在开发过程中有时会遇到需要读取本地.json文件的需求，通常会自己写Reader代码去读，但是这么做写出来的代码有些繁琐（需要关流、创建StringBuilder对象等操作）。最近发现几个小工具可以让需求代码变得更加简洁。
准备：json文件：F:halon.json
{"ID": 10001,"detail": "detail","json_format_version": 1.0,"other_info": {"array_one": [[855, 410],[854, 411],[847, 411],[846, 410],[845, 410],[844, 409]],"array_two": [[832, 303],[829, 303],[828, 302],[825, 302],[824, 301]],"array_three": [[1013, 224],[1012, 225],[1010, 225],[1009, 226],[1023, 224]],"point": [853, 310],"boolean": true}} 1.使用FileReader读取json文件 package com.tool;import com.alibaba.fastjson.JSON;import com.alibaba.fastjson.JSONObject;import com.fasterxml.jackson.databind.ObjectMapper;import java.io.*;import java.nio.file.Files;import java.nio.file.Paths;import java.util.Map;/** * @Author halon * @create 2023/9/ */public class ReadLocalJsonFileDemo { public static void main(String[] args) throws IOException { File file = new File("F:\halon.json"); readerMethod(file); } private static void readerMethod(File file) throws IOException { FileReader fileReader = new FileReader(file); Reader reader = new InputStreamReader(new FileInputStream(file), "Utf-8"); int ch = 0; StringBuffer sb = new StringBuffer(); while ((ch = reader.read()) != -1) { sb.append((char) ch); } fileReader.close(); reader.close(); String jsonStr = sb.toString(); System.out.println(JSON.parseObject(jsonStr)); }}控制台输出：
{"other_info":{"array_two":[[832,303],[829,303],[828,302],[825,302],[824,301]],"array_three":[[1013,224],[1012,225],[1010,225],[1009,226],[1023,224]],"boolean":true,"array_one":[[855,410],[854,411],[847,411],[846,410],[845,410],[844,409]],"point":[853,310]},"ID":10001,"detail":"detail","json_format_version":1.0} 2.使用jacksonAPI读取json文件 package com.tool;import com.alibaba.fastjson.JSON;import com.alibaba.fastjson.JSONObject;import com.fasterxml.jackson.databind.ObjectMapper;import java.io.*;import java.nio.file.Files;import java.nio.file.Paths;import java.util.Map;/** * @Author halon * @create 2023/9/ */public class ReadLocalJsonFileDemo { public static void main(String[] args) throws IOException { File file = new File("F:\halon.json"); jacksonMethod(file); } private static void jacksonMethod(File file) throws IOException { ObjectMapper objectMapper = new ObjectMapper(); System.out.println(objectMapper.readValue(file, Map.class)); }控制台输出：
{ID=10001, detail=detail, json_format_version=1.0, other_info={array_one=[[855, 410], [854, 411], [847, 411], [846, 410], [845, 410], [844, 409]], array_two=[[832, 303], [829, 303], [828, 302], [825, 302], [824, 301]], array_three=[[1013, 224], [1012, 225], [1010, 225], [1009, 226], [1023, 224]], point=[853, 310], boolean=true}} 3.使用nio读取json文件 package com.tool;import com.alibaba.fastjson.JSON;import com.alibaba.fastjson.JSONObject;import com.fasterxml.jackson.databind.ObjectMapper;import java.io.*;import java.nio.file.Files;import java.nio.file.Paths;import java.util.Map;/** * @Author halon * @create 2023/9/ */public class ReadLocalJsonFileDemo { public static void main(String[] args) throws IOException { File file = new File("F:\halon.json"); nioMethod(file); } private static void nioMethod(File file) throws IOException { String jsonString = new String(Files.readAllBytes(Paths.get(file.getPath()))); System.out.println(JSONObject.parseObject(jsonString)); }控制台输出：
{"other_info":{"array_two":[[832,303],[829,303],[828,302],[825,302],[824,301]],"array_three":[[1013,224],[1012,225],[1010,225],[1009,226],[1023,224]],"boolean":true,"array_one":[[855,410],[854,411],[847,411],[846,410],[845,410],[844,409]],"point":[853,310]},"ID":10001,"detail":"detail","json_format_version":1.0}未完待续。。。。