java对象和json的相互转换--(1) 使用@JsonSerialize对javabean进行json格式化
https://blog.csdn.net/wslyk606/article/details/80301782
以json格式输出数据是常用的方式,这次记录下项目中使用的json格式化方法,
使用的jar包为com.fasterxml.jackson.core:jackson-databind,对应的maven依赖为
<dependency>
<groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-databind</artifactId>
<version>2.6.2</version>
</dependency>
1 首先定义一个Student类
- public class Student {
- private String name;
- private int age;
- private int number;
-
- public String getName() {
- return name;
- }
-
- public int getAge() {
- return age;
- }
-
- public int getNumber() {
- return number;
- }
-
- public Student(String name, int age, int number) {
-
- this.name = name;
- this.age = age;
- this.number = number;
- }
- }
2 定义一个要格式化的类 StudentsReport,使用@JsonSerialize进行格式化,对应的格式化类为 StudentsReportSerializer
- import com.fasterxml.jackson.databind.annotation.JsonSerialize;
-
-
- import java.util.List;
-
- import static com.google.common.collect.Lists.newArrayList;
-
- @JsonSerialize(using = StudentsReportSerializer.class)
- public class StudentsReport {
- List<String> names = newArrayList();
- List<Student> studentList = newArrayList();
-
- public List<String> getNames() {
- return names;
- }
-
- public List<Student> getStudentList() {
- return studentList;
- }
-
- public StudentsReport(List<String> names, List<Student> studentList) {
-
- this.names = names;
- this.studentList = studentList;
- }
- }
- import com.fasterxml.jackson.core.JsonGenerator;
- import com.fasterxml.jackson.core.JsonProcessingException;
- import com.fasterxml.jackson.databind.JsonSerializer;
- import com.fasterxml.jackson.databind.SerializerProvider;
-
- import java.io.IOException;
-
- public class StudentsReportSerializer extends JsonSerializer <StudentsReport>{
- @Override
- public void serialize(StudentsReport studentsReport, JsonGenerator jgen, SerializerProvider serializerProvider) throws IOException, JsonProcessingException {
- jgen.writeStartObject(); //start write :"{"
-
- jgen.writeFieldName("studentsName");
- jgen.writeStartArray();// write "["
- for (String name:studentsReport.getNames()
- ) {
- jgen.writeObject(name);
- }
- jgen.writeEndArray();
-
-
- jgen.writeFieldName("studentsData");
- jgen.writeStartArray();
- for (Student student : studentsReport.getStudentList()){
- jgen.writeStartObject();
-
- jgen.writeStringField("name",student.getName());
- jgen.writeNumberField("age",16);
- jgen.writeNumberField("number",1);
-
- jgen.writeEndObject();
- }
- jgen.writeEndArray();
-
- jgen.writeEndObject(); //end :"}"
- }
-
- }
4 进行测试
- import com.fasterxml.jackson.core.JsonProcessingException;
- import com.fasterxml.jackson.databind.ObjectMapper;
-
- import java.util.List;
-
- import static com.google.common.collect.Lists.newArrayList;
-
- public class TestJson {
- public static void main(String[] args) throws JsonProcessingException {
- Student student1 = new Student("Tom",16,1);
- Student student2 = new Student("Jerry",17,2);
- List<Student> studentList = newArrayList();
- studentList.add(student1);
- studentList.add(student2);
-
- List<String> studentsName = newArrayList(student1.getName(),student2.getName());
-
-
-
- StudentsReport report = new StudentsReport(studentsName,studentList);
-
- ObjectMapper mapper = new ObjectMapper();
-
- String jsonReport = mapper.writeValueAsString(report);
-
- System.out.println(jsonReport);
-
- }
- }
输出结果为 {"studentsName":["Tom","Jerry"],"studentsData":[{"name":"Tom","age":16,"number":1},{"name":"Jerry","age":16,"number":1}]}
即 :{
"studentsName":[
"Tom",
"Jerry"
],
"studentsData":[
{
"name":"Tom",
"age":16,
"number":1
},
{
"name":"Jerry",
"age":16,
"number":1
}
]
}
ps:使用的newArrayList()是使用了com.google.guava这个包,对应的maven依赖为
<dependency>
<groupId>com.google.guava</groupId>
<artifactId>guava</artifactId>
<version>12.0.1</version>
</dependency>