JSON資料與Java物件相互轉換
阿新 • • 發佈：2019-01-02
整理下json資料與Java物件轉換。
使用的jar包：
ClassGrade類：
Student類：import java.util.ArrayList; import java.util.List; public class ClassGrade { private String className; private List<Student> students = new ArrayList<Student>(); public String getClassName() { return className; } public void setClassName(String className) { this.className = className; } public List<Student> getStudents() { return students; } public void setStudents(List<Student> students) { this.students = students; } }
import java.util.Date; public class Student { private String userName; private int age; private Date brith; public Student() { super(); } public Student(String userName, int age, Date brith) { super(); this.userName = userName; this.age = age; this.brith = brith; } public String getUserName() { return userName; } public void setUserName(String userName) { this.userName = userName; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public Date getBrith() { return brith; } public void setBrith(Date brith) { this.brith = brith; } }
DateProcessor類：處理Java物件中java.util.Date型別的屬性。
import java.text.SimpleDateFormat; import net.sf.json.JsonConfig; import net.sf.json.processors.JsonValueProcessor; /** * 轉化器 * 將date型別轉換成json規範的字串 * @author Administrator * */ public class DateProcessor implements JsonValueProcessor{ private SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd"); public DateProcessor(String formatStr) { if(formatStr != null) { this.format = new SimpleDateFormat(formatStr); } } @Override public Object processArrayValue(Object object, JsonConfig config) { return format.format(object); } @Override public Object processObjectValue(String str, Object object, JsonConfig config) { return format.format(object); } }
一般情況下，日期轉化成json格式時，其格式比較複雜，比如一個生日："brith":{"date":12,"day":2,"hours":11,"minutes":7,"month":0,"seconds":14,"time":1263265634870,"timezoneOffset":-480,"year":110}，json會轉成這樣格式的，不是我們所熟悉的（yyyy-MM-dd等），使用DateProcessor可以轉換成我們自定義的格式。
MyJSONUtils：
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.Map;
import net.sf.ezmorph.object.DateMorpher;
import net.sf.json.JSONArray;
import net.sf.json.JSONObject;
import net.sf.json.JsonConfig;
import net.sf.json.util.JSONUtils;
public class MyJSONUtils {
/**
* 如果實體包含date型別資料，可以使用config處理
*/
private static JsonConfig config = new JsonConfig();
static {
DateProcessor processor = new DateProcessor("yyyy-MM-dd");
config.registerJsonValueProcessor(Date.class, processor);
initDateFormats();
}
/**
* JSON資料日期格式轉化成date型別的資料<br>
* 前面提到DateProcessor是將date型別轉成JSON格式資料<br>
* 一個是Java物件-->JSON格式資料<br>
* 一個是JSON格式資料-->Java物件
*
* @author WF
* @since 2015-2-4 上午9:54:31
*/
private static void initDateFormats() {
String[] dateFormats = new String[] { "yyyy/MM/dd HH:mm:ss",
"yyyy/MM/dd HH:mm", "yyyy/MM/dd", "yyyyMMdd HH:mm:ss",
"yyyyMMdd HH:mm", "yyyyMMdd", "yyyy-MM-dd HH:mm:ss",
"yyyy-MM-dd HH:mm", "yyyy-MM-dd", "yyyy年MM月dd日 HH:mm:ss",
"yyyy年MM月dd日 HH:mm", "yyyy年MM月dd日" };
JSONUtils.getMorpherRegistry().registerMorpher(
new DateMorpher(dateFormats));
}
/**
* 單個實體轉化成JSON資料
*
* @author WF
* @since 2015-2-4 上午9:25:29
* @param object
* @return
*/
public static String OneBeanToJSON(Object object) {
JSONObject jsonObject = JSONObject.fromObject(object, config);
return jsonObject.toString();
}
/**
* 陣列或者集合轉化成JSON資料
*
* @author WF
* @since 2015-2-4 上午9:25:51
* @param object
* @return
*/
public static String ListToJSON(Object object) {
JSONArray jsonArray = JSONArray.fromObject(object, config);
return jsonArray.toString();
}
/**
* JSON資料轉化成單個實體
*
* @author WF
* @since 2015-2-4 上午11:16:45
* @param jsonStr
* @param clz
* 返回的Java物件的Class
* @param classMap
* 返回的Java物件可能包含其他物件，比如說ClassGrade類中有List<Student> students，
* 需要把Student類的Class塞到classMap裡面，
* key為ClassGrade的屬性名（students），下同
* @return
*/
public static <T> Object JSONToOneBean(String jsonStr, Class<T> clz,
Map<String, Class<?>> classMap) {
JSONObject jsonObject = JSONObject.fromObject(jsonStr);
Object object = JSONObject.toBean(jsonObject, clz, classMap);
return object;
}
/**
* JSON資料轉化成List集合
*
* @author WF
* @since 2015-2-4 上午10:24:55
* @param jsonStr
* @param clz
* @param classMap
* @return
*/
public static <T> List<T> JSONToList(String jsonStr, Class<T> clz,
Map<String, Class<?>> classMap) {
List<T> results = new ArrayList<T>();
T[] ts = JSONToArray(jsonStr, clz, classMap);
if (ts != null) {
for (T t : ts) {
results.add(t);
}
}
return results;
}
/**
* JSON資料轉化成陣列集合
*
* @author WF
* @since 2015-2-4 上午10:25:23
* @param jsonStr
* @param clz
* @param classMap
* @return
*/
@SuppressWarnings("unchecked")
public static <T> T[] JSONToArray(String jsonStr, Class<T> clz,
Map<String, Class<?>> classMap) {
JSONArray jsonArray = JSONArray.fromObject(jsonStr);
T[] ts = null;
try {
Object object = JSONArray.toArray(jsonArray, clz, classMap);
ts = (T[]) object;
} catch (Exception e) {
e.printStackTrace();
}
return ts;
}
}
下面給出一個Map與JSON相互轉化的例子：
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class Test {
public static void main(String[] args) {
List<ClassGrade> grades = new ArrayList<ClassGrade>();
ClassGrade grade = new ClassGrade();
ClassGrade grade2 = new ClassGrade();
List<Student> students = new ArrayList<Student>();
for (int i = 0; i < 2; i++) {
Student user = new Student("admin" + i, i, DateUtils.createDate(2010, i+1, 12+i));
students.add(user);
}
grade.setClassName("一班");
grade.setStudents(students);
grade2.setClassName("二班");
grade2.setStudents(students);
grades.add(grade);
grades.add(grade2);
ClassGrade[] gradesArrs = new ClassGrade[2];
gradesArrs[0] = new ClassGrade();
gradesArrs[0].setClassName("一班");
gradesArrs[0].setStudents(students);
gradesArrs[1] = new ClassGrade();
gradesArrs[1].setClassName("二班");
gradesArrs[1].setStudents(students);
Map<String, Object> map = new HashMap<String, Object>();
map.put("grade", grade);
map.put("grades", grades);
map.put("student", students.get(0));
map.put("students", students);
String jsonStr = MyJSONUtils.OneBeanToJSON(map);
System.out.println("Map-->JSON:" + jsonStr);
Map<String, Class<?>> classMap = new HashMap<String, Class<?>>();
classMap.put("grade", ClassGrade.class);
classMap.put("grades", ClassGrade.class);
classMap.put("student", Student.class);
classMap.put("students", Student.class);
Map<String, Object> resultMap = (Map<String, Object>) MyJSONUtils.JSONToOneBean(jsonStr, Map.class, classMap);
System.out.println("========================================================");
ClassGrade grade3 = (ClassGrade) resultMap.get("grade");
System.out.println("班級：" + grade3.getClassName());
List<Student> list = grade3.getStudents();
for (Student student : list) {
System.out.println(student.getUserName() + "：" + format(student.getBrith()));
}
System.out.println("========================================================");
List<ClassGrade> gradesResult = (List<ClassGrade>) resultMap.get("grades");
for (ClassGrade classGrade : gradesResult) {
System.out.println("班級：" + classGrade.getClassName());
List<Student> list2 = classGrade.getStudents();
for (Student student : list2) {
System.out.println(student.getUserName() + "：" + format(student.getBrith()));
}
}
System.out.println("========================================================");
Student student = (Student) resultMap.get("student");
System.out.println(student.getUserName() + "：" + format(student.getBrith()));
System.out.println("========================================================");
List<Student> studentsResult = (List<Student>) resultMap.get("students");
for (Student student2 : studentsResult) {
System.out.println(student2.getUserName() + "：" + format(student2.getBrith()));
}
System.out.println("========================================================");
}
public static String format(Date date) {
String result = null;
if (date != null) {
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
result = format.format(date);
}
return result;
}
}
控制檯輸出：
Map-->JSON:{"students":[{"age":0,"brith":"2010-01-12","userName":"admin0"},{"age":1,"brith":"2010-02-13","userName":"admin1"}],"student":{"age":0,"brith":"2010-01-12","userName":"admin0"},"grade":{"className":"一班","students":[{"age":0,"brith":"2010-01-12","userName":"admin0"},{"age":1,"brith":"2010-02-13","userName":"admin1"}]},"grades":[{"className":"一班","students":[{"age":0,"brith":"2010-01-12","userName":"admin0"},{"age":1,"brith":"2010-02-13","userName":"admin1"}]},{"className":"二班","students":[{"age":0,"brith":"2010-01-12","userName":"admin0"},{"age":1,"brith":"2010-02-13","userName":"admin1"}]}]}
========================================================
班級：一班
admin0：2010-01-12
admin1：2010-02-13
========================================================
班級：一班
admin0：2010-01-12
admin1：2010-02-13
班級：二班
admin0：2010-01-12
admin1：2010-02-13
========================================================
admin0：2010-01-12
========================================================
admin0：2010-01-12
admin1：2010-02-13
========================================================