LocalDate序列化错误
序列化包含LocalDate字段的类会导致以下错误：
java.lang.InstantiationException: java.time.LocalDate Continuing ... java.lang.RuntimeException: failed to evaluate: =Class.new(); Continuing ... 主类代码：
package javaapplication15; import java.beans.XMLEncoder; import java.io.BufferedOutputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.time.LocalDate; /** * * @author hoshantm */ public class JavaApplication15 { /** * @param args the command line arguments */ public static void main(String[] args) throws FileNotFoundException, IOException { JavaApplication15 japp = new JavaApplication15(); japp.serializaData(); } public void serializaData() throws FileNotFoundException, IOException { XMLEncoder e = new XMLEncoder(new BufferedOutputStream( new FileOutputStream("d:\\temp\\Test.xml"))); Employee emp = new Employee(); emp.setFirstName("John"); emp.setLastName("Doe"); emp.setBirthDate(LocalDate.parse("1965-01-01")); e.writeObject(emp); e.close(); } }
员工类代码：
package javaapplication15; import java.io.Serializable; import java.time.LocalDate; public class Employee implements Serializable { private String firstName; private String lastName; private LocalDate birthDate; public LocalDate employmentDate; public LocalDate getEmploymentDate() { return employmentDate; } public void setEmploymentDate(LocalDate employmentDate) { this.employmentDate = employmentDate; } public LocalDate getBirthDate() { return birthDate; } public void setBirthDate(LocalDate date) { birthDate = date; } public void setLastName(String lastName) { this.lastName = lastName; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getFirstName() { return firstName; } public String getLastName() { return lastName; } }
以下代码修改解决了问题：
package javaapplication15; import java.beans.Encoder; import java.beans.Expression; import java.beans.PersistenceDelegate; import java.beans.XMLDecoder; import java.beans.XMLEncoder; import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.time.LocalDate; /** * * @author hoshantm */ public class JavaApplication15 { /** * @param args the command line arguments */ public static void main(String[] args) throws FileNotFoundException, IOException { JavaApplication15 japp = new JavaApplication15(); japp.serializaData(); } public void serializaData() throws FileNotFoundException, IOException { XMLEncoder e = new XMLEncoder(new BufferedOutputStream( new FileOutputStream("d:\\temp\\Test.xml"))); Employee emp = new Employee(); emp.setFirstName("John"); emp.setLastName("Doe"); emp.setBirthDate(LocalDate.parse("1965-01-01")); e.setPersistenceDelegate(LocalDate.class, new PersistenceDelegate() { @Override protected Expression instantiate(Object localDate, Encoder encdr) { return new Expression(localDate, LocalDate.class, "parse", new Object[]{localDate.toString()}); } }); e.writeObject(emp); e.close(); XMLDecoder d = new XMLDecoder(new BufferedInputStream( new FileInputStream("d:\\temp\\Test.xml"))); Employee e2 = (Employee) d.readObject(); System.out.println(e2.getFirstName()); System.out.println(e2.getLastName()); System.out.println(e2.getBirthDate()); System.out.println(e2.getEmploymentDate()); } }
序列化数据如下所示：
涉及单个LocalDate字段的备用实现：
package javaapplication15; import java.beans.Encoder; import java.beans.Expression; import java.beans.PersistenceDelegate; import java.beans.XMLDecoder; import java.beans.XMLEncoder; import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.time.LocalDate; /** * * @author hoshantm */ public class JavaApplication15 { /** * @param args the command line arguments */ public static void main(String[] args) throws FileNotFoundException, IOException { JavaApplication15 japp = new JavaApplication15(); japp.serializaData(); } public void serializaData() throws FileNotFoundException, IOException { XMLEncoder e = new XMLEncoder(new BufferedOutputStream( new FileOutputStream("d:\\temp\\Test.xml"))); Employee emp = new Employee(); emp.setFirstName("John"); emp.setLastName("Doe"); emp.setBirthDate(LocalDate.parse("1965-01-01")); e.setPersistenceDelegate(LocalDate.class, new PersistenceDelegate() { @Override protected Expression instantiate(Object obj, Encoder encdr) { LocalDate localDate = (LocalDate) obj; return new Expression(localDate, LocalDate.class, "of", new Object[] {localDate.getYear(), localDate.getMonth(), localDate.getDayOfMonth()}); } }); e.writeObject(emp); e.close(); XMLDecoder d = new XMLDecoder(new BufferedInputStream( new FileInputStream("d:\\temp\\Test.xml"))); Employee e2 = (Employee) d.readObject(); System.out.println(e2.getFirstName()); System.out.println(e2.getLastName()); System.out.println(e2.getBirthDate()); System.out.println(e2.getEmploymentDate()); } }
序列化数据如下所示：
请注意，可以修改最后一个实现以包括其他字段，例如LocalDateTime序列化中的小时和分钟。