教你写出StringUtils工具类

/*
*代码很简单，就是判断常用的字符串是不是满足一些条件
*
*里面有判断字符串是不是url，还有构建url的代码等等。
*
*还有很多更使用的判断，自己看代码，老司机我就不多说了
*/
public class StringUtil {
public StringUtil() {
}

public static String trim(String source) {
return source != null?source.trim():source;
}

public static boolean isEmpty(String source) {
return source == null || source.length() == 0;
}

public static boolean isNotEmpty(String source) {
return !isEmpty(source);
}

public static boolean isBlank(String source) {
return source == null || source.length() <= 0 || source.trim().length() <= 0;
}

public static boolean isNotBlank(String source) {
return !isBlank(source);
}

public static boolean isNumeric(String str) {
return !isBlank(str) && str.trim().matches("\\d+");
}

public static boolean isBool(String str) {
return !isBlank(str) && (str.trim().equals("true") || str.trim().equals("false"));
}

public static boolean isEquals(String src, String dest) {
return src == null && dest == null?true:(src != null && dest != null?src.trim().equals(dest.trim()):false);
}

public static boolean isNotEquals(String src, String dest) {
return !isEquals(src, dest);
}

public static boolean isRightUrl(String s) {
if (isEmptyStr(s))
return false;
else {
if (s.startsWith("http://"))
return true;
else
return false;
}
}

public static boolean isInteger(String str) {
byte begin = 0;
if(isBlank(str)) {
return false;
} else {
str = str.trim();
if(str.startsWith("+") || str.startsWith("-")) {
if(str.length() == 1) {
return false;
}

begin = 1;
}

for(int i = begin; i < str.length(); ++i) {
if(!Character.isDigit(str.charAt(i))) {
return false;
}
}

return true;
}
}

public static String buildUrl(String url, HashMap<String, String> params){
if(params != null){
StringBuffer buffer = new StringBuffer(url);
if(buffer.indexOf("?") == -1){
buffer.append("?");
}

buffer.append(buildParam(params));
return buffer.toString();
}else {
return url;
}
}

private static String buildParam(HashMap<String, String> params){
StringBuffer buffer = new StringBuffer();
for (Map.Entry<String, String> entry : params.entrySet()) {
try {
buffer.append(entry.getKey()).append("=").append(URLEncoder.encode(entry.getValue(), "UTF-8")).append("&");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
}
buffer.deleteCharAt(buffer.length()-1);
return buffer.toString();
}
}