1、合并数组
int [] arry1 = {1,2,3,4,5};
int [] arry2 = {6,7,8,9,0};
int [] arry3 = new int[arry1.length+arry2.length];
System.arraycopy(arry1, 0, arry3, 0, arry1.length);
System.arraycopy(arry2, 0, arry3, arry1.length, arry2.length);
System.out.println(Arrays.toString(arry3));
------------------------------------------------------------------------------
[1, 2, 3, 4, 5, 6, 7, 8, 9, 0]
2、对象序列化为json，json反序列化为对象
try {
D d = new D();
d.setA("a");
ObjectMapper om = new ObjectMapper();
ObjectWriter ow = om.writerWithView(d.getClass());
System.out.println(ow.writeValueAsString(d));
ObjectReader or = om.reader(D.class);
D s = or.readValue(ow.writeValueAsString(d));
System.out.println(s.getA());
} catch (JsonProcessingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
----------------------------------------------------------------------------------
{"a":"a","t":{"name":"zhangSan"},"paramTest":"param"}
a
3、json转换为map（bean转换为map键值对）
try {
D d = new D();
d.setA("a");
d.setT(new T("zhangSan"));
d.setParamTest("param");
ObjectMapper om = new ObjectMapper();
ObjectWriter ow = om.writerWithView(d.getClass());
String result = ow.writeValueAsString(d);
System.out.println(result);
JSONObject jasonObject = JSONObject.fromObject(result);
HashMap<String, Object> data = new HashMap<String, Object>();
Iterator it = jasonObject.keys();
// 遍历jsonObject数据，添加到Map对象
while (it.hasNext()) {
String key = String.valueOf(it.next());
Object value = jasonObject.get(key);
data.put(key, value);
}
System.out.println(data.toString());
} catch (JsonProcessingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
-------------------------------------------------------------------------------------
{"a":"a","t":{"name":"zhangSan"},"paramTest":"param"}
{t={"name":"zhangSan"}, a=a, paramTest=param}
4、进制转换
System.out.println(Integer.toBinaryString(8));//十进制转二进制
System.out.println(Integer.toHexString(8));//十进制转十六进制
System.out.println(Integer.toOctalString(8));//十进制转八进制
System.out.println(Integer.valueOf("1000", 2));//二进制转十进制
--------------------------------------------------------------------------------------
1000
8
10
8
5、list自定义排序
List<CollectionTest> list = new ArrayList<CollectionTest>();
list.add(new CollectionTest(1,DateUtils.addHours(new Date(), 2)));
list.add(new CollectionTest(2,DateUtils.addHours(new Date(), 1)));
list.add(new CollectionTest(3,DateUtils.addHours(new Date(), 4)));
list.add(new CollectionTest(4,DateUtils.addHours(new Date(), 3)));
//这里是倒序
Collections.sort(list, new Comparator<CollectionTest>() {
@Override
public int compare(CollectionTest arg0, CollectionTest arg1) {
if (arg0.getOrder1().getTime() < arg1.getOrder1().getTime()) {
return 1;
} else if (arg0.getOrder1().getTime() > arg1.getOrder1().getTime()) {
return -1;
} else {
return 0;
}
}
});
for (CollectionTest collectionTest : list) {
System.out.println(collectionTest.getOrder());
System.out.println(collectionTest.getOrder1());
}
-----------------------------------------------------------------------------------------
3
Fri Jun 26 21:19:05 CST 2015
4
Fri Jun 26 20:19:05 CST 2015
1
Fri Jun 26 19:19:05 CST 2015
2
Fri Jun 26 18:19:05 CST 2015
6、正则表达式基本使用
Pattern p=Pattern.compile(".*.*/.*.*/service/.*.*/.*Service.*");
System.out.println(p.matcher("com/paic/cicp/test/biz/service/impl/UserServiceImpl").matches());
System.out.println(p.matcher("com/paic/cicp/test/biz/service/impl/UserService.i").matches());
String s = "123";
System.out.println(s.matches("\\d{3}"));
---------------------------------------------------------------------------------------
true
true
true
7、分隔，代替split
StringTokenizer tokenizer = new StringTokenizer("I|身份证", "|");
System.out.println(tokenizer.nextToken());
System.out.println(tokenizer.nextToken());
----------------------------------------------------------------------------------------
I
身份证
8、浅复制、深复制
//浅复制（只复制基本类型，不支持自定义复杂类型）
BeanUtils.cloneBean(object)；
//深复制（串行化，支持自定义复杂类型，要求自定义类型实现Serializable）
public static Object deepClone(Object src) throws Throwable {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ObjectOutputStream oos = new ObjectOutputStream(baos);
oos.writeObject(src);
oos.close();
ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());
ObjectInputStream ois = new ObjectInputStream(bais);
Object o = ois.readObject();
ois.close();
return o;
}
//深复制（通过序列换、反序列化实现，支持自定义复杂类型，要求自定义类型实现Serializable）
public static <T> T deepClone1(T t){
T r = null;
try {
ObjectMapper om = new ObjectMapper();
ObjectWriter ow = om.writerWithView(t.getClass());
String serResult = ow.writeValueAsString(t);
System.out.println(serResult);
ObjectReader or = om.reader(t.getClass());
r = or.readValue(serResult);
} catch (JsonProcessingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return r;
}
9、判断字符串是否数字（整数、小数、负数）
public static boolean isNum(String str){
if(StringUtils.isBlank(str))
return false;
else if(str.matches("^\\d+$|-\\d+$") || str.matches("\\d+\\.\\d+$|-\\d+\\.\\d+$"))
return true;
return false;
}
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