三种常用的JSON转换

一、JSON的概述

我们做项目，通常会使用前后端分离的ajax交互，那么前后端交互的数据格式通常是json格式。这里既有牵扯到json和对象集合之间的转换，目前市面上的json转换主要有三种：

 

• Jackson转换
• FastJson转换
• Gson转换

 

下面将会对这三种转换进行简单的入门演示：

二、准备工作

1、新建一个maven工程

工程名任意，打包方式选择jar

2、在pom.xml导入下面依赖

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<dependencies>        <dependency>            <groupId>com.alibaba</groupId>            <artifactId>fastjson</artifactId>            <version>1.2.58</version>        </dependency>        <dependency>            <groupId>com.fasterxml.jackson.core</groupId>            <artifactId>jackson-databind</artifactId>            <version>2.8.1</version>        </dependency>        <dependency>            <groupId>com.google.code.gson</groupId>            <artifactId>gson</artifactId>            <version>2.8.1</version>        </dependency>        <dependency>            <groupId>junit</groupId>            <artifactId>junit</artifactId>            <version>4.11</version>            <scope>compile</scope>        </dependency>    </dependencies>        <build>        <plugins>            <!-- java编译插件 -->            <plugin>                <groupId>org.apache.maven.plugins</groupId>                <artifactId>maven-compiler-plugin</artifactId>                <version>3.7.0</version>                <configuration>                    <source>1.8</source>                    <target>1.8</target>                    <encoding>UTF-8</encoding>                </configuration>            </plugin>        </plugins>    </build>

3、创建用于演示的类

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public class Student implements Serializable {       private String sid;     private String name;     private Integer age;     private String address;       public Student() {     }       public Student(String sid, String name, Integer age, String address) {         this.sid = sid;         this.name = name;         this.age = age;         this.address = address;     }       public String getSid() {         return sid;     }       public void setSid(String sid) {         this.sid = sid;     }       public String getName() {         return name;     }       public void setName(String name) {         this.name = name;     }       public Integer getAge() {         return age;     }       public void setAge(Integer age) {         this.age = age;     }       public String getAddress() {         return address;     }       public void setAddress(String address) {         this.address = address;     }       @Override     public String toString() {         return "Student{" +                 "sid='" + sid + '\'' +                 ", name='" + name + '\'' +                 ", age=" + age +                 ", address='" + address + '\'' +                 '}';     } }

三、案例演示

1、JackSon转换

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public class JackSonTest {       //对象和json字符串之间的转换     @Test     public void jsonAndJsonStr() throws IOException {           //创建学生的对象         Student student = new Student();         student.setSid("1001");         student.setName("张无忌");         student.setAge(18);         student.setAddress("冰火岛");           //创建jackson的转换对象         ObjectMapper om = new ObjectMapper();         //将对象转为json字符串         String studentStr = om.writeValueAsString(student);         System.out.println(studentStr);           //将json字符串转为对象         Student stu = om.readValue(studentStr, Student.class);           System.out.println("stu = " + stu);     }       //list集合和json字符串之间的转换     @Test     public void listAndJsonStr() throws IOException {           //创建list集合         List<Student> studentList = new ArrayList<>();           studentList.add(new Student("1001","刘德华",22,"香港"));         studentList.add(new Student("1002","张学友",21,"香港"));         studentList.add(new Student("1003","郭富城",18,"香港"));         studentList.add(new Student("1004","黎明",19,"香港"));           //创建jackson的转换对象         ObjectMapper om = new ObjectMapper();         String listStr = om.writeValueAsString(studentList);           System.out.println(listStr);           //json字符串转换为集合         List<Student> list = om.readValue(listStr, List.class);           System.out.println(list);     } }

2、FastJson装换

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public class FastJsonTest {       //对象和json字符串之间的转换     @Test     public void jsonAndJsonStr() throws IOException {           //创建学生的对象         Student student = new Student();         student.setSid("1001");         student.setName("张无忌");         student.setAge(18);         student.setAddress("冰火岛");           //创建fastjson的转换对象         JSONObject jsonObject = new JSONObject();         //将对象转换为json字符串         String studentStr = jsonObject.toJSONString(student);           System.out.println(studentStr);           //将json字符串解析为对象         Student stu = JSON.parseObject(studentStr, Student.class);           System.out.println(stu);       }       //list集合和json字符串之间的转换     @Test     public void listAndJsonStr() throws IOException {           //创建list集合         List<Student> studentList = new ArrayList<>();           studentList.add(new Student("1001","刘德华",22,"香港"));         studentList.add(new Student("1002","张学友",21,"香港"));         studentList.add(new Student("1003","郭富城",18,"香港"));         studentList.add(new Student("1004","黎明",19,"香港"));           //创建fastjson的转换对象         JSONObject jsonObject = new JSONObject();           //将集合转换为json字符串         String listStr = jsonObject.toJSONString(studentList);           System.out.println(listStr);           //将json字符串转换为集合         List<Student> list = JSON.parseArray(listStr, Student.class);           System.out.println(list);     } }

3、Gson转换

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public class GsonTest {       //对象和json字符串之间的转换     @Test     public void jsonAndJsonStr() throws IOException {           //创建学生的对象         Student student = new Student();         student.setSid("1001");         student.setName("张无忌");         student.setAge(18);         student.setAddress("冰火岛");           //创建json转换对象         Gson gson = new Gson();           //将对象转换为json字符串         String studentStr = gson.toJson(student);           System.out.println(studentStr);           //将json字符串转换为对象         Student stu = gson.fromJson(studentStr, Student.class);           System.out.println(stu);     }       //list集合和json字符串之间的转换     @Test     public void listAndJsonStr() throws IOException {           //创建list集合         List<Student> studentList = new ArrayList<>();           studentList.add(new Student("1001","刘德华",22,"香港"));         studentList.add(new Student("1002","张学友",21,"香港"));         studentList.add(new Student("1003","郭富城",18,"香港"));         studentList.add(new Student("1004","黎明",19,"香港"));           //创建json转换对象         Gson gson = new Gson();           //将集合转换为json字符串         String listStr = gson.toJson(studentList);           System.out.println(listStr);           //将json字符串转换为集合         List<Student> list = gson.fromJson(listStr, List.class);           System.out.println(list);     } }

四、小结

Gson性能最好，当不断增加的时候到了100000，Gson明细弱于Jackson和FastJson， 这时候FastJson性能是真的牛，另外还可以看到不管数量少还是多，Jackson一直表现优异。

 

数据量转换比较小时，建议使用Gson，其它情况考虑另外两种。

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