将 base 64 字符串另存为图像文件

Question

我有一个包含base64图像的html字符串，如下所示：

<p><img src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAOEAAADhCAMAAAAJbSJIAAABU1BMVEX////qQzU0qFNChfT7vAXb5/1blfVJivXL3Pw9gvTqPzBDh/W5z/vqQTMwp1DqPS7pOSn4/Pn/ /v7vQT97 7z vX 9/copUv2sq3rSz36/P/whHzz9/7tYFX4wLv 9PNIsWTn9Or 7sD5ysZRj/X//fXsUkWl1rHN6NR0wojzl5D61tP1rKZYt3Hq9u386Ob74d/yk4z 6K3 8s01pVz7xDM9kMH80mn8yUnE5My138GMy5z813f5sAvxcyKhwvk8la1BiOg/i9qCyJTo8P3wfnXvdGrual6v3Lqrx/phuXiQt/k6mpc jso4oH44noc2o2lyo/c9krg7mKCVsS5Xq0i1tCWOwWvfuRGnsyyGr/hyrT/Mtxv 67eY0KZruJ6ayMn934v71brtWh/3nBP8x0HtVi70jhrvbifyjmjrTzDygSD  OX94Zn3pRF4rjvk6MKsrSR6AAAL2UlEQVR4nO2b63vaRhbGhYyTIEfifgsGQ0gEiIshl6ZAum4XAw5uu3W77WbThN1sm3a36yT7/3/akRDmJqQzI81IyqP3S54nNrZ PmfOe2bOiOMCBQoUKFCgQIECBQoUyHdKrOT2oziqxEnqtNuslnItRekVkHq9ntLKlarN7mkqlfE3bAahlVq98VTOh6LR2LqiUSEkFycFJYdIU77EPOlWc0phKiM0RCMihdal/oegfSlfnPRapeapvyhTzVxvUswLGlvIVBooCudYKXUzbj83UKmqotFZwm1iivK00Gp6HzLR7BXzorCdlDBKtDQnrVO3EcyUaSrFaAwjdruU0Vh XEq5DWKsxGlpnI9FieluKGPRYqt54jbOjjLd3ESICXbxFozRqNyreiuQmWZrKtoP34pR8BhjU5mGHOTTJAhyoeSRXO0qxZDgMF9IjSNirLoNh3TSKgoU DRGUZB7XZf5MqWiA XTBDImt9xcjolmwcn6YighOqm6thxTLTlGmS kekdecSdVE9WC4Iz/WUkNowv9agpVGPoBXEhEXQ7zdrVZyDMDRBLyhSZbwBK7AC4kCsUSQ76MgjatrBUVFWaLsVtgUEJ3JcYKbBZjojqh7YF7EScsFmOmNHUJUK2p0yr1A6tMjnWN2UAUpiXKizHRktm4/D7E2JRyf6OIrgIiX2xRjeFJz5UiugYo56iuw1TPxSWoA9Lk41JKyGXAPG3A/KcNeNLKu1xk5Bxdo3AdME8ZsPSpA1ZF9puJDUDKNsE1i5844OnY9RSlC iEEeoz7YViUcBweAOQKh XyNnrttWhYEzIF6fjQk9R1SuMJ0U5hEBBPRJ1m0CL0A6gEIuFioVWSbtbcrJQSrt/klMmsmB9Yk69inKpCXGVERGePG41jW/NJBInp1VlKppD0gdMKIT7CZScolywnFgnuq1pfv9sh3oVRVZPtp8QBVEe52AnR5mmMt1z kp7N4F0SuSEoiAUezgDlW5rkjdIVupVVMtRAkDEp DejOnmJuJ2HBkAciUZP0fFqNwjuUvRbRU3w8hgDRI1M4JAOvDLNHuhtTVB3wfVkzXsTa8YC9kY2p7kVhNJ jbBkXi9KEztHUufjqPCMoL0byueKJhOIQqyYnfqnlFk9bcysAmkKmY/KorTkv2/e6I0FUQWVRS1awU8KxTFsTODk okygSQq KVGVFw7O5Ls8CgyHDcw/9ghVCM9Zy7 JJiMgt988Wf8AC9f713S /C4f/ AQYMsRtBO6X74XAy etvQMC84pFrhBh6FlYRP/wbFkEH1yAr3X8a1hC/AGSqGGJ0hcBRPQ8vlAz//puVaUQnbl RJND15 EbxF9/MQcUZMbXlRzRo2T4BjFpbhtijEn/4bCun4XXhDJ1/2IUY4rbT0uiRZ1ZC N 24hO/FdGUcP2Nhne1F7bEGQvXDbH1qrOrBCNbUMM0b39QUv3t0Oo24ZRjvrQKFCSvt8F1GxjJ1NFmeWlT dkkKRL29h6EVQo LHMcNxjgyTVGX/fCqEvywzHGSapkW1Ee/56eXeph8ZJqjOu2Yboy3YN6Xpfki4QV7YRK7j9qIS6bwa4Zhti1KerkHtrTogQP2i7jejUn6uQ48yW4QJR2234c0 h6qHpMrzJ1D8E2Ycbe02PrQE12/jFp1Zh5oabiB/ RfTjjw p6Rz4CM t8TQ9vSYivHuLms7uwR7BstDoev6QjPAgQkuvjkFPcP0OBph8RATI3T06oKTIFSxNHz 1ptOS9LHnCG8dgp7gDcAsVH1OtgxpEj64A3oCWCklXoYUCQ9u3wU9gVXPpiv5ngyQJuHRC1AxBZrF0zfeIzwA2cXDZ9Z0qt4RFhqahJFLiF1ACUkLDVXCVxC72HMKtaNnXiQEGSKUkLSUuk/4GNjSvCUEpEoIsnwgIbFZeIAQ1rR5lBDS1NwHEhL23XQJQW0bkDAcEPqe0JNZenD7U4 ho4Q jqGf3QJI6GPHd5TQm10bqJb6uvN2lNCTuycQoa93wKDO29enGLADUx fREWuQIQ Pk0EHutDT4Tfeu9EGEj4BkhIWkxdP2vz8WQGeF7KXQMJvTddA55505 Quj6ZAU 53xFOuY8ilAAjUEJoMX35PzLCB7fxBSMEHbVxwNsm4fDrj8M4CeH5HXy9ACFCZ8AWF/eW ulHqd0hISTRHdDahc7xtdfyrJT8q8Tz2QFVrDWdgZYu9C4GpNS8/MgjZWdUsVY6fgUiPDqD/kCrrib5 kdek1SnybXS4S0IINgsLBdi8u86IJ8d0eRa6S6s0ACvYnAWt6DDL9UlqMewzCSI9y5BIYQXGnNHfP0zv5I0pAh2o/MrhwuNydsIqknw64RtFkG88wDWBYELjclpVHKVocsgpumR6Tq hAHCC4366tqeJfiR35JU7tND03V4C5ak0I5Gk9GbXSuT2EBsVKihLXTvDBRBVGiAt0s1GaXpyiQ2CPkaUXcK1yGszhxEMJahYZq 3F6CjIrNvRewEB5EwG6oaWfG9vpnY0A1T6kWm3PYKkR D/cKVddb58I/GWXoEnFOCU4TsJAiN8T8we/Xa82OSWwSShTr6eEBlBDDKzStD9lefjQDpNq8HQPLDPIKeMum62YLZWgS20uRkmVAnUJNUhyv0LS0RGOT2NaQznYf2q hvSFukt7MoPaZxFYQ TmNgnp4BQ4hxr7iRm8WJgHgUxHLFIz//BUUENk9dpIiPQ0nzUyCOuLxJfjsGGPzu65H5iaxm6jOAsKrDGGSopX4tywcECFm505G8d5ZBH42jrNxWteAx4ih6vwOVtRj2AHiMoQ4G6c1dRpYQUR/j5FT1n9 iTPdOCKqM6r6ZawgIsaZMw3c4SscQLy974Y6I0xCtJeqOWCMd66wJnCRS9IQEgQRZartDu74DHYAfKMHxCHkuPgcExApWx7Yqqn1f/wZb8AYubTz6yoz3CCqttGoEzNW5nz2u89g80Id8LaNEHLYjrEM45yMsTKYSRIvPfnyK1YhRHk6wnMMPYyo4lSwGSuDxuLvKT35GpypNgrp8tdiFxudcTav45TVeP0C8UnLT3/7DRTxhU1AjrsgIlSrans4gNbVTn8 u HTPv3d97chjIQd6YbI8nQRifJs2LcOZBrhlTf41A8/ eEra0Tw9QtTVdqEUVQZF5HcvyRRco7a2vftfJb/i/ViBN6CshK 7288aTbLt0e1fqWTjiOpVKrSnUp9MG U0Zf3/XRr2yBuubcUr5FYxiZkViq3Z43RfF5Dmg9HjVm7zJvQLRCRbZiG0ZEcVdUZ2QJcUCJl1yQZZebOh3hz23AmR1VVGvaCSCzVNqjnqKY6ebWxy7jXNiJHRIcz zQA5BQlxH22Ybdd21bNvCjQRJQMbSNy5dgi1DW3WVBtKPvkMwNA 83MltJDFxH57d0G KYljjouIqq2sQH44C75ycV VRywRXLEb785WgN84fQiXCK6FkTVNr68sY2jMzqA CeoziI  Vq3DYf6bUOlG66ZhtbgaLZBMA3FUNzFcqPtNo4iBzaORyFKz23tpWxKPaSimKI64oVrPSqvHuP9kzYgStQ wSGqQ5LKNSYvCNTdKqmSzfN0uDojV0pqls2ta03xGs88jFJ2Rvum54bqM8a2IfEM7iNvqMLUNiRpxmoJrhTXxiiMAJ0boGMJhZFJxZGy5Qtmb5FtKt1vMAijxNsYSNpWp0Y7jFK27VYAdVWGPEVGKcsPmXqEoeqjMqVclaSyOxVmR30qjCof/RdWgEr3h22HGSWpDRk slO6Pm9Dhi1QPKmNNyVnoXj9YuZM0UHlZVbzHJ qeKc/LFvMBK2VzaLl13HPAK2kXhkhh1QHxg2zqbg3VBmM2rzhbN4UTv3 9gh8fcNlVfrzhjrGBmFK2reVZ6N5393mBVPp mA mumYxqDaF1BGl9uNYa3v dw0UrpSH9SGGievj/H1cb4et/asMZxf9OsVLxZOqLR7JfX oDYfDkeNhUaj4bx2MejX65VK2o hM1Q8nlbV6XS0fxdXawIFChQoUKBAgQIFChQokCf0fy3M8V9F7y SAAAAAElFTkSuQmCC" alt="google.png" width="225" height="225" /></p>

我想把它保存到一个文件中。我只将 src 部分提取到 base64Content 中，当我运行以下代码时：

private void storeFile(String base64Content, String filename) {
    try {
        byte[] contentBytes = Base64.getMimeDecoder().decode(base64Content.split(",")[1]);
        FileOutputStream imageOutFile = new FileOutputStream("/path/to/file/"+filename);
        imageOutFile.write(contentBytes);
        imageOutFile.close();
    } catch (IOException ex) {
        throw new FileStorageException("Could not store file " + filename + ". Please try again!", ex);
    }
}

我收到以下错误：

java.lang.IllegalArgumentException: Last unit does not have enough valid bits
    at java.util.Base64$Decoder.decode0(Base64.java:734) ~[na:1.8.0_181]
    at java.util.Base64$Decoder.decode(Base64.java:526) ~[na:1.8.0_181]
    at java.util.Base64$Decoder.decode(Base64.java:549) ~[na:1.8.0_181]

我该如何解决这个问题？

更新：base64 字符串不正确，导致问题。更正的 base64 字符串为

data:image/png;base64,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

Answer 1

来自 java.util.Base64 文档：

此类的实现支持以下类型的 RFC 4648 和 RFC 2045 中指定的 Base64。

哑剧

使用 RFC 2045 表 1 中指定的"Base64 字母表" 编码和解码操作。 编码输出必须以每行不超过 76 个字符的行表示，并使用紧跟的回车符"\r" 通过换行符""作为行分隔符。不添加行分隔符 到编码输出的末尾。所有行分隔符或其他 在 base64 字母表中找不到的字符将被忽略 解码操作。

好吧，您的 Base64 弹簧显然不符合要求。

最好像这样使用javax.xml.bind.DatatypeConverter：

byte[] contentBytes = javax.xml.bind.DatatypeConverter.parseBase64Binary(base64Content.split(",")[1]);