最近和一个第三方的系统对接，需要把他们的请求参数保存下来，但是那一长串的json不好读，于是想格式化一下，这种工具有很多，但我想自己弄个来玩下。
刚开始的实现用了很多判断，逻辑很绕。后来想起之前读过一个模板引擎的源码，里面用了状态图，于是我也尝试用了下。
public class Main { ???private static String NEW_LINE = "\r\n"; ???public static void main(String[] args) { ???????String json = "[{\"name\": \"wen\",\"age\": 12,\"flag\": true,\"job\": [{\"name\":\"java\"},{\"name\": \"c++\"}]},{\"name\": \"yun\",\"age\": 13,\"flag\": false}]"; ???????System.out.println(format(json)); ???} ???private static String format(String json) { ???????// 去除原来的格式 ???????json = json.replace("\n", "").replace("\r", "").replace("\t", ""); ???????StringBuilder sb = new StringBuilder(); ???????int prevStatus = 0;// 上一状态 ???????int level = 0;// 缩进层级 ???????for (char c : json.toCharArray()) { ???????????int oper = getOperation(prevStatus, c); ???????????switch (oper) { ???????????????case 1: ???????????????????sb.append(NEW_LINE).append(getTab(level)); ???????????????????break; ???????????????case 2: ???????????????????level++; ???????????????????sb.append(NEW_LINE).append(getTab(level)); ???????????????????break; ???????????????case 3: ???????????????????level--; ???????????????????sb.append(NEW_LINE).append(getTab(level)); ???????????????????break; ???????????????case 4: ???????????????????sb.append(‘ ‘); ???????????????????break; ???????????} ???????????sb.append(c); ???????????prevStatus = getStatus(c); ???????} ???????return sb.toString(); ???} ???// 返回：0直接输出，1换行，2增加缩进并换行，3减少缩进并换行，4前面加空格 ???private static int[][] statusArr = new int[][] { ???????{0, 0, 0, 0, 0, 3}, ?// 普通字符 ???????{1, 2, 2, 0, 0, 0}, ?// {[ ???????{2, 0, 4, 0, 0, 0}, ?// : ???????{3, 1, 4, 0, 0, 0}, ?// , ???????{4, 0, 0, 0, 0, 3},};// }] ???// 根据前一状态和当前字符决定操作 ???private static int getOperation(int status, char c) { ???????return statusArr[status][getStatus(c) + 1]; ???} ???// 字符转换成对应状态 ???private static int getStatus(char c) { ???????int status = 0; ???????switch (c) { ???????????case ‘{‘: ???????????case ‘[‘: ???????????????status = 1; ???????????????break; ???????????case ‘:‘: ???????????????status = 2; ???????????????break; ???????????case ‘,‘: ???????????????status = 3; ???????????????break; ???????????case ‘}‘: ???????????case ‘]‘: ???????????????status = 4; ???????????????break; ???????} ???????return status; ???} ???// 缩进 ???private static String getTab(int level) { ???????StringBuilder sb = new StringBuilder(); ???????for (int i = 0; i < level; i++) { ???????????sb.append(" ???"); ???????} ???????return sb.toString(); ???}}执行结果
[ ???{ ???????"name": "wen", ???????"age": 12, ??????????"flag": true, ???????"job": [ ???????????{ ???????????????"name":"java" ???????????}, { ???????????????"name": "c++" ???????????} ???????] ???}, { ???????"name": "yun", ???????"age": 13, ???????"flag": false ???}]