java— 读取JSON文件的多种方式

小鱼儿 2023-10-04 21:52 47阅读 0赞

大部分内容参考自： [https://blog.csdn.net/csdn\_halon/article/details/120287992][https_blog.csdn.net_csdn_halon_article_details_120287992]

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：D:\\test.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 ##

### 1.1、添加依赖 ###

<dependencies>
            <dependency>
               <groupId>com.alibaba</groupId>
               <artifactId>fastjson</artifactId>
               <version>2.0.12</version>
            </dependency>
        </dependencies>

### 1.2源代码 ###

import com.alibaba.fastjson.JSON;
     
    import java.io.*;
     
    public class ReadLocalJsonFileDemo {
        publicstatic void main(String[] args) throws IOException {
            Filefile = new File("D:\\test.json");
           readerMethod(file);
     
        }
     
        privatestatic void readerMethod(File file) throws IOException {
           FileReader fileReader = new FileReader(file);
            Readerreader = 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();
            StringjsonStr = sb.toString();
           System.out.println(JSON.parseObject(jsonStr));
        }
    }

### 1.3.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 ##

### 2.1、添加依赖 ###

<dependencies>
            <dependency>
               <groupId>com.fasterxml.jackson.core</groupId>
               <artifactId>jackson-databind</artifactId>
               <version>2.13.3</version>
            </dependency>
        </dependencies>

### 2.2源代码 ###

import com.fasterxml.jackson.databind.ObjectMapper;
     
    import java.io.File;
    import java.io.IOException;
    import java.util.Map;
     
    public class ReadLocalJsonFileDemo {
        publicstatic void main(String[] args) throws IOException {
            Filefile = new File("D:\\test.json");
           jacksonMethod(file);
        }
     
        privatestatic void jacksonMethod(File file) throws IOException {
           ObjectMapper objectMapper = new ObjectMapper();
           System.out.println(objectMapper.readValue(file, Map.class));
        }
    }

### 2.3.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 ##

### 3.1、添加依赖 ###

### 3.2源代码 ###

import com.alibaba.fastjson.JSONObject;
     
    import java.io.File;
    import java.io.IOException;
    import java.nio.file.Files;
    import java.nio.file.Paths;
     
    public class ReadLocalJsonFileDemo {
        publicstatic void main(String[] args) throws IOException {
            Filefile = new File("D:\\test.json");
           nioMethod(file);
        }
     
        privatestatic void nioMethod(File file) throws IOException {
            StringjsonString = new String(Files.readAllBytes(Paths.get(file.getPath())));
           System.out.println(JSONObject.parseObject(jsonString));
        }
    }

### 3.3.控制台输出 ###

[https_blog.csdn.net_csdn_halon_article_details_120287992]: https://blog.csdn.net/csdn_halon/article/details/120287992