自己封装的DB4O Template, 可很方便的进行对象保存，更新，级联更新及删除！ 废话不多说， 自己看源码：
/**
* DB4OUtils.java
* com.dzg.ticket.util
*
* ver date author
* ──────────────────────────────────
* 2012-2-10 Administrator
*
* Copyright (c) 2012, TNT All Rights Reserved.
*/
package utils;
import java.io.IOException;
import java.net.URL;
import java.net.URLDecoder;
import java.util.ArrayList;
import java.util.List;
import com.db4o.Db4oEmbedded;
import com.db4o.ObjectContainer;
import com.db4o.ObjectSet;
import com.db4o.config.EmbeddedConfiguration;
import com.db4o.query.Predicate;
//import com.dzg.ticket.bo.Passenger;
//import com.dzg.ticket.bo.Ticket;
//import com.dzg.ticket.bo.User;
/**
* ClassName:DB4OUtils
* Copyright: copyright (c)2012
* @author Deng Zhiguang
* @Date 2012-2-10
* Email: dengzhiguang@gmail.com
* Modification History:
* Date Author Version Reason
* ------------------------------------------
*/
public class DB4OTemplate {
private final static String DB4O_FILE_PATH = getClassPath() + "/db.yap";
private static String getClassPath() {
URL url = DB4OTemplate.class.getResource("/");
String path = null;
try {
path = URLDecoder.decode(url.getPath(), "UTF-8");
} catch (IOException e) {
e.printStackTrace();
}
return path;
}
private static void cascadeClasses(EmbeddedConfiguration configuration, List<Class<?>> classList) {
for (Class<?> c : classList) {
configuration.common().objectClass(c).cascadeOnUpdate(true);
configuration.common().objectClass(c).cascadeOnDelete(true);
}
}
public static <T> List<T> queryByExample(T t) {
List<T> result = new ArrayList<T>();
ObjectContainer db = null;
try {
db = Db4oEmbedded.openFile(DB4O_FILE_PATH);
ObjectSet<T> oSet = db.queryByExample(t);
while (oSet.hasNext()) {
result.add(oSet.next());
}
return result;
} finally {
if (db != null)
db.close();
}
}
public static <T> List<T> query(Class<T> clazz) {
List<T> result = new ArrayList<T>();
ObjectContainer db = null;
try {
db = Db4oEmbedded.openFile(DB4O_FILE_PATH);
ObjectSet<T> oSet = db.query(clazz);
while (oSet.hasNext()) {
result.add(oSet.next());
}
return result;
} finally {
if (db != null)
db.close();
}
}
public static <T> List<T> query(Predicate<T> predicate) {
List<T> result = new ArrayList<T>();
ObjectContainer db = null;
try {
db = Db4oEmbedded.openFile(DB4O_FILE_PATH);
ObjectSet<T> oSet = db.query(predicate);
while (oSet.hasNext()) {
result.add(oSet.next());
}
return result;
} finally {
if (db != null)
db.close();
}
}
public static <T> boolean exists(Predicate<T> predicate) {
ObjectContainer db = null;
try {
db = Db4oEmbedded.openFile(DB4O_FILE_PATH);
ObjectSet<T> oSet = db.query(predicate);
if (oSet.hasNext()) {
return true;
}
} finally {
if (db != null)
db.close();
}
return false;
}
public static <T> void store(T t) {
ObjectContainer db = null;
try {
db = Db4oEmbedded.openFile(DB4O_FILE_PATH);
db.store(t);
} finally {
if (db != null)
db.close();
}
}
/**
* @deprecated
* the same with store() above
*/
public static <T> void cascadeStore(T t, List<Class<?>> cascadeClassList) {
EmbeddedConfiguration configuration = Db4oEmbedded.newConfiguration();
cascadeClasses(configuration, cascadeClassList);
ObjectContainer db = null;
try {
db = Db4oEmbedded.openFile(configuration, DB4O_FILE_PATH);
db.store(t);
} finally {
if (db != null)
db.close();
}
}
public static <T> void delete(Class<T> clazz) {
ObjectContainer db = null;
try {
db = Db4oEmbedded.openFile(DB4O_FILE_PATH);
ObjectSet<T> oSet = db.query(clazz);
while (oSet.hasNext()) {
db.delete(oSet.next());
}
} finally {
if (db != null)
db.close();
}
}
public static <T> void delete(T t) {
ObjectContainer db = null;
try {
db = Db4oEmbedded.openFile(DB4O_FILE_PATH);
ObjectSet<T> targetSet = db.queryByExample(t);
while (targetSet.hasNext()) {
db.delete(targetSet.next());
}
} finally {
if (db != null)
db.close();
}
}
public static <T> void delete(Predicate<T> predicate) {
ObjectContainer db = null;
try {
db = Db4oEmbedded.openFile(DB4O_FILE_PATH);
ObjectSet<T> targetSet = db.query(predicate);
while (targetSet.hasNext()) {
db.delete(targetSet.next());
}
} finally {
if (db != null)
db.close();
}
}
public static <T> void cascadeDelete(T t, List<Class<?>> cascadeClassList) {
EmbeddedConfiguration configuration = Db4oEmbedded.newConfiguration();
cascadeClasses(configuration, cascadeClassList);
ObjectContainer db = null;
try {
db = Db4oEmbedded.openFile(configuration, DB4O_FILE_PATH);
ObjectSet<T> targetSet = db.queryByExample(t);
while (targetSet.hasNext()) {
db.delete(targetSet.next());
}
} finally {
if (db != null)
db.close();
}
}
public static <T> void cascadeDelete(Predicate<T> predicate, List<Class<?>> cascadeClassList) {
EmbeddedConfiguration configuration = Db4oEmbedded.newConfiguration();
cascadeClasses(configuration, cascadeClassList);
ObjectContainer db = null;
try {
db = Db4oEmbedded.openFile(configuration, DB4O_FILE_PATH);
ObjectSet<T> targetSet = db.query(predicate);
while (targetSet.hasNext()) {
db.delete(targetSet.next());
}
} finally {
if (db != null)
db.close();
}
}
public static <T> void update(T example, T target) {
ObjectContainer db = null;
try {
db = Db4oEmbedded.openFile(DB4O_FILE_PATH);
ObjectSet<T> targetSet = db.queryByExample(example);
while (targetSet.hasNext()) {
db.delete(targetSet.next());
db.store(target);
}
} finally {
if (db != null)
db.close();
}
}
public static <T> void update(Predicate<T> predicate, T target) {
ObjectContainer db = null;
try {
db = Db4oEmbedded.openFile(DB4O_FILE_PATH);
ObjectSet<T> targetSet = db.query(predicate);
while (targetSet.hasNext()) {
db.delete(targetSet.next());
db.store(target);
}
} finally {
if (db != null)
db.close();
}
}
public static <T> void cascadeUpdate(T example, T target, List<Class<?>> cascadeClassList) {
EmbeddedConfiguration configuration = Db4oEmbedded.newConfiguration();
cascadeClasses(configuration, cascadeClassList);
ObjectContainer db = null;
try {
db = Db4oEmbedded.openFile(configuration, DB4O_FILE_PATH);
ObjectSet<T> targetSet = db.queryByExample(example);
while (targetSet.hasNext()) {
db.delete(targetSet.next());
db.store(target);
}
} finally {
if (db != null)
db.close();
}
}
public static <T> void cascadeUpdate(Predicate<T> predicate, T target, List<Class<?>> cascadeClassList) {
EmbeddedConfiguration configuration = Db4oEmbedded.newConfiguration();
cascadeClasses(configuration, cascadeClassList);
ObjectContainer db = null;
try {
db = Db4oEmbedded.openFile(configuration, DB4O_FILE_PATH);
ObjectSet<T> targetSet = db.query(predicate);
while (targetSet.hasNext()) {
db.delete(targetSet.next());
db.store(target);
}
} finally {
if (db != null)
db.close();
}
}
/*public static void main(String[] args) {
List<Class<?>> cascadeClassList = new ArrayList<Class<?>>();
cascadeClassList.add(User.class);
cascadeClassList.add(Ticket.class);
cascadeClassList.add(Passenger.class);
User u1 = createUser();
store(u1);
System.out.println("==========================stored");
printAll();
User u3 = createUser();
u3.setUserName("1111");
u3.getTickets().get(0).setFromStation("fromStation");
// update(u1, u3);
cascadeUpdate(u1, u3, cascadeClassList);
System.out.println("==========================updated");
printAll();
// delete(User.class);
// delete(Ticket.class);
// delete(Passenger.class);
cascadeDelete(u3, cascadeClassList);
System.out.println("==========================deleted");
printAll();
}
private static void printAll() {
printUsers();
printTickets();
printPassengers();
}
private static void printUsers() {
System.out.println("===Users===");
List<User> users = query(User.class);
for(User u:users){
System.out.println(u);
}
}
private static void printTickets() {
System.out.println("===Tickets===");
List<Ticket> tickets = query(Ticket.class);
for(Ticket t:tickets){
System.out.println(t);
}
}
private static void printPassengers() {
System.out.println("===Passengers===");
List<Passenger> passengers = query(Passenger.class);
for(Passenger p:passengers){
System.out.println(p);
}
}
private static User createUser() {
User u1 = new User();
Ticket t1 = new Ticket();
Passenger p1 = new Passenger();
u1.getTickets().add(t1);
t1.setPassenger(p1);
u1.setUserName("tom1");
u1.setPassword("123456");
t1.setFromStation("Suzhou");
t1.setToStation("Shanghai");
t1.setStartDate("2012-02-11");
t1.setStartTime("00:10");
p1.setName("tom1 deng");
p1.setIdNumber("3424000000000000");
p1.setPhone("13500000000");
return u1;
}*/
}
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