跨域问题其实之前就有说过，不明白的可以参考我之前的文章，这章主要讲解SpringBoot CROS的支持。
这里主要按照官方文档方式讲述。
SpringBoot CROS 参考： http://docs.spring.io/spring-boot/docs/1.5.4.RELEASE/reference/htmlsingle/#boot-features-cors
Spring CROS 参考： http://docs.spring.io/spring/docs/4.3.9.RELEASE/spring-framework-reference/htmlsingle/#cors
首先是支持Restful的controller，这里就不使用数据库了，简单一点。 UserController.class
package cn.saytime.web; import cn.saytime.bean.JsonResult; import cn.saytime.bean.User; import org.springframework.http.ResponseEntity; import org.springframework.web.bind.annotation.CrossOrigin; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.RequestBody; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; import org.springframework.web.bind.annotation.RestController; import java.util.ArrayList; import java.util.Collections; import java.util.Date; import java.util.HashMap; import java.util.List; import java.util.Map; /** * @author zh * @ClassName cn.saytime.web.UserController * @Description */ @RestController public class UserController { // 创建线程安全的Map static Map<Integer, User> users = Collections.synchronizedMap(new HashMap<Integer, User>()); /** * 根据ID查询用户 * @param id * @return */ @RequestMapping(value = "user/{id}", method = RequestMethod.GET) public ResponseEntity<JsonResult> getUserById (@PathVariable(value = "id") Integer id){ JsonResult r = new JsonResult(); try { User user = users.get(id); r.setResult(user); r.setStatus("ok"); } catch (Exception e) { r.setResult(e.getClass().getName() + ":" + e.getMessage()); r.setStatus("error"); e.printStackTrace(); } return ResponseEntity.ok(r); } /** * 查询用户列表 * @return */ @CrossOrigin @RequestMapping(value = "users", method = RequestMethod.GET) public ResponseEntity<JsonResult> getUserList (){ JsonResult r = new JsonResult(); try { List<User> userList = new ArrayList<User>(users.values()); r.setResult(userList); r.setStatus("ok"); } catch (Exception e) { r.setResult(e.getClass().getName() + ":" + e.getMessage()); r.setStatus("error"); e.printStackTrace(); } return ResponseEntity.ok(r); } /** * 添加用户 * @param user * @return */ @RequestMapping(value = "user", method = RequestMethod.POST) public ResponseEntity<JsonResult> add (@RequestBody User user){ JsonResult r = new JsonResult(); try { users.put(user.getId(), user); r.setResult(user.getId()); r.setStatus("ok"); } catch (Exception e) { r.setResult(e.getClass().getName() + ":" + e.getMessage()); r.setStatus("error"); e.printStackTrace(); } return ResponseEntity.ok(r); } /** * 根据id删除用户 * @param id * @return */ @RequestMapping(value = "user/{id}", method = RequestMethod.DELETE) public ResponseEntity<JsonResult> delete (@PathVariable(value = "id") Integer id){ JsonResult r = new JsonResult(); try { users.remove(id); r.setResult(id); r.setStatus("ok"); } catch (Exception e) { r.setResult(e.getClass().getName() + ":" + e.getMessage()); r.setStatus("error"); e.printStackTrace(); } return ResponseEntity.ok(r); } /** * 根据id修改用户信息 * @param user * @return */ @RequestMapping(value = "user/{id}", method = RequestMethod.PUT) public ResponseEntity<JsonResult> update (@PathVariable("id") Integer id, @RequestBody User user){ JsonResult r = new JsonResult(); try { User u = users.get(id); u.setUsername(user.getUsername()); u.setAge(user.getAge()); users.put(id, u); r.setResult(u); r.setStatus("ok"); } catch (Exception e) { r.setResult(e.getClass().getName() + ":" + e.getMessage()); r.setStatus("error"); e.printStackTrace(); } return ResponseEntity.ok(r); } }User.class
package cn.saytime.bean; import java.util.Date; /** * @author zh * @ClassName cn.saytime.bean.User * @Description */ public class User { private int id; private String username; private int age; private Date ctm; // Getter Setter }JsonResult.class
package cn.saytime.bean; public class JsonResult { private String status = null; private Object result = null; // Getter Setter }我们在static目录新建一个test.html
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> <script src="https://cdn.bootcss.com/jquery/2.1.0/jquery.min.js"></script> <script type="text/javascript"> function crosRequest(){ $.ajax({ url:'http://localhost:8080/users', type:'get', dataType:'json', success:function(data){ console.log(data); } }); } </script> </head> <body> <button onclick="crosRequest()">请求跨域资源</button> </body> </html> 我们使用IDEA的浏览器预览功能，点击谷歌小图标，可以看到打开网址为： http://localhost:63342/springboot-demo/springboot-cros/static/test.html?_ijt=ibtt432ffb9rh0vffqkkug3je8启动SpringBoot工程，默认8080不是使用IDEA的用户，自己找个tomcat启动test.html页面，修改端口为其他，然后启动springboot。
所以证明存在跨域问题。
这里我们在users映射的方法getUserList上面加上@CrossOrigin
@CrossOrigin @RequestMapping(value = "users", method = RequestMethod.GET) public ResponseEntity<JsonResult> getUserList ()然后再次使用上面的方式访问。
表示跨域问题解决。 default @CrossOrigin allows all origins and the HTTP methods specified in the @RequestMapping annotation 上面的官方文档说明，也就是默认的@CrossOrigin允许所有跨域请求。
通过查看CrossOrigin源码可以看到， 默认配置为：
"Access-Control-Allow-Origin" : "*" "Access-Control-Allow-Methods" : "GET,POST,PUT,OPTIONS" "Access-Control-Allow-Credentials" : "true" @Target({ElementType.METHOD, ElementType.TYPE}) @Retention(RetentionPolicy.RUNTIME) @Documented public @interface CrossOrigin { /** @deprecated */ @Deprecated String[] DEFAULT_ORIGINS = new String[]{"*"}; /** @deprecated */ @Deprecated String[] DEFAULT_ALLOWED_HEADERS = new String[]{"*"}; /** @deprecated */ @Deprecated boolean DEFAULT_ALLOW_CREDENTIALS = true; /** @deprecated */ @Deprecated long DEFAULT_MAX_AGE = 1800L; @AliasFor("origins") String[] value() default {}; @AliasFor("value") String[] origins() default {}; String[] allowedHeaders() default {}; String[] exposedHeaders() default {}; RequestMethod[] methods() default {}; String allowCredentials() default ""; long maxAge() default -1L; }It is also possible to enable CORS for the whole controller 也可以用在整个Controller类上面。即该controller所有映射都支持跨域请求。
@CrossOrigin(origins = "http://domain2.com", maxAge = 3600, methods = {RequestMethod.GET, RequestMethod.POST}) @RestController public class UserControllerGlobal CORS configuration In addition to fine-grained, annotation-based configuration you’ll probably want to define some global CORS configuration as well. This is similar to using filters but can be declared withing Spring MVC and combined with fine-grained @CrossOrigin configuration. By default all origins and GET, HEAD and POST methods are allowed.
package cn.saytime.config; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.web.servlet.config.annotation.CorsRegistry; import org.springframework.web.servlet.config.annotation.WebMvcConfigurer; import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter; /** * @author zh * @ClassName cn.saytime.config.CORSConfiguration * @Description */ @Configuration public class CORSConfiguration { @Bean public WebMvcConfigurer corsConfigurer() { return new WebMvcConfigurerAdapter() { @Override public void addCorsMappings(CorsRegistry registry) { // registry.addMapping("/api/**"); registry.addMapping("/**") .allowedOrigins("http://domain.com", "http://domain2.com") .allowedMethods("GET", "POST", "DELETE", "PUT", "OPTIONS") .allowCredentials(false).maxAge(3600); } }; } }