
    }

}

    public static void main(String[] args) {
        Generics<String> generics = new Generics<>();
        generics.setValue("ss");
        System.out.println(generics.getValue());
    }
    
    javac Generics.java
    javap -c Generics
    编译后的代码
     public static void main(java.lang.String[]);
        Code:
       0: new           #3                  // class generics/Generics
       3: dup
       4: invokespecial #4                  // Method "<init>":()V
       7: astore_1
       8: aload_1
       9: ldc           #5                  // String ss
      11: invokevirtual #6                  // Method setValue:(Ljava/lang/Object;)V
      14: getstatic     #7                  // Field java/lang/System.out:Ljava/io/PrintStream;
      17: aload_1
      18: invokevirtual #8                  // Method getValue:()Ljava/lang/Object;
      21: checkcast     #9                  // class java/lang/String
      24: invokevirtual #10                 // Method java/io/PrintStream.println:(Ljava/lang/String;)V
      27: return

public class SubGenerics extends Generics<String> {

    @Override
    public void setValue(String value) {
        System.out.println(value);
    }

    public static void main(String[] args) {
        Generics<String> generics = new SubGenerics();
        generics.setValue("ss");
    }

}

public void setValue(Object value) {
    setValue((String) value);
}

Compiled from "SubGenerics.java"
public class generics.SubGenerics extends generics.Generics<java.lang.String> {
  public generics.SubGenerics();
    Code:
       0: aload_0
       1: invokespecial #1                  // Method generics/Generics."<init>":()V
       4: return

  public void setValue(java.lang.String);
    Code:
       0: getstatic     #2                  // Field java/lang/System.out:Ljava/io/PrintStream;
       3: aload_1
       4: invokevirtual #3                  // Method java/io/PrintStream.println:(Ljava/lang/String;)V
       7: return

  public static void main(java.lang.String[]);
    Code:
       0: new           #4                  // class generics/SubGenerics
       3: dup
       4: invokespecial #5                  // Method "<init>":()V
       7: astore_1
       8: aload_1
       9: ldc           #6                  // String ss
      11: invokevirtual #7                  // Method generics/Generics.setValue:(Ljava/lang/Object;)V
      14: return

  public void setValue(java.lang.Object);
    Code:
       0: aload_0
       1: aload_1
       2: checkcast     #8                  // class java/lang/String
       5: invokevirtual #9                  // Method setValue:(Ljava/lang/String;)V
       8: return
}

/* Add new entry to head node of quicklist.
 *
 * Returns 0 if used existing head.
 * Returns 1 if new head created. */
int quicklistPushHead(quicklist *quicklist, void *value, size_t sz) {
    # 首先取出旧头节点
    quicklistNode *orig_head = quicklist->head;
    # 判断旧头节点的ziplist加上新元素后的大小是否超过限制，这个限制取决于quicklist结构的fill字段
    if (likely(
            _quicklistNodeAllowInsert(quicklist->head, quicklist->fill, sz))) {
        # 没有超过限制就直接将元素加入到旧头节点的ziplist中
        quicklist->head->zl =
            ziplistPush(quicklist->head->zl, value, sz, ZIPLIST_HEAD);
        quicklistNodeUpdateSz(quicklist->head);
    } else {
        # 超过限制就新建一个node
        quicklistNode *node = quicklistCreateNode();
        # 元素加入到新节点的ziplist中
        node->zl = ziplistPush(ziplistNew(), value, sz, ZIPLIST_HEAD);

        quicklistNodeUpdateSz(node);
        # 并成为新的头节点
        _quicklistInsertNodeBefore(quicklist, quicklist->head, node);
    }
    # 更新元素数量
    quicklist->count++;
    quicklist->head->count++;
    # 返回是否有新节点创建
    return (orig_head != quicklist->head);
}