JAVA通过实体类生成数据库查询语句(驼峰命名规则)
import java.io.IOException; import java.lang.reflect.Field; import java.util.HashMap; import java.util.Map; /*** * 通过java Class 生成查询语句 */ public class SelectTable { public static Map<String, String> javaProperty2SqlColumnMap = new HashMap<>(); static { javaProperty2SqlColumnMap.put("Integer", "INTEGER"); javaProperty2SqlColumnMap.put("Short", "tinyint"); javaProperty2SqlColumnMap.put("Long", "bigint"); javaProperty2SqlColumnMap.put("BigDecimal", "decimal(19,2)"); javaProperty2SqlColumnMap.put("Double", "double precision not null"); javaProperty2SqlColumnMap.put("Float", "float"); javaProperty2SqlColumnMap.put("Boolean", "tinyint"); javaProperty2SqlColumnMap.put("Timestamp", "datetime"); javaProperty2SqlColumnMap.put("String", "VARCHAR(255)"); javaProperty2SqlColumnMap.put("Date", "datetime"); } /** * @param args * @throws IOException */ public static void main(String[] args) throws IOException { selectTable(Test.class, "g_test"); } public static String selectTable(Class obj, String tableName) throws IOException { Field[] fields = null; fields = obj.getDeclaredFields(); String column = null; StringBuilder sb = null; sb = new StringBuilder(50); String tableAlias = getTableAlias(tableName); sb.append("select "); for (Field f : fields) { column = f.getName(); if (column.equals("serialVersionUID")) { continue; } String columnName = camelToUnderline(column, 1); sb.append(tableAlias+"."+columnName + ""); sb.append(" as "); sb.append(column); sb.append(" ,"); } sb.deleteCharAt(sb.length() - 1); sb.append(" from " + tableName+" "+tableAlias); String sql = sb.toString(); System.out.println(sql); System.out.println("#----------------------------------------"); return sql; } /** * 获取表名的别名 最后一个单词的首字母 * @param tableName * @return */ public static String getTableAlias(String tableName) { String[] split = tableName.split("_"); String table = split[split.length - 1]; return table.charAt(0) + ""; } /** * 驼峰转下划线 * * @param param * @param charType * @return */ public static String camelToUnderline(String param, Integer charType) { if (param == null || "".equals(param.trim())) { return ""; } int len = param.length(); StringBuilder sb = new StringBuilder(len); for (int i = 0; i < len; i++) { char c = param.charAt(i); if (Character.isUpperCase(c)) { sb.append("_"); } if (charType == 2) { sb.append(Character.toUpperCase(c)); //统一都转大写 } else { sb.append(Character.toLowerCase(c)); //统一都转小写 } } String s = sb.toString(); if (s.startsWith("_")) { s = s.substring(1, s.length()); } return s; } }
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(蓝奏云官网有些地址失效了,需要把请求地址lanzous改成lanzoux才可以)