杂的技巧

1：数组的复制(引用复制)

System.arraycopy(source,index, target, index, len)

 重建数组

Integer [] copyOf = Arrays.copyOf(band,band.size());

 

2：使用预编译sql操作oracle时，性能问题

public void saveInsert(final List<BeanTask> tasks) {
		if (tasks.size() < 1)
			return;
		String sql = "insert into CHANNEL_SWITCH (ID, CHANNEL_ID, CHANNEL_NAME, SWITCH_TIME, K, N, S) values (channelswitch_sequence.Nextval, ?, ?, SYSDATE, ?, ?, ?)";//sysdate会使用oracle每次都重新编译sql,可以得到当前系统时间拼到sql中
		jdbcTemplate.batchUpdate(sql, new BatchPreparedStatementSetter() {
			public void setValues(PreparedStatement ps, int i) throws SQLException {
				BeanTask task = tasks.get(i);
				ps.setString(1, task.getChannelID());
				ps.setString(2, task.getChannelName());
				ps.setDouble(3, task.getK());
				ps.setDouble(4, task.getN());
				ps.setDouble(5, task.getS());
				
			}

			public int getBatchSize() {
				return tasks.size();
			}
		});
	}

 3：使用configuration读取配置文件

maven包

<properties>
<configuration.version>1.6</configuration.version>
</properties>

<dependencies>
<dependency>
<groupId>commons-configuration</groupId>
<artifactId>commons-configuration</artifactId>
<version>${configuration.version}</version>
</dependency>
</dependencies>

 读取list

try {
			PropertiesConfiguration pc = new PropertiesConfiguration("dev.properties");
			Iterator keys = pc.getKeys();
			while (keys.hasNext()) {
				String department = keys.next().toString();
				List<String> dev = pc.getList(department);
				devDepartmentCache.put(department, dev);
			}
		} catch (ConfigurationException e) {
			logger.error("read properties file error :dev.properties", e);
		}

 配置文件中的内容（用逗号分隔）

billing=CCN-BJ-J-5KX
log=CCN-BJ-J-5KV,CCN-BJ-J-3g2

 4：数据组的初始化，总是记不住备忘下

String数组初始化方式：
(1).String[] temp= new String[] {"aa","bb" };

(2).String[] temp= {"aa","bb" };
(3).String[] temp= new String[2];
temp[0]= "aa";
temp[1]= "bb";

 5：list转换为数组

String[] array = (String[])list.toArray(new String[list.size()])

 数组转换为list

List<String> list=Arrays.asList(array);

 基本类型数组与包装类型数组转换

Long[] object = ArrayUtils.toObject(new long[1]);

 6:数组排序

Arrays.sort（） 默认升序