个人觉得fastjson最好用,据说性能也不错

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.example</groupId>
    <artifactId>json</artifactId>
    <version>1.0</version>
    <packaging>jar</packaging>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.7.9</version>
        </dependency>
        <dependency>
            <groupId>commons-logging</groupId>
            <artifactId>commons-logging</artifactId>
            <version>1.2</version>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.38</version>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.5.0</version>
        </dependency>

        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
            <version>2.8.5</version>
        </dependency>

    </dependencies>
    <build>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.5.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

代码

package com.example;

import java.io.IOException;
import java.util.Arrays;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import com.alibaba.fastjson.JSONArray;
import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;

public class TestJson {
    private static Log logger = LogFactory.getLog(TestJson.class);// 定义日志工具
    private static String json = "[{\"id\":1,\"name\":\"张三\",\"age\":30},{\"id\":2,\"name\":\"张三丰\",\"age\":30},{\"id\":3,\"name\":\"张丰\",\"age\":3}]";

    public static void main(String[] args) throws JsonParseException, JsonMappingException, IOException {
        logger.info("jackson");
        jackson();
        logger.info("fastJson");
        fastJson();
        logger.info("gson");
        gson();
    }

    // jackson把json转List
    private static void jackson() throws JsonParseException, JsonMappingException, IOException {
        User users[] = new ObjectMapper().readValue(json, User[].class);
        List<User> list = Arrays.asList(users);// 把数组转成list
        printUser(list);
    }

    // fastJson把json转List
    private static void fastJson() {
        List<User> users = JSONArray.parseArray(json, User.class);
        printUser(users);
    }

    // gson把json转List
    private static void gson() {
        List<User> users = new Gson().fromJson(json, new TypeToken<List<User>>() {
        }.getType());
        printUser(users);
    }

    private static void printUser(List<User> users) {
        for (User user : users) {
            logger.info(user);
        }
    }
}

User.java

package com.example;

public class User {

    private Integer id;
    private Integer age;
    private String name;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "User [id=" + id + ", age=" + age + ", name=" + name + "]";
    }

}