自动生成代码工具 模板工具类

import java.io.BufferedWriter;
import java.io.FileOutputStream;
import java.io.OutputStreamWriter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Optional;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.ijwt.exception.JavaTypeException;
import com.ijwt.exception.MybatisTypeException;

import freemarker.cache.ClassTemplateLoader;
import freemarker.template.Configuration;
import freemarker.template.Template;
import freemarker.template.TemplateExceptionHandler;

/**
 * @author InJavaWeTrust
 */
public enum UtilFreemarker {
	
	INSTANCE;
	
	private static Logger log = LoggerFactory.getLogger(UtilFreemarker.class);
	
	/**
	 * 获取java属性</br>
	 * @param tableName 表名
	 * @return java属性list
	 */
	public List<String> getJavaPropertyList(String tableName) {
		List<String> javaPropertyList = new ArrayList<>();
		List<String> columnNameList = UtilDB.getColumnNameByTableName(tableName);
		columnNameList.forEach(columnName -> javaPropertyList.add(UtilString.INSTANCE.columnNameToJavaName(columnName)));
		return javaPropertyList;
	}
	
	/**
	 * 获取表中列
	 * @param tableName 表名
	 * @return list
	 */
	public List<String> getColumnNameForMybatis(String tableName) {
		return UtilDB.getColumnNameByTableName(tableName);
	}
	
	/**
	 * 得到表中列字段长度最长的列字段
	 * @param tableName 表名
	 * @return 最长的列字段
	 */
	public int getMaxColumnLength(String tableName){
		List<String> columnList = getColumnNameForMybatis(tableName);
		Optional<Integer> opt = columnList.stream().map(String::length).max(Integer::compareTo);
		int maxLen = 0;
		if (opt.isPresent()) {
			maxLen = opt.get();
		}
		return maxLen;
	}
	
	/**
	 * 得到Java属性字段长度最长的字段长度
	 * @param tableName 表名
	 * @return Java属性最长字段长度
	 */
	public int getMaxJavaPropertyLength(String tableName){
		List<String> propertyList = getJavaPropertyList(tableName);
		Optional<Integer> opt = propertyList.stream().map(String::length).max(Integer::compareTo);
		int maxLen = 0;
		if (opt.isPresent()) {
			maxLen = opt.get();
		}
		return maxLen;
	}
	
	/**
	 * 获取表中列注释
	 * @param tableName 表名
	 * @return list
	 */
	public List<String> getRemarks(String tableName) {
		return UtilDB.getColumnCommentByTableName(tableName);
	}
	
	/**
	 * 获取表中列类型并转换成java类型
	 * @param tableName 表名
	 * @return list
	 */
	public List<String> getColumnType(String tableName) {
		List<String> retTypes = new ArrayList<>();
		List<String> typeList = UtilDB.getColumnTypeByTableName(tableName);
		typeList.forEach(type -> {
			try {
				retTypes.add(UtilString.INSTANCE.columnTypeToJavaType(type));
			} catch (JavaTypeException e) {
				log.error(e.getMessage());
			}
		});
		return retTypes;
	}
	
	/**
	 * 获取mybatis类型
	 * @param tableName 表名
	 * @return list
	 */
	public List<String> getMybatisType(String tableName) {
		List<String> retTypes = new ArrayList<>();
		List<String> typeList = UtilDB.getColumnTypeByTableName(tableName);
		typeList.forEach(type -> {
			try {
				retTypes.add(UtilString.INSTANCE.mySqlTypeToJdbcType(type));
			} catch (MybatisTypeException e) {
				log.error(e.getMessage());
			}
		});
		return retTypes;
	}
	
	/**
	 * 获取title
	 * @param tableName 表名
	 * @return
	 */
	public String getTitle(String tableName) {
		return UtilDB.getTableCommentByTableName(tableName);
	}
	
	/**
	 * 获取dataModel
	 * @param tableName 表名
	 * @return Map
	 */
	public Map<Object, Object> getTableInfo(String tableName){
		Map<Object, Object> map = new HashMap<>();
		map.put("title",                 getTitle(tableName));
		map.put("javaPropertyList",      getJavaPropertyList(tableName));
		map.put("mybatisColumns",        getColumnNameForMybatis(tableName));
		map.put("remarks",               getRemarks(tableName));
		map.put("columnTypes",           getColumnType(tableName));
		map.put("mybatisTypes",          getMybatisType(tableName));
		map.put("maxColumnLength",       getMaxColumnLength(tableName));
		map.put("maxJavaPropertyLength", getMaxJavaPropertyLength(tableName));
		return map;
	}
	
	public void generateFile(String fileName, String templateName, Map<Object, Object> map){
		Configuration config = new Configuration(Configuration.VERSION_2_3_23);
		config.setDefaultEncoding("UTF-8");
		config.setTemplateLoader(new ClassTemplateLoader(UtilFreemarker.class, "/"));
		config.setTemplateExceptionHandler(TemplateExceptionHandler.RETHROW_HANDLER);
		try (BufferedWriter out = new BufferedWriter(new OutputStreamWriter(
				new FileOutputStream(fileName), "UTF-8"));) {
			Template template = config.getTemplate(templateName);
			template.process(map, out);
		}catch(Exception e){
			log.error(e.getMessage());
		}
	}
	
}