{"id":5255,"date":"2022-05-13T07:44:00","date_gmt":"2022-05-12T23:44:00","guid":{"rendered":"https:\/\/ixyzero.com\/blog\/?p=5255"},"modified":"2022-05-12T20:54:38","modified_gmt":"2022-05-12T12:54:38","slug":"java%e4%b8%ad%e7%9a%84base64%e7%bc%96%e8%a7%a3%e7%a0%81%e5%92%8c%e5%ad%97%e8%8a%82%e6%95%b0%e7%bb%84%e7%9a%84%e8%af%bb%e5%86%99","status":"publish","type":"post","link":"https:\/\/ixyzero.com\/blog\/archives\/5255.html","title":{"rendered":"Java\u4e2d\u7684base64\u7f16\u89e3\u7801\u548c\u5b57\u8282\u6570\u7ec4\u7684\u8bfb\u5199"},"content":{"rendered":"\n<p>=Start=<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">\u7f18\u7531\uff1a<\/h4>\n\n\n\n<p>\u6742\u9879\u77e5\u8bc6\u7684\u8bb0\u5f55\uff0c\u6bd4\u5982\u6700\u5c0f\u7684png\/gif\u56fe\u7247\u5927\u5c0f\u662f\u591a\u5c11\uff0c\u4ee5\u53ca\u901a\u8fc7\u5b57\u8282\u6570\u7ec4\u5feb\u901f\u751f\u6210\u56fe\u7247\u8fd8\u6709Java\u4e2d\u5982\u4f55\u8fdb\u884cbase64\u7f16\u89e3\u7801\u7b49\u5185\u5bb9\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">\u6b63\u6587\uff1a<\/h4>\n\n\n\n<h5 class=\"wp-block-heading\">\u53c2\u8003\u89e3\u7b54\uff1a<\/h5>\n\n\n\n<p>\u6700\u5c0f\u7684\u900f\u660ePNG \u662f 68 bytes\uff0c\u5982\u679c\u4e0d\u8981\u6c42\u900f\u660e\u8fd8\u53ef\u4ee5\u51cf\u5c11 1 byte\u53ea\u6709 67 bytes\uff1b<br>\u6700\u5c0f\u7684GIF\u662f 35 bytes\u3002<\/p>\n\n\n\n<p>\u5176\u5b83\u7684\u76f4\u63a5\u770b\u4ee3\u7801\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>package com.example;\n\nimport java.io.BufferedWriter;\nimport java.io.FileWriter;\nimport java.io.IOException;\nimport java.nio.file.Files;\nimport java.nio.file.Paths;\nimport java.util.Arrays;\nimport java.util.Base64;\n\n\/**\n * @author ixyzero\n * Created on 2022-05-10\n *\/\npublic class opMisc {\n    public static void main(String&#91;] args) {\n        \/\/ \u5b57\u8282\u6570\u7ec4\u7684\u58f0\u660e\u548c\u6253\u5370\n        byte&#91;] pngBytes = {-119, 80, 78, 71, 13, 10, 26, 10, 0, 0, 0, 13, 73, 72, 68, 82, 0, 0, 0, 1, 0, 0, 0, 1,\n                8, 4, 0, 0, 0, -75, 28, 12, 2, 0, 0, 0, 11, 73, 68, 65, 84, 120, -38, 99, 100, 96, 0, 0, 0, 6, 0,\n                2, 48, -127, -48, 47, 0, 0, 0, 0, 73, 69, 78, 68, -82, 66, 96, -126};\n        System.out.println(Arrays.toString(pngBytes));\n\n        String b64encStr = \"iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mNkYAAAAAYAAjCB0C8AAAAASUVORK5CYII=\";\n        \/\/ base64\u5b57\u7b26\u4e32\u7684\u89e3\u7801\n        byte&#91;] decoded = Base64.getDecoder().decode(b64encStr);\n        System.out.println(Arrays.toString(decoded)); \/\/ print byte array\n\n        \/\/ hex print byte array\n        System.out.println(bytesToHex(decoded));\n\n        \/\/ \u5c06\u5b57\u8282\u6570\u7ec4\u5199\u5165\u6587\u4ef6\n        try {\n            Files.write(Paths.get(\"test-output-bytes.png\"), decoded); \/\/ filetype: PNG image data (68 bytes)\n        } catch (IOException e) {\n            e.printStackTrace();\n        }\n\n        \/\/ \u5c06\u6587\u4ef6\u5185\u5bb9\u8bfb\u5165\u5b57\u8282\u6570\u7ec4\n        try {\n            byte&#91;] fileData = Files.readAllBytes(Paths.get(\"test-output-bytes.png\"));\n            System.out.println(Arrays.toString(fileData));\n        } catch (IOException e) {\n            e.printStackTrace();\n        }\n\n        \/\/ \u5c06\u5b57\u8282\u6570\u7ec4\u8f6c\u6362\u6210\u5b57\u7b26\u4e32\uff08\u76f4\u63a5new String\u5c31\u53ef\u4ee5\uff09\n        String decodedStr = new String(decoded);\n        System.out.println(decodedStr);\n        String decodedStr2 = b64DecodeString(b64encStr);\n        System.out.println(decodedStr2.equals(decodedStr)); \/\/ true\n\n        \/\/ \u5c06\u5b57\u7b26\u4e32\u5199\u5165\u6587\u4ef6\n        try( BufferedWriter writer = new BufferedWriter(new FileWriter(\"test-output-str.png\")) ) {\n            writer.write(decodedStr); \/\/ filetype: data (82 bytes)\n        } catch (IOException e) {\n            e.printStackTrace();\n        }\n        \/\/ \u5c06\u6587\u4ef6\u5185\u5bb9\u8bfb\u5165\u5b57\u8282\u6570\u7ec4\n        try {\n            byte&#91;] fileData = Files.readAllBytes(Paths.get(\"test-output-str.png\"));\n            System.out.println(Arrays.toString(fileData));\n        } catch (IOException e) {\n            e.printStackTrace();\n        }\n\n        String raw = \"hello world\";\n        System.out.println(b64EncodeString(raw));\n        System.out.println(b64DecodeString(b64EncodeString(raw)));\n    }\n\n    public static String b64EncodeString(String plainString) {\n        return  Base64.getEncoder().encodeToString(plainString.getBytes());\n    }\n\n    public static String b64DecodeString(String encodedString) {\n        byte&#91;] bytes = Base64.getDecoder().decode(encodedString);\n        return new String(bytes);\n    }\n\n    private static final char&#91;] HEX_ARRAY = \"0123456789ABCDEF\".toCharArray();\n    public static String bytesToHex(byte&#91;] bytes) {\n        char&#91;] hexChars = new char&#91;bytes.length * 2];\n        for (int j = 0; j &lt; bytes.length; j++) {\n            int v = bytes&#91;j] &amp; 0xFF;\n            hexChars&#91;j * 2] = HEX_ARRAY&#91;v >>> 4];\n            hexChars&#91;j * 2 + 1] = HEX_ARRAY&#91;v &amp; 0x0F];\n        }\n        return new String(hexChars);\n    }\n\n}\n<\/code><\/pre>\n\n\n\n<p><\/p>\n\n\n\n<h5 class=\"wp-block-heading\">\u53c2\u8003\u94fe\u63a5\uff1a<\/h5>\n\n\n\n<p>Smallest possible transparent PNG<br><a href=\"https:\/\/garethrees.org\/2007\/11\/14\/pngcrush\/\" target=\"_blank\" rel=\"noreferrer noopener\">https:\/\/garethrees.org\/2007\/11\/14\/pngcrush\/<\/a><\/p>\n\n\n\n<p>TRANSPARENT BASE64 PNG PIXEL GENERATOR #68 bytes(Smallest 1&#215;1 transparent PNG pixel possible)<br><a href=\"https:\/\/png-pixel.com\/\" target=\"_blank\" rel=\"noreferrer noopener\">https:\/\/png-pixel.com\/<\/a><\/p>\n\n\n\n<p>smallest filesize for transparent single pixel image<br><a href=\"https:\/\/stackoverflow.com\/questions\/2570633\/smallest-filesize-for-transparent-single-pixel-image\" target=\"_blank\" rel=\"noreferrer noopener\">https:\/\/stackoverflow.com\/questions\/2570633\/smallest-filesize-for-transparent-single-pixel-image<\/a><\/p>\n\n\n\n<p>The smallest transparent pixel<br><a href=\"http:\/\/proger.i-forge.net\/%D0%9A%D0%BE%D0%BC%D0%BF%D1%8C%D1%8E%D1%82%D0%B5%D1%80\/[20121112]%20The%20smallest%20transparent%20pixel.html\" target=\"_blank\" rel=\"noreferrer noopener\">http:\/\/proger.i-forge.net\/%D0%9A%D0%BE%D0%BC%D0%BF%D1%8C%D1%8E%D1%82%D0%B5%D1%80\/[20121112]%20The%20smallest%20transparent%20pixel.html<\/a><\/p>\n\n\n\n<p>Portable Network Graphics (PNG) Specification (Second Edition)<br><a href=\"https:\/\/www.w3.org\/TR\/PNG\/\" target=\"_blank\" rel=\"noreferrer noopener\">https:\/\/www.w3.org\/TR\/PNG\/<\/a><\/p>\n\n\n\n<p>Java\u4e2d\u5982\u4f55\u5c06\u56fe\u7247\u8f6c\u6362\u6210\u5b57\u8282\u6570\u7ec4 &#8211; how to convert image to byte array in java? [duplicate]<br><a href=\"https:\/\/stackoverflow.com\/questions\/3211156\/how-to-convert-image-to-byte-array-in-java\" target=\"_blank\" rel=\"noreferrer noopener\">https:\/\/stackoverflow.com\/questions\/3211156\/how-to-convert-image-to-byte-array-in-java<\/a><\/p>\n\n\n\n<p>Java\u4e2d\u5982\u4f55\u6253\u5370\u5b57\u8282\u6570\u7ec4 &#8211; How to print the data in byte array as characters?<br><a href=\"https:\/\/stackoverflow.com\/questions\/6463580\/how-to-print-the-data-in-byte-array-as-characters\" target=\"_blank\" rel=\"noreferrer noopener\">https:\/\/stackoverflow.com\/questions\/6463580\/how-to-print-the-data-in-byte-array-as-characters<\/a><\/p>\n\n\n\n<p>Java\u4e2d\u5982\u4f55\u5c06\u5b57\u8282\u6570\u7ec4\u5b58\u4e3a\u56fe\u7247\u6587\u4ef6 &#8211; How to store a byte array as an image file on disk?<br><a href=\"https:\/\/stackoverflow.com\/questions\/2138913\/how-to-store-a-byte-array-as-an-image-file-on-disk\" target=\"_blank\" rel=\"noreferrer noopener\">https:\/\/stackoverflow.com\/questions\/2138913\/how-to-store-a-byte-array-as-an-image-file-on-disk<\/a><\/p>\n\n\n\n<p>=END=<\/p>\n","protected":false},"excerpt":{"rendered":"<p>=Start= \u7f18\u7531\uff1a \u6742\u9879\u77e5\u8bc6\u7684\u8bb0\u5f55\uff0c\u6bd4\u5982\u6700\u5c0f\u7684png\/gif\u56fe\u7247\u5927\u5c0f\u662f\u591a\u5c11\uff0c\u4ee5\u53ca\u901a\u8fc7\u5b57\u8282\u6570\u7ec4\u5feb\u901f\u751f\u6210\u56fe\u7247\u8fd8 [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23,7],"tags":[1813,369,61,1814],"class_list":["post-5255","post","type-post","status-publish","format-standard","hentry","category-knowledgebase-2","category-programing","tag-arrays-tostring","tag-base64","tag-java","tag-png"],"views":1442,"_links":{"self":[{"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/posts\/5255","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/comments?post=5255"}],"version-history":[{"count":1,"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/posts\/5255\/revisions"}],"predecessor-version":[{"id":5256,"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/posts\/5255\/revisions\/5256"}],"wp:attachment":[{"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/media?parent=5255"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/categories?post=5255"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/tags?post=5255"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}