JSON字符串中获取一个指定字段的值

一、方式一，引用gson工具

测试报文：

{
    "account":"yanxiaosheng",
    "password":"123456"
}

引入pom

<!-- https://mvnrepository.com/artifact/com.google.code.gson/gson -->
<dependency>
    <groupId>com.google.code.gson</groupId>
    <artifactId>gson</artifactId>
    <version>2.6.2</version>
</dependency>

测试类：

import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;

@Test
public void test() throws Exception {
        String json = "{\n" +
                "\t\"account\":\"yanxiaosheng\",\n" +
                "\t\"password\":\"123456\"\n" +
                "}";
        JsonParser jsonParser = new JsonParser();
        JsonElement jsonElement = jsonParser.parse(json);
        JsonObject jsonObject = jsonElement.getAsJsonObject();
        String fieldValue = jsonObject.get("account").getAsString();
        System.out.println(fieldValue);
}

**二、方式二，使用jackson **

{
    "account":"yanxiaosheng",
    "password":"123456",
    "flag":"true"
}

测试类：

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;

@Test
    public void test() throws Exception {
        String json = "{\n" +
                "\t\"account\":\"yanxiaosheng\",\n" +
                "\t\"password\":\"123456\",\n" +
                "\t\"flag\":\"true\"\n" +
                "}";
        ObjectMapper objectMapper = new ObjectMapper();
        JsonNode jsonNode = objectMapper.readTree(json);
        String account = jsonNode.get("account").asText();
        int password = jsonNode.get("password").asInt();
        boolean flag = jsonNode.get("flag").asBoolean();
        System.out.println(account);
        System.out.println(password);
        System.out.println(flag);
    }

三、方式三，使用jackson转换Object

测试报文：

{
    "account":"yanxiaosheng",
    "password":"123456"
}

测试类：

@Test
    public void test() throws Exception {
        String json = "{\n" +
                "\t\"account\":\"yanxiaosheng\",\n" +
                "\t\"password\":\"123456\"\n" +
                "}";
        ObjectMapper objectMapper = new ObjectMapper();
        Login login = objectMapper.readValue(json, DepositTest.Login.class);
        System.out.println(login.toString());
    }

    public static class Login{
        private String account;
        private String password;
        public String getAccount() {
            return account;
        }
        public void setAccount(String account) {
            this.account = account;
        }
        public String getPassword() {
            return password;
        }
        public void setPassword(String password) {
            this.password = password;
        }
        @Override
        public String toString() {
            return "Login{" +
                    "account='" + account + '\'' +
                    ", password='" + password + '\'' +
                    '}';
        }
    }

注意！！！**DepositTest.Login.class ** **DepositTest **需使用自己写的测试类名

四、方式四，使用hutool，获取报文数组数据

测试报文：

{
    "code":"0",
    "message":"",
    "data":[{
        "account":"yanxiaosheng",
        "password":"123456"
    }]
}

引入pom

<dependency>
    <groupId>cn.hutool</groupId>
    <artifactId>hutool-all</artifactId>
    <version>4.1.19</version>
</dependency>

测试类：

  @Test
    public void test() throws Exception {
        String json = "{\n" +
                "\t\"code\":\"0\",\n" +
                "\t\"message\":\"\",\n" +
                "\t\"data\":[{\n" +
                "\t\t\"account\":\"yanxiaosheng\",\n" +
                "\t\t\"password\":\"123456\"\n" +
                "\t}]\n" +
                "}";
        JSONObject jsonObject = new JSONObject(json);
        JSONArray jsonArray = jsonObject.getJSONArray("data");
        JSONObject resultObject = jsonArray.getJSONObject(0);
        String account = resultObject.getStr("account");
        System.out.println(account);
    }