跨域問題其實(shí)之前就有說過，不明白的可以參考我之前的文章，這章主要講解SpringBoot CROS的支持。

這里主要按照官方文檔方式講述。

SpringBoot CROS 參考： http://docs./spring-boot/docs/1.5.4.RELEASE/reference/htmlsingle/#boot-features-cors

Spring CROS 參考： http://docs./spring/docs/4.3.9.RELEASE/spring-framework-reference/htmlsingle/#cors

一、代碼準(zhǔn)備

首先是支持Restful的controller，這里就不使用數(shù)據(jù)庫了，簡單一點(diǎn)。 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 {

	// 創(chuàng)建線程安全的Map
	static Map<Integer, User> users = Collections.synchronizedMap(new HashMap<Integer, User>());

	/**
	 * 根據(jù)ID查詢用戶
	 * @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);
	}

	/**
	 * 查詢用戶列表
	 * @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);
	}

	/**
	 * 添加用戶
	 * @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);
	}

	/**
	 * 根據(jù)id刪除用戶
	 * @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);
	}

	/**
	 * 根據(jù)id修改用戶信息
	 * @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
}

二、測試是否存在跨域問題

我們在static目錄新建一個(gè)test.html

<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Title</title>
	<script src="https://cdn./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()">請求跨域資源</button>
</body>
</html>

1. 我們使用IDEA的瀏覽器預(yù)覽功能，點(diǎn)擊谷歌小圖標(biāo)，可以看到打開網(wǎng)址為： http://localhost:63342/springboot-demo/springboot-cros/static/test.html?_ijt=ibtt432ffb9rh0vffqkkug3je8
2. 啟動(dòng)SpringBoot工程，默認(rèn)8080

不是使用IDEA的用戶，自己找個(gè)tomcat啟動(dòng)test.html頁面，修改端口為其他，然后啟動(dòng)springboot。

所以證明存在跨域問題。

一、@CrossOrigin注解方式 Controller method CORS configuration

這里我們在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訪問。

表示跨域問題解決。 default @CrossOrigin allows all origins and the HTTP methods specified in the @RequestMapping annotation 上面的官方文檔說明，也就是默認(rèn)的@CrossOrigin允許所有跨域請求。

通過查看CrossOrigin源碼可以看到， 默認(rèn)配置為：

"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 也可以用在整個(gè)Controller類上面。即該controller所有映射都支持跨域請求。

@CrossOrigin(origins = "http://",
		maxAge = 3600,
		methods = {RequestMethod.GET, RequestMethod.POST})
@RestController
public class UserController

二、全局CORS配置

Global 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://", "http://")
						.allowedMethods("GET", "POST", "DELETE", "PUT", "OPTIONS")
						.allowCredentials(false).maxAge(3600);
			}
		};
	}
}

三、過濾器實(shí)現(xiàn)跨域 Filter based CORS support

@Configuration
public class MyConfiguration {

	@Bean
	public FilterRegistrationBean corsFilter() {
		UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
		CorsConfiguration config = new CorsConfiguration();
		config.setAllowCredentials(false);
		config.addAllowedOrigin("http://");
		config.addAllowedHeader("*");
		config.addAllowedMethod("*");
		source.registerCorsConfiguration("/**", config);
		FilterRegistrationBean bean = new FilterRegistrationBean(new CorsFilter(source));
		bean.setOrder(0);
		return bean;
	}
}