(一)jwt作用分析以及在Startup.cs里面的基础配置

前后端分离后,登陆系统后生成一个token,然后将呢个token返给前端,前端每次都要带着这个token进行登陆,否则无法访问后端api接口,后端不用去对比,无需存储token,无需对比,后端自动会识别token是否正确，实现了无状态化的验证(无状态化验证)

但是当验证只能在单设备上登陆的时候,必须存储当前用户的最新token，要不然同一个账号就可以在多个设备上登陆了,呢种后端必须要存储生成的token

1:在业务层(controller层)nuget下载3.1.9版本

Microsoft.AspNetCore.Authentication.JwtBear

2：在底层jwt的基础帮助类里面nuget下载

System.IdentityModel.Tokens.Jwt

3：Startup.cs配置

public void ConfigureServices(IServiceCollection services)
{
services.AddControllers();

//跨域配置

string corsUrls = "https://www.xx.yy,http://xxx.yyy.z.hh:xxxx",
if (string.IsNullOrEmpty(corsUrls))
{
throw new Exception("请配置跨请求的前端Url");
}

services.AddCors(options =>
{
options.AddDefaultPolicy(
builder =>
{
builder.WithOrigins(corsUrls.Split(",")).AllowCredentials()
.AllowAnyHeader().AllowAnyMethod().WithExposedHeaders("Authorization");
});
});

//引用jwt的相关配置
services.AddAuthentication(options =>
{
options.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
options.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
}).AddJwtBearer(options =>
{
options.TokenValidationParameters = new TokenValidationParameters
{

SaveSigninToken = true,//保存token,后台验证token是否失效
ValidateIssuer = true,//是否验证Issuer签发人
ValidateAudience = true,//是否验证Audience受众
ValidateLifetime = true,//是否验证失效时间
ValidateIssuerSigningKey = true,//是否验证SecurityKey
ValidAudience = "pms.core",//受众
ValidIssuer = "pms.core.owner",//签发人，这两项和前面签发jwt的设置一致
IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes("BB3647441FFA4B5DB4E64A29B53CE525"))
};
//jwt验证失败
options.Events = new JwtBearerEvents()
{
OnChallenge = context =>
{
//此处代码为终止.Net Core默认的返回类型和数据结果，这个很重，必须
context.HandleResponse();
context.Response.Clear();
context.Response.ContentType = "application/json";
context.Response.StatusCode = 401;
context.Response.WriteAsync(new { message = "授权未通过", status = false, code = 401 }.Serialize());
return Task.CompletedTask;
}
};
});
}

 4：在Startup.cs的Configure方法里面的 app.UseAuthorization();上面需要新增:app.UseAuthentication();(启用jwt的权限验证):

app.UseCors();//启用跨域
app.UseAuthentication();//启用jwt权限认证
app.UseAuthorization();

5：依赖得json帮助类

public static class Exeper {
public static string Serialize(this object obj, JsonSerializerSettings formatDate = null)
{
if (obj == null) return null;
formatDate = formatDate ?? new JsonSerializerSettings
{
DateFormatString = "yyyy-MM-dd HH:mm:ss"
};
return JsonConvert.SerializeObject(obj, formatDate);
}
}