读取JSON文件，并处理json数据（读取JSON中某个值）

需要处理的json文件

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{ "code":200, "message":"Success", "data":{     "fileName":"aa.jpg",     "filePath":"file/aa.jpg",     "base64":"AhCL95h014sgbqPbR9BtOiWgF5t8U2ggQZJqDwwEbScC/5B/QzHK9zqdrvZEXEPQ1"     },     "timestamp":229480701 }

1、使用fastjson，

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//fastjson,    private static void readerMethod(String filePath) throws IOException {        File file = new File(filePath);        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();        JSONObject jsonObject = JSON.parseObject(jsonStr); // 获取json key-value 值        String data = jsonObject.getString("data");        JSONObject parse = (JSONObject) JSONObject.parse(data);        System.out.println(parse.getString("filePath"));    }

需要maven依赖

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>2.0.21</version>
        </dependency>

2、jackson

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private static void toMap(String filePath) throws IOException {     File file = new File(filePath);     ObjectMapper objectMapper = new ObjectMapper();     Map map = objectMapper.readValue(file, Map.class);     System.out.println(map.get("code")); }

需要依赖

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.11.3</version>
        </dependency>

3、nio

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private static void nioMethod(String filePath) throws IOException {     String jsonString = new String(Files.readAllBytes(Paths.get(filePath)));     JSONObject obj = JSONObject.parseObject(jsonString);     String data = obj.getString("data");     JSONObject parse = (JSONObject) JSONObject.parse(data);     String result=parse.getString("filePath"); }

参考：https://blog.csdn.net/csdn_halon/article/details/120287992