将 base 64 字符串保存为图像文件

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>

我想将其保存到文件中。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，导致出现问题。更正后的 base64 字符串为

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

Answer 1

来自java.util.Base64 docs：

The implementation of this class supports the following types of Base64 as specified in RFC 4648 and RFC 2045.

MIME

Uses the "The Base64 Alphabet" as specified in Table 1 of RFC 2045 for encoding and decoding operation. The encoded output must be represented in lines of no more than 76 characters each and uses a carriage return '\r' followed immediately by a linefeed '\n' as the line separator. No line separator is added to the end of the encoded output. All line separators or other characters not found in the base64 alphabet table are ignored in decoding operation.

嗯，你的Base64spring显然不满足要求

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

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

将 base 64 字符串保存为图像文件

Saving a base 64 String as image file

java

base64

image

file

illegalargumentexception