1，转化文件编码
文件的原始编码是inputCharset，转为outputCharset的编码格式
/***
*
* @param srcfile : source file
* @param targfile : target file
* @param inputCharset : from charset
* @param outputCharset : to charset
*/
public static void convertEncoding(File srcfile, File targfile,
String inputCharset, String outputCharset) {
FileInputStream fin = null;
FileOutputStream fout = null;
char[] cbuf = new char[BUFF_SIZE];
int size_char;
try {
fin = new FileInputStream(srcfile);
fout = new FileOutputStream(targfile);
InputStreamReader isr = null;
OutputStreamWriter osw = null;
try {
isr = new InputStreamReader(fin, inputCharset);
osw = new OutputStreamWriter(fout, outputCharset);
while ((size_char = isr.read(cbuf)) != NEGATIVE_ONE) {
osw.write(cbuf, 0, size_char);
}
//
} catch (UnsupportedEncodingException e1) {
e1.printStackTrace();
} catch (IOException e1) {
e1.printStackTrace();
} finally {
try {
isr.close();
osw.close();
} catch (IOException e1) {
e1.printStackTrace();
}
}
} catch (FileNotFoundException e1) {
e1.printStackTrace();
} finally {
try {
if (fin != null) {
fin.close();
}
if (fout != null) {
fout.close();
}
} catch (IOException e1) {
e1.printStackTrace();
}
}
}
2，判断是否是中文字符（包括中文的标点符号，如。）
/**
* 字节数大于1，则返回true
*
* @param c
* @return
*/
public static boolean isChinese(char c) {
return String.valueOf(c).getBytes().length > 1;
}
3，获取文件的MD5值
/**
* Get MD5 of one file！
*
* @param file
* @return
*/
public static String getFileMD5(File file) {
if (!file.exists() || !file.isFile()) {
return null;
}
MessageDigest digest = null;
FileInputStream in = null;
byte buffer[] = new byte[1024];
int len;
try {
digest = MessageDigest.getInstance("MD5");
in = new FileInputStream(file);
while ((len = in.read(buffer, 0, 1024)) != -1) {
digest.update(buffer, 0, len);
}
in.close();
} catch (Exception e) {
e.printStackTrace();
return null;
}
BigInteger bigInt = new BigInteger(1, digest.digest());
return bigInt.toString(16);
}
4，获取实际类型的class
/*** * 获取实际的子类的class * @param clz * @return */ public staticClass getGenricClassType( @SuppressWarnings("rawtypes") Class clz) { Type type = clz.getGenericSuperclass(); if (type instanceof ParameterizedType) { ParameterizedType pt = (ParameterizedType) type; Type[] types = pt.getActualTypeArguments(); if (types.length > 0 && types[0] instanceof Class) { return (Class) types[0]; } } return (Class) Object.class; }
应用：在dao层，GoodsDao 继承GenericDao，在GoodsDao 中就不用重复增删改查了。
package com.common.dao.generic; import java.util.List; import org.hibernate.Criteria; import org.hibernate.SessionFactory; import org.hibernate.criterion.Example; import com.common.util.SystemUtil; /*** * all dao must extends this class * * @author huangwei * * @param*/ public abstract class GenericDao { /*** * generated by spring configuration file */ protected SessionFactory sessionFactory; protected final Class clz = SystemUtil.getGenricClassType(getClass()); public SessionFactory getSessionFactory() { return sessionFactory; } public void setSessionFactory(SessionFactory sessionFactory) { this.sessionFactory = sessionFactory; } /***************************************************************/ public void add(Object obj) { this.sessionFactory.getCurrentSession().save(obj); } public void save(Object obj) { this.add(obj); } public void delete(Object obj) { this.sessionFactory.getCurrentSession().delete(obj); } public void deleteById(int id) { this.sessionFactory.getCurrentSession().delete(get(id)); } public T get(int id) { return (T) this.sessionFactory.getCurrentSession().get(clz, id); } public void update(Object obj) { this.sessionFactory.getCurrentSession().update(obj); } public List getAll() { return (List ) this.sessionFactory.getCurrentSession() .createCriteria(clz).list(); } /*** * Find in DB depending on conditions * * @param obj * @return */ public List find(Object obj) { if (obj == null) { return this.getAll(); } else { Example example = Example.create(obj).excludeZeroes(); Criteria criteria = this.sessionFactory.getCurrentSession() .createCriteria(clz).add(example); return (List )criteria.list(); } } }
package com.shop.jn.dao; import com.common.dao.generic.GenericDao; import com.shop.jn.entity.Goods; public class GoodsDao extends GenericDao{ }
5，合并字节数组
/***
* 合并字节数组
* @param a
* @return
*/
public static byte[] mergeArray(byte[]... a) {
// 合并完之后数组的总长度
int index = 0;
int sum = 0;
for (int i = 0; i < a.length; i++) {
sum = sum + a[i].length;
}
byte[] result = new byte[sum];
for (int i = 0; i < a.length; i++) {
int lengthOne = a[i].length;
// 拷贝数组
System.arraycopy(a[i], 0, result, index, lengthOne);
index = index + lengthOne;
}
return result;
}
6，判断关键字keyword 在srcText 中出现的次数
方式一：
/**
*
* The number of occurrences of find keyword in srcText
*
* @param srcText
* @param keyword
* @return
*/
public static int findStr1(String srcText, String keyword) {
int count = 0;
int leng = srcText.length();
int j = 0;
for (int i = 0; i < leng; i++) {
if (srcText.charAt(i) == keyword.charAt(j)) {
j++;
if (j == keyword.length()) {
count++;
j = 0;
}
} else {
i = i - j;// should rollback when not match
j = 0;
}
}
return count;
}
方式二：
public static int findStr2(String srcText, String keyword) {
int count = 0;
Pattern p = Pattern.compile(keyword);
Matcher m = p.matcher(srcText);
while (m.find()) {
count++;
}
return count;
}
7， 获取字节数组findTarget 在字节数组source中出现的位置
/***
*
* @param source
* @param findTarget
* :key word
* @param pos
* :where start from
* @return index
*/
public static int findBytes(byte[] source, byte[] findTarget, int pos) {
int i, j, k = 0;
i = pos;
j = 0;
while (i < source.length && j < findTarget.length) {
if (source[i] == findTarget[j]) {
++i;
++j;
if (j == findTarget.length) {
k = k + 1;// k++
break;
// j = 0;
}
} else {
i = i - j + 1;
j = 0;
}
}
return k == 0 ? -1 : i - j;
}
/***
* start from 0
*
* @param source
* @param findTarget
* @return
*/
public static int findBytes(byte[] source, byte[] findTarget) {
return findBytes(source, findTarget, 0);
}