将秒转换成日期格式的java方法：

package net.blogjava.frankiegao123.util.time;

import java.util.Arrays;

/**
* 时间计算工具类
*
* @author frankiegao123
*/
public class Time {

/**
* 时间字段常量，表示“秒”
*/
public final static int SECOND = 0;

/**
* 时间字段常量，表示“分”
*/
public final static int MINUTE = 1;

/**
* 时间字段常量，表示“时”
*/
public final static int HOUR = 2;

/**
* 时间字段常量，表示“天”
*/
public final static int DAY = 3;

/**
* 各常量允许的最大值
*/
private final int[] maxFields = { 59, 59, 23, Integer.MAX_VALUE - 1 };

/**
* 各常量允许的最小值
*/
private final int[] minFields = { 0, 0, 0, Integer.MIN_VALUE };

/**
* 默认的字符串格式时间分隔符
*/
private String timeSeparator = ":";

/**
* 时间数据容器
*/
private int[] fields = new int[4];

/**
* 无参构造，将各字段置为 0
*/
public Time() {
this(0, 0, 0, 0);
}

/**
* 使用时、分构造一个时间
* @param hour      小时
* @param minute    分钟
*/
public Time(int hour, int minute) {
this(0, hour, minute, 0);
}

/**
* 使用时、分、秒构造一个时间
* @param hour      小时
* @param minute    分钟
* @param second    秒
*/
public Time(int hour, int minute, int second) {
this(0, hour, minute, second);
}

/**
* 使用一个字符串构造时间<br/>
* Time time = new Time("14:22:23");
* @param time      字符串格式的时间，默认采用“:”作为分隔符
*/
public Time(String time) {
this(time, null);
}

/**
* 使用天、时、分、秒构造时间，进行全字符的构造
* @param day       天
* @param hour      时
* @param minute    分
* @param second    秒
*/
public Time(int day, int hour, int minute, int second) {
initialize(day, hour, minute, second);
}

/**
* 使用一个字符串构造时间，指定分隔符<br/>
* Time time = new Time("14-22-23", "-");
* @param time      字符串格式的时间
*/
public Time(String time, String timeSeparator) {
if(timeSeparator != null) {
setTimeSeparator(timeSeparator);
}
parseTime(time);
}

/**
* 设置时间字段的值
* @param field     时间字段常量
* @param value     时间字段的值
*/
public void set(int field, int value) {
if(value < minFields[field]) {
throw new IllegalArgumentException(value + ", time value must be positive.");
}
fields[field] = value % (maxFields[field] + 1);
// 进行进位计算
int carry = value / (maxFields[field] + 1);
if(carry > 0) {
int upFieldValue = get(field + 1);
set(field + 1, upFieldValue + carry);
}
}

/**
* 获得时间字段的值
* @param field     时间字段常量
* @return          该时间字段的值
*/
public int get(int field) {
if(field < 0 || field > fields.length - 1) {
throw new IllegalArgumentException(field + ", field value is error.");
}
return fields[field];
}

/**
* 将时间进行“加”运算，即加上一个时间
* @param time      需要加的时间
* @return          运算后的时间
*/
public Time addTime(Time time) {
Time result = new Time();
int up = 0;     // 进位标志
for (int i = 0; i < fields.length; i++) {
int sum = fields[i] + time.fields[i] + up;
up = sum / (maxFields[i] + 1);
result.fields[i] = sum % (maxFields[i] + 1);
}
return result;
}

/**
* 将时间进行“减”运算，即减去一个时间
* @param time      需要减的时间
* @return          运算后的时间
*/
public Time subtractTime(Time time) {
Time result = new Time();
int down = 0;       // 退位标志
for (int i = 0, k = fields.length - 1; i < k; i++) {
int difference = fields[i] + down;
if (difference >= time.fields[i]) {
difference -= time.fields[i];
down = 0;
} else {
difference += maxFields[i] + 1 - time.fields[i];
down = -1;
}
result.fields[i] = difference;
}
result.fields[DAY] = fields[DAY] - time.fields[DAY] + down;
return result;
}

/**
* 获得时间字段的分隔符
* @return
*/
public String getTimeSeparator() {
return timeSeparator;
}

/**
* 设置时间字段的分隔符（用于字符串格式的时间）
* @param timeSeparator     分隔符字符串
*/
public void setTimeSeparator(String timeSeparator) {
this.timeSeparator = timeSeparator;
}

private void initialize(int day, int hour, int minute, int second) {
set(DAY, day);
set(HOUR, hour);
set(MINUTE, minute);
set(SECOND, second);
}

private void parseTime(String time) {
if(time == null) {
initialize(0, 0, 0, 0);
return;
}
String t = time;
int field = DAY;
set(field--, 0);
int p = -1;
while((p = t.indexOf(timeSeparator)) > -1) {
parseTimeField(time, t.substring(0, p), field--);
t = t.substring(p + timeSeparator.length());
}
parseTimeField(time, t, field--);
}

private void parseTimeField(String time, String t, int field) {
if(field < SECOND || t.length() < 1) {
parseTimeException(time);
}
char[] chs = t.toCharArray();
int n = 0;
for(int i = 0; i < chs.length; i++) {
if(chs[i] <= ' ') {
continue;
}
if(chs[i] >= '0' && chs[i] <= '9') {
n = n * 10 + chs[i] - '0';
continue;
}
parseTimeException(time);
}
set(field, n);
}

private void parseTimeException(String time) {
throw new IllegalArgumentException(time + ", time format error, HH"
+ this.timeSeparator + "mm" + this.timeSeparator + "ss");
}

public String toString() {
StringBuilder sb = new StringBuilder(16);
sb.append(fields[DAY]).append(',').append(' ');
buildString(sb, HOUR).append(timeSeparator);
buildString(sb, MINUTE).append(timeSeparator);
buildString(sb, SECOND);
return sb.toString();
}

private StringBuilder buildString(StringBuilder sb, int field) {
if(fields[field] < 10) {
sb.append('0');
}
return sb.append(fields[field]);
}

public int hashCode() {
final int PRIME = 31;
int result = 1;
result = PRIME * result + Arrays.hashCode(fields);
return result;
}

public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
final Time other = (Time) obj;
if (!Arrays.equals(fields, other.fields)) {
return false;
}
return true;
}
}