Java字符串方法汇总

1.指定格式参数转map

/**
* 将name1=value1;name2=value2形式的字符串转化为Map<name, value>
* @param values 字符串对象
* @param keySeparator 多个键值对之间分隔符
* @param valueSeparator 各键值之间分隔符
* @return
*/
public static Map<String, String> str2Map(String values, String keySeparator, String valueSeparator) {
Map<String, String> map = new HashMap<>();
values = values == null ? "" : values;
String[] nameValues = values.split(keySeparator);
for (int i = 0; i < nameValues.length; i++) {
String[] tmp = nameValues[i].split(valueSeparator);
// 有的字段值可能为空
if (tmp.length == 2) {
map.put(tmp[0].trim(), tmp[1]);
} else {
map.put(tmp[0].trim(), "");
}
}
return map;
}

2. 字符串null则返回默认值

/**
* @Deprecated 字符串为空则赋值默认值
* @param str 字符串对象
* @param defaultValue 默认值
* @return
*/
public static String nullOrDefault(String str, String defaultValue) {
return str == null ? defaultValue : str.trim();
}

3.驼峰转下划线

private static Pattern humpPattern = Pattern.compile("[A-Z]");
private static final String UNDERLINE = "_";
/**
* 驼峰转下划线
* @param str
* @return
*/
public static String camel2Underline(String str) {
if (str == null || str.equals("")) {
return "";
}
Matcher matcher = humpPattern.matcher(str);
StringBuffer sb = new StringBuffer();
while (matcher.find()) {
matcher.appendReplacement(sb, UNDERLINE + matcher.group(0).toLowerCase());
}
matcher.appendTail(sb);
return sb.toString();
}

4.下划线转驼峰

private static Pattern linePattern = Pattern.compile("_(\\w)");
/**
* 下划线转驼峰
* @param str
* @return
*/
public static String underline2Camel(String str) {
if (str == null || str.equals("")) {
return "";
}
Matcher matcher = linePattern.matcher(str);
StringBuffer sb = new StringBuffer();
while (matcher.find()) {
matcher.appendReplacement(sb, matcher.group(1).toUpperCase());
}
matcher.appendTail(sb);
return sb.toString();
}

5. 移除右侧的零

/**
* 移除右侧的零
* @param str
* @return
*/
public static String removeZeroRight(String str) {
return str.replaceAll("0*$","");
}

6. 移除左侧的零

/**
* 移除左侧的零
* @param str
* @return
*/
public static String removeZeroLeft(String str) {
return str.replaceAll("^0*","");
}

7. 右侧补零

/**
* 右侧补零
* @param str
* @param n
* @return
*/
public static String addZeroRight(String str, int n) {
if (str.length() >= n) {
return str;
}
return str + String.format("%1$0" + (n - str.length()) + "d", 0);
}

8. 左侧补零

/**
* 左侧补零
* @param str
* @param n
* @return
*/
public static String addZeroLeft(String str, int n) {
if (str.length() >= n) {
return str;
}
return String.format("%1$0" + (n - str.length()) + "d", 0) + str;
}

9. 根据证件号获取生日信息

/**
* 根据身份证获取生日信息
* @param idCard 18位身份证号
* @return year-MM-dd
*/
public static String getBirthByIdCard(String idCard) {
if (isEmpty(idCard)){
return "";
}
String birth = idCard.substring(6, 10) + MIDDLELINE + idCard.substring(10, 12) + MIDDLELINE + idCard.substring(12,14);
return birth;
}

10. 根据证件号判断是否是男性

/**
* 判断是否是男性
* @param idCard 18位身份证号
* @return
*/
public static Boolean isManByIdCard(String idCard){
if (isEmpty(idCard)){
return null;
}
String str = String.valueOf(idCard.charAt(idCard.length() - 2));
int sexNum = Integer.valueOf(str);
return sexNum % 2 == 1;
}