最近看到若依图片验证码获取方式时，后台返回的是一串验证码字符串：
例如
/9j/4AAQSkZJRgABAgAAAQABAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQNDAsLDBkSEw8UHRofHh0aHBwgJC4nICIsIxwcKDcpLDAxNDQ0Hyc5PTgyPC4zNDL/2wBDAQkJCQwLDBgNDRgyIRwhMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjL/wAARCAA8AKADASIAAhEBAxEB/8QAHwAAAQUBAQEBAQEAAAAAAAAAAAECAwQFBgcICQoL/8QAtRAAAgEDAwIEAwUFBAQAAAF9AQIDAAQRBRIhMUEGE1FhByJxFDKBkaEII0KxwRVS0fAkM2JyggkKFhcYGRolJicoKSo0NTY3ODk6Q0RFRkdISUpTVFVWV1hZWmNkZWZnaGlqc3R1dnd4eXqDhIWGh4iJipKTlJWWl5iZmqKjpKWmp6ipqrKztLW2t7i5usLDxMXGx8jJytLT1NXW19jZ2uHi4+Tl5ufo6erx8vP09fb3+Pn6/8QAHwEAAwEBAQEBAQEBAQAAAAAAAAECAwQFBgcICQoL/8QAtREAAgECBAQDBAcFBAQAAQJ3AAECAxEEBSExBhJBUQdhcRMiMoEIFEKRobHBCSMzUvAVYnLRChYkNOEl8RcYGRomJygpKjU2Nzg5OkNERUZHSElKU1RVVldYWVpjZGVmZ2hpanN0dXZ3eHl6goOEhYaHiImKkpOUlZaXmJmaoqOkpaanqKmqsrO0tba3uLm6wsPExcbHyMnK0tPU1dbX2Nna4uPk5ebn6Onq8vP09fb3+Pn6/9oADAMBAAIRAxEAPwDtrW1ga1hZoIySikkoOeKsCztv+feL/vgU2z/484P+ua/yqyKiMY8q0IjGPKtCIWdr/wA+0P8A3wKeLK1/59of+/YqUU7pT5Y9h8sexELK0/59Yf8Av2KcLG0/59YP+/YqhJ4k0aG++xS6lbR3HTY8gH861kZWAIIIPpVyouNuaNr+QcsexGLCz/59YP8Av2KcLCz/AOfSD/v2KmFPBFRyx7Byx7EI0+y/59Lf/v2P8KcNOsv+fO3/AO/S/wCFTiqOsa5p+gWDXuoz+TApA3bSxJPQADmqhS55KMI3b6WDliuhaGnWP/Pnb/8Afpf8KcNNsf8Anyt/+/S/4VDpGq2utabBqFm5a3mXchIweuOn4VoCiVPlbjJWaDlj2K40yw/58rb/AL9L/hTxplh/z423/fpf8KsCsrVvFOjaC6JqV/Fbs/3Q3J/IU6dF1JcsI3fkgcYrdF8aXp//AD423/flf8KeNK0//nwtf+/K/wCFR6dq2n6rbiewvILmL+9E4YD646Gr45qZU1F2a1Dlj2Kw0rTv+fC1/wC/K/4U4aTp3/QPtf8Avyv+FWhTxS5Y9g5Y9iqNJ03/AKB9p/35X/Cq2p6Xp8ekXrpY2qusDlWEKgg7TyOK1hVXVv8AkC3/AP17yf8AoJpSjHlegpRjyvQ5Kz/484P+ua/yqyKr2f8Ax5wf9c1/lVkU4/Chx+FDhUF1L5URYVYFRXMXmxEe1UUfPHi6zNv4muJZCxhnkLhh79R+FdDpGt694Ut4rm0uf7S0nALRN1Qe3p9elbPizw79pL7lODyD6GuM0nUJ/D2oGxvT/o7H5WPRc9/p619lQzGWOwapcqlKmtYNfFFdYvdSXl/wDncOWV+57boXi3Ttf0s3trKF2D96jnDRHHf9ea4TXtWu/DnidfEOlXsl1pUrj7ZapNuRSeCcZwM9Qex+uK5a/juPDOprrGkN5cbHEsQ+7g9Rj+6f0PTtild6bbX+b/S3+zrMDug/hUnqAR29sf4Vz4bC4SjNYnn/AHM9NVf1jK2qfVSS/wCC5Sk1bqj6H0zV7XVdNhvrSVZIJV3Kw/zwR0Iryr4qahe6jqdlo0UTLAT5vmH7rnp+n9a43TNc8Q+EoZUtJfLt5m5DAOm71Hocfnj2rqNGh1/WVa41WaGaKUB4zkblOOo2jGMVH1JZXU+u05xnBX5ddW/RaXj1/QfNzrlasT/DLxa2jXLeHNSJQFybYk9GP8HpyeR7n3FesWXirQ7wMItTthIhKvHI/luhHUMrYIP1FeMeIfDBntshdtxGPkf19jWDFJb+IphDqzyw6nEuwzqMmcL2cd3AGM9SOvSidDCZlGWMu4v7aSvZ/wAyW7T663T7rVF5Q909y1v4j+GtGQh9RjuJu0Vr+8b8xwPxIrzHxvp6+Kb6LW9OvUkhmiG1Xz2/l9OxrnY7nwxpR3R20upTDp5pwgP0x/Q1pWnjMLLGLnRUgsCw3NCpG0evTBrelgK+EtWy+EubvLlV12UXqS5KWkxdK8N39ntu9J1WWyvQOVPQn6j/AANdt4a+J2pWOsw6H4sgRJJCqx3acA54BbsQTxkdO9bUGhW01hHdWrrJFIgdHXkMCMgivJfGW9PF1tFcHZFHswx6Y3cmssBiJ5rWlh8Yk9G07Wkrdmt/R3HJezV4n0/G4cZFSisfRLgzWkZJzwOa2RXyxuOFVdW/5Al//wBe0n/oJq2Kq6v/AMgS/wD+vaT/ANBNTL4WTL4WclZ/8eUH/XNf5VZFV7L/AI8oP+ua/wAqsiiPwoI/Chwp2M0gp4qijN1HT0uIj8vNeW+L/D3mwNtT96nKH+leylcjFYmr6Qt2hwOa2w9eph6sa1N2a1E0mrM8A+26pLYnTjAzjpkqSQK7Lwd4blNi63A+Z2yF9K6P/hE3M2ccZrrdG0YWiAEV6eNziWJpOjCmoRk7u3VkRp2d2zzvXPCkhtJYlX7ynH17VsfD7RLvT7D7PeOjkOSgXJ2g9uffNegXOnRzrgqKLLTltzwK81YmoqDw9/dbv89i7K9zK1nRkmtiQvOK8J8XWh0zXkki+R2Afj1B6/yr6ZniDxFcdq858QeErfUr4STWyyEcAkc4rrynHRwWJVWavGzTXdNE1I8yscxpfh6C4CXkVogklAkJIzgnnjPSuw03SLmNhuUlT1B710mhaOkECgoBgY6V0KWka4worgqVJ1HeTb9dSkrGZY2KW9gIIokjjGSERcAZ64Ary/4iWpsI1v47WGa4SQInmx78Z9B68CvahEAuAKwNX0r7S2QucHitMPW9lVjUavZ7d+6+YNXVjK+Gd/qN54ahbVYnjug7Kd8ewsueDjjHBx+Fd+vSuf0awa2ABroFHFRWqKpUlNKybvZbLyQJWVh4qrq//IEv/wDr2k/9BNWxVXV/+QJf/wDXtJ/6Caxl8LFL4WclZf8AHlb/APXNf5VZFczFrVzFEkapEQihRkHt+NSf2/df884f++T/AI1lGtGyM41Y2R0opwrmf+Ehu/8AnnB/3yf8aX/hIrv/AJ5wf98n/Gq9tEftonUCnbQa5b/hJLz/AJ5Qf98n/Gl/4SW8/wCeUH/fJ/xo9tEPbROoEKZzgVKqgVyf/CT3v/PK3/75b/Gl/wCEovf+eVv/AN8t/jR7aIe2ideBTwK47/hKr7/nlb/98t/jS/8ACV33/PK2/wC+W/xo9tEPbROyxkVG1ojtkqK5L/hLb/8A5423/fLf40v/AAl+of8APG2/75b/AOKo9tEPbROziiCDAFTCuH/4TDUP+eNr/wB8t/8AFUv/AAmWo/8APG1/75b/AOKo9tEPbRO6FBjDdRXDf8JnqP8Azxtf++G/+Kpf+E11L/nhaf8AfDf/ABVHtoh7aJ3aIF6CpRXAf8JtqX/PC0/74b/4ql/4TjU/+eFp/wB8N/8AFUe2iHtonoIqrq//ACA9Q/69pP8A0E1xX/Cc6n/zwtP++G/+KqO58Z6jdWs1u8NqElRkYqrZAIxx81TKtGzFKrGzP//Z
直接把内容放到浏览器是无法显示的，需要前面加
data:image/png;base64,
如下
data:image/png;base64,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
参考：
(124条消息) data: image/png； base64 用法详解 ( 作用，语法，优缺点 )_雁 南飞的博客-CSDN博客_data:image
若依Vue（前后端分离版）开源项目分析【完结】_哔哩哔哩_bilibili
