/**
* 用于保存模板文件，内容包括：
* 1，标志位，1 int
* 2，版本 1 int
* 3，数据头长度 1 int
* 4，预留数据头空间 5120 byte
* 5，后续数据长度 0不存在,>0存在
* 7,后续数据
* @author benson
*
*/
import java.io.*;
public class BTemplateFile {
private static final int FLAG = -1;
private static final int HEAD_LENGTH = 5120;
private byte[] head = null;
private static BTemplateFile instance;
//单例模式
public static synchronized BTemplateFile getInstance(){
if (instance == null) {
instance = new BTemplateFile();
}
return instance;
}
/**
* 构造函数
*/
private BTemplateFile() {
super();
// TODO Auto-generated constructor stub
head = new byte[HEAD_LENGTH];
for (int i = 0; i < HEAD_LENGTH; i++) {
head[i] = (byte) 0xff;
}
}
/**
* 创建一个空白的模板文件
*
* @param version
* @param filename
* @throws IOException
*/
public void create(File file) throws IOException {
if (!file.exists()) {
FileOutputStream _out = new FileOutputStream(file);
DataOutputStream _data_out = new DataOutputStream(_out);
_data_out.writeInt(FLAG); // 写入标志
_data_out.writeInt(0); // 写入版本
_data_out.writeInt(0); // head_length
_data_out.write(head);
_data_out.writeInt(0); // 无后续数据
_data_out.write(head); // 填充2000个字节的空数据
_data_out.close();
_out.close();
}
}
/**
* 读取head
*
* @param filename
* @return
* @throws Exception
*/
public Object read_head(File file) throws Exception {
if(!file.exists()){
throw new Exception("读取模板文件不存在！");
}
Object obj = null;
DataInputStream _in = new DataInputStream(new FileInputStream(file));
int flag = _in.readInt();
int version = _in.readInt();
if (flag != FLAG) {
_in.close();
throw new Exception("文件格式错误！");
}
if (version == 0) {
int head_length = _in.readInt();
if (head_length > 0) {
ObjectInputStream _obj_in = new ObjectInputStream(_in);
obj = _obj_in.readObject();
}
}
_in.close();
return obj;
}
/**
* 读取数据对象
*
* @param filename
* @return
* @throws Exception
*/
public Object read_data(File file) throws Exception {
if(!file.exists()){
throw new Exception("读取模板文件不存在！");
}
Object obj = null;
DataInputStream _in = new DataInputStream(new FileInputStream(file));
int flag = _in.readInt();
int version = _in.readInt();
if (flag != FLAG) {
_in.close();
throw new Exception("文件格式错误！");
}
if (version == 0) {
int head_length = _in.readInt();
_in.read(head);
int data_length = _in.readInt();
if (data_length > 0) {
ObjectInputStream _obj_in = new ObjectInputStream(_in);
obj = _obj_in.readObject();
}
}
_in.close();
return obj;
}
/**
* 修改头信息
*
* @param head_str
* @throws Exception
*/
public void modify_head(Object head_obj,File file) throws Exception {
if(!file.exists()){
throw new Exception("读取模板文件不存在！");
}
RandomAccessFile rfile = new RandomAccessFile(file, "rw");
int flag = rfile.readInt();
int version = rfile.readInt();
if (flag != FLAG) {
rfile.close();
throw new Exception("文件格式错误！");
}
if (version == 0) {
ByteArrayOutputStream _out = new ByteArrayOutputStream();
ObjectOutputStream _obj_out = new ObjectOutputStream(_out);
_obj_out.writeObject(head_obj);
_obj_out.flush();
byte[] head_bytes = _out.toByteArray();
if (head_bytes.length < HEAD_LENGTH) {
rfile.writeInt(head_bytes.length);
rfile.write(head_bytes);
} else {
rfile.close();
throw new Exception("头长度超过限制（" + HEAD_LENGTH + "）="
+ head_bytes.length);
}
}
rfile.close();
}
/**
* 修改数据对象
*
* @param data
* @param filename
* @throws Exception
*/
public void modify_data(Object data, File file) throws Exception {
if(!file.exists()){
throw new Exception("读取模板文件不存在！");
}
RandomAccessFile rfile = new RandomAccessFile(file, "rw");
int flag = rfile.readInt();
int version = rfile.readInt();
if (flag != FLAG) {
rfile.close();
throw new Exception("文件格式错误！");
}
if (version == 0) {
int head_length = rfile.readInt();
rfile.skipBytes(HEAD_LENGTH);
ByteArrayOutputStream _out = new ByteArrayOutputStream();
ObjectOutputStream _obj_out = new ObjectOutputStream(_out);
_obj_out.writeObject(data);
_obj_out.flush();
byte[] data_bytes = _out.toByteArray();
rfile.writeInt(data_bytes.length);
rfile.write(data_bytes);
_obj_out.close();
_out.close();
}
rfile.close();
}
/**
* @param args
* @throws Exception
*/
public static void main(String[] args) throws Exception {
// TODO Auto-generated method stub
BTemplateFile b = new BTemplateFile();
String filename = "d:\\tmp\\1\\aa.vav";
File file=new File(filename);
ClientData data = new ClientData();
data.setKey(100);
data.setValue("111111111111111111111111");
data.setSaveName("中国人民*");
ClientData data1 = new ClientData();
data1.setKey(3333333);
data1.setValue("33333333333333");
data1.setSaveName("到搜房数据发生");
b.create(file);
b.modify_head(data1, file);
System.out.println("1 ------");
b.modify_data(data, file);
System.out.println("2 ------");
ClientData head = (ClientData) b.read_head(file);
if (head != null)
System.out.println("head:" + head.getKey() + " " + head.getValue()
+ " " + head.getSaveName());
else
System.out.println("head is null");
ClientData c = (ClientData) b.read_data(file);
if (c != null)
System.out.println("data:" + c.getKey() + " " + c.getValue() + " "
+ c.getSaveName());
else
System.out.println("data is null");
}
}