03.解决前端调用后端跨域问题
2023年1月6日约 881 字大约 3 分钟
03.解决前端调用后端跨域问题
在学习前端的内容，目前在页面上展示一个图表，这些图表的数据其实就是一个json数组，内容如下：
[{"id":1,"name":"zhangs","nickname":"zhangs","desc":"人之初"},{"id":2,"name":"lis","nickname":"lis","desc":"性本善"},{"id":3,"name":"wangw","nickname":"wangw","desc":"性相近"},{"id":4,"name":"zhaol","nickname":"zhaol","desc":"习相远"},{"id":5,"name":"liuq","nickname":"liuq","desc":"苟不教"},{"id":6,"name":"mingb","nickname":"mingb","desc":"性乃迁"}]
原本这些数据在教学网站上，但是自己想着练手一下，通过gin框架来吧这个数组返回，代码如下：
package main
import (
"github.com/gin-gonic/gin"
"net/http"
)
type Date struct {
ID int `json:"id"`
Name string `json:"name"`
Nickname string `json:"nickname"`
Desc string `json:"desc"`
}
func main() {
r:=gin.Default()
a:=[]Date{
{ID: 1, Name: "zhangs", Nickname: "zhangs", Desc: "人之初",},
{ID: 2, Name: "lis", Nickname: "lis", Desc: "性本善",},
{ID: 3, Name: "wangw", Nickname: "wangw", Desc: "性相近",},
{ID: 4, Name: "zhaol", Nickname: "zhaol", Desc: "习相远",},
{ID: 5, Name: "liuq", Nickname: "liuq", Desc: "苟不教",},
{ID: 6, Name: "mingb", Nickname: "mingb", Desc: "性乃迁",},
}
r.GET("/sys/jslist", func(c *gin.Context) {
c.IndentedJSON(http.StatusOK, a)
})
r.Run(":8000")
}
启动golang项目之后，赶忙去前端进行一下请求，结果一片空白，什么数据也没有，打开检查发现跨域了，报错如下：
Access to XMLHttpRequest at 'http://127.0.0.1:8000/sys/jslist?pageIndex=1&pageSize=10' from origin 'null' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource
于是就想着从go的层面解决一下，最后在网上找到了答案，调整go代码如下：
package main
import (
"fmt"
"github.com/gin-gonic/gin"
"net/http"
"strings"
)
type Date struct {
ID int `json:"id"`
Name string `json:"name"`
Nickname string `json:"nickname"`
Desc string `json:"desc"`
}
func main() {
r:=gin.Default()
r.Use(Cors())
a:=[]Date{
{ID: 1, Name: "zhangs", Nickname: "zhangs", Desc: "人之初",},
{ID: 2, Name: "lis", Nickname: "lis", Desc: "性本善",},
{ID: 3, Name: "wangw", Nickname: "wangw", Desc: "性相近",},
{ID: 4, Name: "zhaol", Nickname: "zhaol", Desc: "习相远",},
{ID: 5, Name: "liuq", Nickname: "liuq", Desc: "苟不教",},
{ID: 6, Name: "mingb", Nickname: "mingb", Desc: "性乃迁",},
}
r.GET("/sys/jslist", func(c *gin.Context) {
//c.AbortWithStatus(http.StatusNoContent)
c.IndentedJSON(http.StatusOK, a)
r.Run(":8000")
}
// 跨域
func Cors() gin.HandlerFunc {
return func(c *gin.Context) {
method := c.Request.Method //请求方法
origin := c.Request.Header.Get("Origin") //请求头部
var headerKeys []string // 声明请求头keys
for k, _ := range c.Request.Header {
headerKeys = append(headerKeys, k)
}
headerStr := strings.Join(headerKeys, ", ")
if headerStr != "" {
headerStr = fmt.Sprintf("access-control-allow-origin, access-control-allow-headers, %s", headerStr)
} else {
headerStr = "access-control-allow-origin, access-control-allow-headers"
}
if origin != "" {
c.Writer.Header().Set("Access-Control-Allow-Origin", "*")
c.Header("Access-Control-Allow-Origin", "*") // 这是允许访问所有域
c.Header("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE,UPDATE") //服务器支持的所有跨域请求的方法,为了避免浏览次请求的多次'预检'请求
// header的类型
c.Header("Access-Control-Allow-Headers", "Authorization, Content-Length, X-CSRF-Token, Token,session,X_Requested_With,Accept, Origin, Host, Connection, Accept-Encoding, Accept-Language,DNT, X-CustomHeader, Keep-Alive, User-Agent, X-Requested-With, If-Modified-Since, Cache-Control, Content-Type, Pragma")
// 允许跨域设置 可以返回其他子段
c.Header("Access-Control-Expose-Headers", "Content-Length, Access-Control-Allow-Origin, Access-Control-Allow-Headers,Cache-Control,Content-Language,Content-Type,Expires,Last-Modified,Pragma,FooBar") // 跨域关键设置 让浏览器可以解析
c.Header("Access-Control-Max-Age", "172800") // 缓存请求信息 单位为秒
c.Header("Access-Control-Allow-Credentials", "false") // 跨域请求是否需要带cookie信息 默认设置为true
c.Set("content-type", "application/json") // 设置返回格式是json
}
//放行所有OPTIONS方法
if method == "OPTIONS" {
c.JSON(http.StatusOK, "Options Request!")
}
// 处理请求
c.Next() // 处理请求
}
}
接着再来请求，发现可以拿到数据了：
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