ObjectMapper使用详情

「爱情、让人受尽委屈。」 2023-09-29 13:18 6阅读 0赞

可以使用ObjectMapper进行json和对象间的转换

*  Jackson ObjectMapper(com.fasterxml.jackson.databind.ObjectMapper)是使用Jackson解析JSON最简单的方法。
 *  Jackson ObjectMapper可以从字符串、流或文件解析JSON，并创建Java对象或对象图来表示已解析的JSON
 *  将JSON解析为Java对象也称为从JSON反序列化Java对象
 *  Jackson ObjectMapper也可以从Java对象创建JSON. 从Java对象生成JSON的过程也被称为序列化Java对象到JSON

## 依赖 ##

<dependency>
    	<groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.9.9</version>
    </dependency>

## 1、字符串转实体类 ##

/**
         * 字符串转实体类
         *
         * @param mapper
         * @param jsonString
         */
        public static void stringToStudent(ObjectMapper mapper, String jsonString) {
        
            jsonString = "{\"id\":1001,\"name\":\"Tom\",\"info\":\"一个小男孩\"}";
    
            try {
        
                Student student = mapper.readValue(jsonString, Student.class);
                System.out.println("student = " + student);
                //student = JacksonTest.Student(id=1001, name=Tom, info=一个小男孩)
            } catch (Exception e) {
        
                e.printStackTrace();
            }
        }

## 2、实体类转字符串 ##

/**
         * 实体类转字符串
         *
         * @param mapper
         * @param jsonString
         */
        public static void studentToString(ObjectMapper mapper, String jsonString) {
        
    
            Student student = new Student();
            student.setId(1002);
            student.setName("李四");
            student.setInfo("一个小女孩");
            try {
        
                jsonString = mapper.writeValueAsString(student);
                System.out.println("jsonString = " + jsonString);
                //jsonString = {"id":1002,"name":"李四","info":"一个小女孩"}
            } catch (Exception e) {
        
                e.printStackTrace();
            }
        }

## 3、字符串转 List<实体类> ##

/**
         * 字符串转 List<实体类>
         *
         * @param mapper
         * @param jsonString
         */
        public static void stringToStudentList(ObjectMapper mapper, String jsonString) {
        
            jsonString = "[{\"id\":1001,\"name\":\"Tom\",\"info\":\"一个小男孩\"},{\"id\":1002,\"name\":\"Jane\",\"info\":\"一个小女孩\"}]";
            try {
        
                Student[] stu = mapper.readValue(jsonString, Student[].class);
                for (Student student : stu) {
        
                    System.out.println("student = " + student);
                    //student = JacksonTest.Student(id=1001, name=Tom, info=一个小男孩)
                    //student = JacksonTest.Student(id=1002, name=Jane, info=一个小女孩)
                }
    
                String ss = mapper.writeValueAsString(stu);
                System.out.println("ss = " + ss);
                //ss = [{"id":1001,"name":"Tom","info":"一个小男孩"},{"id":1002,"name":"Jane","info":"一个小女孩"}]
    
            } catch (Exception e) {
        
                e.printStackTrace();
            }
        }

## 扩展： ##

[ObjectMapper的详细使用][ObjectMapper]  
[ObjectMapper常见用法][ObjectMapper 1]  
[Jackson之ObjectMapper对象的使用][Jackson_ObjectMapper]

[ObjectMapper]: https://blog.csdn.net/qq_35318169/article/details/117781224?utm_medium=distribute.pc_relevant.none-task-blog-2~default~baidujs_title~default-0.pc_relevant_aa&spm=1001.2101.3001.4242.1&utm_relevant_index=3
[ObjectMapper 1]: https://blog.csdn.net/weixin_43689953/article/details/108016600
[Jackson_ObjectMapper]: https://www.csdn.net/tags/OtTaAgwsNjMwMjItYmxvZwO0O0OO0O0O.html#1__3