1. java 已知一個對象的引用，如何復制一個對象呢

obj.clone();2樓那個只是兩個引用指向一個對象！

2. Java中，復制一個對象，有什麼好的方法

使用Java的反射機制實現：為了能更好的區分，寫成了兩個類，可以運行下面的代碼看看效果
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class Test {
public static void main(String[] args) throws Exception {
Customer1 c1 = new Customer1();
c1.setName("c1");
List<String> list = new ArrayList<String>();
list.add("1");
list.add("2");
c1.setList(list);
Map<String,String> map = new HashMap<String, String>();
map.put("map1", "map1");
map.put("map2", "map2");
c1.setMap(map);
Customer2 c2 = new Customer2();
//
Class c = c1.getClass();
Class class2 = c2.getClass();
Field fields[] = c.getDeclaredFields();
for (int i = 0; i < fields.length; i++) {
Field field = fields[i];
String fieldName = field.getName();
String firstLetter = fieldName.substring(0, 1).toUpperCase();
String getMethodName = "get" + firstLetter + fieldName.substring(1);
String setMethodName = "set" + firstLetter + fieldName.substring(1);
Method getMethod = c.getMethod(getMethodName, new Class[] {});
Method setMethod = class2.getMethod(setMethodName,
new Class[] { field.getType() });
Object value = getMethod.invoke(c1, new Object[] {});
setMethod.invoke(c2, new Object[] { value });
}
System.out.println(c2.getName());
System.out.println(c2.getList());
System.out.println(c2.getMap());
}
}
class Customer1 {
private String name;
private List<String> list;
private Map<String, String> map;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public List<String> getList() {
return list;
}
public void setList(List<String> list) {
this.list = list;
}
public Map<String, String> getMap() {
return map;
}
public void setMap(Map<String, String> map) {
this.map = map;
}
}
class Customer2 {
private String name;
private List<String> list;
private Map<String, String> map;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public List<String> getList() {
return list;
}
public void setList(List<String> list) {
this.list = list;
}
public Map<String, String> getMap() {
return map;
}
public void setMap(Map<String, String> map) {
this.map = map;
}
}

3. java如何深度一個object

java深復制的例子：
1、創建Employer類，實現Cloneable介面：
class Employer implements Cloneable{
private String username;

public String getUsername() {
return username;
}

public void setUsername(String username) {
this.username = username;
}

@Override
public Object clone() throws CloneNotSupportedException {
return super.clone();
}
}

2、創建Employee類，實現Cloneable介面，並改寫clone方法，實現深復制：
class Employee implements Cloneable{
private String username;
private Employer employer;
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public Employer getEmployer() {
return employer;
}
public void setEmployer(Employer employer) {
this.employer = employer;
}

@Override
public Object clone() throws CloneNotSupportedException {
//克隆Employee對象並手動的進一步克隆Employee對象中包含的Employer對象
Employee employee = (Employee)super.clone();
employee.setEmployer((Employer) employee.getEmployer().clone());
return employee;
}
}

3、這樣，在客戶端拷貝的兩個Employee對象的Employer就互不影響了：
public static void main(String[] args) throws CloneNotSupportedException {
Employer employer = new Employer();
employer.setUsername("arthinking");

Employee employee = new Employee();
employee.setUsername("Jason");
employee.setEmployer(employer);

//employee2由employee深復製得到
Employee employee2 = (Employee) employee.clone();
//這樣兩個employee各自保存了兩個employer
employee2.getEmployer().setUsername("Jason");
System.out.println(employee.getEmployer().getUsername());
System.out.println(employee2.getEmployer().getUsername());
}