JAXB：使用annotation绑定XML(xmlns)
JAXB目前已经集成到了JDK6中，但是还是推荐下载使用最新版的jaxb库， https://jaxb.dev.java.net/
从JAXB2.0开始，可以通过使用annotation进行Object-XMl mapping。
本文将通过以下步骤演示如何使用JAXB annotation绑定使用了namespace的XML文件
1. 创建employees.xml文件
2. 创建Employees.java和Employee.java绑定employees.xml
3. 创建package-info.java和jaxb.index文件
4. 创建XMLParser.java封装marshal/unmarshal操作
5. 创建Test.java运行测试
现在将逐步展开演示
1. 创建employees.xml文件
这是一个很普通的xml文件，用于展示组织内部的成员（employee）状况，这里有一点需要注意的是使用了namespace，这也是本文将要演示的重点。
2. 创建Employees.java和Employee.java绑定employees.xml
package com.javaeye.terrencexu.jaxb;
import java.util.ArrayList;
import java.util.List;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
@XmlRootElement(name = "employees")
public class Employees {
@XmlElement(name = "employee", namespace=NameSpace.ADMIN_URI)
private List<Employee> employees;
public Employees() {
employees = new ArrayList<Employee>();
}
public List<Employee> getEmployees() {
return employees;
}
public void addEmployee(Employee employee) {
employees.add(employee);
}
}
package com.javaeye.terrencexu.jaxb;
import javax.xml.bind.annotation.XmlElement;
public class Employee {
@XmlElement(name = "userId", namespace=NameSpace.ADMIN_URI)
private String userId;
@XmlElement(name = "password", namespace=NameSpace.ADMIN_URI)
private String password;
@XmlElement(name = "name", namespace=NameSpace.ADMIN_URI)
private String name;
@XmlElement(name = "age", namespace=NameSpace.ADMIN_URI)
private int age;
@XmlElement(name = "gender", namespace=NameSpace.ADMIN_URI)
private String gender;
public Employee() {
}
public Employee(String userId, String psw, String name, int age, Gender gender) {
this.userId = userId;
this.password = psw;
this.name = name;
this.age = age;
this.gender = gender.getValue();
}
public String getUserId() {
return userId;
}
public String getPassword() {
return password;
}
public String getName() {
return name;
}
public int getAge() {
return age;
}
public String getGender() {
return gender;
}
}
package com.javaeye.terrencexu.jaxb;
public class NameSpace {
public static final String ADMIN_PREFIX = "admin";
public static final String ADMIN_URI = "http://www.company.com/management/employees/admin";
}
package com.javaeye.terrencexu.jaxb;
public enum Gender {
MALE("Male"),
FEMALE("Female");
private String value;
private Gender(String value) {
this.value = value;
}
public String getValue() {
return this.value;
}
}
3. 创建package-info.java和jaxb.index文件
创建package-info.java注册xmlns, 将该文件放在当前source code的package下面，如果不使用namespace可以不创建该文件
创建jaxb.index注册Employees, Employee，如果不使用包级context，可以不创建该文件
4. 创建XMLParser.java封装marshal/unmarshal操作
package com.javaeye.terrencexu.jaxb;
import java.io.InputStream;
import java.io.StringWriter;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;
public final class XMLParser {
private XMLParser() {}
public static Object unmarshal(InputStream xml, Class<?> clazz) {
Object obj = null;
try {
JAXBContext jc = JAXBContext.newInstance(clazz.getPackage().getName());
Unmarshaller u = jc.createUnmarshaller();
obj = u.unmarshal(xml);
} catch (JAXBException e) {
throw new RuntimeException("Can't unmarshal the XML file, error message: " + e.getMessage());
}
return obj;
}
public static String marshal(Object obj, Class<?> clazz) {
String result = null;
try {
JAXBContext jc = JAXBContext.newInstance(clazz.getPackage().getName());
Marshaller m = jc.createMarshaller();
StringWriter writer = new StringWriter();
m.marshal(obj, writer);
result = writer.toString();
} catch (JAXBException e) {
throw new RuntimeException("Can't marshal the XML file, error message: " + e.getMessage());
}
return result;
}
}
5. 创建Test.java运行测试
package com.javaeye.terrencexu.jaxb;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.List;
public class Test {
public static void main(String[] args) throws FileNotFoundException {
testUnmarshal();
testMarshal();
}
public static void testUnmarshal() throws FileNotFoundException {
Employees employees = (Employees) XMLParser.unmarshal(
new FileInputStream(new File("F:\\workspace\\JavaStudy\\test\\employees.xml")),
Employees.class);
List<Employee> employeeList = employees.getEmployees();
if (employeeList != null && employeeList.size() > 0) {
for (Employee employee : employeeList) {
StringBuilder builder = new StringBuilder();
builder.append("[UserID: ").append(employee.getUserId()).append(", ")
.append("Password: ").append(employee.getPassword()).append(", ")
.append("Name: ").append(employee.getName()).append(", ")
.append("Age: ").append(employee.getAge()).append(", ")
.append("Gender").append(employee.getGender()).append("]");
System.out.println(builder.toString());
}
}
}
public static void testMarshal() {
Employees employees = new Employees();
employees.addEmployee(new Employee("[email protected]", "abc123_", "John Smith", 24, Gender.MALE));
employees.addEmployee(new Employee("[email protected]", "123456", "Christine Chen", 27, Gender.FEMALE));
String result = XMLParser.marshal(employees, Employees.class);
System.out.println(result);
}
}
6. 运行结果：