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Detailed introduction to ajax cross-domain
- angryTomforward
- 2019-08-01 17:54:212514browse
AJAX cross-domain
Note: Part of the content of this article comes from MOOC.com. @MOOC.com: https://www.imooc.com
Course Introduction
●What is AJAX cross-domain problem
●The reasons for AJAX cross-domain problem
●Thinking and methods of solving AJAX cross-domain problems
What is AJAX cross-domain problem
●Simply put, when the front end calls the back-end service interface
●If the service interface is not in the same domain, cross-domain problems will occur
AJAX cross-domain scenario
●The front-end and back-end separation, service-oriented development model
● The front-end and back-end development are independent, and the front-end needs to call a large number of back-end interfaces
●As long as the back-end interfaces are not in the same domain, cross-domain problems will occur
●Cross-domain problems are very common and need to be solved Cross-domain issues are also very important
AJAX cross-domain reasons
●Browser restrictions: Browser security verification restrictions
●Cross-domain (protocol, domain name, port any one Different will be considered as cross-domain)
●XHR (XMLHttpRequest) request
AJAX cross-domain problem solving ideas
●Browser: The browser removes cross-domain verification , of little actual value
●XHR: Do not use XHR, use JSONP, which has many disadvantages and cannot meet current development requirements
●Cross-domain: The callee modification supports cross-domain calls ( Specify parameters); the caller modifies the hidden cross-domain (based on proxy)
Write test code
●Called party back-end code writing: Spring Boot
●Caller front-end Code writing: Jquery
●Introducing the front-end Jasmine testing framework
Why do cross-domain problems occur?
The above picture is also very clear, because the browser itself has restrictions for security (same origin).
●When we send an XMLHttpRequest request, if the requested domain (host domain name, port) is different, then a cross-domain problem will occur (the client cannot obtain the data returned by the server)
It is worth noting that cross-domain problems occur in XMLHttpRequest requests, that is to say, there will be no cross-domain problems if it is not an XMLHttpRequest request
●A very simple example: When writing a web page, , if the URL is not in this domain, the image can still be obtained normally.
Ideas for solving cross-domain problems
Environment setup
2-1 Back-end project
Code writing
1. Create a maven project pom named ajax-server as follows
<?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.myimooc</groupId>
<artifactId>ajax-server</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>ajax-server</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.1.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-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>2. Write the AjaxServerStart class
package com.myimooc.ajax.server;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
/**
* <br>
* 标题: 启动类<br>
* 描述: AJAX跨域讲解后端项目<br>
*
* @author zc
* @date 2018/04/18
*/
@SpringBootApplication
public class AjaxServerStart {
public static void main(String[] args) {
SpringApplication.run(AjaxServerStart.class, args);
}
}3. Write a ResultBean Class
package com.myimooc.ajax.server.vo;
import java.io.Serializable;
/**
* <br>
* 标题: REST请求响应POJO类<br>
* 描述: 封装请求响应结果<br>
*
* @author zc
* @date 2018/04/18
*/
public class ResultBean implements Serializable{
private static final long serialVersionUID = 7867107433319736719L;
private String data;
public ResultBean(String data) {
this.data = data;
}
public String getData() {
return data;
}
public void setData(String data) {
this.data = data;
}
}4. Write TestController class
package com.myimooc.ajax.server.controller;
import com.myimooc.ajax.server.vo.ResultBean;
import com.myimooc.ajax.server.vo.User;
import org.springframework.web.bind.annotation.*;
/**
* <br>
* 标题: 测试控制器<br>
* 描述: 提供REST服务<br>
* 使用 @CrossOrigin 注解支持跨域，可以放到类或方法上面
* @author zc
* @date 2018/04/18
*/
@RestController
@RequestMapping("/test")
//@CrossOrigin
public class TestController {
@GetMapping("/get1")
public ResultBean get1() {
System.out.println("TestController.get1");
return new ResultBean("get1ok");
}
@PostMapping("/postJson")
public ResultBean postJson(@RequestBody User user) {
System.out.println("TestController.postJson");
return new ResultBean("postJson" + user.getName());
}
@GetMapping("/getCookie")
public ResultBean getCookie(@CookieValue(value = "cookie1") String cookie1) {
System.out.println("TestController.getCookie");
return new ResultBean("getCookie" + cookie1);
}
@GetMapping("/getHeader")
public ResultBean getHeader(
@RequestHeader("x-header1") String header1,
@RequestHeader("x-header2") String header2) {
System.out.println("TestController.getHeader");
return new ResultBean("getHeader" + header1+header2);
}
}2-2 Front-end project
Code writing
1. Create a maven project pom named ajax-client as follows
<?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.myimooc</groupId>
<artifactId>ajax-client</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>ajax-client</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.1.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.webjars</groupId>
<artifactId>jquery</artifactId>
<version>3.3.0</version>
</dependency>
<dependency>
<groupId>org.webjars</groupId>
<artifactId>jasmine</artifactId>
<version>2.5.0</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>2. Write index.html
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Index</title>
<link rel="stylesheet" type="text/css" href="/webjars/jasmine/2.5.0/jasmine.css">
<script src="/webjars/jquery/3.3.0/jquery.min.js"></script>
<script src="/webjars/jasmine/2.5.0/jasmine.js"></script>
<script src="/webjars/jasmine/2.5.0/jasmine-html.js"></script>
<script src="/webjars/jasmine/2.5.0/boot.js"></script>
</head>
<body>
<a href="#" onclick="get1()">发生get1请求</a>
<script>
function get1() {
$.getJSON("http://localhost:8080/test/get1").then(
function (res) {
console.log(res);
}
)
}
// 每一个测试用例的超时时间
jasmine.DEFAULT_TIMEOUT_INTERVAL = 1000;
// 请求的接口地址前缀
var base = "http://localhost:8080/test";
// 测试模块
describe("AJAX讲解", function () {
// 测试方法
it("get1请求", function (done) {
// 服务器返回的结果
var result;
$.getJSON(base + "/get1").then(
function (res) {
result = res;
}
);
// 由于是异步请求，需要使用setTimeout来校验
setTimeout(function () {
expect(result).toEqual({
"data":"get1ok"
});
// 校验完成，通知jasmine框架
done();
},100);
});
// // 测试方法
// it("jsonp请求", function (done) {
// // 服务器返回的结果
// var result;
// $.ajax({
// url: base + "/get1",
// dataType: "jsonp",
// jsonp:"callback2",
// success: function (res) {
// result = res;
// }
// });
//
// // 由于是异步请求，需要使用setTimeout来校验
// setTimeout(function () {
// expect(result).toEqual({
// "data":"get1ok"
// });
//
// // 校验完成，通知jasmine框架
// done();
// },100);
// });
// 测试方法
it("postJson请求", function (done) {
// 服务器返回的结果
var result;
$.ajax({
url:base+"/postJson",
type:"POST",
contentType:"application/json;charset=utf-8",
data:JSON.stringify({name:"testName"}),
success:function(res){
result = res;
}
});
// 由于是异步请求，需要使用setTimeout来校验
setTimeout(function () {
expect(result).toEqual({
"data":"postJsontestName"
});
// 校验完成，通知jasmine框架
done();
},100);
});
it("getCookie请求", function (done) {
// 服务器返回的结果
var result;
$.ajax({
url:base+"/getCookie",
xhrFields:{
// 发送 AJAX 请求时带上 cookie
withCredentials:true
},
success:function(res){
result = res;
}
});
// 由于是异步请求，需要使用setTimeout来校验
setTimeout(function () {
expect(result).toEqual({
"data":"getCookietestName"
});
// 校验完成，通知jasmine框架
done();
},100);
});
it("getHeader请求", function (done) {
// 服务器返回的结果
var result;
$.ajax({
url:base+"/getHeader",
headers:{
"x-header1":"AAA"
},
beforeSend:function(xhr){
xhr.setRequestHeader("x-header2","BBB")
},
success:function(res){
result = res;
}
});
// 由于是异步请求，需要使用setTimeout来校验
setTimeout(function () {
expect(result).toEqual({
"data":"getHeaderAAABBB"
});
// 校验完成，通知jasmine框架
done();
},100);
});
});
</script>
</body>
</html>3. Write application .properties
server.port=8081
4. Write the AjaxClientStart class
package com.myimooc.ajax.client;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class AjaxClientStart {
public static void main(String[] args) {
SpringApplication.run(AjaxClientStart.class, args);
}
}5. Start AjaxServerStart and AjaxClientStart, and access http://localhost :8081, click to generate get1 request, resulting in cross-domain problems as follows
Solution to cross-domain
3-1 Prohibition of checking
Cross-domain settings of Chrome browser
●Windows method
Reference document: https://www.cnblogs.com/laden...
Instructions for use: Target input in the properties page Add in the box: --disable-web-security --user-data-dir=C:MyChromeDevUserData
●Mac OS method
Reference document: http://blog.csdn.net/justinji...
使用说明：用命令行打开 Google Chrome：open -a "Google Chrome" --args --disable-web-security
3-2 使用JSONP
代码编写
1.编写JsonpAdvice类
package com.myimooc.ajax.server.controller;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.servlet.mvc.method.annotation.AbstractJsonpResponseBodyAdvice;
/**
* <br>
* 标题: JSONP 全局处理<br>
* 描述: 统一处理JSONP<br>
*
* @author zc
* @date 2018/04/18
*/
@ControllerAdvice
public class JsonpAdvice extends AbstractJsonpResponseBodyAdvice{
public JsonpAdvice() {
// 与前端约定好回调方法名称，默认是callback
super("callback2");
}
}2.修改index.html
// 测试方法
it("jsonp请求", function (done) {
// 服务器返回的结果
var result;
$.ajax({
url: base + "/get1",
dataType: "jsonp",
jsonp:"callback2",
success: function (res) {
result = res;
}
});
// 由于是异步请求，需要使用setTimeout来校验
setTimeout(function () {
expect(result).toEqual({
"data":"get1ok"
});
// 校验完成，通知jasmine框架
done();
},100);
});JSONP的弊端
服务器需要改动代码支持只支持GET发送的不是XHR请求
3-3 支持跨域
常见的JavaEE架构
跨域解决方向
●被调用方解决
●基于支持跨域的解决思路
●基于Http协议关于跨域的相关规定，在响应头里增加指定的字段告诉浏览器，允许调用
●跨域请求是直接从浏览器发送到被调用方
●修改被调用方的Http服务器
调用方解决
●基于隐藏跨域的解决思路
●跨域请求不会浏览器直接发送到被调用方
●而是从中间的Http服务器（Apache、Nginx）转发过去
●修改调用方的Http服务器
被调用方支持跨域
●【重点】Web应用服务器（Tomcat、Netty、WebLogic或应用程序）实现
●Http服务器（Nginx）配置实现
●Http服务器（Apache）配置实现
使用Filter解决
编写代码
1.编写CrosFilter类
package com.myimooc.ajax.server.config;
import org.springframework.util.StringUtils;
import javax.servlet.*;
import javax.servlet.FilterConfig;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
/**
* <br>
* 标题: 服务端解决跨域<br>
* 描述: 使用Filter<br>
*
* @author zc
* @date 2018/04/18
*/
public class CrosFilter implements Filter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
HttpServletResponse res = (HttpServletResponse)response;
HttpServletRequest req = (HttpServletRequest)request;
// 支持所有域
String origin = req.getHeader("Origin");
if (!StringUtils.isEmpty(origin)){
// 支持任何域名的跨域调用 且 支持带cookie（是被调用方域名的cookie，而不是调用方的cookie）
res.addHeader("Access-Control-Allow-Origin",origin);
}
// 指定允许的域，带cookie时，origin必须是全匹配，不能使用 *
// res.addHeader("Access-Control-Allow-Origin","http://localhost:8081");
// 允许所有域，但不能满足带 cookie 的跨域请求
// res.addHeader("Access-Control-Allow-Origin","*");
// 支持所有自定义头
String headers = req.getHeader("Access-Control-Allow-Headers");
if (!StringUtils.isEmpty(headers)){
// 允许所有header
res.addHeader("Access-Control-Allow-Headers",headers);
}
// 允许所有header
// res.addHeader("Access-Control-Allow-Headers","*");
// 指定允许的方法
// res.addHeader("Access-Control-Allow-Methods","GET");
// 允许所有方法
res.addHeader("Access-Control-Allow-Methods","*");
// 允许浏览器在一个小时内，缓存跨域访问信息（即上面三个信息）
res.addHeader("Access-Control-Max-Age","3600");
// 启用 cookie
res.addHeader("Access-Control-Allow-Credentials","true");
chain.doFilter(request,response);
}
@Override
public void destroy() {
}
}2.编写FilterConfig类
package com.myimooc.ajax.server.config;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
/**
* <br>
* 标题: 配置类<br>
* 描述: 注册CrosFilter<br>
*
* @author zc
* @date 2018/04/18
*/
@Configuration
public class FilterConfig {
@Bean
public FilterRegistrationBean registrationBean(){
FilterRegistrationBean filter = new FilterRegistrationBean();
filter.addUrlPatterns("/*");
filter.setFilter(new CrosFilter());
return filter;
}
}3.启动AjaxServerStart和AjaxClientStart，并访问http://localhost:8081，跨域解决
简单请求与非简单请求
●简单请求：浏览器先发送真正的请求后检查
●请求方法：GET、HEAD、POST的一种
●请求header：无自定义header；Content-Type为：text/plain、multipart/form-data、application/x-www-form-urlencoded的一种
●非简单请求：浏览器先发预检命令，检查通过后，才发送真正的请求
●常见的有：PUT、DELETE
●其它条件：发送Json格式的请求、带自定义header的请求
●预检命令：浏览器检测到跨域请求, 会自动发出一个OPTIONS请求, 就是所谓的预检（preflight）请求。当预检请求通过的时候，才发送真正的请求。
Nginx配置
●修改主机hosts文件增加映射本地域名：127.0.0.1 b.com（表示被调用方的域名）
●在conf目录下创建vhost目录
●修改nginx.conf在最后面增加一行代码：include vhost/*.conf;
●在vhost目录下创建b.com.conf
●启动niginx，访问b.com/test/get1
编写b.com.conf
server{
listen 80;
server_name b.com;
location /{
proxy_pass http://localhost:8080/;
add_header Access-Control-Allow-Methods *;
add_header Access-Control-Max-Age 3600;
add_header Access-Control-Allow-Credentials true;
add_header Access-Control-Allow-Origin $http_origin;
add_header Access-Control-Allow-Headers $http_access_control_allow_headers;
if ($request_method = OPTIONS){
return 200;
}
}
}Apache配置
●修改conf/httpd.conf找到LoadModule vhost_alias_module module/mod_vhost_alias.so取消注释
●修改conf/httpd.conf找到LoadModule proxy_module module/mod_ proxy.so取消注释
●修改conf/httpd.conf找到LoadModule proxy_http_module module/mod_ proxy_http.so取消注释
●修改conf/httpd.conf找到LoadModule headers_module module/mod_ headers.so取消注释
●修改conf/httpd.conf找到LoadModule rewrite_module module/mod_ rewrite.so取消注释
●修改conf/httpd.conf找到Include conf/extra/httpd-vhosts.conf取消注释
●修改conf/extra/httpd-vhosts.conf在最后面增加下面的内容即可
<VirtualHost *:80>
ServerName b.com
ErrorLog "logs/b.com-error.log"
CustomLog "logs/b.com-access.log" common
ProxyPass / http://localhost:8080/
# 把请求头的origin值返回到Access-Control-Allow-Origin字段
Header always set Access-Control-Allow-Origin "expr=%{req:origin}"
# 把请求头的Access-Control-Allow-Headers值返回到Access-Control-Allow-Headers字段
Header always Access-Control-Allow-Headers "expr=%{Access-Control-Allow-Headers}"
Header always set Access-Control-Allow-Methods "*";
Header always set Access-Control-Max-Age "3600";
Header always set Access-Control-Allow-Credentials ""true";
# 处理预检命令OPTIONS，直接返回204
RewriteEngine On
RewriteCond %{REQUEST_METHOD}OPTIONS
RewriteRule ^(.*)$"/" [R=204,L]
</VirtualHost>Spring框架支持
在类或方法上使用注解@CrossOrigin即可支持跨域
3-4 隐藏跨域
●使用Nginx反向代理实现
●修改主机hosts文件增加映射本地域名：127.0.0.1 a.com
●在vhost目录下创建a.com.conf
●启动niginx，访问a.com/ajaxserver/get1
编写a.com.conf
server{
listen 80;
server_name a.com;
location /{
proxy_pass http://localhost:8081/;
}
location /ajaxserver{
proxy_pass http://localhost:8080/test/;
}
}使用Apache反向代理实现
修改conf/extra/httpd-vhosts.conf在最后面增加下面的内容即可
<VirtualHost *:80>
ServerName a.com
ErrorLog "logs/a.com-error.log"
CustomLog "logs/a.com-access.log" common
ProxyPass / http://localhost:8081/
ProxyPass /ajaxserverapache http://localhost:8080/test
</VirtualHost>课程总结
4-1 课程总结
课程总结
●产生原因：主要是浏览器对Ajax请求的限制
●解决思路：JSONP、支持跨域、隐藏跨域
●核心原理：了解Http协议关于跨域方面的规定
●Solution: Use Filter, Nginx forward and reverse proxy, Apache forward and reverse proxy, Spring framework support
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