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spring boot ajax跨域的两种方式

时间：2022-05-07 06:21 编辑：来源：阅读：
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摘要：spring boot ajax跨域的两种方式

[b]前言[/b] java语言在多数时，会作为一个后端语言，为前端的php,node.js等提供API接口。前端通过ajax请求去调用java的API服务。今天以node.js为例，介绍两种跨域方式：CrossOrigin和反向代理。 [b] 一、准备工作[/b] [b]pom.xml：[/b]

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 <modelVersion>4.0.0</modelVersion>
 <groupId>com.example</groupId>
 <artifactId>spring-boot-15</artifactId>
 <version>0.0.1-SNAPSHOT</version>
 <packaging>jar</packaging>
 <name>spring-boot-15</name>
 <description>Demo project for Spring Boot</description>
 <parent>
 <groupId>org.springframework.boot</groupId>
 <artifactId>spring-boot-starter-parent</artifactId>
 <version>1.5.3.RELEASE</version>
 <relativePath/> <!-- lookup parent from repository -->
 </parent>
 <properties>
 <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
 <java.version>1.8</java.version>
 </properties>
 <dependencies>
 <dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
 </dependency>
 <dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-devtools</artifactId>
  <scope>runtime</scope>
 </dependency>
 <dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-test</artifactId>
  <scope>test</scope>
 </dependency>
 </dependencies>
 <build>
 <plugins>
  <plugin>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-maven-plugin</artifactId>
  </plugin>
 </plugins>
 </build>
</project>

[b]pom.xml[/b] App.java

package com.example;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication
@SpringBootApplication
public class App {
 public static void main(String[] args) {
 SpringApplication.run(App.class, args);
 }
}

User.java

package com.example;
public class User {
 public int id;
 public String name;
 public int age;
}

MainController.java：

package com.example;
import java.util.ArrayList;
import java.util.List;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
/**
 * *
 */
@RestController
public class MainController {
 @GetMapping("findAllUser")
 public List<User> findAllUser() {
 List<User> list = new ArrayList<>();
 for (int i = 0; i < 20; i++) {
  User user = new User();
  list.add(user);
  user.id = i;
  user.name = "name_" + i;
  user.age = 20 + i;
 }
 return list;
 }
}

项目结构如下图所示： [img]http://img.1sucai.cn/uploads/article/2018010710/20180107100139_0_22354.png[/img] 访问[url=http://localhost:8080/findAllUser]http://localhost:8080/findAllUser[/url] [img]http://img.1sucai.cn/uploads/article/2018010710/20180107100139_1_53016.png[/img] 使用HBuilder创建node.js express项目： [img]http://img.1sucai.cn/uploads/article/2018010710/20180107100140_2_88744.png[/img] 选择ejs模板引擎： [img]http://img.1sucai.cn/uploads/article/2018010710/20180107100140_3_86014.png[/img] index.ejs文件代码如下：

<!DOCTYPE html>
<html>
 <head>
 <title>
  <%= title %>
 </title>
 <link rel='stylesheet' href='/stylesheets/style.css' />
 <script src="//cdn.bootcss.com/angular.js/1.5.6/angular.min.js"></script>
 <script type="text/javascript">
  var app = angular.module('app', []);
  app.controller('MainController', function($rootScope, $scope, $http) {
  $http({
   method: 'GET',
   url: 'http://localhost:8080/findAllUser'
  }).then(function successCallback(r) {
   $scope.rows = r.data;
  });
  });
 </script>
 </head>
 <body ng-app="app" ng-controller="MainController">
 <h1><%= title %></h1>
 <p>Welcome to
  <%= title %>
 </p>
 <br />
 <table>
  <tr ng-repeat="row in rows">
  <td>{{row.id}}</td>
  <td>{{row.name}}</td>
  <td>{{row.age}}</td>
  </tr>
 </table>
 </body>
</html>

通过angular.js的http方法调用api请求右键运行项目： [img]http://img.1sucai.cn/uploads/article/2018010710/20180107100141_4_37305.png[/img] 运行效果： [img]http://img.1sucai.cn/uploads/article/2018010710/20180107100141_5_86987.png[/img] 发现调用ajax请求时跨域失败。 [b]二、spring boot后台设置允许跨域[/b] 这时，修改MainController类，在方法前加@CrossOrigin注解：

/**
 * 
 *
 */
@RestController
public class MainController {
 @CrossOrigin(origins = "http://localhost:3000")
 @GetMapping("findAllUser")
 public List<User> findAllUser() {
 List<User> list = new ArrayList<>();
 for (int i = 0; i < 20; i++) {
  User user = new User();
  list.add(user);
  user.id = i;
  user.name = "name_" + i;
  user.age = 20 + i;
 }
 return list;
 }
}

这是声明findAllUser方法允许跨域，也可以修改App.java，来实现全局跨域：

package com.example;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.web.servlet.config.annotation.CorsRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
@SpringBootApplication
public class App {
 public static void main(String[] args) {
 SpringApplication.run(App.class, args);
 }
 @Bean
 public WebMvcConfigurer corsConfigurer() {
 return new WebMvcConfigurerAdapter() {
  @Override
  public void addCorsMappings(CorsRegistry registry) {
  registry.addMapping("/**").allowedOrigins("http://localhost:3000");
  }
 };
 }
}

registry.addMapping("/**")：为根目录的全部请求，也可以设置为"/user/**"，这意味着是user目录下的所有请求。在访问[url=http://localhost:3000]http://localhost:3000[/url]，效果如下： [img]http://img.1sucai.cn/uploads/article/2018010710/20180107100141_6_10938.png[/img] [b]三、通过node.js的方向代理实现跨域[/b] node.js提供了一些反向代理的中间件，能轻而易举的实现跨域，而不需要spring boot做任何设置。安装express-http-proxy中间件 npm install --save-dev express-http-proxy [img]http://img.1sucai.cn/uploads/article/2018010710/20180107100142_7_57307.png[/img] 修改app.js文件，使其支持反向代理：

var proxy = require('express-http-proxy');
var apiProxy = proxy('http://localhost:8080', {});
app.use('/api', apiProxy);

以“/api”开头的请求转发为spring boot的API服务。完整代码如下：

/**
 * Module dependencies.
 */
var express = require('express')
 , routes = require('./routes')
 , user = require('./routes/user')
 , http = require('http')
 , path = require('path');
var app = express();
// all environments
app.set('port', process.env.PORT || 3000);
app.set('views', __dirname + '/views');
app.set('view engine', 'ejs');
app.use(express.favicon());
app.use(express.logger('dev'));
app.use(express.bodyParser());
app.use(express.methodOverride());
app.use(app.router);
app.use(express.static(path.join(__dirname, 'public')));
// development only
if ('development' == app.get('env')) {
 app.use(express.errorHandler());
}
var proxy = require('express-http-proxy');
var apiProxy = proxy('http://localhost:8080', {});
app.use('/api', apiProxy);
app.get('/', routes.index);
app.get('/users', user.list);
http.createServer(app).listen(app.get('port'), function(){
 console.log('Express server listening on port ' + app.get('port'));
});

修改index.ejs文件：

 var app = angular.module('app', []);
  app.controller('MainController', function($rootScope, $scope, $http) {
  $http({
   method: 'GET',
   url: '/api/findAllUser'
  }).then(function successCallback(r) {
   $scope.rows = r.data;
  });
  });

完整的index.ejs文件如下：

<!DOCTYPE html>
<html>
  <head>
    <title>
      <%= title %>
    </title>
    <link rel='stylesheet' href='/stylesheets/style.css' />
    <script src="//cdn.bootcss.com/angular.js/1.5.6/angular.min.js"></script>
    <script type="text/javascript">
      var app = angular.module('app', []);
      app.controller('MainController', function($rootScope, $scope, $http) {
        $http({
          method: 'GET',
          url: '/api/findAllUser'
        }).then(function successCallback(r) {
          $scope.rows = r.data;
        });
      });
    </script>
  </head>
  <body ng-app="app" ng-controller="MainController">
    <h1><%= title %></h1>
    <p>Welcome to
      <%= title %>
    </p>
    <br />
    <table>
      <tr ng-repeat="row in rows">
        <td>{{row.id}}</td>
        <td>{{row.name}}</td>
        <td>{{row.age}}</td>
      </tr>
    </table>
  </body>
</html>

运行效果如下： [img]http://img.1sucai.cn/uploads/article/2018010710/20180107100142_8_97885.png[/img] [b]总结[/b] 　　第二种通过反向代理的方式是最佳方案。在正式项目中，可以使用node.js控制web前端渲染与spring boot后端提供API服务的组合。这样，可以控制用户在node.js端登录后才能调用spring boot的API服务。在大型web项目中也可以使用node.js的反向代理，把很多子站点关联起来，这样便发挥出了网站灵活的扩展性。以上所述是小编给大家介绍的spring boot ajax跨域的两种方式，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对编程素材网网站的支持！

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