StringUtils.java

/*
 * Copyright 1999-2011 Alibaba Group.
 *  
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *  
 *      http://www.apache.org/licenses/LICENSE-2.0
 *  
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.alibaba.dubbo.common.utils;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import com.alibaba.dubbo.common.Constants;
import com.alibaba.dubbo.common.io.UnsafeStringWriter;
import com.alibaba.dubbo.common.json.JSON;
import com.alibaba.dubbo.common.logger.Logger;
import com.alibaba.dubbo.common.logger.LoggerFactory;

/**
 * StringUtils
 * 
 * @author qian.lei
 */

public final class StringUtils {

    private static final Logger logger = LoggerFactory.getLogger(StringUtils.class);

	public static final String[] EMPTY_STRING_ARRAY = new String[0];

	private static final Pattern KVP_PATTERN = Pattern.compile("([_.a-zA-Z0-9][-_.a-zA-Z0-9]*)[=](.*)"); //key value pair pattern.
	
	private static final Pattern INT_PATTERN = Pattern.compile("^\\d+$");
	
	public static boolean isBlank(String str)
	{
		if( str == null || str.length() == 0 )
			return true;
		return false;
	}

	/**
	 * is empty string.
	 * 
	 * @param str source string.
	 * @return is empty.
	 */
	public static boolean isEmpty(String str)
	{
		if( str == null || str.length() == 0 )
			return true;
		return false;
	}

	/**
	 * is not empty string.
	 * 
	 * @param str source string.
	 * @return is not empty.
	 */
    public static boolean isNotEmpty(String str)
    {
        return str != null && str.length() > 0;
    }
    
    /**
     * 
     * @param s1
     * @param s2
     * @return equals
     */
    public static boolean isEquals(String s1, String s2) {
        if (s1 == null && s2 == null)
            return true;
        if (s1 == null || s2 == null)
            return false;
        return s1.equals(s2);
    }
    
    /**
     * is integer string.
     * 
     * @param str
     * @return is integer
     */
    public static boolean isInteger(String str) {
    	if (str == null || str.length() == 0)
    		return false;
        return INT_PATTERN.matcher(str).matches();
    }
    
    public static int parseInteger(String str) {
    	if (! isInteger(str))
    		return 0;
        return Integer.parseInt(str);
    }

    /**
     * Returns true if s is a legal Java identifier.<p>
     * <a href="http://www.exampledepot.com/egs/java.lang/IsJavaId.html">more info.</a>
     */
    public static boolean isJavaIdentifier(String s) {
        if (s.length() == 0 || !Character.isJavaIdentifierStart(s.charAt(0))) {
            return false;
        }
        for (int i=1; i<s.length(); i++) {
            if (!Character.isJavaIdentifierPart(s.charAt(i))) {
                return false;
            }
        }
        return true;
    }
    
    public static boolean isContains(String values, String value) {
        if (values == null || values.length() == 0) {
            return false;
        }
        return isContains(Constants.COMMA_SPLIT_PATTERN.split(values), value);
    }
    
    /**
     * 
     * @param values
     * @param value
     * @return contains
     */
    public static boolean isContains(String[] values, String value) {
        if (value != null && value.length() > 0 && values != null && values.length > 0) {
            for (String v : values) {
                if (value.equals(v)) {
                    return true;
                }
            }
        }
        return false;
    }
    
	public static boolean isNumeric(String str) {
		if (str == null) {
			return false;
		}
		int sz = str.length();
		for (int i = 0; i < sz; i++) {
			if (Character.isDigit(str.charAt(i)) == false) {
				return false;
			}
		}
		return true;
	}

    /**
     * 
     * @param e
     * @return string
     */
    public static String toString(Throwable e) {
    	UnsafeStringWriter w = new UnsafeStringWriter();
        PrintWriter p = new PrintWriter(w);
        p.print(e.getClass().getName());
        if (e.getMessage() != null) {
            p.print(": " + e.getMessage());
        }
        p.println();
        try {
            e.printStackTrace(p);
            return w.toString();
        } finally {
            p.close();
        }
    }
    
    /**
     * 
     * @param msg
     * @param e
     * @return string
     */
    public static String toString(String msg, Throwable e) {
    	UnsafeStringWriter w = new UnsafeStringWriter();
        w.write(msg + "\n");
        PrintWriter p = new PrintWriter(w);
        try {
            e.printStackTrace(p);
            return w.toString();
        } finally {
            p.close();
        }
    }

	/**
	 * translat.
	 * 
	 * @param src source string.
	 * @param from src char table.
	 * @param to target char table.
	 * @return String.
	 */
	public static String translat(String src, String from, String to)
	{
		if( isEmpty(src) ) return src;
		StringBuilder sb = null;
		int ix;
		char c;
		for(int i=0,len=src.length();i<len;i++)
		{
			c = src.charAt(i);
			ix = from.indexOf(c);
			if( ix == -1 )
			{
				if( sb != null )
					sb.append(c);
			}
			else
			{
				if( sb == null )
				{
					sb = new StringBuilder(len);
					sb.append(src, 0, i);
				}
				if( ix < to.length() )
					sb.append(to.charAt(ix));
			}
		}
		return sb == null ? src : sb.toString();
	}

	/**
	 * split.
	 * 
	 * @param ch char.
	 * @return string array.
	 */
	public static String[] split(String str, char ch)
	{
		List<String> list = null;
        char c;
        int ix = 0,len=str.length();
		for(int i=0;i<len;i++)
		{
			c = str.charAt(i);
			if( c == ch )
			{
				if( list == null )
					list = new ArrayList<String>();
				list.add(str.substring(ix, i));
				ix = i + 1;
			}
		}
		if( ix > 0 )
			list.add(str.substring(ix));
		return list == null ? EMPTY_STRING_ARRAY : (String[])list.toArray(EMPTY_STRING_ARRAY);
	}

	/**
	 * join string.
	 * 
	 * @param array String array.
	 * @return String.
	 */
	public static String join(String[] array)
	{
		if( array.length == 0 ) return "";
		StringBuilder sb = new StringBuilder();
		for( String s : array )
			sb.append(s);
		return sb.toString();
	}

	/**
	 * join string like javascript.
	 * 
	 * @param array String array.
	 * @param split split
	 * @return String.
	 */
	public static String join(String[] array, char split)
	{
		if( array.length == 0 ) return "";
		StringBuilder sb = new StringBuilder();
		for(int i=0;i<array.length;i++)
		{
			if( i > 0 )
				sb.append(split);
			sb.append(array[i]);
		}
		return sb.toString();
	}

	/**
	 * join string like javascript.
	 * 
	 * @param array String array.
	 * @param split split
	 * @return String.
	 */
	public static String join(String[] array, String split)
	{
		if( array.length == 0 ) return "";
		StringBuilder sb = new StringBuilder();
		for(int i=0;i<array.length;i++)
		{
			if( i > 0 )
				sb.append(split);
			sb.append(array[i]);
		}
		return sb.toString();
	}
	
	public static String join(Collection<String> coll, String split) {
	    if(coll.isEmpty()) return "";
	    
	    StringBuilder sb = new StringBuilder();
	    boolean isFirst = true;
	    for(String s : coll) {
	        if(isFirst) isFirst = false; else sb.append(split);
	        sb.append(s);
	    }
	    return sb.toString();
	}

	/**
	 * parse key-value pair.
	 * 
	 * @param str string.
	 * @param itemSeparator item separator.
	 * @return key-value map;
	 */
	private static Map<String, String> parseKeyValuePair(String str, String itemSeparator)
	{
		String[] tmp = str.split(itemSeparator);
		Map<String, String> map = new HashMap<String, String>(tmp.length);
		for(int i=0;i<tmp.length;i++)
		{
			Matcher matcher = KVP_PATTERN.matcher(tmp[i]);
			if( matcher.matches() == false )
				continue;
			map.put(matcher.group(1), matcher.group(2));
		}
		return map;
	}
	
	public static String getQueryStringValue(String qs, String key) {
		Map<String, String> map = StringUtils.parseQueryString(qs);
		return map.get(key);
	}
	
	/**
     * parse query string to Parameters.
     * 
     * @param qs query string.
     * @return Parameters instance.
     */
	public static Map<String, String> parseQueryString(String qs)
	{
	    if( qs == null || qs.length() == 0 )
            return new HashMap<String, String>();
	    return parseKeyValuePair(qs, "\\&");
	}
	
	public static String getServiceKey(Map<String, String> ps) {
	    StringBuilder buf = new StringBuilder();
        String group = ps.get(Constants.GROUP_KEY);
        if (group != null && group.length()>0){
            buf.append(group).append("/");
        }
        buf.append(ps.get(Constants.INTERFACE_KEY));
        String version = ps.get(Constants.VERSION_KEY);
        if (version!= null && version.length()>0){
            buf.append(":").append(version);
        }
        return buf.toString();
	}
	
	public static String toQueryString(Map<String, String> ps) {
		StringBuilder buf = new StringBuilder();
		if (ps != null && ps.size() > 0) {
			for (Map.Entry<String, String> entry : new TreeMap<String, String>(ps).entrySet()) {
				String key = entry.getKey();
				String value = entry.getValue();
				if (key != null && key.length() > 0
						&& value != null && value.length() > 0) {
					if (buf.length() > 0) {
						buf.append("&");
					}
					buf.append(key);
					buf.append("=");
					buf.append(value);
				}
			}
		}
		return buf.toString();
	}
	
	public static String camelToSplitName(String camelName, String split) {
	    if (camelName == null || camelName.length() == 0) {
	        return camelName;
	    }
	    StringBuilder buf = null;
	    for (int i = 0; i < camelName.length(); i ++) {
	        char ch = camelName.charAt(i);
	        if (ch >= 'A' && ch <= 'Z') {
	            if (buf == null) {
	                buf = new StringBuilder();
	                if (i > 0) {
	                    buf.append(camelName.substring(0, i));
	                }
	            }
	            if (i > 0) {
	                buf.append(split);
	            }
	            buf.append(Character.toLowerCase(ch));
	        } else if (buf != null) {
	            buf.append(ch);
	        }
	    }
	    return buf == null ? camelName : buf.toString();
	}
	
	public static String toArgumentString(Object[] args) {
	    StringBuilder buf = new StringBuilder();
        for (Object arg : args) {
            if (buf.length() > 0) {
                buf.append(Constants.COMMA_SEPARATOR);
            }
            if (arg == null || ReflectUtils.isPrimitives(arg.getClass())) {
                buf.append(arg);
            } else {
                try {
                    buf.append(JSON.json(arg));
                } catch (IOException e) {
                    logger.warn(e.getMessage(), e);
                    buf.append(arg);
                }
            }
        }
        return buf.toString();
	}

	private StringUtils(){}
}