SpringCloud-第二章-配置文件 1.配置文件 在SpringBoot构建完之后，会在resource目录下创建一个application.properties文件，这是一个空文件。SpringBoot应用默认就会读取application.properties文件，但我们可以修改为application.yml，个人建议使用yml，因为YMAL的风格会更加适合配置文件。两者的功能上是一致的，只是语法不同，本文不重点介绍语法。
##2.实战
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 @Configuration @EnableConfigurationProperties public class ConditionConfig @Bean public GatewayProperties gatewayProperties () return new GatewayProperties(); } } @Validated @ConfigurationProperties (prefix = "spring.cloud.gateway" )public class GatewayProperties @NotNull @Valid private List<RouteDefinition> routes = new ArrayList<>(); public void setRoutes (List<RouteDefinition> routes) this .routes = routes; } @PostConstruct private void init () System.out.println(JSON.toJSONString(this )); } } @Validated public class PredicateDefinition @NotNull private String name; private Map<String, String> args = new LinkedHashMap<>(); public PredicateDefinition () public PredicateDefinition (String text) int eqIdx = text.indexOf('=' ); if (eqIdx <= 0 ) { throw new ValidationException("Unable to parse PredicateDefinition text '" + text + "'" + ", must be of the form name=value" ); } setName(text.substring(0 , eqIdx)); String[] args = tokenizeToStringArray(text.substring(eqIdx + 1 ), "," ); for (int i = 0 ; i < args.length; i++) { this .args.put(NameUtils.generateName(i), args[i]); } } public void setName (String name) this .name = name; } public void setArgs (Map<String, String> args) this .args = args; } } public class RouteDefinition @NotEmpty private String id; @NotEmpty @Valid private List<PredicateDefinition> predicates = new ArrayList<>(); @NotNull private URI uri; private int order = 0 ; public RouteDefinition () public RouteDefinition (String text) int eqIdx = text.indexOf('=' ); if (eqIdx <= 0 ) { throw new ValidationException("Unable to parse RouteDefinition text '" + text + "'" + ", must be of the form name=value" ); } setId(text.substring(0 , eqIdx)); String[] args = tokenizeToStringArray(text.substring(eqIdx + 1 ), "," ); setUri(URI.create(args[0 ])); for (int i = 1 ; i < args.length; i++) { this .predicates.add(new PredicateDefinition(args[i])); } } public void setId (String id) this .id = id; } public void setPredicates (List<PredicateDefinition> predicates) this .predicates = predicates; } public void setUri (URI uri) this .uri = uri; } public void setOrder (int order) this .order = order; } }
1 2 3 4 5 6 7 8 9 10 11 12 13 spring: cloud: gateway: routes: - id: yml-id uri: www.baidu.com order: -1 predicates: - name: predicatesName args: arg0: 1 arg1: 2 - Path=/echo
以上代码实现用yml文件，映射到类GatewayProperties中。最终的打印结果是
1 {"routes" :[{"id" :"yml-id" ,"order" :-1 ,"predicates" :[{"args" :{"arg0" :"1" ,"arg1" :"2" },"name" :"predicatesName" }],"uri" :"www.baidu.com" }]}
细心的同学可能会注意到@EnableConfigurationProperties、@ConfigurationProperties(prefix = “spring.cloud.gateway”)、@Validated 这三个很重要的注解。是的，如果想实现配置文件直接映射成Bean，@EnableConfigurationProperties和@ConfigurationProperties是必须要配置的，prefix=”spring.cloud.gateway”代表从spring.cloud.gateway开始采集配置。
@Validated 是校验配置的工具注解，除了代码中应用到的注解外，其它常见注解：
@AssertFalse 校验false
@AssertTrue 校验true
@DecimalMax(value=,inclusive=) 小于等于value，inclusive=true，是小于等于
@DecimalMin(value=,inclusive=) 与上类似
@Max(value=) 小于等于value
@Min(value=) 大于等于value
@NotNull 检查Null
@Past 检查日期
@Pattern(regex=,flag=) 正则
@Size(min=, max=) 字符串，集合，map限制大小
@Validate 对po实体类进行校验
这行代码有些不好理解，其实就是RouteDefinition 有两个构造函数，这句配置的意思是调用了有参数的构造函数来定义RouteDefinition对象，使得构建网关的配置更加简洁。
##3.总结
以上的内容，是通过阅读SpringCloudGateway源代码，发现实现方式很优雅，便总结下来。利用好SpringBoot的配置，可以写出很优雅的代码，提高维护性。
