Java自动生成insert,update语句

实体类 User:

public class User {
	private String id;
	private String username;
	private String password;
	public String getUsername() {
		return username;
	}
	
	/**
	 * getter,setter.....
	 */
	
}

自动生成sql类:GenerateSql_Util

	/****
	 * INSERT INTO table(field1,field2) VALUES('value1','value2');
	 * @param obj 传入要生成的实体，需与数据库表的字段一致
	 * @return	拼成的insert 语句
	 */
	public static String getSqlInset(Object obj) {
		try {
			Class<? extends Object> c = obj.getClass();
			//获取所有的字段
			Field[] fields = c.getDeclaredFields();
			//获取实体的类名，需与表名一致
			String tableName = c.getSimpleName();
			//生成INSERT INTO table(field1,field2) 部分
			StringBuffer sbField = new StringBuffer();
			//生成VALUES('value1','value2') 部分
			StringBuffer sbValue = new StringBuffer();
			sbField.append("INSERT INTO " + tableName.toLowerCase() + "(");
			int fieldLength = fields.length;
			for(int i=0;i<fieldLength;i++){
				fields[i].setAccessible(true);
				sbField.append(fields[i].getName().toLowerCase()+',');
				sbValue.append("'"+fields[i].get(obj).toString() +"',");
			}
			return sbField.replace(sbField.length()-1, sbField.length(), ") VALUES(").append(sbValue.replace(sbValue.length()-1, sbValue.length(), ");")).toString();
		} catch (IllegalAccessException e1) {
			e1.printStackTrace();
		}
		return null;
	}
	
	public static String getSqlUpdate(Object obj) {
		try {
			Field[] fields = obj.getClass().getDeclaredFields();
			String tableName = obj.getClass().getSimpleName();
			StringBuffer sb = new StringBuffer();
			sb.append("UPDATE "+ tableName.toLowerCase() +" SET ");
			int fieldLength = fields.length;
			for(int i=0;i<fieldLength;i++){
				fields[i].setAccessible(true);
				sb.append(fields[i].getName() + " = '" + fields[i].get(obj) +"',");
			}
			return sb.replace(sb.length()-1, sb.length(), " ").toString();
		} catch (IllegalAccessException e1) {
			e1.printStackTrace();
		}
		return null;
	}

测试代码：注意update的需要加上where条件

public class test {

	public static void main(String[] args) {
		User u = new User();
		u.setId("1");
		u.setUsername("u1");
		u.setPassword("p1");
		System.out.println(GenerateSql_Util.getSqlInsert(u));
		String updateSql = GenerateSql_Util.getSqlUpdate(u) + " WHERE id = '"+ u.getId()+"';";
		System.out.println(updateSql);
	}
}

结果：

INSERT INTO user(id,username,password) VALUES('1','u1','p1');
UPDATE user SET id = '1',username = 'u1',password = 'p1'  WHERE id = '1';