hashMap里有键值对 Draft_dwg=abc、 Draft_pdf=cdf、Draft_wmf=gph
我现在如何把hashmap中的key得到，并且拼接成字符串的形式，比如字符串1得到 “Draft_dwg, Draft_pdf, Draft_wmf”
字符串2得到"abc,cdf,gph" 因为这两个字符串要插入到sql语句，insert into flat (字符串1) values (字符串2)
------解决方案--------------------
Map map = new HashMap();
Iterator iter = map.entrySet().iterator();
while (iter.hasNext()) {
Map.Entry entry = (Map.Entry) iter.next();
Object key = entry.getKey();
Object val = entry.getValue();
}
------解决方案--------------------
- Java code
public static void main(String[] args) { LinkedHashMap<String, String> map = new LinkedHashMap<>(); map.put("Draft_dwg", "abc"); map.put("Draft_pdf", "cdf"); map.put("Draft_wmf", "gph"); System.out.println(createInsertSQL(map, "flat"));}public static String createInsertSQL(Map<String, String> map, String table) { StringBuilder keys = new StringBuilder(); StringBuilder values = new StringBuilder(); boolean first = true; for (Entry<String, String> entry : map.entrySet()) { if (!first) { keys.append(", "); values.append(", "); } first = false; keys.append(entry.getKey()); values.append("\"" + entry.getValue() + "\""); } return "insert into " + table + " (" + keys + ") values (" + values + ")";}
------解决方案--------------------
补充一下，map有个keySet方法可以得到所有的key，另sql语句的value是用单引号扩起来的
- Java code
Map<String, String> map = new LinkedHashMap<String, String>(); map.put("Draft_dwg", "abc"); map.put("Draft_pdf", "cdf"); map.put("Draft_wmf", "gph"); StringBuffer cols = new StringBuffer(); StringBuffer vals = new StringBuffer(); boolean first = true; for (String key : map.keySet()) { if (!first) { cols.append(", "); vals.append(", "); } first = false; cols.append(key); vals.append("'" + map.get(key) + "'"); } System.out.println("insert into flat (" + cols + ") values (" + vals+ ")");
------解决方案--------------------
- Java code
Map<String, String> map = new HashMap<String, String>(); map.put("Draft_dwg", "abc"); map.put("Draft_pdf", "cdf"); map.put("Draft_wmf", "gph"); Set<String> keys = map.keySet() ; Collection<String> values = map.values() ; System.out.println( keys ); System.out.println( values );