ObjectMapper使用详情-蒲公英云

ObjectMapper使用详情

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();
        }
    }